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Due to climate change, desalination systems have been widely used in recent years as a suitable solution to increase freshwater resources. However, there are some environmental concerns about the disposal of brine water from desalination plants into the sea. In this article, a new probabilistic approach is developed for evaluating the environmental performance of these systems by considering the uncertainties in environmental input data. For this purpose, four levels of desalination plants based on the sizes have been defined. After modeling and performing a deterministic design for each level, the most important variables were identified by employing sensitivity analysis. Afterward, simple formulas for reliability analysis were derived using Bayesian regression to obtain the concentration and dilution of effluents. The sensitivity of these formulas to the input variables was also performed using Sobol analysis. Finally, the Probability of failure (Pf) was calculated for each level using seven reliability methods, including the well-known FORM, SORM, MCS, and four other new methods. Investigations were carried out by considering both the independence and dependence between the variables using the copula function, and the results show the importance of the dependence structure. For example, considering dependence structures based on the Gaussian bivariate copula can decrease the calculated Pf of the four defined levels by nearly 17.5, 21, 27.7, and 39.2%, respectively. The results also show the importance of considering safety factors in actual designs of outfall systems. Implementing safety factors based on an acceptable Pf is a novel approach introduced in this research to control the acceptable hours per year that excess concentration can surpass the environmental criteria. The introduced method can be applied either to design new desalination plants or to evaluate the reliability of existing plants. • A novel approach is developed to evaluate and design water outfalls based on probabilistic environmental criteria. • Variables affecting the performance of desalination outfalls were identified for small to big desalination plants. • Formulas for predicting effluent dilutions were derived using Bayesian regression with a Sobol sensitivity analysis. • Importance of considering variable correlations on the outfall performances is resulted via different reliability methods. • The introduced method is applicable to any new or existing plant and controls the times surpassing environmental criteria. [ABSTRACT FROM AUTHOR]

• Effluent discharge amplifies the hyporheic exchange fluxes in the discharge area. • Higher microbiota diversity and complexity was observed in the discharge area. • Lower abundance of keystone taxa led to reduced community stability in EF area. • Keystone taxa largely determine the metabolic functions and community stability. • Controlling efficiency of keystone taxa on metabolic functions reduced in EF area. We lack a clear understanding of how anthropogenic pressures, exemplified by effluent discharge from wastewater treatment plants, destabilize microbial communities in the hyporheic zone (HZ) of receiving rivers. In this study, the spatiotemporal characteristics of hydrological parameters, and the physicochemical properties of surface and subsurface water in a representative effluent-dominated river were monitored. Sequencing of 16S rRNA amplicons and metagenomes revealed the microbial community structure in the HZ of both effluent discharge area and downstream region. The keystone taxa (taxa vital in determining the composition of each microbial cluster) and the keystone functions they controlled were subsequently identified. Effluent discharge amplified the depth of the oxic/suboxic zone and the hyporheic exchange fluxes in the effluent discharge area, which was 50-120% and 40-300% higher than in the downstream region, respectively. Microbial community structure pattern analysis demonstrated an enhancement in the rate of dispersal, an increase in microbial diversity, and an improved community network complexity in the effluent discharge area. By contrast, the number of keystone taxa in the effluent discharge area was 50-70% lower than that of the downstream region, resulting in reduced community network stability and functionality. The keystone taxa controlling metabolic functions in the networks categorized to effluent discharge area were comprised of more genera related to nitrogen and sulfur cycling, e.g., Dechloromonas, Desulfobacter, Flavobacterium, Nitrosomonas , etc., highlighting a research need in monitoring species associated with nutrient element cycling in the HZ of receiving waterbodies. The results showed that the keystone taxa could contribute positively to network stability, which was negatively correlated to hyporheic exchange fluxes and redox gradients. This study provides valuable insights that will improve our understanding of how river ecosystems respond to changes in anthropogenic pressures. [Display omitted] [ABSTRACT FROM AUTHOR]

