Water Quality Standards In China Research Articles

Key Issues and Challenges in Establishing Regionally Differentiated Water Quality Standard in China

The goal of environmental management in China is transitioning from pollution control to the improvement of ecological quality. The establishment of regional differential water quality standards can better adapt to the ecological characteristics and development needs of different regions. Given the shortcomings of current water quality standards and the needs of technological development, this study analyzed the causes and influencing factors of regional differences in water quality standards and summarized China's regional variations in areas such as the characteristics of receiving water bodies, social attributes, climate conditions, physicochemical properties of water, and aquatic biotic populations. It also examined the impact of regional characteristics on the assessment of biological toxicity. Based on these analyses, the study identified key scientific questions that may arise in the development of regional differential water quality standards in China and outlined future critical research directions in this field. These directions include developing theories and methods for determining the effluent dilution coefficient, establishing methods for identifying regional key water quality indicators and assessing their impact on water quality standards, determining regional characteristic species and their influence on water quality standards, and formulating theories and methods for categorizing different regions across the country. The aim of the study was to provide a reference for the scientific establishment of water quality standards in China.

Freshwater water quality criteria for phthalate esters and recommendations for the revision of the water quality standards

With increasing urbanization and rapid industrialization, more and more environmental problems have arisen. Phthalates (PAEs) are the foremost and most widespread plasticizers and are readily emitted from these manufactured products into the environment. PAEs act as endocrine-disrupting chemicals (EDCs) and can have serious impacts on aquatic organisms as well as human health. In this study, the water quality criteria (WQC) of five PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP)) for freshwater aquatic organisms were developed using a species sensitivity distribution (SSD) and a toxicity percentage ranking (TPR) approach. The results showed that long-term water quality criteria (LWQC) of PAEs using the SSD method could be 13.7, 11.1, 2.8, 7.8, and 0.53 μg/L, respectively. Criteria continuous concentrations (CCC) of PAEs were derived using the TPR method and determined to be 28.4, 13.1, 1.3, 2.5, and 1.6 μg/L, respectively. The five PAEs are commonly measured in China surface waters at concentrations between ng/L and μg/L. DBP, DEHP, and di-n-octyl phthalate (DnOP) were the most frequently detected PAEs, with occurrence rates ranging from 67% to 100%. The ecological risk assessment results of PAEs showed a decreasing order of risk at the national level, DEHP, DBP, DMP, DEP, DnOP. The results of this study will be of great benefit to China and other countries in revising water quality standards for the conservation of aquatic species.

Efficient removal of organic matters and typical odor substances in rural drinking water using Ozone-BAC-UF combined system to meet new water quality standards in China

China has just implemented new drinking water quality standards, canceling the provisions detailed in the previous standards that allowed relatively lenient water quality standards in rural areas, and unifying the water quality requirements for urban and rural areas. In rural areas of China, lakes are important sources of drinking water, but their water typically contain high concentrations of organic pollutants. In addition, removal odorous substances from such sources is challenging. In response to these issues, an ozone-biological activated carbon-ultrafiltration process is proposed and its efficiency in drinking water treatment is explored. The results indicate that O3-BAC pretreatment significantly improved the efficiency of the membrane process in removing organic and odor substances. At an ozone dosage of 2 mg/L, with granular activated carbon as filler and an EBCT of 25 min, the O3-BAC pretreatment allowed removal rates in the membrane system equal to 71.5% of CODMn, 84.2% of UV254, as well as 92.2% and 92.5% of GSM and 2-MIB, respectively, the latter being typical odor compounds. In addition, the function and diversity of the microbial communities in the reactor were evaluated under different pretreatment conditions at different stages: functionally specific microorganisms were enriched in different systems, and some microorganisms contributing to the removal of organic and odorous substances were identified. The effluent from the combined Ozone-BAC-UF process consistently met the new requirements for drinking water in China, implying that the combined system has significant potential for practical applications for drinking water treatment in rural areas.

