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In aquatic ecosystems, endocrine-disrupting compounds (EDCs) pose a growing concern for their potential adverse effects on fish reproduction and development. In lake Pyhäjärvi, located in the urban boreal region of Tampere, Finland, a significant number of sexually immature pikeperch (Sander lucioperca) individuals have been identified in size and age categories that are expected to be sexually mature. To explore if this phenomenon is attributed to estrogenic endocrine disruption, we conducted a comprehensive study comparing fish from lake Pyhäjärvi with those from a nearby reference lake, lake Näsijärvi. Roach (Rutilus rutilus), known for its susceptibility to EDCs, was also included for comparison. We examined various parameters in both pikeperch and roach, including size, condition factor, age, reproductive indicators, biometric indices and gonadal histology. We also assessed liver vitellogenin mRNA levels and genetic sex in roach, and measured estrogen levels in lake waters and wastewater treatment plant effluents. Results revealed that approximately one-third of fish in both species exhibited sexual immaturity in lake Pyhäjärvi, with a female-biased sex ratio. Surprisingly, we found no signs of estrogenic endocrine disruption, indicated by the absence of intersex fish in both species. Furthermore, vitellogenin levels in roach closely resembled those in the reference lake. Estrogens were undetectable in the lake waters, suggesting that factors other than estrogenic EDCs, including other potential endocrine disruptors such as PCBs or heavy metals, may be influencing delayed sexual maturity and skewed sex ratios. Further inquiry is needed to pinpoint these underlying causes. Our study provides essential baseline information on fish sexual development in lake Pyhäjärvi, emphasizing the need for ongoing monitoring and research to understand delayed sexual maturity and biased sex ratios. This is vital given the increasing concern about EDC impacts on aquatic ecosystems and the necessity for effective management strategies to protect these ecosystems' health and integrity., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Eeva-Riikka Vehniainen reports financial support was provided by Kone Foundation (Koneen Säätiö). Eeva-Riikka Vehniainen reports financial support was provided by Pirkkalan kalatalousalue (The Pirkkala fisheries region). Eeva-Riikka Vehniainen reports financial support was provided by City of Tampere and Tampereen Vesi (Tampere water). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Elevated concentrations of sulfate in waterways are observed due to various anthropogenic activities. Elevated levels of sulfate can have harmful effects on aquatic life in freshwaters: sulfate can cause osmotic stress or specific ion toxicity in aquatic organisms, especially in soft waters where Ca 2+ and Mg 2+ concentrations are low. Formerly, chronic toxicity test data in soft water have been scarce. The chronic and acute sulfate toxicity tests conducted with aquatic organisms from 10 families across various trophic levels in this study multiplied the number of tests conducted in soft freshwater conditions and enabled derivation of the species sensitivity distribution (SSD) and sulfate hazardous concentrations for soft freshwaters. The cladoceran Daphnia longispina and freshwater snail Lymnaea stagnalis were the most sensitive to sulfate among the studied species. Harmful effects on the reproduction of D. longispina were observed at 49 mg SO 4 /L while growth of L. stagnalis was inhibited at 217 mg SO 4 /L. Most studied organisms tolerated high sulfate concentrations: the median of chronic effective concentrations (EC10 or LC10) was 1008 mg/L for all the species tested in this study. Based on the species sensitivity distribution of the studied species the hazardous concentration for 5 % of aquatic organism (HC5) in soft waters was 117-194 mg SO 4 /L. Different data set combinations were used to demonstrate the data variability in SSD-based HC5 estimates. The lowest values were produced from combining biotest results from the present study and earlier literature, while the highest values were calculated from the present study only. The derived chronic no-effect concentrations (PNEC) varied between 39 and 65 mg SO 4 /L., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Juha Karjalainen reports financial support was provided by BASF., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Wastewater treatment plants (WWTPs) transmit many chemical contaminants to aquatic environments. Quantitative data on micropollutant emissions via WWTPs are needed for environmental risk assessments and evaluation of mitigation measures. This study compiled published data on substances analysed in effluents from WWTPs in the Baltic Sea region, assessed country related differences in the data sets and estimated micropollutant inputs to the Baltic Sea catchment. Concentration data were found for 1090 substances analysed at 650 WWTPs. Heterogeneity and low number of data points for most substances hindered adequate comparisons of country specific concentrations. Emission estimates were made for the 280 substances analysed in at least five WWTPs in years 2010 to 2019. For selected substances, mass loads were compared to previously published estimations. The study provides data useful for national and Baltic Sea-scale pressure analysis and risk assessments. However, it also highlights the need for broad scope monitoring of micropollutants in wastewater., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Gypsum (CaSO 4 ∙2H 2 O) amendment is a promising way of decreasing the phosphorus loading of arable lands, and thus preventing aquatic eutrophication. However, in freshwaters with low sulfate concentrations, gypsum-released sulfate may pose a threat to the biota. To assess such risks, we performed a series of sulfate toxicity tests in the laboratory and conducted field surveys. These field surveys were associated with a large-scale pilot exercise involving spreading gypsum on agricultural fields covering 18% of the Savijoki River (Finland) catchment area. The gypsum amendment in such fields resulted in approximately a four-fold increase in the mean sulfate concentration for a 2-month period, and a transient, early peak reaching approximately 220 mg/L. The sulfate concentration gradually decreased almost to the pregypsum level after 3 years. Laboratory experiments with Unio crassus mussels and gypsum-spiked river water showed significant effects on foot movement activity, which was more intense with the highest sulfate concentration (1100 mg/L) than with the control. Survival of the glochidia after 24 and 48 h of exposure was not significantly affected by sulfate concentrations up to 1000 mg/L, nor was the length growth of the moss Fontinalis antipyretica affected. The field studies on benthic algal biomass accrual, mussel and fish density, and Salmo trutta embryo survival did not show gypsum amendment effects. Gypsum treatment did not raise the sulfate concentrations even to a level just close to critical for the biota studied. However, because the effects of sulfate are dependent on both the spatial and the temporal contexts, we advocate water quality and biota monitoring with proper temporal and spatial control in rivers within gypsum treatment areas. Environ Toxicol Chem 2022;41:108-121. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., (© 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.)

Sewage sludge is an inevitable byproduct produced in wastewater treatment. Reusing nutrient-rich sludge will diminish the amount of waste ending in soil dumping areas and will promote circular economy. However, during sewage treatment process, several potentially harmful organic chemicals are retained in sludge, but proving the safety of processed sludge will promote its more extensive use in agriculture and landscaping. Environmental risk assessment of sludge requires new methods of characterizing its suitability for various circular economy applications. Bioavailable and bioaccessible fractions are key variables indicating leaching, transport, and bioaccumulation capacity. Also, sludge treatments have a significant effect on chemical status and resulting environmental risks. In this study, the concentrations of polyaromatic hydrocarbons (PAHs), triclosan (TCS), triclocarban (TCC), methyl triclosan (mTCS), and selected active pharmaceutical ingredients (APIs) were determined in different sludge treatments and fractions. Passive samplers were used to characterize the bioavailable and bioaccessible fractions, and the sampler extracts along the sludge and filtrate samples were utilized in the bioassays. The TCS and PAH concentrations did not decrease as the sludge was digested, but the contents diminished after composting. Also, mTCS concentration decreased after composting. The API concentrations were lower in digested sludge than in secondary sludge. Digested sludge was toxic for Aliivibrio fischeri, but after composting, toxicity was not observed. However, for Daphnia magna, passive sampler extracts of all sludge treatments were either acutely (immobility) or chronically (reproduction) toxic. Secondary and digested sludge sampler extracts were cytotoxic, and secondary sludge extract was also genotoxic. The measured chemical concentration levels did not explain the toxicity of the samples based on the reported toxicity thresholds. Bioassays and sampler extracts detecting bioavailable and bioaccessible contaminants in sludge are complementing tools for chemical analyses. Harmonization of these methodswill help establish scientifically sound regulative thresholds for the use of sludge in circular economy applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Spectral cameras are traditionally used in remote sensing of microalgae, but increasingly also in laboratory-scale applications, to study and monitor algae biomass in cultures. Practical and cost-efficient protocols for collecting and analyzing hyperspectral data are currently needed. The purpose of this study was to test a commercial, easy-to-use hyperspectral camera to monitor the growth of different algae strains in liquid samples. Indices calculated from wavebands from transmission imaging were compared against algae abundance and wet biomass obtained from an electronic cell counter, chlorophyll a concentration, and chlorophyll fluorescence. A ratio of selected wavebands containing near-infrared and red turned out to be a powerful index because it was simple to calculate and interpret, yet it yielded strong correlations to abundances strain-specifically (0.85 < r < 0.96, p < 0.001). When all the indices formulated as A/B, A/(A + B) or (A - B)/(A + B), where A and B were wavebands of the spectral camera, were scrutinized, good correlations were found amongst them for biomass of each strain (0.66 < r < 0.98, p < 0.001). Comparison of near-infrared/red index to chlorophyll a concentration demonstrated that small-celled strains had higher chlorophyll absorbance compared to strains with larger cells. The comparison of spectral imaging to chlorophyll fluorescence was done for one strain of green algae and yielded strong correlations (near-infrared/red, r = 0.97, p < 0.001). Consequently, we described a simple imaging setup and information extraction based on vegetation indices that could be used to monitor algae cultures.

