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Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters. [ABSTRACT FROM AUTHOR]

Two pesticide risk indicators, Pesticide Impact Rating Index (PIRI) and Environmental Potential Risk Indicator for Pesticides (EPRIP), were used to determine the likelihood of off-site transport to surface water of pesticides used in a cherry ( Prunus avium cultivars) and an apple ( Malus domestica cultivars) orchard. The predictions of off-site transport of some of the pesticides were verified against actual pesticide concentrations in surface water continuously monitored over two years. To our knowledge, only one other study in the published literature has attempted this. Of the chemicals monitored there was good agreement between the predictions and the field measurements from the apple orchard, but less so for the cherry orchard. In both risk indicators the attenuation factor based on the width of the buffer strip over-estimated the effectiveness of the buffer strip. There was good agreement between the EPRIP and PIRI risk assessment except for ethephon which EPRIP rated a higher risk than PIRI and dithianon which EPRIP rated a lower risk than PIRI. A strong correlation was found between the field observations and the EPRIP predicted environmental concentrations for the majority of cases. This study showed that even simple risk indicators (e.g. PIRI and EPRIP) can be good predictors for a first tier risk assessment of pesticide transport to neighbouring water bodies. [ABSTRACT FROM AUTHOR]

A survey was conducted in eight secondary schools located in two watersheds in Gujarat and Rajasthan (semi-arid region of India) to assess students’ perceptions about groundwater scarcity issues and the impact of the scarcity on their educational opportunities. Survey responses to a detailed questionnaire by a cohort of students in both watersheds; school attendance records of year 8 class students (13–14 years old) and responses gathered via a socio-economic survey involving 500 families in the study area were used in the study. In both watersheds, >90% students identified groundwater scarcity as a major issue. Required to work at home or farm, about 65% students in Gujarat and 60% in Rajasthan missed school for up to 2 days/month; and a smaller proportion (∼ 30%) missed schools for 4 or more days/month. School absenteeism was found to be linked with gender; female students missed schools more frequently than their male counterpart. The school attendance records in Rajasthan showed that the frequency of female students missing schools for 5 or more days/month was on an average 2–10 times greater than that for males. The gender difference in absenteeism in all schools was statistically significant (P < .018**). The study highlighted that groundwater scarcity in the study area, and consequent demand on their time for household work including fetching drinking water are contributing factors towards limiting their educational and economic opportunities. Groundwater scarcity can be one of the key factors that can limit inclusiveness and empowerment of women and need to be considered in policy-making. [ABSTRACT FROM PUBLISHER]

Removal of a persistent antiepileptic drug carbamazepine (CBZ) in aqueous solutions was investigated by using solar photolysis combined with free available chlorine (FAC). The combination of chlorination with simulated or natural sunlight markedly enhanced removal of CBZ in 10 mM phosphate buffer solution (pH 7.0) and river water (pH 7.0) compared with sunlight or FAC alone. Further analysis indicated that the observed enhancements in CBZ removal can be attributed to the in situ hydroxyl radical (HO ) and ozone (O 3 ) production during FAC photolysis. During 70 min simulated sunlight photolysis combined with FAC treatment, HO reaction contributed to 35.8% removal of CBZ and O 3 reaction contributed to 40.6% removal, while only 5.3% of CBZ was removed by HOCl reaction. The oxidation products of CBZ, epoxide CBZ, 10,11-dihydro-10,11-dihydroxy CBZ, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) and 4-aldehyde-9-acridone, were mainly formed from the HO and O 3 attack at the double bond on the central heterocyclic ring of CBZ. Formation of these oxidation products did not cause any increase or decrease in toxicity to microbial species tested through Microbial Assay for Toxicity Risk Assessment (MARA). The initial FAC concentration and pH had a major influence on the removal process of CBZ during FAC photolysis, while temperature had a minor effect only. The combination of chlorination with natural sunlight could provide an effective approach for removal of CBZ and other contaminants during water treatment. [ABSTRACT FROM AUTHOR]

Canola ( Brassica napus L.) is the third largest field crop in Australia by area sown. Genetically modified (GM) and non-GM canola varieties released or being developed in Australia include Clearfield® (imidazolinone tolerant), TT (triazine tolerant), InVigor® (glufosinate-ammonium tolerant), Roundup Ready® - RR® (glyphosate tolerant) and Hyola® RT® (tolerant to both glyphosate and triazine). We used two risk assessment approaches – the Environmental Impact Quotient (EIQ) and the Pesticide Impact Rating Index (PIRI) – to compare the environmental risks associated with herbicides used in the canola varieties (GM and non-GM) that are currently grown or may be grown in the future. Risk assessments found that from an environmental impact viewpoint a number of herbicides used in the production of TT canola showed high relative risk in terms of mobility and ecotoxicity of herbicides. The EIQ field use rating values for atrazine and simazine in particular were high compared with those for glyphosate and trifluralin. Imazapic and imazapyr, which are only used in Clearfield® canola, had extremely low EIQ field use rating values, likely reflecting the very low application rates used for these chemicals (0.02 to 0.04 kg/ha) compared with those used for atrazine and simazine (1.2 to 1.5 kg/ha). The PIRI assessment showed that irrespective of the canola variety grown, trifluralin posed a high toxicity risk to fish (Rainbow trout, Oncorhynchus mykiss ), algae and Daphnia sp. While the replacement of trifluralin with propyzamide had little effect on the mobility score, it greatly decreased the ecotoxicity score to fish, algae and Daphnia sp. due to the lower LC50 values for propyzamide compared with trifluralin. This study has shown that based on likelihood of off-site transport of herbicides in surface water and potential toxicity to non-target organisms, the GM canola varieties have no advantage over non-herbicide tolerant (non HT) or Clearfield® canola. [ABSTRACT FROM AUTHOR]

Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient ( K OC ), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, K OC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron K OC – organic matter–mineral interactions and organic matter chemistry – for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased K OC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between K OC for the whole soils and K OC for the HF-treated soils, indicating that the importance of organic matter–mineral interactions varied greatly amongst these soils. There was as much variation in K OC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to K OC variability. Organic matter chemistry, determined by solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy, was correlated with K OC for the HF-treated soils. In particular, K OC increased with the aromatic C content ( R = 0.64, p = 1 × 10 −6 ), and decreased with O-alkyl C ( R = −0.32, p = 0.03) and alkyl C ( R = −0.41, p = 0.004) content. [ABSTRACT FROM AUTHOR]

Active pharmaceutical ingredients (APIs) can enter the natural environment during manufacture, use and/or disposal, and consequently public concern about their potential adverse impacts in the environment is growing. Despite the bulk of the human population living in Asia and Africa (mostly in low- or middle-income countries), limited work relating to research, development and regulations on APIs in the environment have so far been conducted in these regions. Also, the API manufacturing sector is gradually shifting to countries with lower production costs. This paper focuses mainly on APIs for human consumption and highlights key differences between the low-, middle- and high-income countries, covering factors such as population and demographics, manufacture, prescriptions, treatment, disposal and reuse of waste and wastewater. The striking differences in populations (both human and animal), urbanization, sewer connectivity and other factors have revealed that the environmental compartments receiving the bulk of API residues differ markedly between low- and high-income countries. High sewer connectivity in developed countries allows capture and treatment of the waste stream (point-source). However, in many low- or middle-income countries, sewerage connectivity is generally low and in some areas waste is collected predominantly in septic systems. Consequently, the diffuse-source impact, such as on groundwater from leaking septic systems or on land due to disposal of raw sewage or septage, may be of greater concern. A screening level assessment of potential burdens of APIs in urban and rural environments of countries representing low- and middle-income as well as high-income has been made. Implications for ecological risks of APIs used by humans in lower income countries are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Release of C60 is influenced by soil type. [•] Systems with elevated concentrations of DOC release relatively more C60. [•] Different forms of C60 have similar release behaviour. [•] Non-photoactivated formation of hydrophilic C60 appears to be a possibility in soil. [•] Apparent release of C60 from contaminated biosolids applied to soils will be limited. [Copyright &y& Elsevier]

