Regional risk assessment for point source pollution based on a water quality model of the Taipu River, China

Further Insight into Extractable (Organo)fluorine Mass Balance Analysis of Tap Water from Shanghai, China

The ubiquitous occurrence of per- and polyfluoroalkyl substances (PFAS) and the detection of unexplained extractable organofluorine (EOF) in drinking water have raised growing concerns. A recent study reported the detection of inorganic fluorinated anions in German river systems, and therefore, in some samples, EOF may include some inorganic fluorinated anions. Thus, it might be more appropriate to use the term "extractable fluorine (EF) analysis" instead of the term EOF analysis. In this study, tap water samples (n = 39) from Shanghai were collected to assess the levels of EF/EOF, 35 target PFAS, two inorganic fluorinated anions (tetrafluoroborate (BF4-) and hexafluorophosphate (PF6-)), and novel PFAS through suspect screening and potential oxidizable precursors through oxidative conversion. The results showed that ultra-short PFAS were the largest contributors to target PFAS, accounting for up to 97% of ΣPFAS. To the best of our knowledge, this was the first time that bis(trifluoromethanesulfonyl)imide (NTf2) was reported in drinking water from China, and p-perfluorous nonenoxybenzenesulfonate (OBS) was also identified through suspect screening. Small amounts of precursors that can be oxidatively converted to PFCAs were noted after oxidative conversion. EF mass balance analysis revealed that target PFAS could only explain less than 36% of EF. However, the amounts of unexplained extractable fluorine were greatly reduced when BF4- and PF6- were included. These compounds further explained more than 44% of the EF, indicating the role of inorganic fluorinated anions in the mass balance analysis.

Development of a DREAM-based inverse model for multi-point source identification in river pollution incidents: Model testing and uncertainty analysis

Source identification plays a vital role in implementing control measures for sudden river pollution incidents. In contrast to single-point source identification problems, there have been no investigations into inverse identification of multi-point emissions. In this study, an inverse model is developed based on the observed time series of pollutant concentrations and the DiffeRential Evolution Adaptive Metropolis (DREAM) method to identify multi-point sources with uncertainty quantification. We aim to simultaneously determine source mass, release location and time of multi-point sources. The newly developed DREAM-based model has been tested and verified through both numerical and field data case studies in terms of accuracy, reliability, and computational time. Adapted cases with single-point, two-point and three-point sources in the Songhua River are conducted to test the applicability of the modeling approach, respectively. The developed model can correctly quantify source parameters with a relative error that does not exceed ±0.63%, although it shows that an increase of emission sources may slightly increase the identification error. Among the three source parameters, the identification error of the release time tends to rise more obviously in response to the increase in the number of pollution sources. It is also found that the identification accuracy is primarily sensitive to the river velocity, followed by the dispersion coefficient and the river cross-sectional area. Furthermore, good monitoring strategies, including reducing observation errors, shortening monitoring interval time and selecting the proper monitoring distance between the monitoring and the source sites, help to achieve a better application of the developed model in river pollution incidents.

Mobile resistome of microbial communities and antimicrobial residues from drinking water supply systems in Rio de Janeiro, Brazil

Antibiotic resistance genes (ARGs) are widespread in the environment due to the overuse of antibiotics and other pollutants, posing a threat to human and animal health. In this study, we evaluated antimicrobial residues, bacterial diversity and ARGs in two important watersheds, Guandu and São João, that supply drinking water to Rio de Janeiro city, Brazil. In addition, tap water samples were collected from three different cities in Rio de Janeiro State, including the metropolitan area of Rio de Janeiro city. Clarithromycin, sulfamethoxazole and azithromycin were found in untreated water and drinking water in all samples. A greater abundance of Proteobacteria was observed in Guandu and São João watersheds, with most of the sequences belonging to the Gammaproteobacteria class. A plasmidome-focused metagenomics approach revealed 4881 (Guandu), 3705 (São João) and 3385 (drinking water) ARGs mainly associated with efflux systems. The genes encoding metallo-β-lactamase enzymes (blaAIM, blaGIM, blaIMP, and blaVIM) were detected in the two watersheds and in drinking water samples. Moreover, we demonstrated the presence of the colistin resistance genes mcr-3 and mcr-4 (both watersheds) and mcr-9 (drinking water and Guandu) for the first time in Brazil. Our data emphasize the importance of introducing measures to reduce the disposal of antibiotics and other pollutants capable of promoting the occurrence and spread of the microbial resistome on aquatic environments and predicting possible negative impacts on human health.