There are several methods for studying metal-contaminated freshwater sediments, but more information is needed on which methods to include in ecological risk assessment. In this study, we compliment the traditional Sediment Quality Triad (SQT) approach - including information on chemistry, toxicity and ecological status - with studies on metal bioavailability and metal body residues in local organisms. We studied four mining-affected boreal lakes in Finland by conducting chemical analyses of sediment and water, toxicity tests (L. variegatus, V. fischeri, C. riparius, L. stagnalis), and analysis of benthic organism community structure. In addition, we studied the relationships between metal loading, toxicity, metal bioavailability, and metal body residues in the field-collected biota. Chemistry and benthic organism community structures show adverse effects in those lakes, where the metal concentrations are the highest. However, toxicity was connected to low sediment pH during the experiment, rather than to high metal concentrations. Toxicity was observed in 4 out of 6 toxicity tests including growth test with L. variegatus, bulk sediment test with V. fischeri, and the L. stagnalis toxicity test. The C. riparius test did not show toxicity. Metal body residues in biota were not high enough to induce adverse effects (0.1-4.1 mg Cu/kg fw, 0.01-0.3 mg Ni/kg fw, 2.9-26.7 mg Zn/kg fw and 0.01-0.7 mg As/kg fw). Chemical analyses, metal bioavailability assessment and benthic community structures survey revealed adverse effects in the sediments, where metal concentrations are highest (Lake SJ and Lake KS). Standard toxicity tests were not suitable for studying acid, sulfide-rich sediments and, therefore, benthic structure study and chemical analyses are believed to give more reliable results of the ecological status of these sediments., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Metal contamination in freshwater ecosystems is a global issue and metal discharges to aquatic environments are monitored in order to protect aquatic life and human health. Bioavailability is an important factor determining metal toxicity. In aquatic systems, metal bioavailability depends on local water and sediment characteristics, and therefore, the risks are site-specific. Environmental quality standards (EQS) are used to manage the risks of metals in aquatic environments. In the simplest form of EQSs, total concentrations of metals in water or sediment are compared against pre-set acceptable threshold levels. Now, however, the environmental administration bodies have stated the need to incorporate metal bioavailability assessment tools into environmental regulation. Scientific advances have been made in metal bioavailability assessment, including passive samplers and computational models, such as biotic ligand models (BLM). However, the cutting-edge methods tend to be too elaborate or laborious for standard environmental monitoring. We review the commonly used metal bioavailability assessment methods and introduce the latest scientific advances that might be applied to environmental management in the future. We present the current practices in environmental management in North America, Europe and China, highlighting the good practices and the needs for improvement. Environmental management has met these new challenges with varying degrees of success: the USA has implemented site-specific environmental risk assessment for water and sediment phases, and they have already implemented metal mixture toxicity evaluation. The European Union is promoting the use of bioavailability and BLMs in ecological risk assessment (ERA), but metal mixture toxicity and sediment phase are still mostly neglected. China has regulation only for total concentrations of metals in surface water. We conclude that there is a need for (1) Advanced and up-to-date guidelines and legislation, (2) New and simple scientific methods for assessing metal bioavailability and (3) Improvement of knowledge and skills of administrators., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Passive samplers are promising surrogates for organisms, mimicking bioaccumulation. However, several biological characteristics disturb the passive partitioning process in organisms by accelerating or restraining bioaccumulation, resulting in species-specific body residues of hydrophobic organic contaminants (HOCs). In addition to site-specific characteristics and HOC concentrations, age, sex, diet, biotransformation capability and habitat-specific characteristics may affect body residues. Two passive sampler types, polyethylene (PE) and polydimethylsiloxane (PDMS) were deployed in a PCB-contaminated freshwater lake water and sediment, respectively, to assess their bioaccumulation prediction capacity. In order to understand the importance of biological characteristics in the bioaccumulation process, we explored bioaccumulation in biota from plants and plankton to mussels and fish. The PCB concentrations in the PE sheet reflected the bioavailable concentration of PCBs slightly better than those in the PDMS samplers. Passive samplers were good predictors of PCB concentrations in fish, whereas concentrations in algae and invertebrates were overestimated. When comparing the measured concentrations in biota to the estimated concentrations using the PE samplers, the average regression slope was 0.87 for all biota and 1.22 for fish, and average modeling efficiency (EF) was 3.02 for all biota and 0.6 for fish. The best model performance was achieved for fish in trophic levels 3-4. Bioaccumulation was species-specific and dependent on the trophic level and diet. Closer examination revealed that metabolic capability changes during the life span, and source of nutrition determined the biomagnification of HOCs, which differed between the fish species. Thus, species composition and available prey selection compose a unique bioaccumulation scenario and the resulting body residues. Due to the existing variation in body residues derived from passive samplers, extrapolating the results from one to another ecosystem must be done with caution. Passive samplers, however, offer a very powerful tool for risk assessment on the ecosystem level., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The life cycle parameters of the benthic invertebrate Chironomus riparius make it a relevant organism for use in multi-generation chronic ecotoxicology tests. Since studies on chronic exposures with fullerene carbon nanoparticles have revealed adverse effects at lower concentration ranges, it is crucial to gain understanding of the consequences in following generations. The aims of this study were to investigate whether sediment-associated fullereneC 60 impacts on C. riparius emergence and breeding, thus affecting the growth of the second generation. Larvae were exposed to fullerene-spiked sediment at concentrations of 0.5, 10 and 40 mg/kg sediment dw. Total emergence and breeding success were monitored after the first generation and the newly hatched larvae from the first generation exposure were transferred either to continuous exposure or to pristine sediment without fullerene. Findings indicate that the presence of fullerenes has major impacts on the first generation, mainly shown as delayed emergence time of females. Increased larval growth was observed in the second generation, and we conclude that the C. riparius response to fullerene exposure indicated significant signs of recovery in second-generation larval growth. The result shows the effects to be important for population dynamics, revealing delayed female emergence time, which leads to situation where adults' breeding is impaired., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A key component of understanding the potential environmental risks of fullerenes (C 60 ) is their potential effects on benthic invertebrates. Using the sediment dwelling invertebrate Chironomus riparius we explored the effects of acute (12h and 24h) and chronic (10d, 15d, and 28d) exposures of sediment associated fullerenes. The aims of this study were to assess the impact of exposure to C 60 in the sediment top layer ((0.025, 0.18 and 0.48) C 60 mg/cm 2 ) on larval growth, oxidative stress and emergence rates and to quantify larval body burdens in similarly exposed organisms. Oxidative stress localization was observed in the tissues next to the microvilli and exoskeleton through a method for identifying oxidative stress reactions generated by reactive oxygen species. Rapid intake of fullerenes was shown in acute experiments, whereas body residues decreased after chronic exposure. Transmission electron microscopy analysis revealed oxidative damage and structural changes in cells located between the lipid droplets and next to the microvilli layer in fullerene exposed samples. Fullerene associated sediments also caused changes in the emergence rate of males and females, suggesting that the cellular interactions described above or other effects from the fullerenes may influence reproduction rates., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Mining of sulfide-rich pyritic ores produces acid mine drainage waters and has induced major ecological problems in aquatic ecosystems worldwide. Biomining utilizes microbes to extract metals from the ore, and it has been suggested as a new sustainable way to produce metals. However, little is known of the potential ecotoxicological effects of biomining. In the present study, biomining impacts were assessed using survival and behavioral responses of aquatic macroinvertebrates at in situ exposures in streams. The authors used an impedance conversion technique to measure quantitatively in situ behavioral responses of larvae of the regionally common mayfly, Heptagenia dalecarlica, to discharges from the Talvivaara mine (Sotkamo, Northern Finland), which uses a biomining technique. Behavioral responses measured in 3 mine-impacted streams were compared with those measured in 3 reference streams. In addition, 3-d survival of the mayfly larvae and the oligochaete Lumbriculus variegatus was measured in the study sites. Biomining impacts on stream water quality included increased concentrations of sulfur, sulfate, and metals, especially manganese, cadmium, zinc, sodium, and calcium. Survival of the invertebrates in the short term was not affected by the mine effluents. In contrast, apparent behavioral changes in mayfly larvae were detected, but these responses were not consistent among sites, which may reflect differing natural water chemistry of the study sites. Environ Toxicol Chem 2017;36:147-155. © 2016 SETAC., (© 2016 SETAC.)