The temporal variation of the microplastic concentration was studied in the Langueyú stream, which is located in the department of Tandil, in the southeast of the Buenos Aires province in Argentina. This stream receives discharge from the wastewater treatment plants from a medium-sized city. A quantitative analysis of the microplastic concentration was carried out in different samplings, corresponding to different seasons. The study focused on the most contaminated point, located after the discharge of effluents from plants. Higher concentrations of MPs were found in winter (dry season), having approximately 6 times the concentrations found in summer and autumn (wet seasons). However, these differences would not be a direct consequence of the amount precipitation, but rather would be associated with a seasonal variation of human activities, mainly with respect to the type of clothing used in the cold season. The microfibers correspond to around 60–90% of microplastics found. The discharge from the plants causes changes in the parameters of the stream water, such as high electrical conductivity values, and also provide metallic contaminants such as Ca, Zn, and in smaller amounts Pb, Fe, Ni and Cu, which were found adhered to the microplastics and remain in the stream water in high quantities 3 km after the study point. The microplastic concentration presents a linear empirical correlation with the conductivity, and it was found that conductivity measurements would serve as an indicator of the microplastic concentration in the system under study. [Display omitted] • The highest microplastic concentrations were measured in winter (dry season). • There is no direct consequence of precipitation with microplastic concentration. • Discharges from the plants cause changes in the stream water (conductivity and pH). • Conductivity would serve as an indicator of the microplastic concentration. • Metallic contaminants were found adhered to the microplastics. [ABSTRACT FROM AUTHOR]

Sewage treatment plants (STPs) are one of the sources of pathogens discharged into surface water. An investigation was carried out over the duration of 12 months in Henan Province, China, to evaluate the health influence of municipal wastewater effluent discharge on water quality of the receiving water. A discharge-based quantitative microbial risk assessment (QMRA) was employed, taking into account the vegetables consumption habits of the Chinese, population subgroups with different immune statuses and ages, to evaluate the incremental disease burden from agricultural irrigation and swimming exposure scenarios associated with increased concentration of the protozoan Cryptosporidium and/or Giardia in the receiving river. The results shown that all the STP influent samples contained Cryptosporidium and Giardia with average density of 142.31 oocysts/L and 1187.06 cysts/L, respectively. The QMRA results demonstrated that the estimated additional health burdens due to discharged effluent for both parasites were slightly violated the threshold of 10 −6 DALYs per person per year set by WHO. Mitigation measures should be planned and executed by season since more disease burdens were borne during hot season than other seasons. The sensitivity analysis highlighted the great importance of stability of STP treatment process. This study provides useful information to improve the safety of surface water and deduce the disease burden of the protozoa in Henan Province and other region inside and outside China. [ABSTRACT FROM AUTHOR]

With the intensification of human activities, fresh water resources are increasingly being exposed to contamination from effluent disposal to land. Thus, there is a greater need to identify the sources and pathways of water contamination to enable the development of better mitigation strategies. To track discharges of domestic effluent into soil and groundwater, 10 synthetic double-stranded DNA (dsDNA) 3 3 Double-stranded DNA (dsDNA); single-stranded DNA (ssDNA); base-pair (bp); bromide (Br); polymerase chain reaction (PCR); colony-forming units (cfu); relative mass recovery ( RB ); relative transport speed ( RV ); relative dispersion ( RS ); concentration breakthrough curve (BTC). tracers were developed in this study. Laboratory column experiment and field groundwater and soil lysimeter studies were carried out spiking DNA with oxidation-pond domestic effluent. The selected DNA tracers were compared with a non-reactive bromide (Br) tracer with respect to their relative mass recoveries, speeds of travel and dispersions using the method of temporal moments. In intact stony soil and gravel aquifer media, the dsDNA tracers typically showed earlier breakthrough and less dispersion than the Br tracer, and underwent mass reduction. This suggests that the dsDNA tracers were predominantly transported through the network of larger pores or preferential flow paths. Effluent tracking experiments in soil and groundwater demonstrated that the dsDNA tracers were readily detectable in effluent-contaminated soil and groundwater using quantitative polymerase chain reaction. DNA tracer spiked in the effluent at quantities of 36 μg was detected in groundwater 37 m down-gradient at a concentration 3-orders of magnitude above the detection limit. It is anticipated it could be detected at far greater distances. Our findings suggest that synthetic dsDNA tracers are promising for tracking effluent discharges in soils and groundwater but further studies are needed to investigate DNA-effluent interaction and the impact of subsurface environmental conditions on DNA attenuation. With further validation, synthetic dsDNA tracers, especially when multiple DNA tracers are used concurrently, can be an effective new tool to track effluent discharge in soils and groundwater, providing spatial estimation on the presence or absence of contamination sources and pathways. [ABSTRACT FROM AUTHOR]

