Polar pollutants in municipal wastewater and the water cycle: Occurrence and removal of benzotriazoles

1H-benzo-1,2,3-triazole (BTri) and its methylated analogues (tolyltriazole, TTri) are corrosion inhibitors used in many industrial applications, but also in households in dishwashing agents and in deicing fluids at airports and elsewhere. BTri and one of the TTri-isomers (4-TTri) are typical examples of polar and poorly degradable trace pollutants. Benzotriazole elimination in four wastewater treatment plants (WWTP) in Berlin ranged from 20 to 70% for 5-TTRi over 30 to 55% for BTri to insignificant for 4-TTri. WWTP effluent concentrations were in the range of 7-18 μg/L of BTri, 1-5 μg/L of 4-TTri and 0.8-1.2 μg/L of 5-TTri. BTri and 4-TTri proved to be omnipresent in surface waters of the rivers Rhine and Elbe with concentrations increasing from <0.05 μg/L to around 0.5 μg/L of BTri and 0.2-0.5 μg/L of 4-TTri over 600-700 km. Bank filtration is an important process to generate raw water for drinking water production from surface waters. Even after residence times of several months BTri and 4-TTri were determined in concentrations of a few hundred ng/L in bank filtration water. Isotherm data from batch experiments indicate that activated carbon filtration should be suitable to avoid intrusion of TTri into drinking water in partially closed water cycles. For BTri, however, sorption to activated carbon appears to be too weak and ozonation may be mandatory to remove it from raw waters.     

Occurrence and removal of N-nitrosamines in wastewater treatment plants

The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 μg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage. Aqueous removal efficiencies in activated sludge treatment were in general above 40% for NMOR and above 60% for the other nitrosamines, but could be lower if concentrations were below 8-15 ng/L in primary effluent. We hypothesize that substrate competition in the cometabolic degradation explains the occurrence of such threshold concentrations. An additional sand filtration step resulted in a further removal of nitrosamines from secondary effluents even at low concentrations. Concentrations released to surface waters were largely below 10 ng/L, suggesting a low impact on Swiss water resources and drinking water generation considering the generally high environmental dilution and possible degradation. However, local impacts in case a larger fraction of wastewater is present cannot be ruled out.     

Fate of hormones and pharmaceuticals during combined anaerobic treatment and nitrogen removal by partial nitritation-anammox in vacuum collected black water

Vacuum collected black (toilet) water contains hormones and pharmaceuticals in relatively high concentrations (μg/L to mg/L range) and separate specific treatment has the potential of minimizing their discharge to surface waters. In this study, the fate of estrogens (natural and synthetical hormones) and pharmaceuticals (paracetamol, metoprolol, propranolol, cetirizine, doxycycline, tetracycline, ciprofloxacin, trimethoprim, carbamazepine, ibuprofen and diclofenac) in the anaerobic treatment of vacuum collected black water followed by nitrogen removal by partial nitritation-anammox was investigated. A new analytical method was developed to detect the presence of several compounds in the complex matrix of concentrated black water. Detected concentrations in black water ranged from 1.1 μg/L for carbamazepine to >1000 μg/L for paracetamol. Anaerobic treatment was only suitable to remove the majority of paracetamol (>90%). Metoprolol was partly removed (67%) during aerobic treatment. Deconjugation could have affected the removal efficiency of ibuprofen as concentrations even increased during anaerobic treatment and only after the anammox treatment 77% of ibuprofen was removed. The presence of persistent micro-pollutants (diclofenac, carbamazepine and cetirizine), which are not susceptible for biodegradation, makes the application of advanced physical and chemical treatment unavoidable.     

Nutrient level, microbial activity, and alachlor transformation in aerobic aquatic systems

Alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide) is a moderately toxic herbicide that is frequently found in agriculturally impacted surface waters. To assess primary mechanism(s) that affect its fate in aquatic systems, two field experiments were performed using large mesocosms (n=39) and smaller microcosms with and without microbial inhibitors (n=16). The mesocosm experiment tested the effect of fertility conditions on alachlor fate, assessing alachlor disappearance over time under oligotrophic (total phosphorus (TP) <12 μg/L) through hypereutrophic (TP>80 μg/L) water conditions. Whereas, the microcosm experiment assessed alachlor fate in the presence of microbial inhibitors that selectively blocked eubacterial (chloroamphenicol, streptomycin, and penicillin combined), eukaryotic (cycloheximide), and universal (all inhibitors) microbial activity. First-order alachlor transformation rate coefficients ranged from 0.006 to 0.042 day⁻¹ when microbial inhibitors were not present (half-lives from 16 to 122 days) with the highest rates occurring in hypereutrophic waters. Statistics indicated that mean TP, and universal and eubacterial small sub-unit rRNA level most closely correlated with transformation rate. Further, the inhibitor study indicated that alachlor transformation was biotic (>90%), but that high transformation rates only occurred when eubacterial and eukaryotic domains were both metabolically active. Our results confirm that alachlor transformation is primarily biotic; however, efficient biotransformation only occurs when both major microbial domains in aerobic systems are active.     

Comparing steroid estrogen, and nonylphenol content across a range of European sewage plants with different treatment and management practices

The effluent of 17 sewage treatment works (STW) across Norway, Sweden, Finland, The Netherlands, Belgium, Germany, France and Switzerland was studied for the presence of estradiol (E2), estrone (E1), ethinylestradiol (EE2) and nonylphenol (NP). Treatment processes included primary and chemical treatment only, submerged aerated filter, oxidation ditch, activated sludge (AS) and combined trickling filter with activated sludge. The effluent strength ranged between 87 and 846 L/PE (population equivalent), the total hydraulic retention time (HRT) ranged between 4 and 120 h, sludge retention time (SRT) between 3 and 30 d, and water temperature ranged from 12 to 21 °C. The highest estrogen values were detected in the effluent of the STW which only used primary treatment (13 ng/L E2 and 35 ng/L E1) and on one occasion in one of the STW using the AS system (6.5 ng/L E2, 50.5 ng/L E1, but on three other occasions the concentrations in this STW were at least a factor of 6 lower). For the 16 STW employing secondary treatment E2 was only detected in the effluent of six works during the study period (average 0.7-5.7 ng/L). E1 was detected in the effluent of 13 of the same STW. The median value for E1 for the 16 STW with secondary treatment was 3.0 ng/L. EE2 was only detected in two STW (1.1, <0.8-2.8 ng/L). NP could be detected in the effluent of all 14 STW where this measurement was attempted, with a median of 0.31 μg/L and values ranging from 0.05 to 1.31 μg/L. A comparison of removal performance for E1 was carried out following prediction of the probable influent concentration. A weak but significant (α<5%) correlation between E1 removal and HRT or SRT was observed.     

Mineralogical and geochemical controls of arsenic speciation and mobility under different redox conditions in soil, sediment and water at the Mokrsko-West gold deposit, Czech Republic

Naturally contaminated soil, sediment and water at the Mokrsko-West gold deposit, Central Bohemia, have been studied in order to determine the processes that lead to release of As into water and to control its speciation under various redox conditions. In soils, As is bonded mainly to secondary arseniosiderite, pharmacosiderite and Fe oxyhydroxides and, rarely, to scorodite; in sediments, As is bonded mainly to Fe oxyhydroxides and rarely to arsenate minerals.The highest concentrations of dissolved As were found in groundwater (up to 1141 μg L^− 1), which mostly represented a redox transition zone where neither sulphide minerals nor Fe oxyhydroxide are stable. The main processes releasing dissolved As in this zone are attributed to the reductive dissolution of Fe oxyhydroxides and arsenate minerals, resulting in a substantial decrease in their amounts below the groundwater level. Some shallow subsurface environments with high organic matter contents were characterized by reducing conditions that indicated a relatively high amount of S^− 2,0 in the solid phase and a lower dissolved As concentration (70-80 μg L^− 1) in the pore water. These findings are attributed to the formation of Fe(II) sulphides with the sorbed As. Under oxidizing conditions, surface waters were undersaturated with respect to arsenate minerals and this promoted the dissolution of secondary arsenates and increased the As concentrations in the water to characteristic values from 300 to 450 μg L^− 1 in the stream and fishpond waters. The levels of dissolved As(III) often predominate over As(V) levels, both in groundwaters and in surface waters. The As(III)/As(V) ratio is closely related to the DOC concentration and this could support the assumption of a key role of microbial processes in transformations of aqueous As species as well as in the mobility of As.     