The mining industry is a common source of environmental metal emissions, which cause long-lasting effects in aquatic ecosystems. Metal risk assessment is challenging due to variations in metal distribution, speciation, and bioavailability. Therefore, seasonal effects must be better understood, especially in boreal regions in which seasonal changes are large. We sampled 4 Finnish lakes and sediments affected by mining for metals and geochemical characteristics in autumn and late winter, to evaluate seasonal changes in metal behavior, the importance of seasonality in risk assessment, and the sensitivity and suitability of different risk assessment methods. We compared metal concentrations in sediment, overlying water, and porewater against environmental quality guidelines (EQGs). We also evaluated the toxicity of metal mixtures using simultaneously extracted metals and an acid volatile sulfides (SEM-AVS) approach together with water quality criteria (US Environmental Protection Agency equilibrium partitioning benchmarks). Finally, site-specific risks for 3 metals (Cu, Ni, Zn) were assessed using 2 biotic ligand models (BLMs). The metal concentrations in the impacted lakes were elevated. During winter stratification, the hypolimnetic O2 saturation levels were low (<6%) and the pH was acidic (3.5-6.5); however, abundant O2 (>89%) and neutral pH (6.1-7.5) were found after the autumnal water overturn. Guidelines were the most conservative benchmark for showing an increased risk of toxicity in the all of the lakes. The situation remained stable between seasons. On the other hand, SEM-AVS, equilibrium partition sediment benchmarks (ESBs), and BLMs provided a clearer distinction between lakes and revealed a seasonal variation in risk among some of the lakes, which evidenced a higher risk during late winter. If a sediment risk assessment is based on the situation in the autumn, the overall risk may be underestimated. It is advisable to carry out sampling and risk assessment during periods in which metals are assumed to be the most environmentally harmful. Integr Environ Assess Manag 2016;12:759-771. © 2015 SETAC., (© 2015 SETAC.)

We evaluated the utility of chironomid and lamprey larval responses in ecotoxicity assessment of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F)-, polychlorinated biphenyls (PCB)- and mercury (Hg)-contaminated river sediments. Sediment samples were collected from the River Kymijoki with a known industrial pollution gradient. Sediment for the controls and lamprey larvae were obtained from an uncontaminated river nearby. Contamination levels were verified with sediment and tissue PCDD/F, PCB and Hg analyses. Behaviour of sediment-exposed chironomid and lamprey larvae were measured with Multispecies Freshwater Biomonitor© utilizing quadrupole impedance conversion technique. In addition, mortality, growth and head capsule deformity incidence of chironomids were used as ecotoxicity indicators. WHOPCDD/F+PCB-TEQ in the R. Kymijoki sediments ranged from the highest upstream 22.36 ng g(-1) dw to the lowest 1.50 ng g(-1) near the river mouth. The sum of PCDD/Fs and PCBs correlated strongly with Hg sediment concentrations, which ranged from <0.01 to 1.15 μg g(-1). Lamprey tissue concentrations of PCDD/Fs were two orders and PCBs one order of magnitude higher in the R. Kymijoki compared to the reference. Chironomid growth decreased in contaminated sediments and was negatively related to sediment ∑PCDD/Fs, WHOPCDD/F+PCB-TEQ and Hg. There were no significant differences in larval mortality or chironomid mentum deformity incidence between the sediment exposures. The distinct behavioural patterns of both species indicate overall applicability of behavioural MFB measurements of these species in sediment toxicity bioassays. Chironomids spent less and lampreys more time in locomotion in the most contaminated sediment compared to the reference, albeit statistically significant differences were not detected. Lamprey larvae had also a greater activity range in some of the contaminated sediments than in the reference. High pollutant levels in lamprey indicate risks for biomagnification in the food webs, with potential health risks to humans consuming fish.

There were two main objectives in this study. The first was to compare the accuracy of different prediction methods for the chemical concentrations of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the organism, based on the measured chemical concentrations existing in sediment dry matter or pore water. The predicted tissue concentrations were compared to the measured ones after 28-day laboratory test using oligochaeta worms (Lumbriculus variegatus). The second objective was to compare the bioaccumulation of PAHs and PCBs in the laboratory test with the in situ bioaccumulation of these compounds. Using the traditional organic carbon-water partitioning model, tissue concentrations were greatly overestimated, based on the concentrations in the sediment dry matter. Use of an additional correction factor for black carbon with a two-carbon model, significantly improved the bioaccumulation predictions, thus confirming that black carbon was important in binding the chemicals and reducing their accumulation. The predicted PAH tissue concentrations were, however, high compared to the observed values. The chemical concentrations were most accurately predicted from their freely dissolved pore water concentrations, determined using equilibrium passive sampling. The patterns of PCB and PAH accumulation in sediments for laboratory-exposed L. variegatus were similar to those in field-collected Lumbriculidae worms. Field-collected benthic invertebrates and L. variegatus accumulated less PAHs than PCBs with similar lipophilicity. The biota to sediment accumulation factors of PAHs tended to decrease with increasing sediment organic carbon normalized concentrations. The presented data yields bioconcentration factors (BCF) describing the chemical water-lipid partition, which were found to be higher than the octanol-water partition coefficients, but on a similar level with BCFs drawn from relevant literature. In conclusion, using the two-carbon model method, or the measured freely dissolved pore water concentrations method is recommended for predicting the bioaccumulation of PAHs and PCBs., (Copyright © 2016. Published by Elsevier B.V.)

The nonbiting midge Chironomus riparius was used to study the remediation potential and secondary effects of activated carbon (AC, ø 63-200 μm) in PCB contaminated sediments. AC amendments efficiently reduced PCB bioavailability determined by Chironomus riparius bioaccumulation tests and passive samplers. PCBs were shown to transfer from larvae to adults. Lower PCB concentrations were observed in adult midges emerging from AC amended compared to unamended sediments. Increased reproduction, survival, larval growth and gut wall microvilli length were observed with low AC dose (0.5% sediment dw) compared to unamended sediment, indicating an improved success of larvae in the sediment with low organic carbon content. On the other hand, higher AC doses (2.5% sediment dw) caused adverse effects on emergence and larval development. In addition, morphological changes in the gut wall microvilli layer were observed. This study showed that the secondary effects of AC amendments are dependent on the dose and the sediment characteristics. Metamorphic species, such as C. riparius, may act as a vector for organic pollutants from aquatic to terrestrial ecosystems and according to this study the AC amendments may reduce this transport.

