Toxicity Evaluation and Effect-Based Identification of Chlorine Disinfection Products of the Anti-COVID-19 Drug Chloroquine Phosphate.

Antiviral transformation products (TPs) generated during wastewater treatment are an environmental concern, as their discharge, in considerable amounts, into natural waters during a pandemic can pose possible risks to the aquatic environment. Identification of the hazardous TPs generated from antivirals during wastewater treatment is important. Herein, chloroquine phosphate (CQP), which was widely used during the coronavirus disease-19 (COVID-19) pandemic, was selected for research. We investigated the TPs generated from CQP during water chlorination. Zebrafish (Danio rerio) embryos were used to assess the developmental toxicity of CQP after water chlorination, and hazardous TPs were estimated using effect-directed analysis (EDA). Principal component analysis revealed that the developmental toxicity induced by chlorinated samples could be relevant to the formation of some halogenated TPs. Fractionation of the hazardous chlorinated sample, along with the bioassay and chemical analysis, identified halogenated TP387 as the main hazardous TP contributing to the developmental toxicity induced by chlorinated samples. TP387 could also be formed in real wastewater during chlorination in environmentally relevant conditions. This study provides a scientific basis for the further assessment of environmental risks of CQP after water chlorination and describes a method for identifying unknown hazardous TPs generated from pharmaceuticals during wastewater treatment.

Removal of pharmaceutical in a biogenic/chemical manganese oxide system driven by manganese-oxidizing bacteria with humic acids as sole carbon source.

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition. In this study, a synthesized chemical manganese dioxide (MnO2)-coated quartz sand (MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn2+. We demonstrated a manganese-oxidizing bacterium, Pseudomonas sp. QJX-1, could oxidize Mn2+ to generate BioMnOx using humic acids (HA) as sole carbon source. The coaction of MnQS, QJX-1, and the generated BioMnOx in simultaneously removing caffeine and Mn2+ in the presence of HA was evaluated. We found a synergistic effect between them. MnQS and BioMnOx together significantly increased the caffeine removal efficiency from 32.8% (MnQS alone) and 21.5% (BioMnOx alone) to 61.2%. Meanwhile, Mn2+ leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx, which was beneficial for continuous contaminant removal and system stability. Different degradation intermediates of caffeine oxidized by MnQS and BioMnOx were detected by LC-QTOF-MS analysis, which implied that caffeine was oxidized by a different pathway. Overall, this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.

Mixing regime shapes the community assembly process, microbial interaction and proliferation of cyanobacterial species Planktothrix in a stratified lake.

Lake mixing influences aquatic chemical properties and microbial community composition, and thus, we hypothesized that it would alter microbial community assembly and interaction. To clarify this issue, we explored the community assembly processes and cooccurrence networks in four seasons at two depths (epilimnion and hypolimnion) in a mesotrophic and stratified lake (Chenghai Lake), which formed stratification in the summer and turnover in the winter. During the stratification period, the epilimnion and hypolimnion went through contrary assembly processes but converged to similar assembly patterns in the mixing period. In a highly homogeneous selection environment, species with low niche breadth were filtered, resulting in decreased species richness. Water mixing in the winter homogenized the environment, resulting in a simpler microbial cooccurrence network. Interestingly, we observed a high abundance of the cyanobacterial genus Planktothrix in the winter, probably due to nutrient redistribution and Planktothrix adaptivity to the winter environment in which mixing played important roles. Our study provides deeper fundamental insights into how environmental factors influence microbial community structure through community assembly processes.

Organic P transformations and release from riparian soils responding to water level fluctuation.