Abstract: We studied the sorption–desorption behaviour of two herbicides (diuron and artrazine) in a soil rich in Fe and Al oxides (Ferrosol), either amended freshly with two different types of biochars or that contained biochars aged under field conditions. Standard batch sorption–desorption experiments were conducted on soil samples freshly amended with two biochars, (namely, poultry litter – PL and paper mill – PM sludge) as well on those collected from field 32months after biochar application. Soils that were freshly amended with biochars @ 10tha−1 showed a two (PM) to five (PL) fold increase in sorption of herbicides as compared with that in the unamended soil. For example, the fresh amendments with PL biochar at 10tha−1 led to a highly significant (P <0.001) increase in the Freundlich sorption coefficient (K f ) of atrazine; i.e. 20.71 (n =0.40) as compared with 4.02 (n =0.70) for the control soil. Sorption was reversible in the unamended soil but sorption–desorption hysteresis was prominent in the soil amended with fresh biochars. In contrast, the soil containing aged biochars (at 10tha−1) exhibited sorption–desorption properties that were statistically similar to that of the control soil, especially for atrazine. Ageing of biochars in the soil over a 32months period reduced the sorption capacity by 47% (PM) to 68% (PL) for diuron. These findings may have implications for herbicide efficacy in biochar amended soils. [Copyright &y& Elsevier]

Abstract: The form in which pesticides are transported off-site can have implications for their bioavailability, ecotoxicological impact and the effectiveness of any management strategies implemented to minimise their movement. We have investigated the form in which nine pesticides (carbaryl, fenarimol, azinphos methyl, penconazole, pirimicarb, chlorpyrifos, propiconazole, procymidone and bupirimate) were transported in surface water from an apple and cherry orchard in the Mt. Lofty Ranges, South Australia, over three years. The majority of pesticides monitored were found to move off-site in the dissolved (<1.2μm) phase. Only propiconazole moved off-site predominantly (70–90%) by colloidal transport in association with particulate (>1.2μm) material. Chlorpyrifos was detected in surface drainage water for several months and the predominant phase in which it moved varied between events in a year and during an event. The effectiveness of pesticide physicochemical properties as surrogates for predicting mode of transport of pesticides, in this region was determined by regression of average proportion (%) of each pesticide in the dissolved phase for each event against the relevant physicochemical parameters. There was no relationship between average proportion in the dissolved phase (<1.2μm) and any of the pesticide characteristics considered. This suggests that off-site transport of pesticides is governed by complex biological and hydrological interactions and the use of simple physicochemical properties as surrogates for predicting offsite transport may not be applicable. These results have implications for the effectiveness of management strategies, including buffer strips and sedimentation ponds, to minimise transport and suggest that, unless adequate residency time is available for sorption of the pesticides, these strategies may have limited use for minimising the transport of the pesticides used in the two land uses studied here. This study has highlighted the importance of understanding the mode of transport of pesticides for informing the choice of management strategies to minimise potential offsite transport of pesticides under different field conditions. [Copyright &y& Elsevier]

Abstract: In the Mediterranean climate of this study the growing period (and hence spraying period) for horticultural crops usually occurs from late spring to summer (i.e. October–March). However, runoff predominantly occurs in winter (late April–October) since there is insufficient rain in the spring and summer period for runoff to occur. It is therefore important to establish the runoff potential of pesticide, despite the long contact time with soil. We studied the distribution of the loads transported during individual runoff events, and the proportion of total annual load transported in each event over three seasons. Some insecticides and fungicides (pirimicarb, procymidone, carbaryl, fenarimol and penconazole) transported off-site from and apple and cherry orchard over a period of 30 months showed a strong association between peak pesticide load and peak flow during individual flow events. Others (particularly chlorpyrifos) however showed no obvious relationship between flow and load transported off-site. Throughout the year certain pesticides demonstrated behaviour characteristic of those chemicals that move in the first flush of drainage water in the season. This was particularly evident for pirimicarb, bupirimate, carbaryl and fenarimol, which all have K OC values <1000L/kg. However, for other pesticides the percentage of total annual load transported off-site either increased or remained fairly constant for several runoff events during the season which was most obvious for chlorpyrifos followed by penconazole and procymidone – all with K OC values ≥1500L/kg. Generally, the total amount of pesticide moving off-site from both orchards was <0.5% of the total mass of active ingredient applied, except fenarimol (0.54–2.1%). Only chlorpyrifos, however, showed a positive linear relationship between the load transported off-site during an event and total rainfall (R 2 =0.48, n =26). The results from this study have implications for the development of management strategies to minimise pesticide transport to waterways. [Copyright &y& Elsevier]

Abstract: Local runoff from the catchments in the Mt. Lofty Ranges provides a major source of drinking water for the city of Adelaide, South Australia, Australia. In this study two major land uses (apples and cherries) in the Mt. Lofty Ranges were monitored for off-site transport of pesticides over approximately 30 months. While fungicides have been rarely reported in the literature to be present in surface water, in our studies several fungicides (fenarimol, bupirimate, penconazole, procymidone, propiconazole) were found to be transported off-site in a persistent manner over the study period. Two pesticides (chlorpyrifos and fenarimol) from the apple orchard were of particular concern. The average chlorpyrifos concentrations in 2007 and 2009 were more than ten times the environmental guideline value (0.01μg/L), suggesting potential deleterious effects on aquatic organisms immediately downstream of the apple orchard. Fenarimol was detected in 19 water samples collected from early April to early June 2007 and in 95% of these cases the total concentration exceeded the Australian Drinking Water Quality Guideline (no environmental guidelines are available in Australia for this chemical). For pesticides such as chlorpyrifos and fenarimol at least a ten-fold dilution would be required in the receiving environment for the concentrations to be below current guideline values. Generally more pesticides were detected in drainage water leaving the apple orchard than the cherry orchard, reflecting higher pesticide use at the former. The results from this study indicate that pesticides are of concern in this catchment and strategies for minimising off-site transport need to be developed and evaluated. Data from this study show that while some pesticides move off-site predominantly with the first runoff event some pesticides continue to be transported off-site for months. Some pesticides in the Mt. Lofty Ranges are persisting in soils or on the crop canopy for considerable time periods and being detected in surface runoff water months after the last application. [Copyright &y& Elsevier]

Abstract: We report a survey on the occurrence of estrogens (estrone, E1; 17β-estradiol, E2; 17α-ethynylestradiol, EE2) and xenoestrogens (bisphenol-A, BPA; 4-t-octylphenol, 4-t-OP; 4-nonylphenols, 4-NP; and nonylphenol mono- and di-ethoxylates, NPE1 and NPE2) in effluents from five wastewater treatment plants and their receiving waters in South East Queensland. The total xenoestrogen concentrations in effluent ranged between 2446 ng/L and 6579 ng/L, with 4-NP and NPE1-2 having much higher concentration levels than BPA and 4-t-OP. The estrogen levels in effluent varied from 9.12 to 32.22 ng/L for E1, from 1.37 ng/L to 6.35 ng/L for E2 and from 0.11 ng/L to 1.20 ng/L for EE2. No significant differences (p <0.05) in the concentrations of the selected estrogenic compounds were found for the effluents from the five sewage treatment plants. The estrogens and xenoestrogens were also found in the receiving waters at relatively lower concentration levels due to dilution of effluents in the rivers. Based on the chemical analysis data and relative potency of the compound from in vitro and in vivo bioassays from the literature, the calculated in vitro EEQ values (estrogen equivalents) in the receiving river waters downstream of the effluent discharge points ranged from 1.32 to 11.79 ng/L, while the in vivo EEQ values (vitellogenin response in rainbow trout) ranged from 2.48 to 21.18 ng/L. The three estrogens accounted for the majority of the EEQ in the water samples. This study indicates that the rivers of South East Queensland are at potential risk. [Copyright &y& Elsevier]

Triclosan (TCS) antimicrobial compound is used in personal care products such as shampoos and soaps. The TCS compound can survive the treatment process and is often present in the sewage effluent and biosolids. We investigated the impact of TCS upon selected microbiological and biochemical parameters in two contrasting Australian soils. Substrate-induced respiration and nitrification, plus activities of four enzymes (relevant for carbon and nitrogen turnover), were measured using Organisation for Economic Co-operation and Development protocols after exposing soils to TCS at concentrations of 0, 1, 5, 10, 50, and 100 mg/ kg of soil. Respiration in the sandy soil was not affected by the addition of TCS, but in clay soil it decreased to TCS at 50 mg/ kg of soil. The nitrification process was affected in both soils. In the sandy soil, TCS showed a negative effect on the nitrate and nitrite production at 5 mg/kg. In contrast, in the clay soil, the effect was noticeable only at concentrations greater than 50 mg/kg. The response of four enzymes (acid and alkali phosphatase, β-glucosidase, and chitinase) in the two soils was variable, and only β-glucosidase showed some response to TCS addition. The study demonstrated that TCS at concentrations below 10 mg/kg can disturb the nitrogen cycle in some soils. A first-tier hazard assessment highlighted the need for further work on TCS impact on soil microorganisms. [ABSTRACT FROM AUTHOR]