Effects of environmental and agronomic factors on pond water quality within an intensive agricultural landscape in subtropical southern China

Water quality deterioration, such as eutrophication, can contribute to the degradation of farm pond ecosystems, threatening numerous ecological services and socioeconomic benefits. However, the variability of water quality and the complexity of influencing variables pose large uncertainties for pond management practices and watershed planning. This study integrated a self-organizing map (SOM) and partial least squares structural equation modeling (PLS-SEM) to evaluate the nitrogen (N) and phosphorus (P) variations in 39 typical farm ponds in the Dongting Lake basin, and related the variations to pond internal factors, external environment, and agronomic management. The results indicated that 39 monitored farm ponds faced a high risk of eutrophication owing to high N and P levels, and that total N (TN), total P (TP), and particulate P (PP) generally exceeded the threshold of level V surface water quality standards in China (2.0 mg N L−1 and 0.2 mg P L−1). Simultaneously, pond water quality showed high spatiotemporal variability, and pollution hotspots occurred mostly during the overlapping periods of fallow-dry-winter and planting-rainy-spring. Based on the constructed SEM model, external environmental factors (meteorology, catchment landscape composition, configuration, topography, and soil chemical properties), pond internal characteristics, and agronomic management combined explained 60.2 ± 2.9 % and 54.2 ± 3.1 % of the N and P variations, respectively. There were intricate interactions among the above latent variables, including such meteorology positively moderated the paths of soil chemical properties→pond P and landscape composition→pond N and P; landscape composition, soil, and pond internal characteristics mediated the effects of other variables on variations of N and P. The total effects (indirect effects + direct effects) of landscape composition on the variations of pond N and P were higher than those of other variables. Among all the indicators composing latent variables, agricultural and residential land area percentage, rainfall, water depth, and fish farming were relatively important in pond water quality variations. The constructed model and analytical results offer essential information for the accurate management and restoration of pond water quality.

Synthesis of Calcium Silicate Hydrate from Coal Gangue for Cr(VI) and Cu(II) Removal from Aqueous Solution.

Both the accumulation of coal gangue and potentially toxic elements in aqueous solution have caused biological damage to the surrounding ecosystem of the Huainan coal mining field. In this study, coal gangue was used to synthesize calcium silicate hydrate (C-S-H) to remove Cr(VI) and Cu(II)from aqueous solutions and aqueous solution. The optimum parameters for C-S-H synthesis were 700 °C for 1 h and a Ca/Si molar ratio of 1.0. Quantitative sorption analysis was done at variable temperature, C-S-H dosages, solution pH, initial concentrations of metals, and reaction time. The solution pH was precisely controlled by a pH meter. The adsorption temperature was controlled by a thermostatic gas bath oscillator. The error of solution temperature was controlled at ± 0.3, compared with the adsorption temperature. For Cr(VI) and Cu(II), the optimum initial concentration, temperature, and reaction time were 200 mg/L, 40 °C and 90 min, pH 2 and 0.1 g C-S-H for Cr(VI), pH 6 and 0.07 g C-S-H for Cu(II), respectively. The maximum adsorption capacities of Cr(VI) and Cu(II) were 68.03 and 70.42 mg·g−1, respectively. Furthermore, the concentrations of Cu(II) and Cr(VI) in aqueous solution could meet the surface water quality standards in China. The adsorption mechanism of Cu(II) and Cr(VI) onto C-S-H were reduction, electrostatic interaction, chelation interaction, and surface complexation. It was found that C-S-H is an environmentally friendly adsorbent for effective removal of metals from aqueous solution through different mechanisms.

China is establishing its water quality standards for enhancing protection of aquatic life in freshwater ecosystems

Water quality standards (WQS) are derived to give scientifically-robust and legally-binding guidance on acceptable risks of chemical contaminants with a view to protecting aquatic ecosystems and biodiversity. In China, anthropogenic chemical pollution of water bodies is a major threat to aquatic life. China, therefore, urgently needs to establish a scientifically-robust, functional WQS system that will ensure chemical contaminants are maintained at acceptable levels that protect aquatic ecosystems. In this article, we review the significant need for comprehensive national-scale protection of aquatic ecosystems and the challenges associated with using the Environmental Quality Standards for Surface Water (GB3838−2002) to protect aquatic ecosystems in China. We have also summarized information about recent developments in the aquatic life criteria for freshwater ecosystems in China and in other jurisdictions. Finally, we have made recommendations for the future direction and development of WQS in China that could be tailored to suit regional environmental characteristics and native aquatic species so as to offer better, regional-specific protection to aquatic life in freshwater ecosystems.