Impact of Agricultural Non-Point Source Pollution on River Water Quality: Evidence From China

Identifying the effect of agricultural non-point source pollutants on water quality is very important for water pollution management. This study used NH3N as an indicator to empirically study the influence of fertilizer application on river water quality based on panel data of 46 prefecture-level cities and 18 state-controlled water quality monitoring points through which the main streams of Yangtze River and Yellow River flow from 2004 to 2019. It is found that: (1) An increase in agricultural fertilizer application amount will exacerbate water pollution, and the worsening water quality in the upper watershed and the influence of precipitation will lead to transboundary water pollution in the lower watershed. (2) The amount of fertilizer application and fertilizer application intensity had a threshold effect on river water quality pollution. When the former exceeded the threshold value of 11.496 tons, and the latter exceeded the threshold value of 7.991 ton/km2, the positive effect of fertilizer application on pollutants in rivers was further enhanced. (3) The amount of fertilizer applied had a long-term effect on water quality through a lagged effect, and as the number of lags increased, the accumulative effect of the negative influence gradually rose. Based on the findings of the empirical study, it is proposed that the inter-basin and inter-regional synergy should be formed in the prevention and control of agricultural non-point source pollution, and the overall top-level design of agricultural subsidies and agricultural environmental policies in the areas along the basin should be considered.

Mutual environmental drivers of the community composition, functional attributes and co-occurrence patterns of bacterioplankton in the composite aquatic ecosystem of Taihu watershed in China

This study aimed to determine the environmental and ecological factors influencing the planktonic prokaryotic community profiles in the composite ecosystem comprising Taihu Lake, Taipu River and Jinze Reservoir in the Taihu Watershed in China. A total of 42 water samples were intermittently collected from different sites in 6 months across four seasons. Physicochemical characteristics of the ecosystem, bacterioplankton diversity and composition, the presence of co-occurrence patterns, and environmental predictors of ecological modules in the bacterioplankton network were determined. The central species played a more important role in regulating the structure and function of the bacterioplankton community and in responding to environmental contamination than the entire community. The relative abundance of the phylum Proteobacteria and the class Betaproteobacteria varied significantly between months and locations, which were identified as core functional taxa. A non-random co-occurrence pattern and function-driven modular structure were observed in the bacterioplankton co-occurrence network. Dissolved oxygen and ammonium nitrogen were the major and mutual environmental predictors of the bacterioplankton community composition, functional attributes and relative abundance of ecological modules. The results improve our understanding of the impact of anthropogenic contamination on bacterioplankton diversity and biogeochemical cycles and the formulation of strategies for bioremediation of the Taihu Watershed.

Establishment of an integrated decision-making method for planning the ecological restoration of terrestrial ecosystems

Ecological restoration of terrestrial ecosystems facilitates environmental protection and enhances sustainable development of land resources. With increasingly severe land degradation, new and effective methods must be developed for the restoration of ecological functions. In this study, we developed a regional risk assessment approach to support the planning of ecological restoration of a terrestrial ecosystem located in the Daye area in central China. The study area was divided into six sub-regions where ecological risks were characterized by building a non-linear model to represent ecological interactions among the risk components there. Socio-economic conditions in the areas were evaluated and presented using an analytic hierarchy process. Assessment of different stakeholders there was conducted based on multiple-criteria decision analysis. Then, integrated assessment was performed using the technique of order preference for an ideal solution. We divided the degraded land in Daye into areas with different priorities for restoration or rectification and presented corresponding sequential time intervals for the action. The results are as follows: (i) the top priority rectification areas (totaling 358 km²) are mainly distributed in northeast and northwest regions; (ii) the high priority rectification areas are concentrated in the central region spanning 226 km²; (iii) the medium priority rectification areas comprised a large amount of arable and forest land spanning 605 km²; and (iv) the low priority rectification areas cover the rest part of the Daye area spanning 195 km². The assessment tool was proven to be useful in planning regional ecological restoration in terrestrial ecosystems.