The potential of mid-infrared (MIR) spectroscopy in combination with partial least-squares (PLS) regression was investigated to predict the soil sorption (distribution) coefficient (Kd) of a nonionic pesticide (diuron). A calibration set of 101 surface soils collected from South Australia was utilized for reference sorption data and MIR spectra. Principal component analysis (PCA) was performed on the spectra to detect spectral outliers. The MIR-PLS model was developed and validated by dividing the initial data set into four validation sets. The model resulted in a coefficient of determination (R²) of 0.69, a standard error (SE) of 5.57, and a residual predictive deviation (RPD) of 1.63. The normalized sorption coefficient for the organic compound (Koc) approach, on the other hand, resulted in R², SE, and RPD values of 0.42,7.26, and 1.25, respectively. However, the significant statistical difference between the two models was mainly due to two outliers detected via PCA. Apart from spectral outliers, the performance of the two models was essentially similar for the rest of the calibration set Outlier detection by the MIR-PLS model may gainfully be employed as a tool for improving prediction of Kd. The MIR-based model can provide a direct estimation of Kd values based on the integrated properties of organic and mineral matter reflected in the infrared spectra. [ABSTRACT FROM AUTHOR]

The fate and removal of the estrogens 17β-estradiol (E2), estrone (E1), and 17α-ethynylestradiol (EE2) and of the xenoestrogens bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), 4-nonylphenol (4-NP), and nonylphenol mono- and diethoxylate (NPEO1 and NPEO2, respectively) were investigated in four South Australian sewage treatment plants (STPs; plants A-D) with different treatment technologies. The concentrations in the effluent from the two-year survey were similar to those reported in other studies. In the effluent, 4-NP, NPEO1, and NPEO2 had total concentrations up to 8 μg/L, which were much higher than those of BPA and 4-t-OP. Estrone had the highest concentrations among the three estrogens, ranging between 13.3 and 39.3 ng/L, whereas the concentrations for E2 and EE2 varied between 1.0 and 4.2 ng/L and between 0.1 and 1.3 ng/L, respectively. The removal rates for the estrogens and xenoestrogens were variable but consistent with the plant performance parameters (biochemical oxygen demand, suspended solids, and ammonia). Considering all the estrogenic compounds analyzed in the present study, plant D, with a series of anaerobic and aerobic lagoons, was the least efficient of the four STPs in the removal of these compounds. The removal rates for 4-NP, NPEO1, and NPEO2 within the plants were 92% for plant A, with conventional activated sludge treatment; 80% for plant B, with two oxidation ditches; 70% for plant C, with three bioreactors; and 64% for plant D, with 10 lagoons in series. Comparatively, the removal of estrogens was lower, with rates ranging between 47 and 68% for E2 at the four plants. Both E1 and EE2 were more persistent during treatment, especially in plants C and [ABSTRACT FROM AUTHOR]

Naturally occurring charcoals are increasingly being recognized as effective sorbents for organic compounds. In this study we investigated the sorption of benzene and toluene in single-sorbate and bi-sorbate systems on different types of charcoals produced in laboratory, employing the batch sorption technique. Air dried plant materials from Phalaris grass (Phalaris tuberosa) and Red Gum wood (Eucalyptus camadulensis) were combusted under limited oxygen supply at 250°C, 450°C, and 850°C. The resulting charcoals were characterized for their specific surface areas, total cation content, and pore size distributions (pore size distribution only for wood combusted at 450°C and 850°C). For the materials treated at 850°C not only the surface area, microporosity, and total amount of sorbed sorbate increased markedly, but also the non-linearity of the sorption isotherm. The pore size distributions and surface areas as well as an indifferent sorption behaviour and competition effects for both sorbates indicated that pore filling mechanisms were the dominating processes governing the sorption on these microporous, high temperature treated materials. For the materials treated at lower temperatures the affinity of toluene was higher compared to that of benzene. In the bi-sorbate system the overall uptake of benzene increased. These phenomena might be due to the stronger hydrophobicity of toluene, and to a varying potential for swelling of the matrix and pore deformation by the two sorbates. The significantly lower sorption capacity of the Phalaris-derived material compared to the Red Gum charcoal correlated with its smaller surface area and higher cation content. [Copyright &y& Elsevier]

Abstract: Triclosan (TCS) is an antimicrobial agent widely used in many personal care products. This study investigated the occurrence of TCS in effluents, biosolids and surface waters, and its fate in wastewater treatment plants (WWTPs). The aqueous concentrations of TCS in nineteen effluents from Australian WWTPs ranged from 23 ng/L to 434 ng/L with a median concentration of 108 ng/L, while its concentrations in nineteen biosolids ranged from 0.09 mg/kg to 16.79 mg/kg on dry weight basis with a median concentration of 2.32 mg/kg. The removal rates for TCS in five selected WWTPs were found to range between 72% and 93%. Biological degradation was believed to be the predominant removal mechanism for TCS in the WWTPs. However, adsorption onto sludge also played a significant role in the removal of TCS in the WWTPs. TCS at concentrations up to 75 ng/L was detected in surface waters (outfall, upstream, and downstream) from five rivers receiving effluent discharge from WWTPs. Preliminary risk assessment based on the worst-case scenario showed that the TCS concentrations in surface waters might lead to risks to aquatic organisms such as algae. Based on the TCS levels in the biosolids, application of biosolids on agricultural land may also cause adverse effects in the soil environment. [Copyright &y& Elsevier]

To have an effective barrier against invading termites around building structures and to assess the potential risks to the urban environment and human beings, we need to understand the fate of termiticides applied in urban soil. The movement and degradation of a new termiticide, fipronil, were investigated in Australian soils following standard termiticide treatment methods (surface application under slab and trenching treatments along walls). Surface application studies in three field sites showed slow dissipation and little movement for fipronil in all three soils under the simulated slab during a three-year period. The greatest mass of the chemical residues remained in the quartzite sand layer (thickness, 5 cm), and only small amounts of these were found to have migrated into the soil layers (depth, 0-15 cm) underneath the quartzite sand layer. Of the three metabolites (desulfinyl, sulfide, and sulfone) found in the soils, the sulfone derivative had the highest concentration. Persistence of fipronil was affected by application rate. The time for 50% loss of the total toxic components (fipronil plus its metabolites) in the quartzite sand layer (thickness, 5 cm) ranged from 200 to 326 d for the low rate (0.15 g active ingredient/m2) and from 633 to 674 d for the high application rate (3 g active ingredient/m²). One-year trenching studies at two sites in Adelaide (Roseworthy Farm [RF] and Terretfield [TF]; South Australia, Australia) showed that vertical movement and dissipation of fipronil occurred in the soils. The average concentration of fipronil in the trenches (depth, 0-30 cm) decreased from 33.7 to 14.9 mg/kg in the loam soil at the RF site and from 39.4 to 14.6 mg/kg in the clay soil at the TF site over the year. With time under the natural weather condition, fipronil and its derivatives were found in the deeper soil sections without treatment (depth, 20-30 cm). However, laboratory studies using repacked soil columns showed low mobility in the loam soil from the RF site and a variably charged clay soil from Malanda (Queensland, Australia) under intermittent wetting and drying conditions. [ABSTRACT FROM AUTHOR]