Municipal wastewater treatment plants (WWTPs) are frequently suspected as significant point sources or conduits of microplastics to the environment. To directly investigate these suspicions, effluent discharges from seven tertiary plants and one secondary plant in Southern California were studied. The study also looked at influent loads, particle size/type, conveyance, and removal at these wastewater treatment facilities. Over 0.189 million liters of effluent at each of the seven tertiary plants were filtered using an assembled stack of sieves with mesh sizes between 400 and 45 μm. Additionally, the surface of 28.4 million liters of final effluent at three tertiary plants was skimmed using a 125 μm filtering assembly. The results suggest that tertiary effluent is not a significant source of microplastics and that these plastic pollutants are effectively removed during the skimming and settling treatment processes. However, at a downstream secondary plant, an average of one micro-particle in every 1.14 thousand liters of final effluent was counted. The majority of microplastics identified in this study had a profile (color, shape, and size) similar to the blue polyethylene particles present in toothpaste formulations. Existing treatment processes were determined to be very effective for removal of microplastic contaminants entering typical municipal WWTPs. [ABSTRACT FROM AUTHOR]

The release into the environment of antimicrobial compounds from both human and agricultural sources is a growing global concern. The Grand River watershed, the largest mixed-use watershed in southern Ontario, receives runoff from intensive animal production as well as municipal wastewater effluents from a rapidly increasing human population. A survey of surface waters and wastewater effluents was conducted across the watershed to assess the occurrence and distribution of several antimicrobials (i.e., trimethoprim, sulfamethoxazole, sulfamethazine, lincomycin, and monensin) and chemical indicators (i.e., ammonia, nitrate, ibuprofen, venlafaxine, atrazine) and to characterize exposure levels. The human antimicrobials trimethoprim and sulfamethoxazole were detected in the urban areas of the main channel at mean concentrations of 8 ± 7 ng/L and 31 ± 24 ng/L, respectively, but at much lower concentrations in the agricultural tributaries. In contrast, the veterinary antimicrobial sulfamethazine was detected at a mean concentration of 11 ± 9 ng/L in the main channel, and at a much higher concentration in the agricultural tributaries. Lincomycin was detected in only two river samples and not in the effluents while monensin was not detected in all samples. The herbicide atrazine was detected at very low concentrations in the surface waters of both the tributaries and the main channel. The concentrations of the antimicrobials and chemical indicators generally increased downstream of the confluences with agricultural tributaries and effluent outfalls. In the wastewater effluents, the concentrations of trimethoprim, sulfamethoxazole, ibuprofen, and venlafaxine decreased with increasing treatment levels (i.e., secondary to tertiary) as indicated by ammonia/nitrate concentrations. There was a strong correlation among trimethoprim, sulfamethoxazole, and venlafaxine in the main channel and in the wastewater effluents. While the environmental concentrations of antimicrobials in the watershed are low relative to toxicity thresholds, their persistence in the environment may be an important consideration in defining strategies for future water management. [ABSTRACT FROM AUTHOR]