Spatiotemporal distribution, risk assessment and source appointment of metal(loid)s in water and sediments of Danjiangkou Reservoir, China.

Danjiangkou Reservoir is the biggest artificial reservoir in China. But spatiotemporal distribution and risks of metal(loid)s in it were still unclear after the operation of Middle Route of South-to-North Water Diversion Project. In this study, distribution pattern of fifteen metal(loid)s in the Danjiangkou Reservoir was investigated. It was shown that metal(loid)s concentrations in the water were much lower than the drinking water quality standards in China, while Sb, Co, Cd and Cr were identified as the major pollutants in the sediments. Environment-metal(loid)s correlation analysis revealed total organic carbon, sulfate, temperature, dissolved oxygen and total phosphorus markedly controlled metal(loid)s distribution in the water, while organic carbon, total phosphorus and ammonia nitrogen shaped their distribution in the sediments. Results of risk assessment further revealed that the sediments of Danjiangkou Reservoir were minor to moderate polluted, and Sb, Cd exhibited the highest potential ecological risk. Additionally, source identification showed agricultural activities (25.3%), industrial and mining activities (17.5%) and natural processes (57.2%) were the dominant sources of metal(loid)s burden in the sediments. Overall, the results are of significance to understanding the ecological risk and pollution sources in the Danjiangkou Reservoir, which is essential for the effective management of metal(loid)s pollution.

Analysis of the features and causes of the contamination in the Shandi River basin

This study examined the contamination of the surface water in the Shandi River basin in Yangquan, Shanxi province. A total of 11 sampling points (numbered S1-S2, S3-S4, S5–S11) were selected from the upstream to the downstream of the river, and 19 indexes were selected for inspection to identify the causes and features of contaminated water in the basin. The Nemerow Pollution Index was applied to evaluate the quality of the surface water and the overall extent of contamination in the basin. The result revealed that the content of Cl-, As, Cr6+, CN-, and volatile phenols met the grade III water quality standards in China, and the remaining indexes exceeded the standards by varying degrees. The five sources of contamination in the basin negatively affect the environment. The presence of contaminants at the sampling points was in the following order, from highest to lowest: SO42-= Mn = NH3-N> Fe2+= Hg >Fe3+> Cd > Zn = F->COD>NO3 -= NO2-. The severity of the comprehensive contamination indexes decreased in the order of S6 > S9 > S7 > S11 > S10 > S3 > S8 > S5 >S4.

The distribution and sources of polycyclic aromatic hydrocarbons in shallow groundwater from an alluvial-diluvial fan of the Hutuo River in North China

This paper has investigated the concentration and distribution of polycyclic aromatic hydrocarbons in shallow groundwater from an alluvial-diluvial fan of the Hutuo River in North China. Results show that the concentration levels of 16 priority polycyclic aromatic hydrocarbons range from 0 to 92.06 ng/L, do not conform to drinking water quality standards in China (GB 5749- 2006). However, the concentration figures of priority polycyclic aromatic hydrocarbons are much lower than that of other studies conducted elsewhere in China. In addition, highly-concentrated polycyclic aromatic hydrocarbons (50–92 ng/L) are fragmentarily distributed. The composition of polycyclic aromatic hydrocarbons from this study indicates that low molecular polycyclic aromatic hydrocarbons are predominant in groundwater samples, medium molecular compounds occur at low concentrations, and high molecular hydrocarbons are not detected. The polycyclic aromatic hydrocarbon composition in groundwater samples is basically the same as that of gaseous samples in the atmosphere in this study. Therefore, the atmospheric input is assumed to be an important source of polycyclic aromatic hydrocarbons, no less than wastewater discharge, adhesion on suspended solids, and surface water leakage. Ratios of specific polycyclic aromatic hydrocarbons demonstrate that they mainly originate from wood or coal combustion as well as natural gas and partially from petroleum according to the result of principal component analysis. On the whole, conclusions are drawn that the contamination sources of these polycyclic aromatic hydrocarbons are likely petrogenic and pyrolytic inputs. Future investigations by sampling topsoil, vadose soil, and the atmosphere can further verify aforementioned conclusions.