Abstract: Cadmium is perhaps environmentally the most significant heavy metal in soils. Bioavailability, remobilization and fate of Cd entering in soils are usually controlled by adsorption–desorption reactions on Fe oxides. Adsorption of Cd on soil colloids including Fe oxides has been extensively studied but Cd desorption from such soil minerals has received relatively little attention. Some factors that affect Cd adsorption on goethite include pH, temperature, aging, type of index cations, Cd concentrations, solution ionic strength and presence of organic and inorganic ions. This research was conducted to study the influence of pH, temperature and aging on Cd desorption from goethite. Batch experiments were conducted to evaluate Cd desorption from goethite with 0.01M Ca(NO3)2. In these experiments Cd desorption was observed at 20, 40 and 70°C in combination with aging for 16h, 30, 90 and 180d from goethite that adsorbed Cd from solutions containing initial Cd concentrations of 20, 80 and 180μM. Following the adsorption step Cd desorption was measured by 15 successive desorptions after aging at various temperatures. At the lowest amount of initially adsorbed Cd and equilibrium pH 5.5, cumulative Cd desorption decreased from 71% to 17% with aging from 16h to 180d and the corresponding decrease at equilibrium pH 6.0 was from 32% to 3%. There was a substantial decrease in Cd desorption with increasing equilibration temperature. For example, in goethite with the lowest amount of initial adsorption at equilibrium pH 5.5, cumulative Cd desorption decreased from 71% to 31% with increase in temperature from 20 to 70°C, even after 16h. Dissolution of Cd adsorbed goethite in 1M HCl, after 15 successive desorptions with 0.01M Ca(NO3)2, indicated that approximately 60% of the Cd was surface adsorbed. Overall, dissolution kinetics data revealed that 23% to 88% Cd could not be desorbed, which could possibly be diffused into the cracks and got entrapped in goethite crystals. At elevated temperature increased equilibrium solution pH favoured the formation of CaCO3 and CdCO3 which reasonably decreased Cd desorption. Cadmium speciation showed the formation of calcite and otavite minerals at 40 and 70°C due to increase in pH (>9.5) during aging. X-ray diffraction analysis (XRD) of these samples also revealed the formation of CaCO3 at elevated temperatures with aging. While mechanisms such as Cd diffusion and/or entrapment into fissures and cracks in goethite structure with increase in temperature and aging are possible. [Copyright &y& Elsevier]

We investigated how the NMR properties of uniformly 13C-labeled benzene molecules are influenced by sorption to charcoals produced in the laboratory and collected from the field following wildfires. Uniformly 13C-labeled benzene was sorbed to two charcoals produced in the laboratory at 450 and 850 °C. The chemical shift of benzene sorbed to the higher-temperature charcoal was 5–6 ppm lower than that of benzene sorbed to the lower-temperature charcoal. This difference was attributed to stronger diamagnetic ring currents (which cause a shift to lower ppm values) in the more condensed or ‘graphitic’ high-temperature charcoal. The chemical shift of benzene sorbed to two charcoals collected from the field following wildfires indicated a degree of charcoal graphitization intermediate between that of the two laboratory-prepared charcoals. Variable contact time and dipolar dephasing experiments showed that the molecular mobility of sorbed benzene molecules increased with increasing charcoal graphitization, and also increased with increasing benzene concentration. We propose that the chemical shift displacement of molecules sorbed to charcoal could be used to identify molecules sorbed to black carbon in heterogeneous matrixes such as soils and sediments, and to establish how condensed or ‘graphitic’ the black carbon is. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatography method with diode-array detection (HPLC-DAD) is described for the determination of three neonicotinoid insecticides imidacloprid, thiacloprid, and thiamethoxam in soil and water. The soil samples were extracted with acetonitrile, while the water samples were extracted using C18 cartridges. The mean recoveries plus standard deviations for spiked soil samples were 82 ± 4.2% for thiamethoxam, 99 ± 4.2% for imidacloprid and 94 ± 1.4% for thiacloprid. The recoveries for water samples ranged from 87 ± 3.4% for thiamethoxam to 97 ± 3.9% for imidacloprid and 97 ± 2.6% for thiacloprid. The limits of quantitation (LOQ) were 0.1, 0.1, 0.01 mg/kg in soil (5 g), and 2, 2, 0.5 µg/L in water (50 mL) for thiamethoxam, imidacloprid, and thiacloprid, respectively. [ABSTRACT FROM AUTHOR]

We investigated bioavailability and biodegradation of carbaryl (1-naphthyl methylcarbamate) in a soil with a long history of pesticide contamination from a storage facility located at Mamoon Kanjan, Pakistan. Carbaryl is weakly sorbed and generally considered to be easily degradable in soil. Extraction studies revealed that 49% of the total carbaryl in soil (88.0 mg kg-1) was not water-extractable and also not bioavailable, as demonstrated by inoculation of the contaminated soil with a carbaryl-degrading, mixed bacterial culture. Inoculation of the contaminated soil with the carbaryl-degrading culture showed that the bacteria were capable of degrading only the available (i.e., water-extractable) fraction of the pesticide. When the soil was pulverized in a ball mill to enhance the release of residue, an additional 19% of the carbaryl became bioavailable. A significant proportion of residue (≈33%) remained unavailable. The long (>12 years) contact time between the pesticide and soil (i.e., aging), allowing possible sequestration into soil nanopores and the organic matter matrices, is suggested to have rendered the pesticide unavailable for microbial degradation. High concentration (88.0 mg kg-1) in soil facilitated its persistence and sequestration. Results from the present study demonstrate that even a weakly sorbed and easily degradable pesticide, carbaryl, is effectively sequestrated in soil with time, rendering it partly inaccessible to microorganisms and affecting the bioavailability of the compound. [ABSTRACT FROM AUTHOR]

The potential of five nonionic surfactants, Triton X-100, Brij35, Ethylan GE08, Ethylan CD127, and Ethylan CPG660 for enhancing release of carbaryl and ethion from two long-term contaminated soils was evaluated using the batch method. Incorporation of the surfactants into soils enhanced the release of both pesticides to various extents, which could be related to the type of pesticides and type and the amount of surfactants added. Release of ethion was dramatically enhanced by aqueous concentrations of surfactants above their critical micelle concentration values. This was attributed to solubility enhancement through incorporation of the highly hydrophobic compound within surfactant micelles. A concentration of 10 g L−1 of various surfactants released >70% of the total ethion from the soil irrespective of the surfactant. For carbaryl, the surfactants were effective at low concentrations and dependence on concentration was lower than in the case of ethion. The ethylan surfactants (GE08, CD127, and CPG660) had a higher potential than Triton X-100 and Brij35 for releasing the pesticides. However, there was still a significant portion of carbaryl (11% of the total) and ethion (17% of the total) left in the soil. Our study also showed that there must be an optimal concentration of each surfactant to maximize the mass transfer of pesticides. At some threshold concentration level, additional surfactant started to inhibit the mass transfer of solute from the soil into the water. The results suggested that surfactants could help remediation of soils polluted by pesticides. The choice of surfactant should be made based on the properties of pesticides. [ABSTRACT FROM AUTHOR]

Sorption and degradation of the five selected endocrine disrupting chemicals (EDCs) including bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), 4-tert-octylphenol (4-t-OP) and 4-n-nonylphenol (4-n-NP) have been investigated in the laboratory using sediment and groundwater from an aquifer in Bolivar, South Australia. The sorption coefficients measured on the sediment were in the following order: 4-n-NP>4-t-OP>EE2>E2>BPA. The sorption coefficients (Kf values) for the five EDCs were 3.89, 21.8, 24.2, 90.9 and 195, respectively. The alkylphenols 4-t-OP and 4-n-NP had strong binding on the sediment while BPA had a weak affinity. Degradation experiments of the five EDCs showed that E2 and 4-n-NP degraded quickly under aerobic conditions with a half-life of 2 and 7 days, respectively. EE2 degraded slowly with an estimated half-life of 81 days in the aquifer material under aerobic conditions while the other two chemicals (BPA and 4-t-OP) remained almost unchanged. Little or no degradation of the five EDCs except slow degradation for E2 was observed within 70 days under anaerobic conditions in native groundwater. [Copyright &y& Elsevier]