This study assessed the human health risk of exposure to legacy PAHs in the Nwaenebo River sediments that received effluents for over two decades from the Nigeria National Petroleum Corporation (NNPC) petroleum product Depot in Emene, Enugu, Nigeria. The study went further to estimate economic costs of the sediment PAHs pollution based on the human health risk of exposure. The human health risks were determined by estimating carcinogenic and mutagenic risks via Benzo[a]pyrene total potential equivalent (BaP TPE) and mutagenic equivalent quotient (MEQ). The economic costs of the sediment pollution comprised costs due to mortality and those due to morbidity and were estimated using the value of statistical lives (VSLs) and cost of illness (CoI), respectively. The study, with an appropriate selection of sampling points established that the NNPC petroleum Depot was responsible for the Nwaenebo River sediment PAHs pollution with ƩPAHs concentration 14.3–163 mg/kg. The carcinogenic and mutagenic risks varied from 1.3*10^-5 to 4.7*10^-5 and 1.4*10^-5 to 6.0*10^-5 respectively. Based on risk threshold of 10^-6, these risks were high. The long term economic costs of pollution of the sediments by the PAHs were estimated at 60.5 million USD and 0.46 million USD for mortality and morbidity costs, respectively. [Display omitted] • Nwaenebo river PAHs sediment pollution is due to the Enugu petroleum depot. • The health risk of legacy PAHs due to the petroleum depots is significant. • The 4-and 5-member ring PAHs are predominant in the Nwaenebo River sediment. • The economic cost of legacy PAHs pollution of Nwaenebo River sediment is huge. [ABSTRACT FROM AUTHOR]

Abstract: Contaminants released from wastewater treatment plants can persist in surface waters for substantial distances. Much research has gone into evaluating the fate and transport of these contaminants, but this work has often assumed constant flow from wastewater treatment plants. However, effluent discharge commonly varies widely over a 24-hour period, and this variation controls contaminant loading and can profoundly influence interpretations of environmental data. We show that methodologies relying on the normalization of downstream data to conservative elements can give spurious results, and should not be used unless it can be verified that the same parcel of water was sampled. Lagrangian sampling, which in theory samples the same water parcel as it moves downstream (the Lagrangian parcel), links hydrologic and chemical transformation processes so that the in-stream fate of wastewater contaminants can be quantitatively evaluated. However, precise Lagrangian sampling is difficult, and small deviations – such as missing the Lagrangian parcel by less than 1h – can cause large differences in measured concentrations of all dissolved compounds at downstream sites, leading to erroneous conclusions regarding in-stream processes controlling the fate and transport of wastewater contaminants. Therefore, we have developed a method termed “verified Lagrangian” sampling, which can be used to determine if the Lagrangian parcel was actually sampled, and if it was not, a means for correcting the data to reflect the concentrations which would have been obtained had the Lagrangian parcel been sampled. To apply the method, it is necessary to have concentration data for a number of conservative constituents from the upstream, effluent, and downstream sites, along with upstream and effluent concentrations that are constant over the short-term (typically 2–4h). These corrections can subsequently be applied to all data, including non-conservative constituents. Finally, we show how data from other studies can be corrected. [Copyright &y& Elsevier]

Abstract: Antibiotic transport downstream from a wastewater treatment plant effluent discharge was evaluated along stream reaches on Mud Creek, Spring Creek, and Decatur Branch in northwestern Arkansas, USA. Water and streambed samples were collected during August and September 2006 and analyzed for multiple antibiotics representing five classes (beta-lactams, macrolides, quinolones, sulfonamides, and tetracyclines). Antibiotics within the classes macrolides, quinolones, and sulfonamides were detected in the water column at all three stream reaches. Several of these same antibiotics, as well as antibiotics from the class tetracycline, were measured in streambed material at quantities significantly greater than those observed in the water column. Pseudo-partitioning coefficients ranged from 4 to >8000Lkg−1. Most of the antibiotics studied were significantly retained in the reaches at Mud Creek and Spring Creek and traveled kilometer-scale distances (S net, 3.3–20.2km) with low uptake velocities (, 2.9–16.1×10−6 ms−1) and rates (U net 0.01–37.9×10−6 μgm−2 s−1). Some antibiotics increased in concentration downstream from the effluent discharge at Decatur Branch, suggesting possible release from within the fluvial channel or additional sources along the stream reach. In general, antibiotics traveled kilometer-scale distances before significant dilution occurred through in-stream processes (e.g., advection, dispersion, sorption, uptake and/or degradation) within the fluvial channel of these effluent-dominated streams. [Copyright &y& Elsevier]