The sorption efficiency and possible secondary effects of activated carbon (AC) (ø 63-200 μm) was studied with Lumbriculus variegatus in three PCB contaminated sediments applying long AC-sediment contact time (3 years). AC amendment efficiently reduced PCB bioavailability as determined with both, L. variegatus bioaccumulation test and passive samplers. However, dose related secondary effects of AC on egestion rate and biomass were observed (applied doses 0.25% and 2.5% sediment dry weight). The sorption capacity and secondary effects remained similar when the experiments were repeated after three years of AC-sediment contact time. Further, transmission electron microscopy (TEM) samples revealed morphological changes in the L. variegatus gut wall microvilli layer. Sediment properties affected both sorption efficiency and secondary effects, but 2.5% AC addition had significant effects regardless of the sediment. In, conclusion, AC is an efficient and stable sorbent to decrease the bioavailability of PCBs. However, sediment dwelling organisms, such as Oligochaete worms in this study, may be sensitive to the carbon amendments. The secondary effects and possible morphological changes in benthic organisms should not be overlooked as in many cases they form the basis of the aquatic food webs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The possible toxicity of nanoparticles (NPs) to aquatic organisms needs to be investigated for chronic effects at low concentrations. Chronic effects of carbon NPs, fullerenesC60, on the midges of Chironomus riparius at different life stages on larvae and adult midges were investigated. Sediment associated fullerenesC60 were studied by 10-day growth and 42-day emergence tests with artificial sediment at nominal concentration ranges 0.0004-80 mg/kg dry weight. The body length decreased in the lower tested concentrations (0.0025-20 mg/kg), but the effect vanished with higher concentrations. Delayed emergence rate observed at 0.5 mg/kg. The observed effects correlated with analyzed sediment particle sizes indicating that small agglomerates of fullerene have more significant effects on C. riparius than larger agglomerates observed with higher C60 doses. The results reveal that fullerene may pose risks to benthic organisms, emerging as changes in the ecotoxic parameters studied here which inflects by the survival of the population., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred from the sediment to the water column. Measured lipid-normalized PCB concentrations in biota were generally below equilibrium lipid concentrations relative to the sediment (CLip ⇌Sed ) or water (CLip ⇌W ), indicating that PCB levels in the organisms were below the maximum partitioning levels. The present study shows the application versatility of equilibrium sampling devices in the field and facilitates a thermodynamic understanding of exposure and fate of PCBs in a contaminated lake and its discharge course., (© 2015 SETAC.)

Knowledge on the internal distribution of halogenated organic chemicals (HOCs) would improve our understanding of dose-effect relationships and subsequently improve risk assessment of contaminated sites. Herein, we determine the concentrations of HOCs based on equilibrium partitioning in storage lipids, membrane lipids, and proteins in field-contaminated fish using equilibrium sampling devices. The study shows the importance of protein as a sorptive phase in lean fish. Our results provide a basis for using species-specific equilibrium partitioning coefficients between sorptive tissues and fish internal water as a substitute for K(ow) in, for example, upgrading models that simulate food-chain accumulation of the chemical.

Depending on environmental conditions, fullerenes (nC60) have the potential to settle to the bottom sediments. In this study the distribution of nC60 was investigated in the labile zone between sediment and water. Three freshwater-sediment systems representing oligohumic, mesohumic, and polyhumic lakes with varying sediment composition and structure were used to investigate the target of fullerenes. The largest portion of water suspended fullerenes was found in the sediment, but a part re-suspended relatively quickly to water-stabile particles associated with natural particles. Rapid initial re-suspending was followed by a slower one offering a continuous pathway to the water phase. Re-suspending was highest from the sediment with a high amount of amorphous matter, small particles and a highly aliphatic character, amounting to 9±1% of the initial amount of fullerenes, whereas it was 4±1% in aromatic sediments with larger particles and less amorphous matter. These results indicate that bottom sediments can retain fullerenes but a portion may remain mobile depending on sediment character. Re-suspended fullerenes may again be available to aquatic species-this knowledge should thus be taken into account in the environmental risk assessment of fullerenes., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Understanding the fate of persistent organic chemicals in the environment is fundamental information for the successful protection of ecosystems and humans. A common dilemma in risk assessment is that monitoring data reveals contaminant concentrations in wildlife, while the source concentrations, route of uptake and acceptable source concentrations remain unsolved. To overcome this problem, different models have been developed in order to obtain more precise risk estimates for the food webs. However, there is still an urgent need for studies combining modelled and measured data in order to verify the functionality of the models. Studies utilising field-collected data covering entire food webs are particularly scarce. This study aims to contribute to tackling this problem by determining the validity of two bioaccumulation models, BIOv1.22 and AQUAWEBv1.2, for application to a multispecies aquatic food web. A small boreal lake, Lake Kernaalanjärvi, in Finland was investigated for its food web structure and concentrations of PCBs in all trophic levels. Trophic magnification factors (TMFs) were used to measure the bioaccumulation potential of PCBs, and the site-specific environmental parameters were used to compare predicted and observed concentrations. Site-specific concentrations in sediment pore water did not affect the modelling endpoints, but accurate site-specific measurements of freely dissolved concentrations in water turned out to be crucial for obtaining realistic model-predicted concentrations in biota. Numerous parameters and snapshot values affected the model performances, bringing uncertainty into the process and results, but overall, the models worked well for a small boreal lake ecosystem. We suggest that these models can be optimised for different ecosystems and can be useful tools for estimating the bioaccumulation and environmental fate of PCBs., (© 2013 Elsevier B.V. All rights reserved.)

The regulation of endogenous metabolites is still not fully understood in aquatic invertebrates exposed concurrently to toxicants and hypoxia. Despite the prevalence of hypoxia in the aquatic environment, toxicity estimations seldom account for multiple stressors thereby differing from natural conditions. In this study, we examined the influence of hypoxia (<30% O2) on contaminant uptake and the composition of intracellular metabolites in Lumbriculus variegatus exposed to benzo(a)pyrene (B(a)P, 3μgL(-1)), chlorpyrifos (CPF, 100μgL(-1)) or pentachlorophenol (PCP, 100μgL(-1)). Tissue extracts of worms were analyzed for 123 metabolites by gas chromatography-mass spectrometry and metabolite levels were then related to treatments and exposure time. Hypoxia markedly increased the accumulation of B(a)P and CPF, which underlines the significance of oxygen in chemical uptake. The oxygen effect on PCP uptake was less pronounced. Succinate and glycerol-3-phosphate increased significantly (p<0.0001) following hypoxic treatment, whereas sugars, cysteine, and cholesterol were effectively repressed. The buildup of succinate coupled with the corresponding decline in intracellular 2-oxo- and 2-hydroxy glutaric acid is indicative of an active hypoxia inducible factor mechanism. Glutamate, and TCA cycle intermediates (fumarate, and malate) were disturbed and evident in their marked suppression in worms exposed concurrently to hypoxia and PCP. Clearly, hypoxia was the dominant stressor for individuals exposed to B(a)P or CPF, but to a lesser extent upon PCP treatment. And since oxygen deprivation promotes the accumulation of different toxicants, there may be consequences on species composition of metabolites in natural conditions., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Increasing usage of fullerenes (C60 ) increases their opportunities to be released into the environment. For risk assessment, it is important to understand the environmental fate and ecotoxicological effects of C60 . In the present study, fullerene settling was measured during a 1-yr period with 4 different lake waters and an artificial freshwater, and Daphnia magna immobilization and fullerene accumulation was also measured in each of the lake waters. Depending on the characteristics of the lake waters, fullerenes either exhibited extended water stability or settled rapidly; in all waters, there was a fraction that remained stable after 1 yr. Water stability was affected by the quality and molecular size distribution of dissolved natural organic matter (DNOM). Increasing DNOM molecular sizes with high aromatic content enhanced water stability. Immobilization of D. magna was generally quite low (under 20%) and highly variable after 24 h and 48 h at initial fullerene concentrations up to 10 mg/L. Substantial settling occurred during the time period for acute toxicity assays (i.e., 48 h), which should be anticipated when conducting toxicity assays. There were no significant differences in the quantity of accumulated fullerenes among the different lake waters at fullerene concentrations of 0.5 mg/L, but there were differences at 2 mg/L., (Copyright © 2013 SETAC.)