To manage eutrophication of reservoirs, it is important to consider the potential for unexpected releases of organic phosphorus (OP) from areas around the reservoir where the water level fluctuates. In this study, we investigated the absorption and release of OP from a riparian soil/sediment from the Miyun Reservoir under fluctuating water levels using laboratory simulations. The total organic phosphorus (TOP) content in the soils/sediments ranged from 250.76 to 298.62 mg/kg, which accounted for between 5.6 and 38.5% of the total phosphorus (TP) content. We measured three OP fractions and found that the concentration of moderately labile OP (MLOP) was the highest, followed by labile OP (LOP), and the concentration of non-labile OP (NLOP) was the lowest. As the soils and sediments dried, they adsorbed phosphorus (P). The inorganic phosphorus (IP) contents were significantly and negatively correlated with the LOP and MLOP contents, indicating exchange between IP with these two fractions when the concentrations of bioavailable phosphorus in the soil are low. During flooding, the physicochemical properties varied at the sediment-water interface, inducing the release of Fe/Al-P. Some of the LOP and MLOP in the sediments were mineralized to IP. Our results suggest that when there are external P inputs, P may be released when sediments around a reservoir are subjected to wetting and drying as water levels fluctuate, which may cause P enrichment in reservoirs, especially in areas with poor water exchange.

Defect-enhanced photocatalytic removal of dimethylarsinic acid over mixed-phase mesoporous TiO2.

Much attention has been paid to the pollutant dimethylarsenic acid (DMA), because of its high toxicity even at very low doses. Although TiO2 photocatalytic oxidation (PCO) is one of the few effective methods for treating DMA-containing water, the efficient decomposition of DMA and simultaneous removal of toxic arsenic species remains a significant but challenging task. Here, defective mesoporous TiO2 with mixed-phase structure was synthesized and used as both photocatalyst and adsorbent for DMA removal. Due to the reduced band-gap and enhanced separation of photogenerated charge carriers, the oxygen-deficient TiO2 nanostructures exhibited 4.2 times higher PCO efficiency than commercial TiO2 (P25). More importantly, the high surface area of the mesoporous TiO2 provided sufficient active sites for in-situ adsorption and reaction, resulting in the efficient removal of as-formed As(V). Combining the experimental and characterization results, the different roles of reactive species during PCO reactions were clarified. In the presence of hole (h+) as the dominant oxidation species, DMA was demethylated and transformed into MMA. Thereafter, MMA was subsequently reduced to As(III) by photo-generated electrons. Superoxide radicals (O2•-) played a significant role in oxidizing As(III) into As(V), which was finally adsorptively removed by the mesoporous TiO2.

Using high-throughput sequencing to assess the impacts of treated and untreated wastewater discharge on prokaryotic communities in an urban river.

In many megacities wastewater is an important source of surface water, particularly during drought periods. While changes in surface water chemistry associated with effluent inflow have generally been well-studied, few data have been collected on the effects to prokaryotic communities. The objective of this study was to explore the impacts of treated and untreated wastewater discharges on prokaryotic community in an urban river. High-throughput sequencing was conducted for analyzing the prokaryotic community composition and function in river water, treated wastewater and untreated wastewater. Results revealed that the prokaryotic community compositions in the upstream river reach were dominated by treated wastewater discharge. In the middle- and downstream river reaches, untreated effluent volumes are higher, thus affecting the structure of the prokaryotic community, promoting a rise in Cyanobacteria and Thaumarchaeota. Function annotation revealed a number of genes associated with xenobiotic metabolism and human diseases were observed in river and wastewater samples, suggesting wastewater discharge to river may pose a risk to human health. Quantitative real-time PCR results revealed that the treated and untreated wastewater discharges also affected the abundance of ammonia oxidation bacteria (AOB) and ammonia oxidation archaea (AOA) in river.

Chlorination of antiviral drug ribavirin: Kinetics, nontargeted identification, and concomitant toxicity evolution.

Residual antiviral drugs in wastewater may increase the risk of generating transformation products (TPs) during wastewater treatment. Therefore, chlorination behavior and toxicity evolution are essential to understand the secondary ecological risk associated with their TPs. Herein, chlorination kinetics, transformation pathways, and secondary risks of ribavirin (RBV), one of the most commonly used broad-spectrum antivirals, were investigated. The pH-dependent second-order rate constants k increased from 0.18 M-1·s-1 (pH 5.8) to 1.53 M-1·s-1 (pH 8.0) due to neutral RBV and ClO- as dominant species. 12 TPs were identified using high-resolution mass spectrometry in a nontargeted approach, of which 6 TPs were reported for the first time, and their chlorination pathways were elucidated. The luminescence inhibition rate of Vibrio fischeri exposed to chlorinated RBV solution was positively correlated with initial free active chlorine, probably due to the accumulation of toxic TPs. Quantitative structure-activity relationship prediction identified 7 TPs with elevated toxicity, concentrating on developmental toxicity and bioconcentration factors, which explained the increased toxicity of chlorinated RBV. Overall, this study highlights the urgent need to minimize the discharge of toxic chlorinated TPs into aquatic environments and contributes to environmental risk control in future pandemics and regions with high consumption of antivirals.