Microbial reduction of Fe(lll) in illite was studied to evaluate the possibility of microbial utilization of Fe(lll) in sedimentary clays and to determine the effects of bioreduction on clay composition and structure. A subsurface bacterium (Shewanella putrefaciens CN32) and illite separates (<0.2 µm) from St. Peter Formation sandstone in 0gle County, IL, were used in laboratory experiments. Illite suspensions buffered at pH 7 with bicarbonate were inoculated with CN32 and provided with H[sub 2] as an electron donor. In selected treatments, anthraquinone-2,6-disulfonate (AQDS), was included as an electron shuttle to facilitate the bioreduction. Fe(ll) production in inoculated treatments was determined by extraction with 0.5 N HCl and compared to uninoculated controls to establish the extent of biological reduction. The resulting solids were characterized by Mössbauer spectroscopy and scanning and transmission electron microscopy (SEM and TEM). The characterization of the starting illite material revealed that it contained a minor component of goethite (α-Fe00H) in addition to fibrous illite. The starting material (both goethite and illite) contained 6% (w/ w) total Fe, and 82% of the total Fe was Fe(lll). Approximately 30% of total Fe was associated with goethite. At the end of a 30-day incubation, residual goethite and illite remained. The extent of reduction was much greater in the presence of AQDS (25%) than in its absence (0%). Modeling of Mössbauer spectra of the bioreduced material indicated that both goethite and illite were reduced but to a different extent. Additionally, TEM evidence suggested that there was a dramatic change in illite morphology upon bioreduction from fibrous needles to plates. The ability of bacteria to utilize Fe(lll) in illite has important implications for microbial functions and survival mechanisms, as well as many geological processes, in the subsurface. [ABSTRACT FROM AUTHOR]

Hormone steroids are a group of endocrine disruptors, which are excreted by humans and animals. In this paper, we briefly review the current knowledge on the fate of these steroids in the environment. Natural estrogenic steroids estrone (E1), 17β-estradiol (E2) and estriol (E3) all have a solubility of approximately 13 mg/l, whereas synthetic steroids 17α-ethynylestradiol (EE2) and mestranol (MeEE2) have a solubility of 4.8 and 0.3 mg/l, respectively. These steroids have a moderate binding on sediments and are reported to degrade rapidly in soil and water. Estrogenic steroids have been detected in effluents of sewage treatment plants (STPs) in different countries at concentrations ranging up to 70 ng/l for E1, 64 ng/l for E2, 18 ng/l for E3 and 42 ng/l for EE2. E2 concentrations in river waters from Japan, Germany, Italy and the Netherlands ranged up to 27 ng/l. In addition, E2 concentrations ranging from 6 to 66 ng/l have also been measured in mantled karst aquifers in northwest Arkansas. This contamination of ground water has been associated with poultry litter and cattle manure waste applied on the land. Although hormone steroids have been detected at a number of sources worldwide, currently, there is limited data on the environmental behaviour and fate of these hormone steroids in different environmental media. Consequently, the exposure and risk associated with these chemicals are not adequately understood. [Copyright &y& Elsevier]

Investigates the nature of soil organic matter and relationship with the sorption of carbon in pesticides. Evidence of high concentration of alkyl C and smallest concentration of carbonyl C in soil; Presence of linear sorption coefficients between carbaryl and phosalone compounds.

Urbanisation will be one of the 21st century's most transformative trends. By 2050, it will increase from 55% to 68%, more than doubling the urban population in South Asia and Sub-Saharan Africa. Urbanisation has multifarious (positive as well as negative) impacts on the wellbeing of humans and the environment. The 17 UN Sustainable Development Goals (SDGs) form the blueprint to achieve a sustainable future for all. Clean Water and Sanitation is a specific goal (SDG 6) within the suite of 17 interconnected goals. Here we provide an overview of some of the challenges that urbanisation poses in relation to SDG 6, especially in developing economies. Worldwide, several cities are on the verge of water crisis. Water distribution to informal settlements or slums in megacities (e.g. >50% population in the megacities of India) is essentially non-existent and limits access to adequate safe water supply. Besides due to poor sewer connectivity in the emerging economies, there is a heavy reliance on septic tanks, and other on-site sanitation (OSS) system and by 2030, 4.9 billion people are expected to rely on OSS. About 62–93% of the urban population in Vietnam, Sri Lanka, the Philippines and Indonesia rely on septic tanks, where septage treatment is rare. Globally, over 80% of wastewater is released to the environment without adequate treatment. About 11% of all irrigated croplands is irrigated with such untreated or poorly treated wastewater. In addition to acute and chronic health effects, this also results in significant pollution of often-limited surface and groundwater resources in Sub-Saharan Africa and Asia. Direct and indirect water reuse plays a key role in global water and food security. Here we offer several suggestions to mitigate water and food insecurity in emerging economies. Unlabelled Image • Urbanisation will be one of the 21st century's most transformative trends. • Worldwide several cities are on the verge of water crisis. • Over 80% of wastewater is poorly treated and is used to irrigate 11% of all croplands. • About 60–90% of the urban population in many emerging economies relies on septic tanks. • We offer several suggestions to mitigate water and food insecurity in emerging economies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Irrigated crops showed varied impact on the hydraulic and solute exchange to the river. • Annual flow to the river under almond was 2.1 times higher than wine grapes. • 20, 60, and 40 m buffers needed for grapes, almond, and annual horticulture, respectively, to control solutes to the river. • Solute residence time was twice long for grapes compared to almonds and annual horticulture. Abstract Riparian zones are essential to preserve water quality of rivers adjacent to large areas of irrigated agriculture. We used HYDRUS (2D/3D) to quantify the long-term (8 years) influence of crops (almonds, wine grapes and potato-carrot) irrigated with recycled water on water and solute exchange at the Gawler River interface in relation to vegetation buffer widths from 10 to 110 m. We found that under almond and annual horticulture the likely average annual water flow from the irrigated area to the river was nearly twice as much (2.1 and 1.8, respectively) that under wine grapes. The hydraulic exchange at river interface for different irrigated crops was found to be sensitive to the buffer widths. For wine grapes, almonds and annual horticulture, the average annual hydraulic balance reached an equilibrium at 20, 65 and 55 m buffer widths, respectively. Furthermore, for wine grapes, with a 20 m buffer width, the average annual load of salts became negligible. This study shows that buffer widths of 20, 60, and 40 m for irrigated wine grapes, almond, and annual horticulture, respectively, are needed to restrict the migration of salts to the river. Further refinements are possible by incorporating the influence of preferential flow paths, improved water stress response functions, and addressing the data limitations for calibration of the model for solute dynamics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Chlorine has a higher reactivity with oxazepam than with diazepam. • pH affects the kinetic rate constants by impacting the reactant species of reactants. • The C-3 of 1,4-benzodiazepine structure is the main site of attack. • Transformation products will be comparatively stable during chlorination process. Abstract The pharmaceutical benzodiazepine diazepam and its metabolite oxazepam have been detected in wastewater treatment plants effluents, surface water and treated drinking water, but their transformation during chlorination process is not well understood. We investigated the reactions of diazepam and oxazepam with free available chlorine using a high-resolution mass analyzer and theoretical calculation to elucidate the fate of benzodiazepines during water chlorination process. The obtained apparent second-order rate constants (k app) for chlorine reaction with diazepam and oxazepam varied from 0.01 to 1.7 M−1 s−1 and 0.7 to 31.6 M−1 s−1 in the pH range of 5.5–10.0, respectively. Under typical wastewater disinfection conditions of neutral pH values, free chlorine concentrations of 5 mg L−1 and contact times of up to 2 h, the corresponding half-lives for diazepam (∼180 min) and oxazepam (∼61 min) suggest that diazepam will be partly transformed during disinfection. Conversely, oxazepam will be considerably transformed during wastewater disinfection. The pH-dependency of k app for diazepam could be explained by the reactions between neutral diazepam and HClO species. The kinetic pattern for oxazepam can be well described by species-specific reactions involving oxazepam or Cl 2 and Cl 2 O species. In total, fifteen and eight transformation products were identified for chlorination of diazepam and oxazepam, respectively. The C-3 of 1,4-benzodiazepine structure was the main site of attack, leading predominantly to the oxidation and then cleavage of the C(3)-N(4) bond, as well as diazepine ring contractions. Based on mass balance estimation, the main chlorination product for diazepam and oxazepam are 7-chloro-1-methyl-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2,3-dione and 6-chloro-4-phenyl-2(1H)-quinazolinone, respectively. [ABSTRACT FROM AUTHOR]