Assessment of the underlying molecular events leading to xenobiotic toxicity is challenging especially when techniques are applied in isolation. We examined transcriptional and metabolic changes in Lumbriculus variegatus exposed to benzo(a)pyrene (B(a)P), cadmium (Cd) or pentachlorophenol (PCP) by DNA microarrays (7422 ESTs) and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the DNA damage response of worms exposed to B(a)P was assessed by a capillary electrophoresis laser induced fluorescence (CE-LIF) immunoassay. We found elevated expression of oxidative stress responsive genes, which correlated positively with the changes in antioxidant vitamin precursors including alpha-tocopherol and cholecalciferol. Other genes with strong differential expressions were mostly involved in actin related processes and proteolysis, despite an apparent delayed Cd response. Phosphates, sugars and fatty acids were effectively reduced and suggested that chemical treatments may have interfered with energy metabolism. The increased amount of B(a)P diol-epoxide (BPDE)-DNA adducts in exposed worms appeared to correlate with the variability in uridine, inosine and xanthine, which are key components of nucleoside metabolism. This suggests that DNA damage was imminent or peaked within 6h. The results conformed to transcriptional changes in B(a)P exposed worms and compliment other approaches to elucidate underlying molecular changes., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The trophic transfer of pyrene metabolites was studied using Gammarus setosus as a predator and the invertebrates Lumbriculus variegatus and Chironomus riparius as prey. The results obtained by liquid scintillation counting confirmed that the pyrene metabolites produced by the aquatic invertebrates L. variegatus and C. riparius were transferred to G. setosus through the diet. More detailed analyses by liquid chromatography discovered that two of the metabolites produced by C. riparius appeared in the chromatograms of G. setosus tissue extracts, proving their trophic transfer. These metabolites were not present in chromatograms of G. setosus exclusively exposed to pyrene. The present study supports the trophic transfer of PAH metabolites between benthic macroinvertebrates and common species of an arctic amphipod. As some PAH metabolites are more toxic than the parent compounds, the present study raises concerns about the consequences of their trophic transfer and the fate and effects of PAHs in natural environments., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronger on HS than on AS sediment. Lipid content in AS was reduced already at the lowest AC doses applied (AC(p) and AC(m) 0.05%, AC(g) 0.25%). In addition, hormesis-like response was observed in growth (AS) and reproduction (AS, HS) indicating that AC may disturb organisms even at very low doses. Potential ecological effects need to be further evaluated in an amendment- and site-specific manner.

An environmentally realistic method to test fullerene (C(60) ) toxicity to the benthic organism Chironomus riparius was created by allowing suspended fullerenes to settle down, making a layer on top of the sediment. To test the hypothesis that higher food concentrations will reduce toxic responses, two food concentrations were tested (0.5 and 0.8% Urtica sp.) in sediment containing fullerene masses of 0.36 to 0.55 mg/cm(2) using a 10-d chronic test. In the 0.5% food level treatments, there were significant differences in all growth-related endpoints compared with controls. Fewer effects were observed for the higher food treatment. Fullerene agglomerates were observed by electron microscopy in the gut, but no absorption into the gut epithelial cells was detected. In the organisms exposed to fullerenes, microvilli were damaged and were significantly shorter. The potential toxicity of fullerene to C. riparius appears to be caused by morphological changes, inhibiting larval growth., (Copyright © 2012 SETAC.)

The trophic transfer of pyrene metabolites was evaluated by a 2-month exposure of the freshwater annelid Lumbriculus variegatus (Oligochaeta) to pyrene, followed by feeding to juvenile brown trout (Salmo trutta). The results obtained by scintillation counting (SC) proved that the pyrene metabolites produced by L. variegatus were transferred to juvenile S. trutta through diet. More detailed analyses by LC-FLD (liquid chromatography with fluorescence detection) showed that an unknown pyrene metabolite originating from L. variegatus was present in fish liver. This metabolite, although yet not properly identified, may be the glucose conjugate of 1-hydroxy-pyrene. This metabolite was not present in chromatograms of fish that were fed pyrene-spiked food pellets. In addition, the strongly bound tissue residue of L. variegatus, which was nonextractable neither by organic solvents nor by the proteolytic enzyme Proteinase K, was most likely not available for the fish through diet. Altogether, the present study shows that the metabolites of pyrene produced at low levels of the food chain may be potentially available for upper levels through diet, raising a concern about their potential toxicity to predators and supporting their inclusion in the risk assessment of PAHs., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This study evaluated the toxicological sensitivity of non-feeding larval stages of a key Antarctic species (Antarctic krill, Euphausia superba) to p,p'-dichlorodiphenyl dichloroethylene (p,p'-DDE) exposure. The aqueous uptake clearance rate of 84 mL g(-1) preserved weight (p.w.) h(-1) determined for p,p'-DDE in Antarctic krill larvae is comparable to previous findings for small cold water crustaceans and five times slower than the rates reported for an amphipod inhabiting warmer waters. Natural variations in larval physiology appear to influence contaminant uptake and larval krill behavioural responses, strongly highlighting the importance of time of measurement for ecotoxicological testing. Sublethal narcosis (immobility) was observed in larval Antarctic krill from p,p'-DDE body residues of 0.2 mmol/kg p.w., which is in agreement with findings for adult krill and temperate aquatic species. The finding of comparable body residue-based toxicity of p,p'-DDE between polar and temperate species supports the tissue residue approach for environmental risk assessment of polar ecosystems., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Effects of fullerene-spiked sediment on a benthic organism, Lumbriculus variegatus (Oligochaeta), were investigated. Survival, growth, reproduction, and feeding rates were measured to assess possible adverse effects of fullerene agglomerates produced by water stirring and then spiked to a natural sediment. L. variegatus were exposed to 10 and 50 mg fullerenes/kg sediment dry mass for 28 d. These concentrations did not impact worm survival or reproduction compared to the control. Feeding activities were slightly decreased for both concentrations indicating fullerenes' disruptive effect on feeding. Depuration efficiency decreased in the high concentration only. Electron and light microscopy and extraction of the worm fecal pellets revealed fullerene agglomerates in the gut tract but not absorption into gut epithelial cells. Micrographs also indicated that 16% of the epidermal cuticle fibers of the worms were not present in the 50 mg/kg exposures, which may make worms susceptible to other contaminants., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Persistent organic pollutants (POPs) are persistent, toxic and bioaccumulative anthropogenic organic chemicals, capable of undergoing long range environmental transport to remote areas including the Antarctic. p,p'-dichlorodiphenyl dichloroethylene (p,p'-DDE) has been identified as a dominant POP accumulating in Antarctic krill (Euphausia superba), which is a key Southern Ocean species. This study examined the developmental toxicity of p,p'-DDE via aqueous exposure to Antarctic krill larvae. p,p'-DDE exposure was found to stimulate developmental timing in the first three larval stages of Antarctic krill, while extended monitoring of larvae after a five day exposure period had ended, revealed delayed inhibitory responses during development to the fourth larval stage. Stimulatory responses were observed from the lowest p,p'-DDE body residue tested of 10.1±3.0 μmol/kg (3.2±0.95 mg/kg) preserved wet weight, which is comparable to findings for temperate species and an order of magnitude lower than the exposure level found to cause sublethal behavioural effects in Antarctic krill. The delayed responses included increased mortality, which had doubled in the highest p,p'-DDE treatment (95±8.9% mortality at 20 μg/L p,p'-DDE) compared to the solvent control (44±11% mortality) 2 weeks after end of exposure. Development of surviving metanauplius larvae to calyptopis 1 larvae was delayed by 2 days in p,p'-DDE exposed larvae compared with untreated larvae. Finally, the developmental success of surviving p,p'-DDE exposed larvae was reduced by 50 to 75% compared to the solvent control (100% developmental success). The lowest observed effect concentration for all delayed effects was 1 μg/L, the lowest exposure concentration tested. These findings demonstrate the importance of delayed and indirect effects of toxicant exposure. Further, the findings of this study are important for environmental risk assessment of POPs in the Southern Ocean ecosystem and strongly highlight the significance of developmental endpoints for ecotoxicological testing., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Fate of organic contaminants under UV irradiation as environmental variable was studied. Aqueous solutions of pentachlorophenol and phenanthrene were subjected to simulated solar radiation and monitored during ≤ 93 h. Immobilization tests were conducted using Daphnia magna neonates in pre-irradiated water for the assessment of photoproduct-mediated toxicity. We observed a time-dependent decrease in exposure concentrations following irradiation, which correlated positively with reduced immobilization of the animals. A complete disappearance of the lowest and highest concentrations of pentachlorophenol was noted after 25 h and 75 h, respectively. Survivorship of the animals increased until 100% and correlated positively with irradiation time. However, phenanthrene was rather persistent under irradiation, with less than 25% decline in exposure concentrations after 93 h. Neonates were not immobilized at maximum aqueous solubility of phenanthrene. Rate constants (k) for the photodegradation of pentachlorophenol at 0.41, 0.59, 1.1, and 2.1 mg l(-1) were in the range of 7.2 × 10(-2) and 4.9 × 10(-2)h(-1), showing a slight decrease with increasing initial pentachlorophenol concentration. Nonetheless, pentachlorophenol degradation in the studied concentration range could still be described by the pseudo-first-order kinetics. K values for phenanthrene at 0.12 and 0.22 mg l(-1) were 2.9 × 10(-3)h(-1) and 4.2 × 10(-3)h(-1), respectively., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Using the freshwater annelid Lumbriculus variegatus (Oligochaeta), the presence of cytochrome P450 (CYP) isozymes was investigated by analyzing metabolites of the polycyclic aromatic hydrocarbon (PAH) pyrene in treatments with and without the CYP inhibitor piperonyl butoxide (PBO). The results show a low biotransformation capability of L. variegatus (7% of total pyrene body burden as metabolites at 168 h). Addition of PBO resulted in a significant reduction of metabolites, suggesting the presence of a CYP in L. variegatus. Besides 1-hydroxypyrene, three peaks representing unknown metabolites were detected in LC-FLD (liquid chromatography with fluorescence detection) chromatograms of L. variegatus. Deconjugations showed that sulfonation and glucosidation are involved in the formation of these unknowns. Further studies with the time of flight mass analyzer provided the identification of the glucose-sulfate conjugate of 1-hydroxypyrene. The same metabolites were detected in the solvent-nonextractable fraction by incubation of the tissue residues with proteinase K, suggesting that part of these metabolites are bound to proteins. Overall, the slow biotransformation of pyrene by L. variegatus (involving CYP) supports the use of this species in standard bioaccumulation tests; however, the tissue-bound metabolite fraction described in the current study deserves further investigation for its toxicity and availability to upper trophic levels through diet., (Copyright © 2011 SETAC.)

