Occurrence,spatial and seasonal variation,and environmental risk of pharmaceutically active compounds in the Pearl River basin,South China

● 38 PhACs and 2 pesticides were detected in the three rivers of the Pearl River basin. ● Anti-inflammatory/analgesics drugs were the predominant PhACs. ● The concentrations of PhACs showed seasonal and spatial variation. ● Diazepam and ibuprofen were the two PhACs with a moderate environmental risk. The occurrence, fate, and environmental risk of 40 pharmaceutically active compounds (PhACs) from surface waters and sediments were comprehensively investigated in the Beijiang River, Xijiang River, and Maozhou River of the Pearl River basin, South China. Salicylic acid and diclofenac (anti-inflammatory drugs), gemfibrozil (a lipid regulator), carbamazepine (an antiepileptic drug), diazepam (a psychoactive drug), and 2-methyl-4-chloro-phenoxyacetic acid (MCPA, a pesticide) were the most ubiquitous compounds in the studied region. The average concentrations of detected PhACs in surface waters and sediments ranged from 0.17 to 19.1 ng/L and 0.10 to 10.4 ng/g, respectively. Meanwhile, PhACs concentration in surface waters and sediments varied greatly among and within the Beijiang River, Xijiang River, and Maozhou River. The largest annual flux of PhACs of the Xijiang River and Beijiang River was more than 11 000 kg per annum, whereas only 25.7 kg/a in the Maozhou River. In addition, the estimated emissions of PhACs in the Beijiang River, Xijiang River, and Maozhou River ranged respectively from 0.28 to 4.22 kg/a, 0.12 to 6.72 kg/a, and 6.66 to 91.0 kg/a, and the back-estimated usage varied with a range from 12.0 to 293 kg/a, 6.79 to 944 kg/a, 368 to 17 459 kg/a. Moreover, the emissions of PhACs showed a close relationship with the gross domestic product (GDP) of each city along the Pearl River. The environmental risk assessment suggested that diazepam and ibuprofen had a moderate risk in this region.     

Occurrence and fate of typical antibiotics in wastewater treatment plants in Harbin,North-east China

• The concentration distributions and removals of 12 antibiotics were investigated. • Macrolides and fluoroquinolones presented relatively higher concentrations. • The removal of antibiotics did not differ among the different treatment processes. As a new pollutant, antibiotics in the environment and their removal in wastewater treatment plants (WWTPs) have gained considerable attention. However, few studies investigated antibiotics in the north-eastern areas of China. By employing high-performance liquid chromatography-tandem mass spectrometry, the concentration distribution and removal of 12 antibiotics belonging to four types (cephalosporins, sulfonamides, fluoroquinolones, and macrolides) were investigated in influents and effluents as well as the removal efficiencies of four typical treatment processes in 18 wastewater treatment plants of Harbin City, north-eastern China. Macrolides and fluoroquinolones presented relatively higher detection concentrations and rates both in the water and in the sludge phases. Sulfonamides and cephalosporins displayed higher detection concentrations in the water phase. The representative antibiotics in influents and effluents included ROX, NOR, OFL, SMX, AZI, and CLA, with detection rates above 95%. The detection rates of the other six antibiotics exceeded 30%. In the sludge, the other five antibiotics, except SMX, presented relatively higher detection concentrations and rates, with detection rates greater than 95%. For cephalosporin, the detection rates of CTX and CFM in the sludge were 0. The removal efficiencies for the 12 antibiotics differed greatly, with average values ranging from 30% to 80% and the highest values for cephalosporin. The removal of antibiotics did not differ significantly among the four different treatment processes.     