Safety Regulations and the Uncertainty of Work-Related Road Accident Loss: The Triple Identity of Chinese Local Governments Under Principal-Agent Framework

This study examines how government safety regulations affect the uncertainty of work-related road accident loss (UWRAL) by considering the multi-identity of local governments in the relationship among the central government, the local governments, and enterprises. Fixed effects panel models and mediation analyses with bootstrapping were conducted to test the hypotheses using Chinese provincial panel data from 2008 to 2014. Given the complexity and nonlinear characteristics of road safety systems, a new approach based on self-organized criticality theory is proposed to measure the uncertainty of road accident loss from a complex system perspective. We find that a regional government with detailed safety work planning (SWP), high safety supervision intensity (SSI), and safety information transparency (SIT) can decrease the UWRAL. Furthermore, our findings suggest that SSI and SIT partially mediate the relationship between the SWP of regional governments and the UWRAL, with 19.7% and 23.6% indirect effects, respectively. This study also provides the government with managerial implications by linking the results of risk assessment to decision making for risk management.

Appraising the risk level of physicochemical and bacteriological twin contaminants of water resources in part of the western Niger Delta region

This study was carried out to assess the physicochemical and bacteriological contaminants of surface, shallow well and municipal borehole waters in part of the western Niger Delta as a way of safeguarding public health against waterborne diseases. A total of 72 water samples collected from the study area were analysed and their results show that the pH average value ranges from 6.2 in the dry to 8.5 in the rainy seasons for surface water, 6.6 and 8.3 for shallow well water and 6.5 to 8.4 for borehole water. The turbidity in surface water varies from 8.1 to 26.2 Formazin Attenuation Unit (FAU), 0.3 to 2.9 FAU in shallow well water and 0.4 to 4.8 FAU in borehole water. Electrical conductivity (EC) value varies from 1010 to 1840 μs/cm for surface water, 201 to 950 μs/cm for shallow well water and 670 to 1650 μs/cm for borehole water. Total dissolved solids range from 0.1 to 2.6 mg/l in surface water, 0.2 to 4.1 mg/l in shallow well water and 0.3 to 4.4 mg/l in borehole water. The value of the total hardness ranges from 44 to 120 mg in surface water, 46 to 96 mg in shallow well water and 70 to 130 mg in borehole water. The nitrate value ranges from 1.1 to 10.6 mg in surface water, 3.0 to 8.4 mg in shallow well water and 3.7 to 9.6 mg in borehole water. The value of sulphate content varies from 4.6 to 38.5 mg in surface water, 6.2 to 34.8 mg in shallow well water and 5.7 to 55.7 mg in borehole water. The value of phosphate concentrations in surface water varies from 1.0 to 9.0 mg, 0.7 to 3.4 mg in shallow well water and 1.0 to 4.7 mg in borehole water. The bacteriological analysis using the membrane filtration technique revealed the presence of faecal bacteria and total coliform counts. The presence of the analysed twin contaminants in the studied water resources reduced their water quality. The physicochemical and bacteriological data were subjected to statistical and correlation tests. It was concluded that their concentration levels were independent of intra-seasonal changes. The likely natural and artificial sources of contaminants are run-offs from fertilized lands, septic tanks, industrial discharges, sewage and waste disposal, algae blooms and erosion from natural deposits. The inherent risk is water-related diseases such as waterborne diseases, water-washed diseases, water-based diseases and diseases transmitted by water-related insect vectors. Water resources should be protected through proper sanitation systems, limiting of up-stream discharges, maintenance of wellheads, boiling and municipal water treatment plants. Educational advice should be given to the inhabitants on the dangers posed by continuous drinking of contaminated water. These measures will prevent disease outbreak and public health burden in the area.

A Comprehensive Review of Microfluidic Water Quality Monitoring Sensors

Water crisis is a global issue due to water contamination and extremely restricted sources of fresh water. Water contamination induces severe diseases which put human lives at risk. Hence, water quality monitoring has become a prime activity worldwide. The available monitoring procedures are inadequate as most of them require expensive instrumentation, longer processing time, tedious processes, and skilled lab technicians. Therefore, a portable, sensitive, and selective sensor with in situ and continuous water quality monitoring is the current necessity. In this context, microfluidics is the promising technology to fulfill this need due to its advantages such as faster reaction times, better process control, reduced waste generation, system compactness and parallelization, reduced cost, and disposability. This paper presents a review on the latest enhancements of microfluidic-based electrochemical and optical sensors for water quality monitoring and discusses the relative merits and shortcomings of the methods.