Disinfectant-induced ammonia oxidation disruption in microbial N-cycling process in aquatic ecosystem after the COVID-19 outbreak.

Anthropogenic activities significantly impact the elemental cycles in aquatic ecosystems, with the N-cycling playing a critical role in potential nutrient turnover and substance cycling. We hypothesized that measures to prevent COVID-19 transmission profoundly altered the nitrogen cycle in riverine ecosystems. To investigate this, we re-analyzed metagenomic data and identified 60 N-cycling genes and 21 host metagenomes from four urban reaches (one upstream city, Wuhan, and two downstream cities) along the Yangtze River. Our analyses revealed a marked decrease in the abundance of bacterial ammonia monooxygenase genes, as well as in the host, ammonia-oxidizing autotrophic Nitrosomonas, followed by a substantial recovery post-pandemic. We posited that discharge of sodium hypochlorite (NaOCl) disinfectant may be a primary factor in the reduction of N-cycling process. To test this hypothesis, we exposed pure cultures of Nitrosomonas europaea to NaOCl to explore the microbial stress response. Results indicated that NaOCl exposure rapidly compromised the cell structure and inhibited ammonia oxidation of N. europaea, likely due to oxidative stress damage and reduced expression of nitrogen metabolism-related ammonia monooxygenase. Using the functional tagging technique, we determined that NaOCl directly destroyed the ammonia monooxygenase protein and DNA structure. This study highlights the negative impacts of chlorine disinfectants on the function of aquatic ecosystems and elucidates potential mechanisms of action.

Spatiotemporal distribution and transport flux of organophosphate esters in the sediment of the Yangtze River.

The Yangtze River Basin is an important area for organophosphate esters (OPEs) consumption and emission. Studies proved high OPE detection in Yangtze River water, but there is limited information about the spatiotemporal distribution and transport flux of OPEs in sediment. The present study investigated 16 OPEs in sediment from upstream to mid-downstream of the Yangtze River. The mean concentration of OPEs was 84.30 ng/g, and alkyl-OPEs was the primary component. Great specific surface area and high content of organic carbon significantly increased OPE concentration in Three Gorges Reservoir (TGR) by physical adsorption and chemical bonds (p < 0.05), making TGR the most contaminated area in mainstream. No significant differences in OPE constituents were found in seasonal distribution. Four potential sources of OPEs were identified by principal component analysis and self-organizing maps, and traffic emissions were the dominant source for OPEs. The hazard quotient model results indicated that aryl-OPEs showed moderate risks in the mainstream of Yangtze River, alkyl-OPEs and Cl-OPEs showed low risks. TGR was a significant sink of OPEs in Yangtze River and buried 7.41 tons of OPEs in 2020, a total of 14.87 tons of OPE were transported into the sea by sediment.

Microbe-mediated simultaneous nitrogen reduction and sulfamethoxazole/N-acetylsulfamethoxazole removal in lab-scale constructed wetlands.

Constructed wetlands (CWs) are increasingly used to treat complex pollution such as nitrogen and emerging organic micropollutants from anthropogenic sources. In this study, the denitrification, anaerobic ammonium oxidation, dissimilatory nitrate reduction to ammonium, and nitrous oxide release rates following exposure to the frequently detected sulfonamides sulfamethoxazole (SMX) and its human metabolite, N-acetylsulfamethoxazole (N-SMX), were investigated in lab-scale CWs. Over a period of 190 d, the denitrification rates were noticeably inhibited in the SMX and N-SMX groups at week 5. Subsequently, the denitrification rates recovered, accompanied by an increase in the relevant nitrogen reduction and antibiotic resistance genes (ARGs). The composition of the microbial community also changed during this process. After the denitrification rates recovered, Burkholderia_Paraburkholderia and Gordonia exhibited a significant positive correlation with SMX exposure, which simultaneously reduced nitrate concentrations and degraded antibiotics. Burkholderia_Paraburkholderia is a key carrier of ARGs. Finally, nitrogen reduction (> 90%) and antibiotic removal (> 80%) also recovered in both SMX- and N-SMX-exposed lab-scale CWs during the operation, which revealed the interaction of SMX or N-SMX removal and nitrogen reduction.