Abstract: Umm Al Nar Power and Desalination Plant is one of the largest plants in Abu Dhabi Emirate, United Arab Emirates. The plant was built in the mid eighties and its capacity was increased in 2001. The present plant capacity after the extension is 1000 Mega Watt power and 165 Million Gallon water per day. Recently, it was decided to develop and reclaim the Raha Beach coastal area near the plant for housing and recreation purposes. This requires reclamation of a large area in the Airport Channel, which is a large channel connected to the plant vicinity. A comprehensive study was carried out by Water & Power Research Center of Abu Dhabi Water & Electricity Authority to investigate the impact of the reclamation activities in the Airport Channel on the flow pattern in the plant vicinity and the recirculation of effluents from the outfalls of the plant to its intakes. The paper describes the two-dimensional numerical hydrodynamic flow model used in the study. The model results showing the effects of the reclamation activities on the flow pattern and the brine disposal of the plant is presented and discussed. [Copyright &y& Elsevier]

Abstract: Phosphorus (P) loads from point sources have a significant influence on dissolved P concentrations in streams and sediment-water column dynamics. The goal of this study was to quantify dissolved P concentrations and sediment-P interactions in Ozark (USA) headwater streams with high point source P loads. Specifically, the objectives were to: (1) compare soluble reactive P (SRP) upstream and downstream from wastewater treatment plant (WWTP) effluent discharges; (2) examine longitudinal gradients in SRP downstream from WWTPs; (3) evaluate the effect of WTTP P inputs on sediment-water column P equilibrium and sediment exchangeable P. Water and sediment samples were collected, extracted and analyzed from July 2002 through June 2003 at these Ozark streams. Mean SRP concentrations in the select Ozark streams were significantly greater downstream from effluent discharges (0.08–2.10mgL−1) compared to upstream (0.02–0.12mgL−1). Effluent discharge from the WWTPs increased equilibrium concentrations between stream sediments and the water column; mean sediment equilibrium P concentration (EPC0) was between 0.01–0.07mgL−1 upstream from WWTP and the increase downstream was proportional to that observed in water column SRP. Sediment exchangeable P (EXP) was greater downstream from the effluent discharges (0.3–6.8mgkg−1) compared to upstream (0.03–1.4mgkg−1), representing a substantial transient storage of P inputs from WWTPs. Furthermore, P was generally not retained in these stream reaches when dilution was considered using a hydrologic tracer and was released in one stream reach where effluent P concentrations decreased over the study period. Thus, the effect of the WWTPs was profound in these streams increasing water column and sediment-bound P, and also reducing the ability of these stream reaches to retain P. In P-enriched streams, effluent P discharges likely regulate sediment and aqueous phase P equilibrium and sediment bioavailable P, not the sediments. [Copyright &y& Elsevier]

To circumvent wastewater concern of textile industry and cost-effectively utilize waste cooking oil, this study replaced water with waste cooking oil (WCO) in reactive dyeing, and enabled circulated utilization of WCO without jeopardizing dyeing quality, as well as value addition to WCO industry. Current textile dyeing process discharges tremendous amount of wastewater comprised of high concentrations of salts and hydrolyzed dyes. However, none of the existing remediation methods, such as optimization of dyeing processes, chemical modifications of fibers and post-dyeing treatments, showed effectiveness or efficiency. In a dual-phase reactive dyeing, oil and water were used to disperse dye particles and swell cotton fibers. Dyes could be quickly dissolved in water phase and adsorbed into cotton fibers from the interface of water and oil. Though non-edible WCO could be used as a medium for salt-free reactive dyeing, WCO degraded during dyeing and showed gradually deteriorated dyeing quality if repeatedly used. For the first time, this work quantified influence of glycerol and sodium fatty acid, two main WCO hydrolysates, on dyeing results, and revealed the influencing mechanism. As a solution, alkaline refinement was applied after each dyeing cycle to revive functionality of the WCO medium, and could effectively enable WCO reusable in reactive dyeing. Effluent from conventional reactive dyeing could contain up to 100 g/L electrolytes and 50% of initially added dyes, while effluent from WCO reactive dyeing contained no electrolytes and minimal amount of dyes, and could be discharged after simple treatment. Regarding value addition to WCO, textile route might also be economically favorable than biodiesel route. Overall, the WCO reactive dyeing system could have good industrialization potential as a cleaner textile wet process. Image 1 • Waste cooking oil (WCO) was used for cotton dyeing with constantly good quality. • Circulated dyeing of cotton could be realized with minimal waste discharge. • Application of WCO in cotton dyeing had high industrialization potential. • Effluent of WCO dyeing met highest discharge standard with simple treatment. [ABSTRACT FROM AUTHOR]