Environmental fate of multiwalled carbon nanotubes and graphene oxide across different aquatic ecosystems

The industrial use and widespread application of carbon-based nanomaterials have caused a rapid increase in their production over the last decades. However, toxicity of these materials is not fully known and is still being investigated for potential human and ecological health risks. Detecting carbon-based nanomaterials in the environment using current analytical methods is problematic, making environmental fate and transport modeling a practical way to estimate environmental concentrations and assess potential ecological risks. The Water Quality Analysis Simulation Program 8 (WASP8) is a dynamic, spatially resolved fate and transport model for simulating exposure concentrations in surface waters and sediments. Recently, WASP has been updated to incorporate processes for simulating the fate and transport of nanomaterials including heteroaggregation and phototransformation. This study examines the fate and transport of multiwalled carbon nanotubes (MWCNT), graphene oxide (GO) and reduced graphene oxide (rGO) in four aquatic ecosystems in the southeastern United States. Sites include a seepage lake, a coastal plains river, a piedmont river and an unstratified, wetland lake. A hypothetical 50-year release is simulated for each site-nanomaterial pair to analyze nanomaterial distribution between the water column and sediments. For all nanomaterials, 99% of the mass loaded moves though systems of high and low residence times without being heteroaggregated and deposited in the sediments. However, significant accumulation in the sediments does occur over longer periods of time. Results show that GO and rGO had the highest mass fraction in the water column of all four sites. MWCNT were found predominantly in the sediments of the piedmont river and seepage lake but were almost entirely contained in the water column of the coastal plains river and wetland lake. Simulated recovery periods following the release estimate 37+ years for lakes and 1-4 years for rivers to reduce sediment nanomaterial concentrations by 50% suggesting that carbon-based nanomaterials have the potential for long-term ecological effects.

An Integrated Framework for Environmental Multi-Impact Spatial Risk Analysis

Quantitative risk analysis is being extensively employed to support policymakers and provides a strong conceptual framework for evaluating decision alternatives under uncertainty. Many problems involving environmental risks are, however, of a spatial nature, i.e., containing spatial impacts, spatial vulnerabilities, and spatial risk-mitigation alternatives. Recent developments in multicriteria spatial analysis have enabled the assessment and aggregation of multiple impacts, supporting policymakers in spatial evaluation problems. However, recent attempts to conduct spatial multicriteria risk analysis have generally been weakly conceptualized, without adequate roots in quantitative risk analysis. Moreover, assessments of spatial risk often neglect the multidimensional nature of spatial impacts (e.g., social, economic, human) that are typically occurring in such decision problems. The aim of this article is therefore to suggest a conceptual quantitative framework for environmental multicriteria spatial risk analysis based on expected multi-attribute utility theory. The framework proposes: (i) the formal assessment of multiple spatial impacts; (ii) the aggregation of these multiple spatial impacts; (iii) the assessment of spatial vulnerabilities and probabilities of occurrence of adverse events; (iv) the computation of spatial risks; (v) the assessment of spatial risk mitigation alternatives; and (vi) the design and comparison of spatial risk mitigation alternatives (e.g., reductions of vulnerabilities and/or impacts). We illustrate the use of the framework in practice with a case study based on a flood-prone area in northern Italy.

Modeling Approach for Water-Quality Management to Control Pollution Concentration: A Case Study of Ravi River, Punjab, Pakistan

One of the challenging problems of Punjab, the most populous province of Pakistan, is the surface water-quality problem of the Ravi River, which flows through the main cities of the province. At present, the overall status of water quality is very polluted, primarily due to residential and industrial wastewater directly discharged into the Ravi River through a network of drains. Due to the poor quality of the water, the river ecosystem is not favorable for the aquatic and surrounding environment. Hence, management options are proposed to reduce pollution. Therefore, the study was formulated to identify the main sources of pollution along the Ravi River and their potential impact on the course of the river channel. In addition, the study applied a numerical model WASP 8.1 (Water Quality Simulation Program) to discover the best strategy for the improvement of water quality. Through the model simulation it was found that, if the flow at headwater and link canals is increased up to 50%, along with 75% improvement in the pollution concentration of drains through wastewater-treatment facilities, the water quality of the Ravi River can be improved up to an acceptable limit of water-quality standards.

Adapting ecological risk valuation for natural resource damage assessment in water pollution

Ecological risk assessment can address requirements of natural resource damage assessment by quantifying the magnitude of possible damages to the ecosystem. This paper investigates an approach to assess water damages from pollution incident on the basis of concentrations of contaminants. The baseline of water pollution is determined with not-to-exceed concentration of contaminants required by water quality standards. The values of damage cost to water quality are estimated through sewage treatment cost. To get a reliable estimate of treatment cost, DEA is employed to classify samples of sewage plants based on their efficiency of sewage treatment. And exponential fitting is adopted to determine the relation between treatment cost and the decrease of COCs. The range of damage costs is determined through the fitting curves respectively based on efficient and inefficient samples.