The equilibrium sampling in silicone is increasingly applied to measure freely dissolved concentrations and chemical activities within bioaccumulation research of hydrophobic organic chemicals. Two equilibrium methods were applied to PCB-contaminated soil and sediment, and directly calibrated with respect to equilibrium partitioning concentrations in lipids (C(lipid,partitioning)): (i) Solid phase microextraction in the headspace above the sample (HS-SPME) required optimization for its application to PCBs, and it was calibrated above external partitioning standards in olive oil. (ii) Equilibrium sampling with internally coated glass jars with varying thicknesses of silicone (PDMS) resulted in proportionality between coating and analyte mass, which confirmed several validity criteria. C(lipid,partitioning) was here determined as product of PDMS concentration and PDMS to lipid partition ratio. The results of the two methods were in good agreement and thus validated each other. Finally, the coated glass jar method was applied to field sediment containing invertebrates, which lead to C(lipid,partitioning) that were about two times higher than measured lipid-normalized concentrations in the organisms. Temperature differences and animal lipid structure were discussed as possible reasons for this discrepancy. Both methods combine high analytical performance, reduced equilibration times and new calibration possibilities, which makes them suited for bioaccumulation research and environmental monitoring.

This study presents the bioavailability of four spiked compounds to Lumbriculus variegatus, in sediment samples from three river basins in Europe: the Elbe, the Llobregat, and the Scheldt. Twenty sediment samples differing in physical and chemical properties were spiked with chlorpyrifos, pyrene, tetrachloribiphenyl, and tetrabromo diphenyl ether. The main focus of this study was to compare the suitability of two chemical approaches-the rapidly desorbing fraction method based on the Tenax extraction and the freely dissolved chemical concentration method based on polyoxymethylene passive sampling-for predicting the bioavailability of sediment-associated hydrophobic compounds. It appears that accessible concentration estimated by Tenax extraction does not result in equal freely dissolved concentrations based on polyoxymethylene passive sampling results. The present data show that freely dissolved concentration in pore water mainly determines the uptake by organisms and, therefore, the polyoxymethylene passive sampling method was a successful approach to estimating the bioavailability of sediment-associated lipophilic contaminants (log octanol-water partitioning coefficient >6). The sediment characteristics or river basin differences had only a minor effect on the bioavailability estimates. Overall, passive samplers have not been tested to a sufficient extent in various chemicals or exposure matrixes. For this reason, bioassays are still needed in the risk assessment process in order to verify results based on passive sampling methods.

The effects of temperature and sediment-chemical contact time on desorption and bioaccumulation of sediment-spiked (14)C-labelled 2,2',4,4'-tetrabromo diphenyl ether (BDE-47) and benzo(a)pyrene (BaP) were examined. Experiments were performed after 2 or 6 weeks and 23 or 24 months sediment-chemical contact time at 10 and 20 degrees C. Desorption was measured in a sediment-water suspension using Tenax extraction, and bioaccumulation was measured by exposing Lumbriculus variegatus (Oligochaeta) to BDE-47 and BaP-spiked sediments in a 10d kinetic study. Biota-sediment accumulation factors (BSAFs) ranged between 2.9 and 4.3 for BDE-47 and between 0.5 and 0.9 for BaP. Thus, temperature and aging had a minor effect on bioavailability estimates. On the other hand, the difference between the chemicals was clear and could not be interpreted solely by reference to the size of the desorbing fractions, although the rapidly desorbing fraction-revised estimate clearly reduced the difference. The remaining discrepancy may be related to methodological (Tenax extraction vs. worm exposure) and/or biological (digestive extraction) causes. However, the data support the role of diffusional forces in the bioavailability of sediment-associated organic contaminants. Therefore, desorption-revised bioavailability estimates would lead to more precise bioavailability estimates than the traditional sediment organic carbon-organisms' lipids-based equilibrium partitioning approach.

The relationship between desorption kinetics and bioavailability of sediment-associated 2,2',4,4,5' pentabromo diphenyl ether [(14)C] (BDE-99) and 2,3,7,8 tetrachlorodibenzo(p)dioxin [(3)H] (TCDD) was examined in the contaminated sediments. The desorption kinetics were measured in a sediment-water suspension using Tenax extraction, and bioaccumulation was examined by exposing Lumbriculus variegatus (Oligochaeta) to BDE-99 and TCDD spiked sediment in a 14-day kinetic study. Both chemicals had a high affinity to the finest particle size fraction (<20 microm) and the large, very slowly desorbing fraction (58-75%). The biota-sediment accumulation factors ranged between 1.9 and 4.4 for BDE-99 and between 1.4 and 2.8 for TCDD. The chemical outflux from the rapidly desorbing fraction and influx into organisms shows the connection between desorption and bioavailability. Despite this, normalization to the rapidly desorbing fraction was unable to reduce differences in bioavailability estimates between the chemicals. Thus, it is evident that chemical extraction in the mixed system (Tenax tubes) does not fully describe the bioavailable fraction that worms face in stagnant sediments in a similar way for all chemicals. However, when all desorbing domains were included in the calculation, the difference between the chemicals disappears. Desorbing fractions were also able to reduce variability in the biota-sediment accumulation factors between the tested sediments when organic carbon-based sediment chemical concentrations were modified by the desorbing fractions.

The aim of this work was to study the toxicity and biotransformation of polyaromatic hydrocarbon (PAH) pyrene in the oligochaete aquatic worm, Lumbriculus variegatus. PAHs are ubiquitous environmental pollutants that pose a hazard to aquatic organisms, and metabolizing capability is poorly known in the case of many invertebrate species. To study the toxicity and biotransformation of pyrene, the worm was exposed for 15 days to various concentrations of water-borne pyrene. The dorsal blood vessel pulse rate was used as a sublethal endpoint. Pyrene biotransformation by L. variegatus was studied and the critical body residues (CBR) were estimated for pyrene toxicity. The toxicokinetics of pyrene uptake was evaluated. A combination of radiolabeled (14C) and nonlabeled pyrene was used in the exposures, and liquid scintillation counting (LSC) and high-pressure liquid chromatography were employed in both water and tissue residue analyses. The results showed that L. variegatus was moderately able to metabolize pyrene to 1-hydroxypyrene (1-HP), thus demonstrating that the phase-I-like oxidizing enzyme system metabolizes pyrene in L. variegatus. The amount of the 1-HP was 1-2% of the amount of pyrene in the worm tissues. The exposure to pyrene reduced the blood vessel pulse rate significantly (p<0.05), showing that pyrene had a narcotic effect. The estimated CBRs remained constant during the exposure time, varying from 0.120 to 0.174 mmol pyrene/kg worm wet weight. The bioconcentration factors (BCF) decreased as exposure concentration increased. It was suggested that the increased toxicity of pyrene accounted for the decrease in BCFs by lowering the activity of the organism.