Widespread usage of per- and polyfluoroalkyl substances (PFASs) has caused major environmental contamination globally. The hydrophilic and hydrophobic properties of PFASs affect the sorption behaviour and suggest organic carbon may not be the only factor affecting sorption. We reviewed the quality of all data published in peer-reviewed literature on sorption of PFASs to critically evaluate the role organic carbon (OC) and other properties have in sorption of PFASs in soils or sediments. The largest data sets available were for perfluorooctanoic acid (PFOA, n = 147) and perfluorooctane sulfonic acid (PFOS, n = 178), and these analyses showed very weak correlations between sorption coefficient (K d ) and OC alone (R 2  = 0.05–0.07). When only laboratory-derived K d values of PFASs and OC were analysed, the R 2 values increased for PFOA (R 2  = 0.24, n = 42), PFOS (R 2  = 0.38, n = 69), perfluorononanoic acid (PFNA, R 2  = 0.77 n = 12), and perfluorodecanoic acid (PFDA, R 2  = 0.78, n = 13). However, the relationships were heavily skewed by one or two high OC values. Similarly there was no significant relationship between K d values and pH for PFOS (R 2  = 0.06) and PFOA (R 2  = 0.07), across a range of environmental pH values. Our analyses showed sorption behaviour of a range of PFASs could not be explained by a single soil or sediment property. Multiple regression models better explained the sorption behaviour of a number of PFASs. Regressions of OC and pH together explained a significant proportion of the variation in K d values for 9 out of 14 PFASs and 8 of these regressions had ≥10 data points. This review highlighted that at least OC, pH and clay content are properties having significant effect on sorption. There is a clear need for more data and studies with thorough characterisation of soils or sediments to better understand their role in PFASs sorption. Current assessments based on OC alone are likely to be erroneous. [ABSTRACT FROM AUTHOR]

• Overlooked contribution of PBMs towards the DBP formation was critically reviewed. • Elastomers, tire waste, polyelectrolytes, and MPs serve as potent DBP precursors. • Leached DOC and dissolved nitrogen from PBMs play a key role in DBP formation. • DBPs formation potential of polyelectrolytes was found as high as ∼2 mg/L. • DBPs formation potential of different microplastics ranged from 1.9 to 15,990 µg/L. Disinfection by-products (DBPs) are formed through the disinfection of water containing precursors such as natural organic matter or anthropogenic compounds (e.g., pharmaceuticals and pesticides). Due to the ever increasing use of plastics, elastomers, and other polymers in our daily lives, polymer-based materials (PBMs) are detected more frequently and at higher concentrations in water and wastewater. The present review provides a comprehensive and systematic analysis of the contribution of PBMs - including elastomers, tire waste, polyelectrolytes, and microplastics - as precursors of DBPs in water and wastewater. Literature shows that the presence of PBMs can lead to the leaching of dissolved organic matter (DOM) and subsequent formation of DBPs upon disinfection in aqueous media. The quantity and type of DBPs formed strongly depends on the type of polymer, its concentration, its age, water salinity, and disinfection conditions such as oxidant dosage, pH, temperature, and contact time. DOM leaching from elastomers and tire waste was shown to form N -nitrosodimethylamine up to concerning levels of 930 ng/L and 466,715 ng/L, respectively upon chemical disinfection under laboratory conditions. Polyelectrolytes can also react with chemical disinfectants to form toxic DBPs. Recent findings indicate trihalomethanes formation potential of plastics can be as high as 15,990 µg/L based on the maximum formation potential under extreme conditions. Our analysis highlights an overlooked contribution of DOM leaching from PBMs as DBP precursors during disinfection of water and wastewater. Further studies need to be conducted to ascertain the extent of this contribution in real water and wastewater treatment plants. [Display omitted] [ABSTRACT FROM AUTHOR]

Studies were undertaken to assess sorption of seven endocrine-disrupting chemicals (EDCs), namely, estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA), 4-tert-octyl phenol (4-t-OP), and 4-n-nonyl phenol (4-n-NP) on four soils (from sandy to clay soil) with different physicochemical properties and biodegradation of five EDCs (BPA, E2, EE2, 4-t-OP, and 4-n-NP) in a loam soil associated with wastewater reuse. We also characterized the biotransformation of E2 to E1 in the loam soil under aerobic and anaerobic conditions. Sorption test using a batch equilibrium method demonstrated that alkylphenols (4-t-OP and 4-n-NP) had the strongest sorption onto soils, followed by estrogens (EE2, E2, E1, E3) and BPA. This laboratory study showed that all five EDCs, including the degradation product E1, were degraded rapidly in the soil within 7 d under aerobic conditions. However, under anaerobic conditions in the soil, little or no degradation of the five EDCs was noted except for E2, which showed slow degradation during the 70-d study. The calculated half-lives for E2 under anaerobic conditions were 24 d in the soil. Estradiol was found to be biotransformed to E1 under both aerobic and anaerobic conditions. The study suggested that the five EDCs as well as E1, which may be present in reclaimed wastewater, would not persist in well-aerated soil. But these EDCs persisting in anaerobic soil may affect soil and groundwater quality and ecosystem. [ABSTRACT FROM AUTHOR]

Indaziflam is a relatively new herbicide for which sorption–desorption information is lacking, and nothing is available on its metabolites. Information is needed on the multiple soil and pesticide characteristics known to influence these processes. For four soils, the order of sorption was indaziflam (N-[1R,2S)-2,3-dihydro-2,6-dimethyl-1H-inden-1-yl]-6-[(1R)-1-fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam:Kf= 5.9, 1/nf= 0.7,Kfoc= 447; sandy loam:Kf= 3.9, 1/nf= 0.9,Kfoc= 276) > triazine indanone metabolite (N-[(1R,2S)-2,3-dihydro-2,6-dimethyl-3-oxo-1H-inden-1-yl]-6-[(1R)-1-fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam:Kf= 2.1, 1/nf= 0.8,Kfoc= 177; sandy loam:Kf= 1.7, 1/nf= 0.9,Kfoc= 118) > fluoroethyldiaminotriazine metabolite (6-[(1R-1-Fluoroethyl]-1,3,5-triazine-2,4-diamine) (sandy clay loam:Kf= 0.3, 1/nf= 0.9,Kfoc= 28; sandy loam:Kf= 0.3, 1/nf= 0.9,Kfoc= 22) = indaziflam carboxylic acid metabolite (2S,3R)-3-[[4-amino-6-[(1R)-1-fluoroethyl]-1,3,5-triazin-2-yl]amino]-2,3-dihydro-2-methyl-1H-indene-5-carboxylic acid) (sandy clay loam:Kf= 0.3, 1/nf= 0.9,Kfoc= 22; sandy loam:Kf= 0.5, 1/nf= 0.8,Kfoc= 32). The metabolites being more polar than the parent compound showed lower sorption. Desorption was hysteretic for indaziflam and triazine indanone metabolite, but not for the other two metabolites. Unsaturated transient flowKd's were lower than batchKd's for indaziflam, but similar for fluoroethyldiaminotriazine metabolite. BatchKd's would overpredict potential offsite transport if desorption hysteresis is not taken into account. [ABSTRACT FROM AUTHOR]

Batch experiments were conducted to evaluate the sorption-desorption behaviour of 14C-labelled carboxylic acids (citric and oxalic) and amino acids (glutamic, alanine, phenylalanine and lysine) on pure minerals (kaolinite, illite, montmorillonite, ferrihydrite and goethite). The sorption experiments were complemented by ATR-FTIR spectroscopy to gain possible mechanistic insight into the organic acids-mineral interactions. In terms of charge, the organic solutes ranged from strongly negative (i.e., citric) to positively charged solutes (i.e., lysine); similarly the mineral phases also ranged from positively to negatively charged surfaces. In general, sorption of anionic carboxylic and glutamic acids was higher compared to the other compounds (except lysine). Cationic lysine showed a stronger affinity to permanently charged phyllosilicates than Fe oxides. The sorption of alanine and phenylalanine was consistently low for all minerals, with relatively higher sorption and lower desorption of phenylalanine than alanine. Overall, the role of carboxylic functional groups for the sorption and retention of these carboxylic and amino acids on Fe oxides (and kaolinite) and of amino group on 2:1 phyllosilicates was noticeable. Mineral properties (surface chemistry, specific surface area), chemistry of the organic compounds (pKa value, functional groups) and the equilibrium pH of the system together controlled the differences in sorption-desorption patterns. The results of this study aid to understand the effects of mineralogical and chemical factors that affect naturally occurring low molecular weight organic compounds sorption under field conditions. [ABSTRACT FROM AUTHOR]