The response of microbial compositions and functions to chronic single and multiple antibiotic exposure by batch experiment.

Understanding the response of the microbial community to external disturbances such as micropollutants is vital for ecological risk evaluation. In this study, the effect of chronic antibiotic exposure on community compositions and functions was investigated by two batch experiments. The first experiment investigated the effect of chronic sulfamethoxazole (SMX) exposure, while the second investigated the combined effect of dissolved organic matter (DOM) sources and multi-antibiotic exposure. The results showed that the community responses to chronic antibiotic exposure depended on the dynamic balance among community resistance, adaptation, recovery, and selection, leading to nonlinear composition diversity variations. The disturbance strength of chronic SMX exposure increased with concentration (0.5-50 µg/L). However, complex sources and structures of coexisting organic matter might delay the disturbance by elevating metabolic activity and generating functional redundancy. Especially, when nutrient was a limiting factor, the disturbance strength by DOM source was greater than that by chronic antibiotic exposure. The resistance of abundant taxa to external distributions resulted in a low explanation of community diversity, while rare taxa played key roles in response to community variation and thereby affected community assembly. Long-term SMX exposure reduced the number of key species and favored the deterministic assembly process by 21%. However, elevated community adaptability might weaken the influence of antibiotic selection. Chronic SMX exposure elevated the relative abundance of sulfonamide resistance genes (sul1, sul2) by a factor of 1.2-4.3, while that of nitrogen-fixing genes (nifH, nifK) and the metabolic pathways related to the toluene, ethylbenzene, and dioxin degradation decreased. However, the combined influence of DOM sources and multi-antibiotic exposure barely caused the difference in the genes linking to element metabolism and drug resistance of microbial communities between blank and exposed groups. This study suggested that more concern should be given to the chronic environmental effect of organic micropollutants.

The heterogeneous effects of Chinese industrial parks on environmental pollution.

As a form of regional agglomeration, industrial parks create huge benefits for China's economic development, but they also generate considerable environmental externalities and are expected to become the breakthrough to achieve green transformation. This study builds a panel data set by combining a variety of data on the environmental and economic characteristics of firms, industrial parks, and regions, and empirically investigates the effects of establishing industrial parks on emissions of COD, NH3, SO2, and dust. We find such effects are heterogeneous across scales of investigation and types of industrial parks. After entering the industrial parks, firms can reduce their environmental pollution, and the emissions of COD, SO2 and dust have decreased by 9.3 %, 13.4 % and 4.6 %, respectively. However, the study at the regional level finds that, after the establishment of industrial parks, the overall emissions of COD, NH3, SO2, and dust have increased by 37.9 %, 365 %, 45.5 % and 34.9 %, respectively. The expansion of production scale and the increase of pollution-intensive industries are the main factors that cause more serious regional pollution. Meanwhile, the improvement of pollution treatment is very limited. After the establishment of a new park, the emission intensities of newly entered firms are higher than those of pre-existing firms, indicating industrial parks may lower environmental requirements in exchange for economic growth. Parks with clean dominant industries, high levels of water reuse and technical innovation tend to emit less pollutants. Based on the results, this study gives four suggestions for establishing environment-friendly industrial parks, that is, to plan the industrial layout rationally, to speed up the construction of pollution treatment facilities, to increase the environmental threshold for entrance, and to promote technical innovation.

Distribution, sources, and potential health risks of fluoride, total iodine, and nitrate in rural drinking water sources of North and East China.