Screening of antimycotics in Swedish sewage treatment plants - Waters and sludge

Concentrations of six pharmaceutical antimycotics were determined in the sewage water, final effluent and sludge of five Swedish sewage treatment plants (STPs) by solid phase extraction, liquid/solid extraction, and liquid chromatography-electrospray tandem mass spectrometry. The antimycotics were quantified by internal standard calibration. The results were used to estimate national flows that were compared to predictions based on sales figures. Fluconazole was the only one of the six investigated antimycotics that was detected (at concentrations ranging from 90 to 140 ng L⁻¹) in both raw sewage water and final effluent. Negligible amounts of this substance were removed from the aqueous phase, and its levels were below the limit of quantification in all of the analyzed sludge samples. In contrast, clotrimazole, ketoconazole and econazole were present in all of the sludge samples, at concentrations ranging between 200 and 1000 μg kg⁻¹, dry weight. There were close correlations between the national measured and predicted antimycotic mass flows. Antimycotic fate analysis, based on sales figures, indicated that 53% of the total amount of fluconazole sold appeared in the final effluents of the STPs, while 1, 155, 35, 209 and 41% of the terbinafine, clotrimazole, ketoconazole, econazole and miconazole sold appeared in the digested dewatered sludge.     

Arsenic accumulation in irrigated agricultural soils in Northern Greece

The accumulation of arsenic in soils and food crops due to the use of arsenic contaminated groundwater for irrigation has created worldwide concern. In the Chalkidiki prefecture in Northern Greece, groundwater As reach levels above 1000 μg/L within the Nea Triglia geothermal area. While this groundwater is no longer used for drinking, it represents the sole source for irrigation.This paper provides a first assessment of the spatial extent of As accumulation and of As mobility during rainfall and irrigation periods. Arsenic content in sampled soils ranged from 20 to 513 mg/kg inside to 5-66 mg/kg outside the geothermal area. Around irrigation sprinklers, high As concentrations extended horizontally to distances of at least 1.5 m, and to 50 cm in depth. During simulated rain events in soil columns (pH = 5, 0 μg As/L), accumulated As was quite mobile, resulting in porewater As concentrations of 500-1500 μg/L and exposing plant roots to high As(V) concentrations. In experiments with irrigation water (pH = 7.5, 1500 μg As/L), As was strongly retained (50.5-99.5%) by the majority of the soils. Uncontaminated soils (< 30 mg As/kg) kept soil porewater As concentrations to below 50 μg/L. An estimated retardation factor R_f = 434 for weakly contaminated soil (< 100 mg/kg) indicates good ability to reduce As mobility. Highly contaminated soils (> 500 mg/kg) could not retain any of the added As. Invoked mechanisms affecting As mobility in those soils were adsorption on solid phases such as Fe/Mn-phases and As co-precipitation with Ca. Low As accumulation was found in collected olives (0.3-25 μg/kg in flesh and 0.3-5.6 μg/kg in pits). However, soil arsenic concentrations are frequently elevated to far above recommended levels and arsenic uptake in faster growing plants has to be assessed.     

Toxic cyanobacterial breakthrough and accumulation in a drinking water plant: a monitoring and treatment challenge

The detection of cyanobacteria and their associated toxins has intensified in recent years in both drinking water sources and the raw water of drinking water treatment plants (DWTPs). The objectives of this study were to: 1) estimate the breakthrough and accumulation of toxic cyanobacteria in water, scums and sludge inside a DWTP, and 2) to determine whether chlorination can be an efficient barrier to the prevention of cyanotoxin breakthrough in drinking water. In a full scale DWTP, the fate of cyanobacteria and their associated toxins was studied after the addition of coagulant and powdered activated carbon, post clarification, within the clarifier sludge bed, after filtration and final chlorination. Elevated cyanobacterial cell numbers (4.7 × 10⁶ cells/mL) and total microcystins concentrations (up to 10 mg/L) accumulated in the clarifiers of the treatment plant. Breakthrough of cells and toxins in filtered water was observed. Also, a total microcystins concentration of 2.47 μg/L was measured in chlorinated drinking water. Cyanobacterial cells and toxins from environmental bloom samples were more resistant to chlorination than results obtained using laboratory cultured cells and dissolved standard toxins.     