Spatial and Seasonal Patterns of Nutrients and Heavy Metals in Twenty-Seven Rivers Draining into the South China Sea

Due to the acceleration of industrialization and urbanization in recent decades, the majority of coastal rivers and estuaries in China have been moderately or severely contaminated by a variety of pollutants. We investigated the spatial and seasonal variations of water nutrients (permanganate index, chemical oxygen demand, biochemical oxygen demand, ammonium, nitrate, total nitrogen, and total phosphorus) and heavy metals (Hg, Pb, Cu, Zn, Se, As, Cd, Cr, Fe, and Mn) in 27 subtropical rivers draining into the South China Sea. Our results indicated that the average concentrations of all water quality parameters except ammonium, total nitrogen, and total phosphorus satisfied the requirements for grade III of the surface water quality standard of China. The concentrations of both nutrients and heavy metals showed a strong spatial variation. Cluster analysis classified the 27 rivers into three spatial clusters corresponding to low, moderate, and high pollution levels. In terms of seasonal variation, the values of chemical oxygen demand and biochemical oxygen demand in wet seasons were significantly lower than those in dry seasons. Multivariate statistical analyses demonstrated that river nutrients might mainly originate from domestic, industrial, and agricultural wastewaters, while heavy metals likely came from industrial activities and natural weathering processes. The findings of this study suggest that for reducing the pollution of subtropical rivers draining into the South China Sea, further efforts should be made to control nitrogen and phosphorus export from catchments.

Distribution and ecological risk assessment of cadmium in water and sediment in Longjiang River, China: Implication on water quality management after pollution accident

In early January 2012, the Longjiang River was subjected to a serious cadmium (Cd) pollution accident, which led to negatively environmental and social impacts. A series of measures of emergency treatment were subsequently taken to reduce water Cd level. However, little information was available about the change of Cd level in environmental matrices and long-term effect of this pollution accident to aquatic ecosystem. Thus, this study investigated the distribution of Cd in water and sediment of this river for two years since pollution accident, as well as assessed its ecological risk to aquatic ecosystem of Longjiang River. The results showed that it was efficient for taking emergency treatment measures to decrease water Cd concentration to below the threshold value of national drinking water quality standard of China. There was high risk (HQ > 1) to aquatic ecosystem in some of reaches between February and July 2012, but low or no risk (HQ < 1) between December 2012 to December 2013. Cd concentration in sediment in polluted reaches increased after pollution accident and emergency treatments in 2012, but decreased in 2013. During flood period, the sediment containing high concentration of Cd in Longjiang River was migrated to downstream Liujiang River. Cd content in sediment was reduced to background level after two years of the pollution accident occurrence. The study provides basic information about Cd levels in different media after pollution accident, which is helpful in evaluating the effectiveness of emergency treatments and the variation of ecological risk, as well as in conducting water management and conservation.

Multi-Elements in Source Water (Drinking and Surface Water) within Five Cities from the Semi-Arid and Arid Region, NW China: Occurrence, Spatial Distribution and Risk Assessment.

The purpose of this study was to identify the concentration of multi-elements (MEs) in source water (surface and drinking water) and assess their quality for sustainability. A total of 161 water samples including 88 tap drinking waters (DW) and 73 surface waters (SW) were collected from five cities in Xi’an, Yan’an, Xining, Lanzhou, and Urumqi in northwestern China. Eighteen parameters including pH, electrical conductivity (EC), total organic carbon (TOC) total nitrogen (TN), chemical compositions of anions (F−, Cl−, NO3−, HCO3−, SO42−), cations (NH4+, K+, Na+, Ca2+, Mg2+), and metals (lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu)) were analyzed in the first time at the five cities . The results showed that pH values and concentrations of Cl−, SO42−, Na+, K+, Ca2+, Mg2+ and Cd, Cr, Cu in DW were within the permissible limits of the Chinese Drinking Water Quality Criteria, whereas the concentrations of other ions (F−, NO3−, NH4+ and Pb) exceeded their permissible values. In terms of the SW, the concentrations of F−, Cl−, NO3−, SO42− were over the third range threshold i.e., water suitable for fishing and swimming of the Surface Water Quality Standards in China. The spatial distributions of most MEs in source water are similar, and there was no clear variation for all ions and metals. The metals in DW may be caused by water pipes, faucets and their fittings. The noncarcinogenic risk of metals in DW for local children are in decreasing order Cr > Cd > Pb > Cu. The carcinogenic risk from Cr exposure was at the acceptable level according to threshold of USEPA. Although the comprehensive index of potential ecological assessment of Cr, Cd, Pb and Cu in SW ranked at low risk level and was in the order of Huang River in Xining > Peaceful Canal in Urumqi > Yan River in Yan’an > Yellow River in Lanzhou, their adverse effects to ecology and human health at a low concentration in local semi-arid and arid areas should not be ignored in the long run.