Wastewater discharge is considered to be a significant point source of microplastic (MPs) release into the marine environment. This study is the first attempt to quantify MPs released from the wastewater outfall from Bandar Abbas City into the Persian Gulf. Two wastewater discharge stations at Gursuzan and Suru were sampled. MPs were isolated by an oxidative procedure and subsequent density separation using ZnCl 2 solution. The average MP concentration in wastewater and sludge were 70.66 (±14.12, SD) MP.35 L−1 and 6070 (±807.25) MPs.kg−1, respectively at Confidence Level (CL) (95.0%). The most commonly recovered polymers were polyethylene (PE) and polypropylene (PP) in all size classes. Our findings provides a baseline of MP concentration in wastewater streams and slurry that is discharged from the Bandar Abbas wastewater treatment facility into the Persian Gulf. This highlights the need to undertake more studies at water treatment plants in the region for a realistic assessment of MP discharge into the Persian Gulf. • First data of MPs from a wastewater treatment plant in the Persian Gulf. • An average of 1.2 × 10 8 MPs day−1 could be released into the Persian Gulf from Bandar Abbas city. • Shape dominance of MPs in effluent and sludge were fiber > film > fragment > granule. • Polyethylene (PE) and polypropylene (PP) were dominant polymers. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) play a pivotal role in removal of microplastics (MPs) particles before the waste streams are discharged into aquatic environments. Indiscriminate disposal of the effluent and untreated wastewater not only contribute to accumulation of MP in the marine environment, but they can also act as a carrier for various hydrophobic compounds and contributors of pollutants that leach from them via natural degradation. In this assessment, we have summarized the MP concentrations in influent and effluent streams, and provide quantification of the discharges from these WWTPs. Almost 50% of the global wastewater influent of 3,562,082 × 105 m3 remains untreated. Some conservative estimates indicate that treated effluent disposal can add around 1.47 × 1015 MPs annually, whereas the discharge of untreated effluent is likely to add a staggering 3.85 × 1016 MPs annually to the aquatic environments. The efficiency of MP removal in wastewater treatment plants varies between 88 and 99.9%, indicating the potential of capturing the majority of the MP from escaping into the freshwater and marine environment. Based on WWTP removal efficiencies for MPs, calculations suggest that if all the globally produced wastewater was treated prior to release, a reduction of over 90% of the current amount of MP inputs into the aquatic environment could be achieved. From the number of studies conducted and assessments made on MPs in waste streams, it is obvious the methodologies followed were quite different, and the use of acids and heating are likely to deteriorate the MPs, emphasizing the need to develop harmonized protocols for microplastic assessment in wastewater treatment plants. • Wastewater treatment plants are the major pathway for microplastic input into aquatic environments. • The MP removal efficiency of WWTPs varies between 88 and 99.9%. • Treated and untreated effluent discharges are likely to contribute over 3.85 × 1016 MPs a year. [ABSTRACT FROM AUTHOR]