Abstract: Imidazolinones are chiral herbicides, comprised of two enantiomers with differential herbicidal activity. In this study, the selective degradation of enantiomers of the three imidazolinone herbicides, imazapyr, imazethapyr and imazaquin, was determined in a variety of soils selected to cover a broad range of physico-chemical characteristics. The R(+) enantiomer of all three herbicides, which has greater herbicidal activity (up to eight times), was found to degrade faster than the less active S(−) enantiomer. The enantiomer fraction (EF) was used as a descriptor of enantio-selectivity of the imidazolinone herbicides. The EF values increased with increasing incubation time for imidazolinones with a fast initial phase followed by a slower phase. While the enantio-selectivity was not significant in acidic soils (pHw 5.02 and 5.20), it was highly significant (P <0.001) in alkaline soils (pHw 7.6, 8.2 and 8.7). Significant positive correlations of EF values of imazapyr (P <0.001, R 2 =0.41), imazethapyr (P <0.002, R 2 =0.47) and imazaquin (P <0.001, R 2 =0.54) were found with the soil pHw ranging from 5.02 to 8.7. However, no correlation of EF was found with other soil properties. In addition to showing enantioselective degradation of the three herbicides in the soils studied, the study highlighted that for imidazolinones the herbicidally more active enantiomer can be preferably degraded by microorganisms. [Copyright &y& Elsevier]

The present study assessed contamination and toxicity of sediments from seven remediated and remnant wetland sites within Sydney Olympic Park, Australia, and four unremediated Sites adjacent to its boundary using chemical analysis and a luminescent bacterial biosensor assay (Escherichia coli). Concentrations of metals (Pb, Cr, Cu, Ni, Zn, Cd, and As) and persistent organic chemicals (DDT and its metabolites, dichlorodiphenyldichloroethane and dichlorodiphenyldichloroethylene; polycyclic aromatic hydrocarbons; polychlorinated biphenyls; and polychlorinated dibenzo-p-dioxins and dibenzofurans) in sediments and their pore-water samples were determined. Zinc concentrations were the highest of the metals in the sediments (84-618 mg/kg), and at eight sites, metal concentrations in sediments exceeded the Australian ecological trigger values for Pb, Zn, and Ni. Concentrations of organic contaminants in the sediments exceeded the trigger values at all 11 sites for DDTs, at 6 sites for polycyclic aromatic hydrocarbons, and 5 sites for polychlorinated biphenyls. Sediment samples from the four unremediated sites outside the Sydney Olympic Park had dioxin concentrations greater than 200 pg (toxic equivalency per gram). The same four sites were identified as contaminated in pore-water toxicity tests with the luminescent biosensor, generally consistent with the bioavailable fractions of the contaminants (pore-water and Tenax® extraction data), as well as dioxin levels, in the sediments. Preliminary toxicity identification and evaluation tests of the pore water from the four sites outside the park demonstrated that organic contaminants were the main cause of toxicity to E. coli, with no evidence that metals contributed to the toxicity of the pore water. [ABSTRACT FROM AUTHOR]

Abstract: The effect of solvent-conditioning on the sorption of diuron and phenanthrene was investigated. The organic carbon-normalized sorption coefficients (K OC) for diuron and phenanthrene (determined from single initial concentrations of 0.8mgL−1 and 1.5mgL−1, respectively) were consistently higher following solvent-conditioning of a whole soil with five organic solvents (acetonitrile, acetone, methanol, chloroform and dichloromethane). The relative increase in K OC was inversely related to the polarity of the conditioning solvent (i.e. greater increases in K OC were observed for the least polar solvents: chloroform and dichloromethane). The effect of solvent-conditioning on the sorption properties of the same soil that had been lipid-extracted using accelerated solvent extraction (ASE) was also investigated. Since lipid extraction involves treatment with a non-polar solvent (95:5 dichloromethane:methanol) one may have expected no further increase in K OC on solvent-conditioning. On the contrary, the lipid-extracted soil exhibited very similar increases in K OC as the whole soil. This demonstrated that lipid removal and solvent-conditioning, which both increased K OC for this soil, are quite separate phenomena. [Copyright &y& Elsevier]

Abstract: We investigated the effectiveness of two types of biochars in reducing the bioavailability of two soil-applied insecticides (chlorpyrifos and carbofuran) to Spring onion (Allium cepa). The biochars prepared from the pyrolysis of Eucalyptus spp. wood chips at 450 and 850°C (BC850) were thoroughly mixed into the soil to achieve 0%, 0.1%, 0.5% and 1% by soil weight. A spring onion crop was grown for 5 wk in the biochar-amended soils spiked with 50mgkg−1 of each pesticide. The loss of both pesticides due to degradation and or sequestration in soils decreased significantly with increasing amounts of biochars in soil. Over 35 d, 86–88% of the pesticides were lost from the control soil, whereas it was only 51% of carbofuran and 44% of chlorpyrifos from the soil amended with 1.0% BC850. Despite greater persistence of the pesticide residues in biochar-amended soils, the plant uptake of pesticides decreased markedly with increasing biochar content of the soil. With 1% of BC850 soil amendment, the total plant residues for chlorpyrifos and carbofuran decreased to 10% and 25% of that in the control treatment, respectively. The BC850 was particularly effective in reducing phytoavailability of both pesticides from soil, due to its high affinity for and ability to sequester pesticide residues. [Copyright &y& Elsevier]

Both visible near-infrared (VNIR) and mid-infrared (MIR) spectroscopy have been claimed to better predict pesticide sorption in soils than other methods. We compared the performances of VNIR and MIR spectroscopy for predicting both organic carbon content (foc) and the sorption affinity (Kd) of diuron in 112 surface soils from South Australia. Separate calibration models were developed between VNIR and MIR spectra, and foc and Kd using partial least-squares (PLS) regression. MIR clearly outperformed VNIR for predictions of both foc and Kd in soils. Correlation (R²) and accuracy (RPD) indices were 0.4 and 1.3 for the VNIR-PLS model versus 0.8 and 2.3 for the MIR-PLS model, respectively, for Kd prediction. PLS loadings for sorption prediction were compared in terms of the soil information they contained. While VNIR loading did not include any direct spectral information regarding soil minerals, MIR loading included peaks associated with sand, clays, and carbonates. Perhaps by better predicting foc and integrating the effects of OC as well as minerals, the MIR- PLS model provided a better prediction for diuron Kd values in our calibration set. [ABSTRACT FROM AUTHOR]

The influence of lipids on the sorption of diuron and phenanthrene to soils was investigated. Accelerated solvent extraction (ASE) was used to extract lipids from twelve soil horizons. Extractable lipids accounted for 3–13% of organic C. The organic carbon-normalized sorption coefficients (K OC) for diuron and phenanthrene were consistently higher for the lipid-extracted soils than for the whole soils (average of 31% for diuron and 29% for phenanthrene), indicating that lipids compete for or block sorption sites on the organic matter. Sorption experiments on one pair of HF-treated soils indicated that the blocking effects of minerals and lipids are independent, since lipid extraction and HF-treatment combined increased K OC by more than either treatment alone. Lipids extracted from whole and HF-treated soils were very similar in composition, consisting predominantly of long-chain polymethylene structures. K OC of the lipid itself was lower than for any of the whole soils and soil fractions (lipid extracted and HF-treated) for diuron, but higher for phenanthrene. Solid-state 13C NMR spectra of the HF-treated soils before and after lipid extraction indicated that 15–20% of alkyl C was removed by ASE and that no other structures were affected. [Copyright &y& Elsevier]

Even though it is well established that soil C content is the primary determinant of the sorption affinity of soils for non-ionic compounds, it is also clear that organic carbon-normalized sorption coefficients (K OC) vary considerably between soils. Two factors that may contribute to K OC variability are variations in organic matter chemistry between soils and interactions between organic matter and soil minerals. Here, we quantify these effects for two non-ionic sorbates—diuron and phenanthrene. The effect of organic matter–mineral interactions were evaluated by comparing K OC for demineralized (HF-treated) soils, with K OC for the corresponding whole soils. For diuron and phenanthrene, average ratios of K OC of the HF-treated soils to K OC of the whole soils were 2.5 and 2.3, respectively, indicating a substantial depression of K OC due to the presence of minerals in the whole soils. The effect of organic matter chemistry was determined by correlating K OC against distributions of C types determined using solid-state 13C NMR spectroscopy. For diuron, K OC was positively correlated with aryl C and negatively correlated with O-alkyl C, for both whole and HF-treated soils, whereas for phenanthrene, these correlations were only present for the HF-treated soils. We suggest that the lack of a clear effect of organic matter chemistry on whole soil K OC for phenanthrene is due to an over-riding influence of organic matter–mineral interactions in this case. This hypothesis is supported by a correlation between the increase in K OC on HF-treatment and the soil clay content for phenanthrene, but not for diuron. [Copyright &y& Elsevier]