Spatial distribution and ecological risk assessment of heavy metals in surface sediments from a typical plateau lake wetland, China

Surface sediment (0-15 cm) samples were collected from 31 different grid points throughout the Yilong Lake in April 2004. Samples were subjected to a total digestion technique and analyzed for As, Cd, Cr, Pb, Ni, Cu, and Zn in order to study spatial distribution characteristics based on Kriging method and assess their ecological risks posed by these heavy metals. Results showed that the mean concentrations of these heavy metals were lower than potential effect levels. Patches of higher heavy metal concentrations occurred in the inflow area of the Cheng River and northeast area nearby the road and railway. The higher concentrations of As and Cr also appeared in the east area (lake outlet), while the patches of lower concentrations were uniformly distributed at the southwest corner between Luosewan and Xiaoguoxi. The heavy metal loads such as As, Cd and Pb might come from the common sources due to industrial sewage and traffic pollution, while higher concentrations of Ni, Cr, and Zn in these sediments were dominated by parent rocks. However, Cu originated from both sources. Sediments with respect to As, Cd and Cu were grouped below the effect range low (ERL) at all sites, and with respect to Cr and Pb were grouped into the range from ERL to the effect range median (ERM) at more than 50% of sampling sites. The mean heavy metal toxic units in the Yilong Lake decreased following the order Pb > Cr > As > Ni > Zn > Cd > Cu, with higher contributions to the sum of toxic units of Pb, Cr and As.     

A simulation framework for water allocation to meet the environmental requirements of urban rivers: model development and a case study for the Liming River in Daqing City,China

In this paper, we describe the development of a simulation framework for allocating water from different sources to meet the environmental flows of an urban river. The model permits the development of a rational balance in the utilization of storm water, reclaimed water from wastewater treatment plants, and freshwater from reservoirs with consideration of the limited capacities of different water resources. It is designed to permit the full utilization of unconventional water sources for the restoration of river water quality by increasing river flow and improving water quality. To demonstrate practical use of the model, a case study is presented in which the model was used to simulate the environmental water allocation for the Liming River in Daqing City, China, based on the three water sources mentioned above. The results demonstrate that the model provides an effective approach for helping managers allocate water to satisfy the river’s environmental water requirements.     

Ecological risk assessment from the viewpoint of surface water pollution in Xiamen City,China

The ecological security of urban surface water is subject to significant risk due to rapid urbanization. Pollutant discharge and accumulation are among the most critical stressors endangering urban surface water and affecting the normal operation of urban aquatic ecosystem services. In this study, we assessed how pollutant accumulation stresses water purification systems, which perform important urban ecosystem services. First, we applied a water environmental capacity model to calculate thresholds of urban surface water environmental capacity under a given water quality target. Second, based on a stepwise regression method, an equation was used to describe the relationship between stressor factors (pollutant accumulation) and measurable socioeconomic indicators. Third, an ecological risk index was used as an assessment endpoint indicator to assess the negative ecological effect of pollutant accumulation. Finally, risk level was classified according to the risk quotient method. Taking Xiamen City as an example, we analyzed the contribution of different sources of pollutants and evaluated the urban ecological risk posed by two major contaminants present in the environment by measuring chemical oxygen demand (COD) and ammonium nitrogen (NH₄⁺-N). The results show that the ecological risk indexes of both COD and NH₄⁺-N are expected to decrease from 2020 to 2030; that of COD is expected to fall from medium to low, whereas that of NH₄⁺-N is expected to fall from high to medium. These findings demonstrate that the ecological risk posed to the surface water in Xiamen City can be reduced by controlling population growth, optimizing industrial structure, and promoting economic development.     