Microplastics (MPs, <5 mm in size) are classified as emerging contaminants but treatment processes are not designed to remove these small particles. Wastewater treatment systems have been proposed as pathways for MPs pollution to receiving waters but quantitative and qualitative data on MP occurrence and transport remains limited, hindering risk assessment and regulation. Here, for the first time, the stepwise abundance and loading of MPs (60–2800 μm) in a tertiary wastewater treatment plant in the UK was assessed by sampling from May 2017 to February 2018. Microplastics were found in all sampling campaigns, with an average inflow of 8.1 × 108 (95% CI, 3.8 × 108 to 1.2 × 109) items day−1. Their prevalence decreased from influent to final effluent. Overall abundances decreased on average by 6%, 68%, 92%, and 96% after the pre-treatment, primary, secondary, and tertiary treatment stages respectively, although considerable variability occurred throughout the year. Sufficient particles remained in the treated effluent to generate an average discharge of 2.2 × 107 (95% CI, 1.2 × 107 to 3.2 × 107]) particles day−1 to the recipient river. Secondary MPs were predominant, while primary MP abundances were minimal. Fibres comprised 67% of all items, followed by films (18%) and fragments (15%). Chemical characterisation confirmed the presence of different types of polymers, with polypropylene fibres and fragments most abundant (23%). This research informs understanding of how wastewater effluent may channel MPs to the natural environment and their composition, and helps understand control points for optimising advanced treatment processes. Image 1 • Average inflow rate of microplastics in wastewater was 8.1 × 108 particles day−1. • Fibres were the most abundant type of microplastic. • FTIR-ATR analysis revealed polypropylene was the most abundant synthetic polymer. • Tertiary treatment appears to remove 97% of influent microplastics. • More than 1.2 × 107 particles day−1 may be discharged from the WWTP. [ABSTRACT FROM AUTHOR]

The insectivorous tree swallow was chosen as an indicator species toinvestigate the uptake of pulp mill-related chlorinated hydrocarbonsfrom emergent aquatic insects. Nest box populations were monitored for reproductive success at locations upstream and downstream of pulp mills on two river systems in British Columbia, Canada. Also, 16-day-old nestlings were collected and analysed for polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), pesticides, chlorophenols and chloroguaiacols. Most reproductive parameters were not different between populations at upstream and downstream locations, and were equivalent to or greater than those recorded for other tree swallow populations. Chlorinated hydrocarbon contamination of nestlings was low at all sites. The highest tissueconcentrations were detected downstream of pulp mills on the Fraser River, where PCDD and PCDF patterns along with the presence of pentachlorophenol (PCP) suggested that the primary source of contaminants was past use of PCP for timber preservation. Although the absolute tissue concentration of contaminants was less, the toxic concentration (as estimated with I-TEQs) was greatest in nestlings downstream of a pulp mill on the Thompson River. The proportionately larger contributions from 2,3,7,8-TCDF and PCB-77 elevated these TEQs in comparison toother populations. Nest success was the one reproductive measure that showed substantial reductions in downstream populations on both rivers; however, there was little indication that nest failures were thedirect result of contamination. Failures were largely due to parental abandonment, and, while poor parental attentiveness and nest abandonment have been associated with chlorinated hydrocarbon tissue concentrations in other studies, our 1-year assessment was insufficient to establish any link with pulp mill effluent exposure. Nestling growth models showed some subtle differences in growth patterns between nestbox p [ABSTRACT FROM AUTHOR]

Three phase procedures of toxicity identification evaluation (TIE) were conducted using Daphnia magna to identify the toxicant in effluent discharged from a chemical plant in Nanjing. Phase I toxicity characterization procedures suggested nonpolar organic compounds were responsible for the whole effluent toxicity. In phase II toxicity identification procedures, the effluent toxicity was recovered by C18 solid-phase extraction and concentration steps. Gas chromatography/mass spectrometry (GC/MS) of the concentrate indicated that benzopyrone and phenol were present in the effluent at sufficient concentrations to cause the effluent toxicity. In phase III toxicity confirmation procedures, benzopyrone and phenol mixture tests and mass balancedeterminations with toxic units (TU) confirmed these compounds were the key toxicants accounting for 44.6% and 32.9% of the whole effluent toxicity, respectively. [ABSTRACT FROM AUTHOR]