Relating nutrient and herbicide fate with landscape features and characteristics of 15 subwatersheds in the Choptank River watershed

Excess nutrients and agrochemicals from non-point sources contribute to water quality impairment in the Chesapeake Bay watershed and their loading rates are related to land use, agricultural practices, hydrology, and pollutant fate and transport processes. In this study, monthly baseflow stream samples from 15 agricultural subwatersheds of the Choptank River in Maryland USA (2005 to 2007) were characterized for nutrients, herbicides, and herbicide transformation products. High-resolution digital maps of land use and forested wetlands were derived from remote sensing imagery. Examination of landscape metrics and water quality data, partitioned according to hydrogeomorphic class, provided insight into the fate, delivery, and transport mechanisms associated with agricultural pollutants. Mean Nitrate-N concentrations (4.9 mg/L) were correlated positively with percent agriculture (R² = 0.56) and negatively with percent forest (R² = 0.60). Concentrations were greater (p = 0.0001) in the well-drained upland (WDU) hydrogeomorphic region than in poorly drained upland (PDU), reflecting increased denitrification and reduced agricultural land use intensity in the PDU landscape due to the prevalence of hydric soils. Atrazine and metolachlor concentrations (mean 0.29 μg/L and 0.19 μg/L) were also greater (p = 0.0001) in WDU subwatersheds than in PDU subwatersheds. Springtime herbicide concentrations exhibited a strong, positive correlation (R² = 0.90) with percent forest in the WDU subwatersheds but not in the PDU subwatersheds. In addition, forested riparian stream buffers in the WDU were more prevalent than in the PDU where forested patches are typically not located near streams, suggesting an alternative delivery mechanism whereby volatilized herbicides are captured by the riparian forest canopy and subsequently washed off during rainfall. Orthophosphate, CIAT (6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine), CEAT (6-chloro-N-ethyl-1,3,5-triazine-2,4-diamine), and MESA (2-[(2-ethyl-6-methylphenyl) (2-methoxy-1-methylethyl)amino]-2-oxoethanesulfonic acid) were also analyzed. These findings will assist efforts in targeting implementation of conservation practices to the most environmentally-critical areas within watersheds to achieve water quality improvements in a cost-effective manner.     

An updated weight of evidence approach to the aquatic hazard assessment of Bisphenol A and the derivation a new predicted no effect concentration (Pnec) using a non-parametric methodology

An aquatic hazard assessment establishes a derived predicted no effect concentration (PNEC) below which it is assumed that aquatic organisms will not suffer adverse effects from exposure to a chemical. An aquatic hazard assessment of the endocrine disruptor Bisphenol A [BPA; 2, 2-bis (4-hydroxyphenyl) propane] was conducted using a weight of evidence approach, using the ecotoxicological endpoints of survival, growth and development and reproduction. New evidence has emerged that suggests that the aquatic system may not be sufficiently protected from adverse effects of BPA exposure at the current PNEC value of 100 μg/L. It is with this background that; 1) An aquatic hazard assessment for BPA using a weight of evidence approach, was conducted, 2) A PNEC value was derived using a non parametric hazardous concentration for 5% of the specie (HC₅) approach and, 3) The derived BPA hazard assessment values were compared to aquatic environmental concentrations for BPA to determine, sufficient protectiveness from BPA exposure for aquatic species. A total of 61 studies yielded 94 no observed effect concentration (NOEC) and a toxicity dataset, which suggests that the aquatic effects of mortality, growth and development and reproduction are most likely to occur between the concentrations of 0.0483 μg/L and 2280 μg/L. This finding is within the range for aquatic adverse estrogenic effects reported in the literature. A PNEC of 0.06 μg/L was calculated. The 95% confidence interval was found to be (0.02, 3.40) μg/L. Thus, using the weight of evidence approach based on repeated measurements of these endpoints, the results indicate that currently observed BPA concentrations in surface waters exceed this newly derived PNEC value of 0.06 μg/L. This indicates that some aquatic receptors may be at risk for adverse effects on survival, growth and development and reproduction from BPA exposure at environmentally relevant concentrations.     

Occurrence and implications of estrogens and xenoestrogens in sewage effluents and receiving waters from South East Queensland

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.     