Characterization and sources of PAHs in an urban river system in Beijing,China

Water samples from 20 locations on rivers in the Tongzhou District of Beijing were collected four times from July 2005 to March 2006. In addition, sediment samples were collected in July 2005. All samples were analyzed for 16 US Environmental Protection Agency (EPA) priority pollutants polycyclic aromatic hydrocarbons (PAHs). The concentration, distribution, seasonal variation, and sources of the 16 PAH compounds identified in the water samples, suspended particles, and surface sediments were then evaluated. The concentrations of PAHs in the water and suspended particle and surface sediment samples ranged from 87.3 to 1,890 ng l⁻¹, 1,330 to 27,700 ng g⁻¹, and 156 to 8,650 ng g⁻¹, respectively. These results demonstrated that rivers in the Tongzhou District of Beijing had a high level of PAH pollution, especially in the suspended particles. The highest and lowest concentrations of PAHs in the water samples were observed in summer and spring. However, the seasonal variations in the concentration of PAHs in the suspended particles were more complicated. The dominant compounds in the water, suspended particle, and surface sediment samples were two-, three- and four-ring PAH compounds, respectively. Ratio analysis illustrated that fuel-burning was the primary source of PAHs in the study area. Gasoline, diesel, coal, and coke oven sources were identified and the contributions of the different fuel-burning sources were then calculated using factor analysis and multiple linear regression. These analyses revealed that coal combustion, gasoline combustion plus coke oven emission, and diesel combustion accounted for 38.8%, 38.5%, and 22.7% of the PAHs in suspended particles, respectively.     

PPCPs in a drinking water treatment plant in the Yangtze River Delta of China: Occurrence,removal and risk assessment

• 39 PPCPs were investigated at a DWTP using the Yangtze River as its water source. • Grab and continuous sampling were conducted for the comparison of data consistency. • Ketoprofen & carbamazepine can be risk management indicators because of the high RQ. The occurrence and removal of 39 targeted pharmaceuticals and personal care products (PPCPs) from source water, through a drinking water treatment plant (DWTP) to the water supply station, were investigated around the central part of Yangtze River Delta in China using both grab sampling and continuous sampling. Totally 24 of the 39 targeted PPCPs were detected in raw water, and 12 PPCPs were detected in the finished water. The highest observed concentration was enrofloxacin (85.623 ng/L) in raw water. Removal efficiencies were remarkably negative correlated with log K_ow (r = -0.777, p<0.01) after calibration control of concentration, indicating that more soluble PPCPs are easier to remove by the combined process (prechlorination and flocculation/precipitation), the concentration level also had a great impact on the removal efficiency. The normal process in the pilot DWTP seems to be ineffective for PPCPs control, with the limited removal efficiency of less than 30% for each step: pre-chlorination, flocculation and precipitation, post-chlorination and filter. There were notable differences between the data from continuous sampling and grab sampling, which should be considered for different monitoring purposes. The chlorination and the hydrolytic decomposition of PPCPs in the water supply pipe may attenuate PPCPs concentration in the pipeline network. The PPCPs examined in the effluent of DWTP do not impose a potential health risk to the local consumers due to their RQ value lower than 0.00067.     

Distribution,enrichment mechanism and risk assessment for fluoride in groundwater: a case study of Mihe-Weihe River Basin,China

● High fluorine is mainly HCO₃·Cl-Na and HCO₃-Na type. ● F⁻ decreases with the increase of depth to water table. ● High fluoride is mainly affected by fluorine-containing minerals and weak alkaline. ● Fluorine pollution is mainly in the north near Laizhou Bay (wet season > dry season). ● Groundwater samples have a high F⁻ health risk (children > adults). Due to the unclear distribution characteristics and causes of fluoride in groundwater of Mihe-Weihe River Basin (China), there is a higher risk for the future development and utilization of groundwater. Therefore, based on the systematic sampling and analysis, the distribution features and enrichment mechanism for fluoride in groundwater were studied by the graphic method, hydrogeochemical modeling, the proportionality factor between conventional ions and factor analysis. The results show that the fluorine content in groundwater is generally on the high side, with a large area of medium-fluorine water (0.5–1.0 mg/L), and high-fluorine water is chiefly in the interfluvial lowlands and alluvial-marine plain, which mainly contains HCO₃·Cl-Na- and HCO₃-Na-type water. The vertical zonation characteristics of the fluorine content decrease with increasing depth to the water table. The high flouride groundwater during the wet season is chiefly controlled by the weathering and dissolution of fluorine-containing minerals, as well as the influence of rock weathering, evaporation and concentration. The weak alkaline environment that is rich in sodium and poor in calcium during the dry season is the main reason for the enrichment of fluorine. Finally, an integrated assessment model is established using rough set theory and an improved matter element extension model, and the level of groundwater pollution caused by fluoride in the Mihe-Weihe River Basin during the wet and dry seasons in the Shandong Peninsula is defined to show the necessity for local management measures to reduce the potential risks caused by groundwater quality.     