Small-scale water sources serving villages and towns are the main source of drinking water in rural areas. Compared to centralized water sources, rural water sources are less frequently monitored for water quality and have poor post-treatment facilities, making them vulnerable to drinking health risks. To reveal the hydrochemical characteristics, contaminant sources, and health risks in rural water sources, 189 water samples were collected from lakes and reservoirs, rivers, and groundwater in North and East China for major ions, nutrient salts, microelements, and stable isotope analysis. Statistical analysis and isotopic tracing were performed, as well as human health risk assessment. The exceeding threshold rates for fluoride (F-) and nitrate (NO3-) in surface water were 1.8 % and 9.1 %, respectively. For groundwater, the exceeding threshold rates were 20.9 % for F-, 15.7 % for total iodine (TI), and 4.5 % for NO3-. F- and TI were mainly derived from the leaching of fluoride- and iodine-containing minerals by cationic exchange, and NO3- is mainly derived from nitrogen in the soil (31.7-43.9 %), the use of ammonia fertilizers (24.3-36.1 %), and the discharge of manure and sewage (19.4-31.9 %). Nitrogen in the soil can be an important source of nitrate in the aquatic environment, and soils with higher clay content have a greater retention effect on the migration of nitrogen pollutants from the surface to the groundwater. F- in water sources contributes most to human health risks for drinking, followed by NO3- and TI, and a higher proportion of groundwater (37 %) present health risks for drinking than surface water (14 %) for children. Authorities should give high priority to optimizing the choice of water sources and technology for water treatment, and rational measures should be taken to protect water sources from the threats of anthropogenic pollution.

The influence of wet-to-dry season shifts on the microbial community stability and nitrogen cycle in the Poyang Lake sediment.

In lake environments, seasonal changes can cause exposure of the lake sediment, leading to soil formation. Although previous studies have explored how environmental changes influence microbial functioning in the water-level-fluctuating zone, few studies have investigated how wholescale habitat changes affect microbial composition, community stability and ecological functions in lake environments. To address this issue, our study investigated the effects of sediment-to-soil conversion on microbial composition, community stability and subsequent ecological functioning in Poyang Lake, China. Our results revealed that, during sediment-to-soil conversion, the number of total and unique operational taxonomic units (OTUs) decreased by 40 % and 55 %, respectively. Moreover, sediment-to-soil conversion decreased the microbial community connectivity and complexity while significantly increasing its stability, as evidenced by increased absolute values of negative/positive cohesion. In sediment and soil, the abundance of dominant bacteria, and bacterial diversity strongly affected microbial community stability, although this phenomenon was not true in water. Furthermore, the specific microbial phyla and genes involved in the nitrogen cycle changed significantly following sediment-to-soil conversion, with the major nitrogen cycling processes altering from denitrification and dissimilatory nitrate reduction to ammonium to nitrification and assimilatory nitrate reduction to ammonia. Moreover, a compensation mechanism was observed in the functional genes related to the nitrogen cycle, such that all the processes in the nitrogen cycle were maintained following sediment-to-soil conversion. The oxidation-reduction potential strongly affected network complexity, microbial stability, and nitrogen cycling in the sediment and soil. These results aid in the understanding of responses of microorganisms to climate change and extreme drought. Our findings have considerable implications for predicting the ecological consequences of habitat conversion and for ecosystem management.

Dam construction alters planktonic microbial predator‒prey communities in the urban reaches of the Yangtze River.

While dam construction supports social and economic development, changes in hydraulic conditions can also affect natural aquatic ecosystems, especially microbial ecosystems. The compositional and functional traits of multi-trophic microbiota can be altered by dam construction, which may result in changes in aquatic predator-prey interactions. To understand this process, we performed a large-scale sampling campaign in the urban reaches of the dam-impacted Yangtze River (1 995 km) and obtained 211 metagenomic datasets and water quality data. We first compared the compositional traits of planktonic microbial communities upstream, downstream, and in a dam reservoir. Results showed that Bacteroidetes (R-strategy) bacteria were more likely to survive upstream, whilst the reservoir and downstream regions were more conducive to the survival of K-strategy bacteria such as Actinobacteria. Eukaryotic predators tended to be enriched upstream, whilst phototrophs tended to be enriched in the reservoir and downstream regions. Based on bipartite networks, we inferred that the potential microbial predator-prey interactions gradually and significantly decreased from upstream to the downstream and dam regions, affecting 56% of keystone microbial species. Remarkably, functional analysis showed that the abundance of the photosynthetic gene psbO was higher in the reservoir and downstream regions, whilst the abundance of the KEGG carbohydrate metabolic pathway was higher upstream. These results indicate that dam construction in the Yangtze River induced planktonic microbial ecosystem transformation from detritus-based food webs to autotroph-based food webs.