We investigated the effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia. The quantification of genes involved in the biogeochemical cycling of carbon and nitrogen was used to assess potential impacts on ecosystem functions. The effects of disturbance on bacterial community structure were assessed by PCR- denaturing gradient gel electrophoresis of 16S rRNA genes, and clone library analysis was used to phylogenetically characterize significant shifts. Significant (P < 0.05) shifts in bacterial community structures were associated with alteration of the sediment's physicochemical properties, particularly nutrient loading from the WWTP discharge. The effects were greatest at the sampling location 400 m downstream of the outfall where the stream flow is reduced. This highly affected stretch of sediment contained representatives of the gammaproteobacteria that were absent from less-disturbed sites, including Oceanospirillales and Methylococcaceae. 16S rRNA gene sequences from less-disturbed sites had representatives of the Caulobacteraceae, Sphingomonadaceae, and Nitrospirae which were not represented in samples from disturbed sediment. The diversity was lowest at the reference site; it increased with proximity to the WWTP outfall and declined toward highly disturbed (400 m downstream) sites (P < 0.05). The potential for biological transformations of N varied significantly with the stream sediment location (P < 0.05). The abundance of amoA, narG, and nifH genes increased with the distance downstream of the outfall. These processes are driven by N and C availability, as well as redox conditions. Together these data suggest cause and effect between nutrient loading into the creek, shift in bacterial communities through habitat change, and alteration of capacity for biogeochemical cycling of N. [ABSTRACT FROM AUTHOR]

Abstract: Organic matter has long been recognized as the main sorbent phase in soils for hydrophobic organic compounds (HOCs). In recent times, there has been an increasing realization that not only the amount, but also the chemical composition, of organic matter can influence the sorption properties of a soil. Here, we show that the organic carbon-normalized sorption coefficient (K OC) for diuron is 27–81% higher in 10 A11 horizons than in 10 matching A12 horizons for soils collected from a small (2ha) field. K OC was generally greater for the deeper (B) horizons, although these values may be inflated by sorption of diuron to clays. Organic matter chemistry of the A11 and A12 horizons was determined using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. K OC was positively correlated with aryl C (r 2 =0.59, significance level 0.001) and negatively correlated with O-alkyl C (r 2 =0.84, significance level <0.001). This is only the second report of correlations between whole soil K OC and NMR-derived measures of organic matter chemistry. We suggest that this success may be a consequence of limiting this study to a very small area (a single field). There is growing evidence that interactions between organic matter and clay minerals strongly affect K OC. However, because the soil mineralogy varies little across the field, the influence of these interactions is greatly diminished, allowing the effect of organic matter chemistry on K OC to be seen clearly. This study in some way reconciles studies that show strong correlations between K OC and the chemistry of purified organic materials and the general lack of such correlations for whole soils. [Copyright &y& Elsevier]

The transport and bioavailability of cadmium is governed mainly by its adsorption–desorption reactions with minerals such as goethite—a common iron oxide mineral in variable charged and highly weathered tropical soils. Soil factors such as pH, temperature, solution Cd concentration, ionic strength and ageing affect Cd adsorption on goethite. The desorption behaviour of Cd from goethite at low concentrations is not fully understood. This study investigates the adsorption–desorption of Cd at low Cd concentrations (Cd adsorbed on goethite from 20 to 300μM Cd solutions) in Na and Ca nitrate solutions of 0.03M nominal ionic strengths.Synthetic goethite prepared by ageing a ferric hydroxide gel at high pH and room temperature was used for Cd adsorption and desorption studies. For desorption experiment 10 successive desorptions were made for the whole range of initial Cd concentrations (20–300μM) in the presence of 0.01M Ca(NO3)2 or 0.03M NaNO3 solutions.Cadmium adsorption was found to be higher in Na+ than Ca2+ probably due to the competition of Ca2+ ions with Cd2+ ions for adsorption sites on the surfaces of goethite. The effect of index cation on Cd adsorption diminished with increase in pH from 5.0 to 6.0. Cadmium desorption decreased with increase in pH from 5.0 to 6.0 in both Na and Ca systems. After 10 successive desorptions with 0.03M NaNO3 at the lowest initially adsorbed Cd approximately 45%, 20% and 7% of the adsorbed Cd was desorbed at pH 5.0, 5.5 and 6.0, respectively. The corresponding desorptions in the presence of 0.01M Ca(NO3)2 were 49%, 22% and 8%, respectively. The Freundlich parameter, k, based on each progressive step of desorption at different adsorbed concentration increased with increasing desorption step, which may indicates that a fraction of Cd was resistant to desorption. Low Cd desorbability from goethite may be due to its specific adsorption and/or possibly as a result of Cd entrapment in the cracks or defects in goethite structure. [Copyright &y& Elsevier]

The ability of rhizosphere of four plant species to promote the degradation of charcoal-fixed atrazine and simazine in cement blocks of a long-term contaminated soil when mixed with a normal soil at 1:1 ratio was tested. Of the four selected plants viz., rye grass (Lolium perenne), tall fescue (Festuca arundinacae), Pennisetum (Pennisetum clandestinum) and a spring onion (Allium sp.) used in this study, only P. clandestinum was able to survive in herbicide contaminated soil while other plants died within few days after germination/transplanting. Both atrazine and simazine were degraded at a faster rate in contaminated soil planted to P. clandestinum than in unplanted soil. Within 80 days, nearly 45% and 52% of atrazine and simazine, respectively, were degraded in soil planted to P. clandestinum while only 22% and 20% of the respective herbicide were degraded in the unplanted soil. During 80-day experimental period, both microbial biomass and soil dehydrogenase activity were significantly increased (7-fold) in soil planted to P. clandestinum over that in unplanted soil. The suspension of contaminated rhizosphere soil, planted to P. clandestinum exhibited an exceptional capability to degrade both atrazine (300 μg) and simazine (50 μg) in a mineral salts medium over that of non-rhizosphere soil suspension. Results indicate that P. clandestinum, a C4 plant, may be useful for remediation of soils contaminated with atrazine and simazine. [Copyright &y& Elsevier]

The aim of this study was to establish partitioning coefficients (K d) of perfluorooctanoic acid (PFOA) in a wide range of soils and determine if those values can be predicted from soil properties using multiple linear regression (MLR) and from infrared spectra of soils using partial least squares regression (PLSR). For 100 different soils, the K d values of spiked radiolabelled 14C-PFOA ranged from 0.6 to 14.8 L/kg and significantly decreased with soil depth (p < 0.05) due to soil properties that change with depth. The MLR modelling revealed that PFOA sorption was significantly (p < 0.05) influenced, in decreasing order, by organic carbon (OC) content, silt-plus-clay content and soil pH. Soils were partitioned into all soils and surface soils alone. The MLR models using OC, silt-plus-clay content and pH together explained most of the variation in sorption in all soils as well as surface soils alone (0-15 cm). However, correlations between soil properties and K d values in some soils could not be explained by the MLR model. Modelling of K d prediction in soils with PLSR and diffuse reflectance (mid) infrared Fourier transform spectroscopy (DRIFT) showed comparable success in explaining the predictions of K d values, including some of the outliers identified in the MLR model. The PLSR loading weights suggested that quartz, and possibly pyrophyllite minerals, were inversely correlated with the K d values. Given that MLR requires a-priori characterisation of a range of soil properties and PLSR-DRIFT is a method based on the direct relationship between spectra and soil components, mid-infrared spectroscopy may be a more economical and rapid technique to predict the solid-liquid partitioning of PFOA in soils. Unlabelled Image • Measured data on K d values for 100 Australian soils for PFOA • Key soil properties identified to predict sorption using MLR and DRIFT-PLSR • Sorption decreases with increasing depth in soil profile. • DRIFT-PLSR offers a better model to predict K d from soil properties than MLR. [ABSTRACT FROM AUTHOR]