Mercury distribution,speciation and potential ecological risk assessment in sediments from Lake Taihu,China

Abstract

Twenty-one surface sediments collected from seven surroundings areas of Lake Taihu in two different years were analyzed for total mercury (THg) concentrations, physicochemical characteristics and speciation using a sequential extraction method to assess spatial distribution, sources, and potential ecological risk. Surface sediments from Lake Taihu contained elevated levels of Hg in two sampling years with THg levels ranging from 77 to 346?ng/g (mean 145?ng/g) in October 2010 and ranging from 122 to 573?ng/g (mean 266?ng/g) in November 2012, respectively. The mean THg concentrations in all studied surface sediments exhibited an increasing trend over time. The oxidizable fraction (F3) and residual fraction (F4) were the predominant Hg species in sediments, while more mobile Hg phases of acid-soluble fraction (F1) and reducible fraction (F2) made up less than 0.5% THg. Significant relationships were found between total organic carbon (TOC) and THg and geochemical speciation indicating an important role for organic matter in affecting distribution, mobility, and bioavailability of Hg in sediments. As evidenced by Hakanson’s potential risk index the total ecological risk of Hg was low in the entire Lake Taihu in 2010 but considered moderate in Zhushan Bay, West Coast, and Meiliang Bay in 2012. These findings provide conservation managers with information needed to more effectively regulate the environment of Lake Taihu.     

Geochemical speciation and risk assessment of metals in the river sediments from Dan River Drainage,China

This study investigates the partitioning of metals in surface sediments from the Dan River drainage basin, the source of drinking water for the South to North Water Transfer Project, China, to determine their bioavailability and associated levels of risk. Sediment samples were collected from 99 sites along the Dan River, and the concentration of each element fraction was determined using sequential extraction and inductively coupled plasma-mass spectrometry. The residual fraction was the major phase for most metals sampled. Among the non-residual fractions, greater proportions of Zn, Mn and Cd were transported in in the available phase, whereas Ba, Sb, Pb and As were mainly found in the reducible phase. The oxidisable phase was important for the transport of Ni, Co, Cr and Cu in sediments. This analysis of sediments from the Dan River basin indicates a very high risk of pollution from Cd, Co, Mn, Sb and Zn. Combined with the sediments with extremely high concentrations, the Dan, Laoguan and Yinhua rivers, which have been affected by ore-mining activities, pose a very high risk to the surrounding areas and should be the subject of future studies.     

山东南四湖底泥典型重金属的形态分布、稳定度与风险评价

为研究南四湖底泥重金属赋存形态与稳定度的空间差异,利用柱状底泥采样器分别在南阳湖、独山湖、昭阳湖和微山湖采集原位柱状样,在对典型重金属Pb、Cd、Hg、As形态分析的基础上,结合地积累指数法和潜在生态风险指数法,对表层底泥(0-4 cm)重金属污染程度进行评价,并对其稳定性进行分析.结果表明,南四湖的4个湖区采样点位表...     

Occurrence and health risk assessment of trace heavy metals via groundwater in Shizhuyuan Polymetallic Mine in Chenzhou City,China