Potential for phytoextraction of PCBs from contaminated soils using weeds

A comprehensive investigation of the potential of twenty-seven different species of weeds to phytoextract polychlorinated biphenyls (PCBs) from contaminated soil was conducted at two field sites (Etobicoke and Lindsay) in southern Ontario, Canada. Soil concentrations were 31 μg/g and 4.7 μg/g at each site respectively. All species accumulated PCBs in their root and shoot tissues. Mean shoot concentrations at the two sites ranged from 0.42 μg/g for Chenopodium album to 35 μg/g for Vicia cracca (dry weight). Bioaccumulation factors (BAF = [PCB]_{plant tissue}/[PCB]_{mean soil}) at the two sites ranged from 0.08 for Cirsium vulgare to 1.1 for V. cracca. Maximum shoot extractions were 420 µg for Solidago canadensis at the Etobicoke site, and 120 µg for Chrysanthemum leucanthemum at the Lindsay site. When plant density was taken into account with a theoretical density value, seventeen species appeared to be able to extract a similar or greater quantity of PCBs into the shoot tissue than pumpkins (Curcurbita pepo ssp. pepo) which are known PCB accumulators. Therefore, some of these weed species are promising candidates for future phytoremediation studies.     

Cross-phylum extrapolation of the Daphnia magna chronic biotic ligand model for zinc to the snail Lymnaea stagnalis and the rotifer Brachionus calyciflorus

We investigated if the chronic zinc biotic ligand model (BLM) developed earlier for the arthropod Daphnia magna could be extrapolated to predict chronic ecotoxicity of zinc as a function of water chemistry to two species from other phyla, i.e. the mollusc Lymnaea stagnalis and the rotifer Brachionus calyciflorus. We chronically exposed these two species to zinc in six natural surface waters. These water covered a wide range of pH (6.8-8.3), dissolved organic carbon (1.2-12.7 mg/L) and Ca (8.8-118 mg/L). Across all waters tested, the 28d-EC10s (200-1629 μg Zn/L) and EC50s (382-2026 μg Zn/L) for L. stagnalis spanned a 8.1-fold and 5.3-fold range, respectively. The 2d-EC10s (142-550 μg Zn/L) and 2d-EC50s (195-1104 μg Zn/L) for B. calyciflorus spanned a 3.9-fold and 5.7-fold range, respectively. The data indicated that higher pH and higher concentrations of Ca and DOC were generally associated with lower toxicity (higher ECx values). Furthermore, the chronic Zn BLM for D. magna, when calibrated only to reflect the intrinsic sensitivity of L. stagnalis and B. calyciflorus, was able to predict all ECx values with a less than 1.6-fold error, which demonstrates that the chronic D. magna Zn BLM can be extrapolated to other invertebrate phyla. This lends further support to the use of the chronic Zn BLM to account for bioavailability of zinc in aquatic risk assessment and the derivation of environmental quality standards.     

Lead isotopes reveal different sources of lead in balsamic and other vinegars

Fifty-eight brands of balsamic vinegars were analyzed for lead concentrations and isotopic compositions (²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, and ²⁰⁸Pb) to test the findings of a previous study indicating relatively high levels of lead contamination in some of those vinegars — more than two thirds (70%) of them exceeded California's State Maximum Level (34 μg/L) based on consumption rates ≥ 0.5 μg Pb per day. The Lead isotopic fingerprints of all those vinegars with high lead concentrations were then found to be primarily anthropogenic. This isotopic analysis unquestionably reveals multiple contamination sources including atmospheric pollutant Pb and an unidentified contamination source, likely occurring after grape harvest. Organically grown grape vinegars display the same Pb content and isotopic signatures as other vinegars. This implies that pesticides might not be a significant source of pollutant Pb in vinegars. A significant post-harvest contamination would be inherited from chemicals added during production and/or material used during transport, processing or storage of these vinegars. This is consistent with the highest Pb levels being found in aged vinegars (112 ± 112 μg/L) in contrast to other vinegars (41.6 ± 28.9 μg/L) suggesting contamination during storage. It is, therefore, projected that lead levels in most vinegars, especially aged balsamic and wine vinegars, will decrease with improvements in their manufacture and storage processes consequential to recent concerns of elevated levels of lead in some vinegars.     