The transport and bioavailability of sediment-associated contaminants are often controlled by the contaminants' desorbing behaviour. This study examines the desorption kinetics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), diphenyl ethers (PCDEs) and hydroxydiphenyl ethers (HO-PCDEs) from the highly contaminated River Kymijoki sediment in Finland. The desorption kinetics data were generated using Tenax((R)) extraction, and a first-order three-compartment kinetic model was fitted to the data. The desorption data was compared to the previously published accumulation data from this same location to investigate the relationship between the rapidly desorbing fraction (F(r)) and biota-sediment accumulation factors (BSAFs) as well as semipermeable membrane device sediment accumulation factors (SSAFs). The PCDDs, PCDFs, PCDEs and HO-PCDEs were tightly attached to sediment particles and formed a large very slowly desorbing fraction (F(vs)). Rapidly desorbing fractions (F(r)) varied between 0.8% and 8% of total amount in sediment. The size of the desorbing fraction was congener-specific and F(r) decreased with the increasing lipophilicity of congeners. The size of the F(r) was unable to explain the small variation in the BSAFs of Lumbriculus variegatus but may help to explain the observed variation in the SSAFs. To our best knowledge, this study is the first effort to investigate the desorption of PCDDs, PCDFs, PCDEs and HO-PCDEs in field-contaminated sediments. The major finding that the very slow desorption of these chemicals will continue years, provides essential information for the modern risk assessment process.

The desorption and bioavailability of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) were studied in spiked natural sediments at six concentrations. The desorption kinetics were measured in a sediment-water suspension using Tenax resin extraction, and the bioavailability was measured by exposing Lumbriculus variegatus (Oligochaeta) to PCB 77-spiked sediment in a 14-d kinetic study. In addition, freely dissolved pore-water concentrations were measured using the polyoxymethylene solid-phase extraction method. The present study examined whether bioavailability can be defined more accurately by measuring the size of desorbing fractions and the pore-water concentrations than by using the standard equilibrium partitioning approach. The importance of ingested sediment in bioaccumulation also was investigated. Our data showed a clear, decreasing trend in the rapid-desorbing fractions and in the standard biota-sediment accumulation factors (BSAF) with increasing concentration in sediment. Desorbing fractions-refined BSAFs were more uniform across the concentration treatments, and the pore-water PCB 77 concentration predicted tissue concentrations close to observed values. In the risk assessment process, pore-water concentration or desorbing fractions would lead to more precise bioavailability estimates compared with those from the traditional equilibrium partitioning approach. The result also showed, however, that sediment-ingesting worms had access to an additional bioavailable chemical fraction that was especially evident when PCB 77 pore-water concentrations most likely approached the solubility limit. Thus, feeding may modify the bioavailable fraction that cannot be explained by simple equilibrium partitioning models.

The xenobiotics accumulated in sediments represent a hazard to organisms. In order to study the toxic effects of xenobiotics in organisms, body residue has been proposed as a more relevant dose-metric than the environmental concentration of the chemical. In this study, the benthic oligochaetes Lumbriculus variegatus were exposed to sediment-spiked pentachlorophenol (PCP) in a chronic study at different exposure concentrations. The aim was to examine sublethal toxic effects in sediment-dwelling and sediment-ingesting organisms, and to link the effects with chemical body residues. Growth, reproduction, and egestion rate were used as sublethal endpoints. Bioaccumulation, sublethal toxic effects, and biotransformation of PCP were investigated by exposing organisms to both artificial and natural sediments with similar organic carbon content. Sediment characteristics were assumed to have an effect on toxicity since PCP retarded both growth and reproduction in L. variegatus in the artificial sediment. In natural sediment, growth, and reproduction was also reduced in control treatments, probably indicating poor nutritional quality. Most of the extracted chemicals in L. variegatus tissues were water-soluble metabolites, indicating that L. variegatus was capable of biotransforming PCP. The extractable parent PCP body residues (CBR(50)) for L. variegatus growth and reproduction were in agreement with the values estimated for respiratory uncouplers in the literature.

Several approaches have been used to evaluate biological impairment in aquatic ecosystems which can be categorized as either laboratory or field. In the recent years, the laboratory toxicity test approach has been extended to field exposures where ambient factors are allowed to influence the test response. Field exposures of laboratory test organisms require method modifications. In this paper, a novel in situ method is described which measures growth, survival and emergence of sediment inhabiting insects (Diptera: Chironomidae) that are used in standardized laboratory toxicity testing. Two standard chironomid species (Chironomus riparius and Chironomus tentans) were used to test the suitability of the approach and to compare the performance of the species. The larvae were transferred to the laboratory for emergence after 7 days in situ exposure which was compared to laboratory responses. Growth, survival and emergence were significantly lower in the in situ pre-exposure than in the laboratory. Also, emergence success was significantly lower in one reference sediment (LMR) than in the other test sediments in both in situ and the laboratory treatment. These lower response levels likely resulted from sediment characteristics and artifacts related to the exposure in the in situ chamber. Feeding and water quality within the exposure chamber appear to be factors that may differ markedly from the laboratory exposure and may affect organism responses. C. riparius developed (growth, emergence time) faster than C. tentans in all treatments, otherwise the species responded similarly. C. riparius may be a better alternative for the chronic in situ exposures because of shorter exposure times and reduced feeding requirements.

The success of the rapidly desorbing fraction as an available fraction was challenged by using sediment ingesting and non-ingesting oligochaetes (Lumbriculus variegatus) together with passive samplers (semipermeable membrane devices, SPMDs) in accumulation and kinetic modelling exercises for carbon-14 labelled model compounds (pyrene, benzo[a]pyrene and 3,4,3',4'-tetrachlorobiphenyl). Passive samplers clearly produced lower uptake rate constants and steady state factors than either of the oligochaete treatments when residue concentrations were based on animal lipid or total SPMD weight. The rapidly desorbing chemical fractions in sediments did not show a significant relationship with the biota sediment accumulation factors or SPMD accumulation factors. A distinctly better relationship was observed between the accumulation factors and the desorption rate constants. The results support the assumption that desorption plays an important role in bioavailability, although animal behaviour and the diffusional limitations of hydrophobic contaminants in sediment together probably affect the actual available pool.

Desorption kinetics were determined for fluoranthene (FLU) and trifluralin (TF) spiked onto Lake Erie and Lake Huron, USA, sediments at three concentrations (10, 40, 100 mg/kg dry wt). Following four months of equilibration, desorption was measured by extraction with Tenax and the data were fit to a first-order three-compartment kinetic model. The rate constants of the rapidly (k(rap)), slowly (k(slow)), and very slowly (k(vs)) desorbing fractions were on the order of 10(-1)/h, 10(-2-3)/h, and 10(-4)/h, respectively. The t99.9 (time required for 99.9% of the FLU and TF to desorb from each pool value) for each compartment indicated that FLU and TF desorption from rapid, slow, and very slow compartments were on the order of hours, days, and years, respectively. Higher rates of desorption were observed for FLU and TF from the Lake Huron sediments and this was not apparently related to the total organic carbon (TOC), particle size distribution, or polarity (carbon-to-nitrogen ratio) of the sediments. In general, the total fraction of the initial contaminant amounts that desorbed over the time course was directly related to concentration, which we hypothesized was due to the combined effects of saturation of high-energy (slow and very slow) binding sites in the organic carbon matrix and hysteresis. In extrapolations to field conditions, FLU and TF were predicted to persist in the sediments for years due to the very slow desorption of an estimated 31 to 53% of the bulk concentrations. Based on the rapidly desorbing fractions, the bioavailable amounts of the contaminants were predicted to be between 31 to 55% of bulk sediment concentrations.