Dam construction reshapes sedimentary pollutant distribution along the Yangtze river by regulating sediment composition.

Dam construction has far-reaching impacts on pollutant accumulation and the pollutant-induced quality of aquatic environments. Nonetheless, its large-scale effects on pollutant distribution in sediments, which greatly contribute to the environmental impacts of coexisting pollutants, remain poorly understood. We collected sediments from the Yangtze River during the dry and normal seasons (with 'normal' defined in terms of precipitation level), and examined how dam construction alters the spatial trajectories of both inorganic and organic pollutants in the sediments. Sediment composition exhibited linear variation from the upper to the lower reaches, with clay and silt particles dominating the sediment in the Three Gorges Reservoir and sand particles dominating in the middle-lower reaches. Accordingly, upstream of the Three Gorges Dam (TGD), sedimentary carbon, nitrogen, phosphorus, heavy metal, polycyclic aromatic hydrocarbons (PAHs), and oxygenated PAHs (OPAHs) contents increased toward the TGD owing to its regulation of the spatial variation in sediment particle size. The TGD caused upstream sedimentary accumulation of pollutants to be higher nearer to the TGD than in the upper reaches by 17%-129% for carbon, nitrogen, and phosphorus, 7%-51% for heavy metals, 30% for PAHs, and 140% for OPAHs. Pollutant content was sharply lower below the TGD, by 0.58-11.15 times for carbon, nitrogen, and phosphorus, 0.1-2.6 times for heavy metals, 1.7 times for PAHs, and 5.6 times for OPAHs. Upstream of the TGD, levels of NH4+-N, the main form of N in the interstitial water of the Yangtze River, increased lineary toward the TGD, whereas those of NO3--N and NO2--N decreased. Sedimentary organic matter source contributions were consistent along the Yangtze River, being on an average 46% for C3 plants and 28% for soil organic substances, further confirming the dam's regulatory effect on pollutants. These findings provide a foundation for future assessments of the environmental impact of dam-induced river fragmentation and hydrological alterations, and for developing advanced watershed pollutant management strategies.

Sources and pathways of nutrients in the semi-arid region of Beijing-Tianjin, China.

Semiarid regions worldwide are particularly prone to eutrophication, which causes immense ecological and economic problems. One region that is in transition and requires systematic research for effective intervention is the dry landscape of Beijing-Tianjin (P. R. China). We investigated the sources and spatiotemporal loads of nitrogen and phosphorus species over a one-year period in the Haihe catchment that drains the megacity of Beijing. Although wastewater treatment was improved in recent years, the rivers were heavily contaminated by 0.3-5.3 mg P L(-1) and 3.0-49 mg N L(-1), with toxic levels of nitrite (≥1 mg NO(2)-N L(-1)) and ammonia (≥0.6 mg NH(3)-N L(-1)). The average NH(4)(+) (16.9 mg N L(-1)) increased by 160% compared to 1996-levels. Mass fluxes and δ(15)N-signatures revealed that nutrients originated almost exclusively from sewage. Furthermore, the water balance demonstrated that >90% of the polluted river water was diverted for irrigation, thereby threatening food safety and groundwater quality. Per capita loads of 1.42 kg N/yr and 115 g P/yr were comparable to the peak discharges typical of Europe and the United States in 1970-1990, but concentrations were 2-3 times higher in the Beijing-Tianjin region. Our research identified sewage as the predominant nutrient source in this semiarid region, which suggests that state-of-the-art wastewater treatment would drastically mitigate eutrophication and even more rapidly than was previously observed in Europe.