Risk perception of aquatic pollution originated from chemical industry clusters in the coastal area of Jiangsu province, China

According to "the Layout Scheme of the Chemical Industry in Jiangsu Province From 2016 to 2030" and "the Development Planning in the Coastal Area of Jiangsu Province, China," several chemical industry clusters will be located in the coastal area of Jiangsu province, China, and the risk of surface water pollution will be inevitably higher in the densely populated region. To get to know the risk acceptance level of the residents near the clusters, public perception was analyzed from the five risk factors: the basic knowledge about the pollution, the negative effects on aquatic environment imposed by the clusters, the positive effects brought by the clusters, the trust of controlling aquatic pollution, and the acceptance of the clusters. Twenty-four statements were screened out to describe the five factors, and about 600 residents were covered in three typical clusters surveyed. On the whole, the youth showed a higher interest on the survey, and middle-aged people were likely to be more concerned about aquatic pollution incident. There was no significant difference on risk perception of the three clusters. The respondents investigated had good knowledge background on aquatic pollution and the residents identified with the benefits brought by the clusters. They were weak in risk awareness of pollution originated from the chemical enterprises' groups. Although the respondents regarded that chemical industry clusters did not expose all points of pollutants' generation to the public, they inclined to trust the administration agencies on controlling the pollution and welcome the construction of chemical clusters in their dwelling cities. Besides, risk perception showed obvious spatial distribution. The closer were the samples' sites to the clusters and the rivers receiving pollutants, the higher were the residents' perceived risk, benefit, and trust. However, there was no identical spatial difference on risk acceptance, which might be comprehensively influenced by various factors. Demographic variables on diverse risk acceptance levels were further illustrated, and some useful conclusions might be provided for managing the response of residents to aquatic pollution and helping identify effective precautionary measures in the vicinity of chemical industry clusters.

Industrial water resources management based on violation risk analysis of the total allowable target on wastewater discharge

To improve the capabilities of conventional methodologies in facilitating industrial water allocation under uncertain conditions, an integrated approach was developed through the combination of operational research, uncertainty analysis, and violation risk analysis methods. The developed approach can (a) address complexities of industrial water resources management (IWRM) systems, (b) facilitate reflections of multiple uncertainties and risks of the system and incorporate them into a general optimization framework, and (c) manage robust actions for industrial productions in consideration of water supply capacity and wastewater discharging control. The developed method was then demonstrated in a water-stressed city (i.e., the City of Dalian), northeastern China. Three scenarios were proposed according to the city’s industrial plans. The results indicated that in the planning year of 2020 (a) the production of civilian-used steel ships and machine-made paper & paperboard would reduce significantly, (b) violation risk of chemical oxygen demand (COD) discharge under scenario 1 would be the most prominent, compared with those under scenarios 2 and 3, (c) the maximal total economic benefit under scenario 2 would be higher than the benefit under scenario 3, and (d) the production of rolling contact bearing, rail vehicles, and commercial vehicles would be promoted.

Assessment of the Effects of Total Emission Control Policies on Surface Water Quality in China: 2004 to 2014

Water quality deterioration is a problem throughout the globe, especially in China. The Chinese government established national total emission control (TEC) policies related to the nation's surface water quality over the past 10 yr to restore, protect, and promote healthy water quality. The objective of this study is to evaluate the effects of China's TEC policies by analyzing three water quality constituents (ammonium nitrogen [NH-N], dissolved oxygen [DO], and the permanganate index [COD]) at 73 monitoring stations, which account for most of the surface waters of eastern China. The seasonal Mann-Kendall test revealed that approximately 60, 50, and 65% of stations had nonsignificant trends for COD, NH-N, and DO, respectively. Concentrations of COD and NH-N significantly (α = 0.05) decreased by 27.4 and 38.4% at the monitoring stations over the 11-yr study period, whereas DO significantly (α = 0.05) increased by 24.7%. Correlation analysis indicated that the water quality improved at approximately 30% (COD) and 20% (NH-N) of monitoring sites with the reduction of water pollutant emissions from industrial sources. A seasonal pattern was observed for the three water quality parameters at most of the stations but not at a regional scale. Results also indicated that COD concentrations decreased significantly (α = 0.05) at most river stations but increased significantly (α = 0.05) at nearly all lake stations, suggesting that TEC in China might be more effective for rivers than for lakes and reservoirs. Although there are many nonsignificant relationships with the water quality constituents selected as top pollutants in China, a few noticeable significant relationships were established.