Polybrominated diphenylethers (PBDEs) are ubiquitous environmental contaminants showing rapid temporal increase in some sample types. The compounds are known to biomagnify in aquatic food webs and are assumed to archive into sediments and soils. Currently, no direct evidence indicates whether sediment-associated PBDEs are available for biota. The aim of the present study was to explore the uptake and elimination of two common congeners (47 and 99) in sediment-inhabiting invertebrates to shed light on possible bioavailability of sediment-associated PBDEs. Two clean lake sediments were spiked with environmentally relevant concentrations of 14C-labeled tetra- and pentabromo diphenylether, and oligochaetes (Lumbriculus variegatus) were exposed for three or four weeks to allow kinetic accumulation calculations. Subsequent depuration tests were performed after three weeks of exposure to obtain depuration rates. Both congeners were clearly bioavailable, and only slight differences in steady-state tissue concentrations were found between the four sediment-ingesting oligochaete treatments (biota sediment accumulation factors [BSAFs], 3.0-3.7). The tetrabromo diphenylether-exposed oligochaetes that did not ingest sediment had clearly lower influx rates (0.1 vs 1-3 nmol h(-1)) than sediment-ingesting worms. Also, the estimated BSAF (1.8) was statistically different from that of the sediment-ingesting oligochaetes. These findings support the significance of feeding behavior in bioaccumulation of very hydrophobic organic contaminants. Depuration of both congeners was biphasic, indicating two kinetically different compartments in L. variegatus. Compartment A made up 73 to 92% of total radioactivity in tissues and had relatively fast depuration rates (half-lives, 10.5-47.5 h); the smaller compartment B had very slow depuration rates. No significant biotransformation of PBDEs was evident. The present study clearly demonstrates that the sediment-associated PBDEs, like other hydrophobic organic contaminants of environmental concern, are not totally sequestered from sediment-inhabiting oligochaetes and are subject to trophic transfer.

Only a fraction of all sediment-associated hydrophobic organic contaminants are bioavailable, and a simple Tenax extraction procedure may estimate this fraction. Bioavailability is assumed to coincide with the rapidly and, possibly, slowly desorbing sediment-associated contaminant. River sediment was spiked with radiolabeled (14C) and nonradiolabeled (12C) 3,4,3',4'-tetrachlorobiphenyl (TCBP), and desorption kinetics using Tenax extraction were obtained at 10 degrees C and 22 degrees C. Bioaccumulation was measured in Lumbriculus variegatus, Chironomus tentans, and Hyalella azteca. Desorption of TCBP was triphasic at 22 degrees C and slowed at 10 degrees C to show only biphasic kinetics. The rapidly desorbing fractions decreased with increasing TCBP sediment concentration. The biota sediment accumulation factors, biota accumulation factors, and sediment clearance coefficients (ks) also decreased with increasing sediment TCBP concentration. The rapidly plus slowly desorbing fractions and the total TCBP desorbed when 99.9% of the rapidly desorbing fraction had desorbed were used to estimate bioavailable TCBP. These Tenax-based fractions did not explain the decreasing bioavailability with increasing TCBP load. Several factors, such as animal behavior and TCBP water solubility limitations, were evaluated to explain the concentration effect, but the most likely cause was severe diffusion limitations in whole sediment that were not predicted by the fully mixed Tenax extraction. Therefore, desorbing fractions determined by Tenax extraction overestimated the bioavailable fractions in sediments.

Hydrophobic organic chemicals achieve equilibrium in sediments and soils by adsorption and desorption processes driven by diffusion into organic material of particle aggregates. Exposure of benthic animals to contaminated sediments results in bioaccumulation and, in theory, a steady state is established between sediment organic carbon and the organism lipids. The purpose of this study was to test the importance of sediment-chemical contact time in bioaccumulation of pyrene and benzo[a]pyrene to the freshwater oligochaete, Lumbriculus variegatus. Also, the applicability of semi-permeable membrane devices (SPMDs) in mimicking accumulation of sediment-associated chemicals by benthic invertebrates was evaluated. Feeding and nonfeeding animals were exposed to dual spiked lake sediment in five consecutive 144 h accumulation tests. SPMDs were exposed in five consecutive single point 12 h exposures to test the effect of aging of sediment on accumulation. SPMDs were also exposed in a 28 day accumulation test to determine uptake rate coefficients. Increase in sediment-chemical contact time decreased pyrene and benzo[a]pyrene uptake clearance coefficients of successive exposures for both feeding and nonfeeding animals. This decrease in bioavailability was strongest at the start of contact and slowed down with time. Ingestion of sediment considerably increased accumulation of both compounds indicating the importance of feeding behavior in bioaccumulation of sediment-associated chemicals. The significance of ingested sediment as uptake route for pyrene varied between exposures. This was probably due to combined effect of variable ingestion rate and decreasing bioavailable fraction of chemical. Availability of PAHs decreased also for SPMDs with increasing sediment chemical contact time. SPMDs reached curvilinear portion of overall uptake curve in 28 days and calculated uptake clearance constants (k(s), g sediment/g SPMD per hour) corresponded to constants calculated for nonfeeding organisms. The results of this work emphasize the significance of sediment-chemical contact time in bioaccumulation and the importance of feeding behavior of deposit feeders in bioaccumulation of sediment-associated contaminants. Both should be taken into account when performing and modeling bioaccumulation of sedimented contaminants. Furthermore, uptake of sediment-associated PAHs by SPMDs appeared to mimic uptake by nonfeeding organisms. However, more research is needed to compare the uptake of artificial devices to sediment-dwelling species in sediment exposures.

Bioaccumulation, depuration and biotransformation of radiolabelled pyrene and benzo[a]pyrene were studied in the freshwater oligochaete Lumbriculus variegatus in spiked Lake Mekrijärvi (Eastern Finland) sediment in two sets of experiments (I and II). In experiment I bioaccumulation, depuration and biotransformation of PAHs were studied. In experiment II biotransformation was investigated further using three different solvent extractions and the ability of L. variegatus to biotransform was based on the change of proportion of the parent PAH in tissue. Bioaccumulation of both chemicals was fast and an apparent steady level was reached within a week. Biotransformation results obtained by solvent extractions were in agreement with each other, although hexane appeared to be less efficient solvent for B[a]P than chloroform:methanol or ethyl acetate:acetone/cyclohexane. The relative proportion of parent PAHs in tissues decreased continously during the 504 and the 336 h exposures in experiments I and II, respectively. After 336 h exposure in experiment II, approximately 60% of pyrene and 90% of B[a]P associated radioactivity was still in the parent compound. Depuration of the parent compounds in clean sediment was fast. Most of the parent chemicals were depurated within 72 h but the possible biotransformation products remained mainly in tissues. Feeding behavior of the animals (sediment ingesting vs. noningesting) did not affect pyrene biotransformation but the proportion of parent B[a]P in tissues was larger in feeding animals. This was probably due to faster uptake rate of B[a]P to feeders than nonfeeders and slow biotransformation rate of the chemical. Our results suggest that biotransformation of pyrene and B[a]P in L. variegatus is likely and it should be taken into account when studying bioaccumulation of PAHs in assessing hazard of sediment contamination.

A method was developed for monitoring the feeding activity of larvae of the midge Chironomus riparius. The egestion rate (mg dry wt feces/mg dry wt larva/h) of the deposit-feeding larvae was measured and used as an indication of the feeding activity. Both the egestion rate and survival of several metal-adapted and reference larvae were measured in five test sediments with various Cd and Zn concentrations. The reference larvae suffered increased mortality in two contaminated sediments by comparison with field-exposed larvae. The feeding of all individuals decreased in the most polluted test sediment but also in another supposedly clean reference sediment. No differences were found in egestion rates between the reference and field-exposed larvae. This observation, however, does not reliably answer the hypothesis whether the feeding activity of the adapted and nonadapted midge larvae differs in metal-contaminated sediments because the data are based on total egestion during the short (96-h) experiment and the progress of feeding was not followed., (Copyright 1998 Academic Press.)