Hydrogeochemical characterization and groundwater quality assessment in intruded coastal brine aquifers (Laizhou Bay, China).

The aquifer in the coastal area of the Laizhou Bay is affected by salinization processes related to intense groundwater exploitation for brine resource and for agriculture irrigation during the last three decades. As a result, the dynamic balances among freshwater, brine, and seawater have been disturbed and the quality of groundwater has deteriorated. To fully understand the groundwater chemical distribution and evolution in the regional aquifers, hydrogeochemical and isotopic studies have been conducted based on the water samples from 102 observation wells. Groundwater levels and salinities in four monitoring wells are as well measured to inspect the general groundwater flow and chemical patterns and seasonal variations. Chemical components such as Na+, K+, Ca2+, Mg2+, Sr2+, Cl-, SO42-, HCO3-, NO3-, F-, and TDS during the same period are analyzed to explore geochemical evolution, water-rock interactions, sources of salt, nitrate, and fluoride pollution in fresh, brackish, saline, and brine waters. The decreased water levels without typical seasonal variation in the southeast of the study area confirm an over-exploitation of groundwater. The hydrogeochemical characteristics indicate fresh-saline-brine-saline transition pattern from inland to coast where evaporation is a vital factor to control the chemical evolution. The cation exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. Meanwhile, isotopic data indicate that the brine in aquifers was either originated from older meteoric water with mineral dissolution and evaporation or repeatedly evaporation of retained seawater with fresher water recharge and mixing in geological time. Groundwater suitability for drinking is further evaluated according to water quality standard of China. Results reveal high risks of nitrate and fluoride contamination. The elevated nitrate concentration of 560mg/L, which as high as 28 times of the standard content in drinking water is identified in the south region. In addition, the nitrate and ammonia data of the Wei River suggests decreasing nitrification rate in the study area from inland to estuary. High fluoride concentration, larger than 1mg/L, is also detected in an area of about 50% of the study region. The saltwater intrusion is analyzed to be responsible for part of dissolution of minerals containing fluoride. Therefore, water treatment before drinking is needed in urgent to reduce the health expose risk.

Seasonal Pollution Characteristics and Source Identification of Polycyclic Aromatic Hydrocarbons and Organochlorine Pesticides in Surface Water of Baiyangdian Lake

Seasonal variations of 17 polycyclic aromatic hydrocarbons(PAHs) and 15 persistent organochlorine pesticides(OCPs) were analyzed during spring and summer in surface water from 12 sampling sites of Baiyangdian lake to elucidate their seasonal pollution characteristics and sources. The results showed that total concentrations of PAHs in surface water of Baiyangdian lake ranged from 35.38 to 88.06 ng·L-1(46.57 ng·L-1 in average) in spring and 25.64 to 301.41 ng·L-1(76.23 ng·L-1 in average) in summer, respectively, and total concentrations of OCPs ranged from 0.69 to 4.50 ng·L-1(1.77 ng·L-1 in average) in spring and 0.11 to 3.20 ng·L-1(0.90 ng·L-1 in average) in summer, respectively. Seasonal pollution characteristics of PAHs in surface water during two different seasons showed that the total concentration of PAHs was much higher in summer than in spring at three sampling sites of Baiyangdian lake including Qiantang, Guancheng and Anxin bridge, and the level of PAHs in spring was much higher than that in summer at the other nine sites. While seasonal pollution characteristics of OCPs showed that the total concentration of OCPs was much higher in summer than in spring in samples of Guancheng sites, and the level of OCPs in spring was slightly higher than that in summer in the rest of samples. From the perspective of spatial and temporal variations in the composition patterns of PAHs and OCPs in surface water of Baiyangdian lake, PAHs were predominated by 3-ring PAHs with 45.92% and 61.36%(52.60% in average) of total PAHs in spring, while in summer Nap was the chief component of 2-ring PAHs in three sampling sites including Qiantang, Guancheng and Anxin bridge with 84.91%, 91.04% and 78.10% of the total, respectively, and 3-ring PAHs were primary pollutants in the other nine sites with 37.14% to 53.90%(48.94% in average) of the total. Residues of HCHs and DDTs were detected in different degrees and β-HCH was the main pollutant at all sampling sites with 29.94% and 100%(59.87% in average) of total HCHs in spring, while β-HCH was the predominant compounds at five sampling sites with 57.55% and 80.23%(61.98% in average) in summer and α-HCHs and δ-HCH were abundant at other sampling sites. Source analysis based on isomer ratios indicated that the main source of PAHs in Baiyangdian lake originated from combustion sources, and additional sources for several sampling sites could be petroleum processes. Ratios of HCH isomers and DDT congeners confirmed that environmental historical residues and long range atmospheric transport were the major sources of OCPs contamination in the study area. Compared with the water quality standard of China and other countries or organizations, concentrations of PAHs and OCPs in surface water of Baiyangdian lake did not exceed the target values of the standard. However, the concentrations of α-HCH and p,p'-DDD in Anxin bridge and Quantou sites exceeded the limit of human health ambient water quality criteria developed by EPA, which reflected that α-HCH and p,p'-DDD would have a potential hazards risk to the residents from Baiyangdian district.