The Shizhuyuan Polymetallic Mine in Chen-zhou City is an important multi-metal deposit in China. After a dam accident in 1985, there are still a number of mining plants, smelters and tailing ponds in this area. These had the potential to pollute the surrounding groundwater. In this study, groundwater samples were collected from 20 residents’ wells in this area during both dry and wet seasons. In particular, this study focused on the exposure and the health risk assessment of trace heavy metal in groundwater. Multiple statistical analysis and fuzzy comprehensive method were employed to reveal the distribution characteristics of heavy metal and to assess the groundwater quality. Results indicated that Cr, Fe, Ni, Cu, Zn, As, Cd, Ba, Hg and Pb were widespread with low exposure levels. There were 19 wells with low level exposure and one well with a moderate level exposure in the dry season. All of the wells were in low level exposure during the wet season. As and Mn exhibited potential non-carcinogenic concern, because their maximum hazard quotient (HQ) was higher than 1.0. This may cause adverse health effect on adults in dry season or on children in both seasons. Only As, showed that the maximum carcinogenic risk was more than 10⁻⁴, suggesting a high cancer risk for children in both dry and wet seasons. Therefore, analysis and reduction the concentrations of As and Mn in groundwater are needed in order to protect the health of residents and especially children in the area.     

Tracking Cryptosporidium in urban wastewater treatment plants in a cold region: Occurrence,species and infectivity

• Cryptosporidium in WWTPs in a cold region was investigated in different seasons. • The overall removal efficiency of Cryptosporidium in WWTPs was over 84%. • The infectivity rate declined below 53% in effluents mainly due to disinfection. • The infectivity of Cryptosporidium increased with a seasonal drop in temperature. • Low temperature promotes binding protein retention and virulence genes expression. This study investigated the occurrence, species, infectivity and removal efficiency of Cryptosporidium spp. across typical wastewater treatment train. Samples from different process units were collected seasonally and synchronously from four wastewater treatment plants (WWTPs) in Northeastern China. Live Cryptosporidium oocysts were identified in most samples from both influent (97.50%) and effluent (90.00%) wastewaters of the four WWTPs, at an average density of 26.34 and 4.15 oocysts/L, respectively. The overall removal efficiency was 84.25%, and oocysts were mainly removed (62.01%) by the modified secondary sedimentation process. Ten Cryptosporidium species were identified in the effluent samples. C. andersoni, C. bovis, and C. ryanae were the three most prevalent species. Oocyst viability assays indicated no reduction of excystation rate during the primary and secondary wastewater treatments (varied in the range of 63.08%–68.50%), but the excystation rate declined to 52.21% in the effluent after disinfection. Notably, the Cryptosporidium oocysts showed higher infection intensity in the cold season (winter and spring) than that in summer and autumn. The influences of environmental temperature on virulence factors of Cryptosporidium were further examined. It was observed that more extracellular secretory proteins were bound on the oocyst surface and several virulence genes were expressed relatively strongly at low temperatures, both of which could facilitate oocyst adhesion, invasion, and host immune evasion. This research is of considerable interest since it serves as an important step towards more accurate panoramic recognition of Cryptosporidium risk reduction in WWTPs, and especially highlights the potential health risk associated with Cryptosporidium in cold regions/seasons.     

Spatial health risk assessment and hierarchical risk management for mercury in soils from a typical contaminated site,China

Due to rapid urbanization and the implementation of ecological civilization construction in China, many industrial factories have been closed or relocated. Therefore, numbers of contaminated sites were generated with contaminated soils which may pose a risk to receptors living nearby. This study presented a spatial health risk assessment and hierarchical risk management policy making for mercury (Hg) in soils from a typical contaminated site in the Hunan Province, central China. Compared with the second class value (0.3 mg/kg) of the Chinese Environmental Quality Standard for Soils, the mean concentrations of Hg in the three soil depths exceeded the second class value. The non-carcinogenic risk of Hg probably posed adverse health effects in 41, 30 and 36 % of the surface soil, the moderate soil and subsoil, respectively, under a sensitive land scenario. The non-carcinogenic risk temporarily posed no adverse health effects in most areas under an insensitive land scenario except for the area around sampling site S29. Spatially, the central, southwest and northeast parts of the contaminated land under a sensitive land scenario should be regarded as the priority regions. For non-carcinogenic effects, the exposure pathways that resulted in the higher levels of exposure risk were ingestion and inhalation of vapors, followed by dermal contact and inhalation of particles. A risk-based integrated risk management policy including the hierarchical risk control values for different soil depths and the calculated remediation earthwork was proposed with consideration of the cost-benefit effect for the related decision-makers.     