Validation of analysis of arsenic in water samples using Wagtech Digital Arsenator

Groundwater, the only source of potable water for millions of people in Bangladesh during dry season, is often contaminated with arsenic (As) above the allowable drinking water limit of 50 μg/L. Testing well water - with arsenic field test kits (FTKs) - and switching to safe-wells can effectively reduce exposure to As. FTKs are low cost, provide fast results, and are commercially available. There are between 10 and 11 million shallow tubewells in Bangladesh. Approximately, 5 million have been tested using FTKs. FTKs with color comparator rely on visual identification for generating qualitative results, which may not be highly reliable at the lower range because human eyes have low sensitivity in this range and sensitivity varies from person to person. The Wagtech Digital Arsenator does not suffer from this limitation and should, in theory, be able to generate quantitative, accurate, and reliable results. The instrument has a linear range of 0-100 μg/L, an accuracy of ± 20% for the 50 μg/L quality control standards, and a detection limit of about 4.4 μg/L. All Arsenators employed in this investigation also displayed high bias for 50 μg/L arsenic standard and were calibrated in order to improve measurement accuracy and reliability. Analyses of 179 raw and 92 treated well waters in the field and in two analytical laboratories were found to be highly correlated with the Spearman rank correlation coefficient of ≥ 0.800, indicating that Arsenator results are perhaps nearly as accurate and reliable as those from analytical laboratories.     

Occurrence of seven artificial sweeteners in the aquatic environment and precipitation of Tianjin,China

Seventy water samples, including wastewaters, tap waters, fresh surface waters, coastal waters, groundwaters, and precipitation samples, from Tianjin, China, were analyzed for seven commonly used artificial sweeteners (ASs). The concentrations of the investigated ASs were generally in the order of wastewater treatment plant (WWTP) influent > WWTP effluent > surface water > tap water > groundwater ≈ precipitation, while the composition profiles of ASs varied in different waters. Acesulfame, sucralose, cyclamate, and saccharin were consistently detected in surface waters and ranged from 50 ng/L to 0.12 mg/L, while acesulfame was the dominant AS in surface and tap waters. Aspartame was found in all of the surface waters at a concentration up to 0.21 μg/L, but was not found in groundwaters and tap waters. Neotame and neohesperidin dihydrochalcone were less frequently detected and the concentrations were low. The concentrations of the ASs in some of the surface waters were of the same order with those in the WWTP influents, but not with the effluents, indicating there are probably untreated discharges into the surface waters. The ASs were detected in precipitation samples with high frequency, and acesulfame, saccharin, and cyclamate were the predominant ASs, with concentrations ranging from 3.5 ng/L to 1.3 μg/L. A gross estimation revealed that precipitation may act as a source for saccharin and cyclamate in the surface environment of Tianjin city. Moreover, the presence of ASs in the atmosphere was primarily assessed by taking 4 air samples to evaluate their potential source in precipitation.     

Evaluation of the Abraxis Strip Test for Microcystins™ for use with wastewater effluent and reservoir water

Rapid tests for the microcystin-type cyanobacterial toxins that are designed to be able to be used in the field have recently become available. The tests provide a semi-quantitative result over a relatively narrow concentration range (10-fold) and are available with detection limits relevant for drinking water and recreational water compliance testing (1 μg/L and 10 μg/L, respectively). The aim of this research was to assess the applicability of these tests for the determination of microcystin-related toxicity in treated effluent from the Western Treatment Plant and potable source water from Tarago Reservoir, both near Melbourne, Australia. Accuracy, precision, cross-reactivity, matrix effects and inter-operator variability were assessed. The claimed mLR concentration response range of the tests was confirmed within reasonable limits, although the false negative and false positive rates were significant for spike concentrations below 2.5 μg/L (Recreational Strip Test). Inter-operator variability was reasonably high (CV = 23%) and this was exacerbated by the use of untrained scorers. Contributing to this was significant inter-assay variability in test band intensity (CV = 28%). The strip tests responded to all 8 microcystin analogues tested and also to a mixture of another 7 analogues contained in a Certified Bloom Material. Cross-reactivity was always greater than 50%. Matrix effects due to the test waters or to cyanobacterial cell material were also relatively minor, being of the order of 2-fold at the maximum. Overall, these Strip Tests were found to be reliable for relatively rapid detection of microcystins around the upper limits of their response ranges, as recommended by the manufacturer. While the Recreational Water Strip test was less reliable in the lower ranges, it can be used in conjunction with the Drinking Water Strip test to reduce uncertainty around the 1 μg/L concentration. Despite limitations, both strip tests provide near real-time information which can assist with day to day operational decisions. When results indicate microcystin concentrations near compliance limits it is recommended that use of the test kits should be supported by accurate quantitative toxin testing together with traditional algal cell counts, and possibly emerging qPCR methods for species and toxin gene detection.     