Research on the application of the modified aquatic mat pond and integrated vertical-flow constructed wetland coupling process based on luffa sponges for micro-polluted water treatment

This paper presents a scientific performance study of the application of the modified aquatic mat pond (MAMP)-integrated vertical-flow constructed wetland (IVCW) coupling process for treating micro-polluted river water using luffa sponge material. In addition, the surface modifications of luffa sponge were investigated. The results showed that luffa sponge functioned well in a bench scale experiment and in a demonstration project, and the main effluent water indexes reached the class IV standard defined by the surface water quality standard of China (GB3838-2002). However, natural luffa sponge is easily hydrolyzed and should be replaced at regular intervals. A microwave-enhanced KH550 (Silane coupling agent gamma-aminopropyltriethoxysilane) coupling method for modifying luffa sponges were performed to reduce the water absorption rate and prolong the engineering service time of the sponge. The results showed that the water absorption rate of the tested luffa sponge fibers was reduced to 22.39% after the fourth set of modifications, and an orthogonal test revealed that the priority order for the factors that affected the modification process was KH550 concentration >microwave reaction time >NAOH concentration > soaking time. The optimal set of modification conditions for luffa sponge fibers was 2% (w/w) NAOH, 1% (w/w) KH550, 30 min of soaking and 180 s of microwave treatment.

Developing surface water quality standards in China

A methodology for setting lake nutrient standard was proposed in this study based on review of water quality standards (WQS) in China and understanding of lake nutrient criteria. There are very few studies about lake nutrient criteria and water body classification system, which may cause difficulties in nutrient level assessment and management. This paper reviewed WQS system in the US, EU, and Japan, and then presented the development procedures for revising surface WQS in different periods in China. The amendment includes indicators, standard values, and framework of the standard system. However, current WQS set in light of the criteria and standards of the US and Europe couldn’t adapt to the natural conditions of lakes in China. Therefore, by learning from the water quality criteria setting method of USA and taking the regional differences into consideration, a methodology of combining structure equation model and expert elicitation was recommended for setting WQS. Furthermore, it considered to investigate the differences (climate, elevation and geographical condition, etc.) in each region, and set lake nutrient criteria and standards on regional scale. Consequently, the proposed methodology for setting standards could be applied to each region in China. Yungui ecoregion was taken as an example for setting up the lake nutrient standards with considering TP, Chl-a, TN and CODMn four influence factors for designated use attainment, and a suitable TP standard 0.02mg/L was recommended by using the proposed methods.

Wastewater Treatment in Chinese Rural Areas

In the last 10 years, the extent of wastewater treated in China has increased by 57%, the great amounts of sewage have threatened people's health as well the natural environment. In the last 10 years, the sewage treatment rate has improved, in December 2013, 99.1% of Chinese cities and 82.6% counties have sewage treatment plants. This review paper describes the current situation and has suggestion of how to overcome future sewage problems especially water pollution in China from domestic, agriculture and industrial sectors. It also discusses the urban/ rural wastewater for treatment including sewerage systems, treatment plants and water quality standards in China. The paper highlights the challenges of effective wastewater treatment in rural areas as a particular issue due to lack of monitoring and law support. This has led to ineffective management of treatment plants, financial difficulties; inappropriate sewerage, treatment facilities and standards; as well as poor awareness.