Different response of bacterial community to the changes of nutrients and pollutants in sediments from an urban river network

• Bacterial community varied spatially in sediments from the urban river network. • Key environmental factors shaping bacterial community were detected by RDA. • Bacterial co-occurrence networks changed at different levels of nutrient and metal. • Potential indicator species were selected to predict pollution risk in sediment. Microbial communities in sediment are an important indicator linking to environmental pollution in urban river systems. However, how the diversity and structure of bacterial communities in sediments from an urban river network respond to different environmental factors has not been well studied. The goal of this study was to understand the patterns of bacterial communities in sediments from a highly dense urbanized river network in the lower Yangtze River Delta by Illumina MiSeq sequencing. The correlations between bacterial communities, the environmental gradient and geographical distance were analyzed by redundancy analysis (RDA) and network methods. The diversity and richness of bacterial community in sediments increased from upstream to downstream consistently with the accumulation of nutrient in the urban river network. Bacterial community composition and structure showed obvious spatial changes, leading to two distinct groups, which were significantly related to the characteristics of nutrient and heavy metal in sediments. Humic substance, available nitrogen, available phosphorus, Zn, Cu, Hg and As were selected as the key environmental factors shaping the bacterial community in sediments based on RDA. The co-occurrence patterns of bacterial networks showed that positive interaction between bacterial communities increased but the connectivity among bacterial genera and stability of sediment ecosystem reduced under a higher content of nutrient and heavy metal in average. The sensitive and ubiquitous taxa with an overproportional response to key environmental factors were detected as indicator species, which provided a novel method for the prediction of the pollution risk of sediment in an urban river network.     

Particle-bound polycyclic aromatic hydrocarbons in typical urban of Yunnan-Guizhou Plateau: Characterization,sources and risk assessment

• The sampling was conducted in city on the Yunnan-Guizhou Plateau for one year. • The groups of PAHs revealed their different environmental fates and migration paths. • Seasonal biomass burning could affect the concentration by long-distance transport. • Industrial sources and traffic emissions were the main contributor of PAHs. • Living in industrial areas or winter had higher health risk by exposure PAHs in PM_2.5. Monthly particle-phase ambient samples collected at six sampling locations in Yuxi, a high-altitude city on the edge of Southeast Asia, were measured for particle-associated PAHs. As trace substances, polycyclic aromatic hydrocarbons (PAHs) are susceptible to the influences of meteorological conditions, emissions, and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path. The daily concentrations of total PM_2.5-bound PAHs ranged from 0.65 to 80.76 ng/m³, with an annual mean of 11.94 ng/m³. Here, we found that the concentration of PM_2.5-bound PAHs in winter was significantly higher than that in summer, which was mainly due to source and meteorology influence. The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs, while precipitation and low temperature exacerbated this difference. According to the concentration variation trend of PM_2.5-bound PAHs and their relationship with meteorological conditions, a new grouping of PAHs is applied, which suggested that PAHs have different environmental fates and migration paths. A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle, but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting. Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_2.5-bound PAHs than that in other regions, and the risk in winter was three times than in summer.     

Development and application of a comprehensive ecological risk assessment indicator system in Xiamen,China

Urban ecological risk is one of the important factors that may restrict the social and economic development. Therefore, it is of great significance to carry out a comprehensive assessment of ecological risks so that an ecological risk prevention and control plan can be scientifically formulated. In this paper, a comprehensive ecological risk assessment indicator system of Xiamen was established based on local ecological properties and socioeconomic status. This indicator system covers seven indicators including air pollution, soil pollution, water pollution, fresh water consumption, change in land use, occupation of key zones with ecological functions, and road network expansion. Based on this indicator system and in conjunction with the single factor assessment of ecological risks, this study constructed a model of comprehensive ecological risk assessment and forecasted the comprehensive ecological risk of Xiamen in 2020. The results showed that the comprehensive ecological risk level of Xiamen in 2020 is medium and the main stressors are the discharge of air and water pollutants. From the perspective of risk receptors, i.e. the ecosystem services, the risk posed to the ecosystem services associated to the maintenance of air quality and water purification is the highest. Therefore, this study proposed the recommendations on ecological risk prevention and regulation in Xiamen based on the comprehensive assessment of ecological risks, in the hope to provide scientific support for local ecological protection and sustainable development.     