An assessment of the fate, behaviour and environmental risk associated with sunscreen TiO₂ nanoparticles in UK field scenarios

The fate of Ti was examined in an activated sludge plant serving over 200,000 people. These studies revealed a decrease of 30 to 3.2 μg/L of Ti < 0.45 μm from influent to effluent and a calculated Ti presence of 305 mg/kg DW in wasted sludge. Thus, using sludge as a fertiliser would result in a predicted deposition of up to 250 mg/m² of Ti to soil surfaces using a recommended maximal agricultural application rate. Given the major use of TiO₂ in many industrial and domestic applications where loss to the sewer is possible, this measured Ti was presumed to have been largely TiO₂, a proportion of which will be nanoparticle sized. To assess the behaviour of engineered nanoparticle (ENP) TiO₂ in sewage and toxicology studies, Optisol (Oxonica Materials Ltd) and P25 (Evonik Industries AG), which are representative of forms used in sunscreen and cosmetic products, were used. These revealed a close association of TiO₂ ENPs with activated sludge. Using commercial information on consumption, and removal rates for sewage treatment, predictions were made for river water concentrations for sunscreen TiO₂ ENPs for the Anglian and Thames regions in Southern England. The highest predicted value from these exercises was 8.8 μg/L for the Thames region in which it was assumed that one in four people used the recommended application of sunscreen during a low flow (Q95) period. Ecotoxicological studies using potentially vulnerable species indicated that 1000 μg/L TiO₂ ENP did not affect the viability of a mixed community of river bacteria in the presence of UV light. Direct exposure to TiO₂ ENPs did not impair the immuno-effectiveness of earthworm coelomocyte cells at concentrations greatly above those predicted for sewage sludge.     

Organochlorines and heavy metals in wild caught food as a potential human health risk to the indigenous Māori population of South Canterbury, New Zealand

Increasing concentrations of anthropogenic contaminants in wild kai (food) of cultural, recreational and economic importance to the indigenous Māori of New Zealand is a potential human health risk. Contaminants that are known to bioaccumulate through the food chain (e.g., organochlorine pesticides (OCPs), PCBs and selected heavy metals) were analysed in important kai species including eel (Anguilla sp.), brown trout (Salmo trutta), black flounder (Rhombosolea retiaria) and watercress (Nasturtium officinale) from important harvesting sites in the region of South Canterbury. Eels contained relatively high wet weight concentrations of p,p′-DDE (8.6-287 ng/g), PCBs (³²Σ_PCB; 0.53-58.3 ng/g), dieldrin (< 0.05-16.3 ng/g) and Σchlordanes (0.03-10.6 ng/g). Trout and flounder contained lower concentrations of organochlorines than eels, with p,p′-DDE wet weight concentrations ranging from 2.2 to 18.5 ng/g for trout and 6.4 to 27.8 ng/g for flounder. Total arsenic wet weight concentrations were below detection limits for eels but ranged from 0.27 to 0.89 μg/g for trout and 0.12 to 0.56 μg/g for flounder. Mercury concentrations ranged from 0.02 to 0.56 μg/g, 0.11 to 0.50 μg/g and 0.04 to 0.10 μg/g (ww) for eel, trout and flounder respectively. Lifetime excess cancer risk was calculated through established risk assessment procedures, highlighting dieldrin, ΣPCBs and p,p′-DDE in eels and arsenic in trout and flounder as primary contaminants of concern. A second non-cancer chronic health risk assessment indicated that mercury and PCBs were a potential concern in eels and mercury in trout. A cumulative lifetime cancer risk assessment showed potential health risk for consumption of some species, even at low consumption rates and provided the basis for establishing recommended dietary consumption limits for harvest sites within the study region.