Amendment of water quality standards in China: viewpoint on strategic considerations.

Water quality standards (WQS) are the most important tool for protection of quality of aquatic environments in China and play a decisive role in the management of China's aquatic environments. Due to limited scientific information available previously, WQS were developed largely based on water quality criteria (WQC) or WQS recommended by developed countries, which may not be suitable for current circumstances in China. The Chinese government recently initiated the revision of Environmental Quality Standards for Surface Water (EQSSW) (GB3838-2002) to meet the challenge of environmental protection. This review analyzed how the WQS developed and applied in China differ from those of more developed countries and pointed out that the lack of strong scientific bases for China's WQC pose major limitations of current WQS. We focus on discussing the six aspects that require high attention on how to establish a national WQC system to support the revision of WQS (Table 1) such as development of methodology, refining water function zoning, establish priority pollutants list, improving protection drinking water sources, development of site-specific water quality criteria, and field toxicity test. It is essential that China and other developing countries established a relatively mature system for promulgating, applying, and enforcing WQC and to implement a dynamic system to incorporate most recent research results into periodically updated WQS.

Response Behaviors of Heavy Metals at Tidal Currents Interface and Salinity Interface in the Estuary Area

In China, trace metals (such as dissolved Cu, Zn, Pb, Cd, and Cr) are the routine mandatory monitoring indicators in existing Freshwater Quality Standard (FWQS, 2002) and Seawater Quality Standard (SWQS, 1997). Using Daliao River estuary as an example, we tried to research the general response patterns of these metals in estuarine system. Firstly, we determined the location of FSI (freshwater-seawater interface) and TCI (tidal currents interface), which were based on biological, chemical and geographic similarities by descriptive and quantitative methods, respectively. Secondly, two hypotheses were proposed to explain the difference based on distribution coefficient Kd along salinity and SS (suspended solids) gradient, these results revealed that the indicators for As, Cd and Cr may be prone to be affected by salinity, and the ones in the second pattern may be more sensitive to SS. Finally, we classified the response behaviors into two patterns based on the changing trends along the distance and magnitudes affected by the FSI and TCI: 1the obvious boundary break point from FSI for As, Cd and Cr; 2 the boundary zones from TCI for Zn, Cu, Pb and Ni. The partitioning behaviors showed similar changing trends at particle and sediment phases, especially for particle phase, depending on the concentration of SS along the salinity. The difference between general behaviors for the two patterns mainly existed at water phase. In general, this paper highlighted the need to consider the background difference of trace metals and identified the sensitive indicators controlled by different environment factors (such as salinity and SS) based on the native estuarine characteristics. Our work will assist the implementation of updating the current water quality standards in China.

Assessment of heavy metal contamination in water body and riverbed sediments of the Yanghe River in the Bohai Sea, China

Several famous beach bathing places and aquiculture areas locate in the Yanghe River coast of the Bohai Sea, which are very sensitive to the quality of water and sediment from river discharges. To assess heavy metal contamination, heavy metal in water body and riverbed sediments was investigated in the flood and dry seasons in 2013 at 8 sites along the Yanghe River. All heavy metal concentrations in water body were very low and less than the threshold value of drinking water quality standard of China. There was no significant correlation between heavy metal pollution in water body and riverbed sediments. Sediment pollution was assessed by five approaches including pollution load index (PLI), geo-accumulation index (I geo), potential ecological risk index (RI), cluster analysis (CA) and principal component analysis (PCA). The results of heavy metal contamination in riverbed sediments showed that: (1) the mean PLI in the range of 1.0–1.1 indicated a progressive deterioration, and the I geo revealed the pollution in the order of Cd > Cu > Zn > Pb > Cr; (2) the RI presented that the pollution in the downstream was much higher than that in the upstream; (3) the contamination decreased in the upstream due to decreased domestic wastewater where far from the development zone Funing Town, while it increased in the downstream because of dense population and tourists in the coastal zone; and (4) the PCA and FA demonstrate that domestic sewage was a major source of heavy metal contamination.