Some characteristics of the distribution of heavy metals in urban topsoil of Xuzhou,China

An assessment is presented of distribution characteristics of heavy metals in the urban topsoil from the city of Xuzhou. The concentrations of Ag, Al, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Sc, Se, Sn, V and Zn have been determined from 21 soil samples. Examination of lognormal distribution plots indicates that the diagrams of Al, Be, Fe, Ga, Li, and V are almost linear suggesting that these metals are almost unaffected by anthropogenic activities while the plots for As, Cd, Cu, Pb, Pd, Pt, Se, Zn and others are not linear probably due to anthropogenic activities from which these metals are delivered to the soils. Al is used for mineralogical normalization of these data. An evaluation of background values for topsoil is also carried out by means of lognormal distribution plots. The results show our background values obtained from the lognormal distribution plots are comparable to those values of uncontaminated soils of Xuzhou obtained by previous work except for Cd and Hg. At present, no explanation for the exceptions Cd and Hg can be given.     

Occurrence,removal, and environmental risks of pharmaceuticals in wastewater treatment plants in south China

Pharmaceutically active compounds in wastewater released from human consumption have received considerable attention because of their possible risks for aquatic environments. In this study, the occurrence and removal of 10 pharmaceuticals in three municipal wastewater treatment plants in southern China were investigated and the environmental risks they posed were assessed. Nifedipine, atenolol, metoprolol, valsartan and pravastatin were detected in the influent wastewater. The highest average concentration in the influents was observed for metoprolol (164.6 ng/L), followed by valsartan (120.3 ng/L) in August, while median concentrations were higher in November than in August. The total average daily mass loadings of the pharmaceuticals in the three plants were 289.52 mg/d/person, 430.46 mg/d/person and 368.67 mg/d/person, respectively. Elimination in the treatment plants studied was incomplete, with metoprolol levels increasing during biological treatment. Biological treatment was the most effective step for PhACs removal in all of the plants studied. Moreover, the removal of PhACs was observed with higher efficiencies in August than in November. The WWTP equipped with an Unitank process exhibited similar removals of most PhACs as other WWTPs equipped with an anoxic/oxic (A/O) process or various anaerobic-anoxic-oxic (A²/O) process. The environmental risk assessment concluded that all of the single PhAC in the effluents displayed a low risk (RQ<0.1) to the aquatic environments.

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Ecological risk assessment of pesticide residues in Taihu Lake wetland, China

As a major ecosystem type, wetland provides invaluable ecological services. Environmental pollution, especially pesticides pollution should be paid more attention to keep wetlands healthy. Based on the risk quotient method, coupled with a probabilistic risk assessment model, this paper proposed a methodology suitable for ecological risk assessment of pesticide residues for wetland ecosystems. As an important industrializing and ecologically vulnerable area in China, the Taihu Lake wetland was chosen for the case study. The risks of eight pesticides in Taihu Lake wetland were assessed, as single substances and in mixtures. The assessment indicates that risks of the representative species are not significant. In general, the herbicide is found to be more toxic for algae, whereas insecticides pose more risks to zooplankton, insect and fish. For each pesticide in the wetland, the ecological risk it poses is acceptable. But the combined ecological risk posed by mixture can harm more than 10% of species of the wetland ecosystem, mainly dominated by dichlorvos, dimethoate and malathion contributions. These results imply that pesticide residues have been posing pressures on the ecosystem of the Taihu Lake wetland. It is recommended that proper countermeasures should be implemented to reduce the risks.