Organic micropollutants in rivers downstream of the megacity Beijing: sources and mass fluxes in a large-scale wastewater irrigation system.

The Haihe River System (HRS) drains the Chinese megacities Beijing and Tianjin, forming a large-scale irrigation system severely impacted by wastewater-borne pollution. The origin, temporal magnitudes, and annual mass fluxes of a wide range of pharmaceuticals, household chemicals, and pesticides were investigated in the HRS, which drains 70% of the wastewater discharged by 20 million people living in Beijing. Based on Chinese consumption statistics and our initial screening for 268 micropollutants using high-resolution mass spectrometry, 62 compounds were examined in space and time (2009-2010). The median concentrations ranged from 3 ng/L for metolachlor to 1100 ng/L for benzotriazole and sucralose. Concentrations of carbendazim, clarithromycin, diclofenac, and diuron exceed levels of ecotoxicological concern. Mass-flux analyses revealed that pharmaceuticals (5930 kg/year) and most household chemicals (5660 kg/year) originated from urban wastewaters, while the corrosion inhibitor benzotriazole entered the rivers through other pathways. Total pesticide residues amounted to 1550 kg/year. Per capita loads of pharmaceuticals in wastewater were lower than those in Europe, but are expected to increase in the near future. As 95% of the river water is diverted to irrigate agricultural soil, the loads of polar organic micropollutants transported with the water might pose a serious threat to food safety and groundwater quality.

Partitioning and sources of PAHs in wastewater receiving streams of Tianjin, China.

Polycyclic aromatic hydrocarbons (PAHs) partitioning among dissolved phase, suspended particulate matter, pore water, and sediment was studied in one moderately contaminated river (Yongding New River) and two highly contaminated drainage canals (South Drainage Canal and North Drainage Canal) of Tianjin, China. PAHs concentrations in sediment (ranged from 0.2 to 195 µg/g) showed positive relations with both total organic carbon contents (ranged from 0.7% to 31.1%, dw) and black carbon contents (ranged from 0.1% to 2.1%, dw) in the sediments. Moreover, most of the measured organic carbon normalized partition coefficients of PAHs in the three streams were 0.76 to 1.54 log units higher than the predicted values. These indicated that strong and nonlinear sorption of PAHs by carbonaceous geosorbents such as black carbon (BC) existed in the streams, and BC was an important part of the carbonaceous particles controlling the partitioning of PAHs in the sediments of this study. PAH component ratio analyses suggested that PAHs in the three streams, effluent samples from wastewater treatment plants, and soil samples by the riverbank had similar main sources, which is coal/petroleum combustion. We suggested the transportation and transformation of both carbonaceous particles and PAHs during wastewater treatment process, surface runoff, etc, should be studied further in order to make decisions on PAHs controlling measures.

Oxygenated polycyclic aromatic hydrocarbons in the surface water environment: Occurrence, ecotoxicity, and sources.

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) have been ubiquitously detected in atmospheric, soil, sediment, and water environments, some of which show higher concentrations and toxicities than the parent polycyclic aromatic hydrocarbons (PAHs). The occurrence, source, fate, risks and methods of analysis for OPAHs in the atmosphere, soil, and the whole environment (comprising the atmosphere, soil, water, and biota) have been reviewed, but reviews focusing on OPAHs in the water environment have been lacking. Due to the higher polarity and water solubility of OPAHs than PAHs, OPAHs exist preferentially in water environments. In this review, the occurrence, ecological toxicity and source of OPAHs in surface water environments are investigated in detail. Most OPAHs show higher concentrations than the corresponding PAHs in surface water environments. OPAHs pose non-ignorable ecological risks to surface water ecosystems. Wastewater treatment plant effluent, atmospheric deposition, surface runoff, photochemical and microbiological transformation, and sediment release are possible sources for OPAHs in surface water. This review will fill important knowledge gaps on the migration and transformation of typical OPAHs in multiple media and their environmental impact on surface water environments. Further studies on OPAHs in the surface environment, including their ecotoxicity with the co-existing PAHs and mass flows of OPAHs from atmospheric deposition, surface runoff, transformation from PAHs, and sediment release, are also encouraged.