Development and testing of a fast conceptual river water quality model

Modern, model based river quality management strongly relies on river water quality models to simulate the temporal and spatial evolution of pollutant concentrations in the water body. Such models are typically constructed by extending detailed hydrodynamic models with a component describing the advection-diffusion and water quality transformation processes in a detailed, physically based way. This approach is too computational time demanding, especially when simulating long time periods that are needed for statistical analysis of the results or when model sensitivity analysis, calibration and validation require a large number of model runs. To overcome this problem, a structure identification method to set up a conceptual river water quality model has been developed. Instead of calculating the water quality concentrations at each water level and discharge node, the river branch is divided into conceptual reservoirs based on user information such as location of interest and boundary inputs. These reservoirs are modelled as Plug Flow Reactor (PFR) and Continuously Stirred Tank Reactor (CSTR) to describe advection and diffusion processes. The same water quality transformation processes as in the detailed models are considered but with adjusted residence times based on the hydrodynamic simulation results and calibrated to the detailed water quality simulation results. The developed approach allows for a much faster calculation time (factor 10⁵) without significant loss of accuracy, making it feasible to perform time demanding scenario runs.

Analysis of the relationship between economic growth and industrial pollution in Zaozhuang, China-based on the hypothesis of the environmental Kuznets curve

In Zaozhuang, economic development affects the discharge amount of industrial wastewater, chemical oxygen demand (COD), and ammonia nitrogen (NH3-N). To reveal the trend of water environmental quality related to the economy in Zaozhuang, this paper simulated the relationships between industrial wastewater discharge, COD, NH3-N load, and gross domestic product (GDP) per capita for Zaozhuang (2002-2012) using environmental Kuznets curve (EKC) models. The results showed that the added value of industrial GDP, the per capita GDP, and wastewater emission had average annual growth rates of 16.62, 16.19, and 17.89 %, respectively, from 2002 to 2012, while COD and NH3-N emission in 2012, compared with 2002, showed average annual decreases of 10.70 and 31.12 %, respectively. The export of EKC models revealed that industrial wastewater discharge had a typical inverted-U-shaped relationship with per capita GDP. However, both COD and NH3-N showed the binding curve of the left side of the "U" curve and left side U-shaped curve. The economy in Zaozhuang had been at the "fast-growing" stage, with low environmental pollution according to the industrial pollution level. In recent years, Zaozhuang has abated these heavy-pollution industries emphatically, so pollutants have been greatly reduced. Thus, Zaozhuang industrial wastewater treatment has been quite effective, with water quality improved significantly. The EKC models provided scientific evidence for estimating industrial wastewater discharge, COD, and NH3-N load as well as their changeable trends for Zaozhuang from an economic perspective.

Analysis of Surface Water Pollution Accidents in China: Characteristics and Lessons for Risk Management

Understanding historical accidents is important for accident prevention and risk mitigation; however, there are no public databases of pollution accidents in China, and no detailed information regarding such incidents is readily available. Thus, 653 representative cases of surface water pollution accidents in China were identified and described as a function of time, location, materials involved, origin, and causes. The severity and other features of the accidents, frequency and quantities of chemicals involved, frequency and number of people poisoned, frequency and number of people affected, frequency and time for which pollution lasted, and frequency and length of pollution zone were effectively used to value and estimate the accumulated probabilities. The probabilities of occurrences of various types based on origin and causes were also summarized based on these observations. The following conclusions can be drawn from these analyses: (1) There was a high proportion of accidents involving multi-district boundary regions and drinking water crises, indicating that more attention should be paid to environmental risk prevention and the mitigation of such incidents. (2) A high proportion of accidents originated from small-sized chemical plants, indicating that these types of enterprises should be considered during policy making. (3) The most common cause (49.8% of the total) was intentional acts (illegal discharge); accordingly, efforts to increase environmental consciousness in China should be enhanced.

Estimating and Predicting Metal Concentration Using Online Turbidity Values and Water Quality Models in Two Rivers of the Taihu Basin, Eastern China

Turbidity (T) has been widely used to detect the occurrence of pollutants in surface water. Using data collected from January 2013 to June 2014 at eleven sites along two rivers feeding the Taihu Basin, China, the relationship between the concentration of five metals (aluminum (Al), titanium (Ti), nickel (Ni), vanadium (V), lead (Pb)) and turbidity was investigated. Metal concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS). The linear regression of metal concentration and turbidity provided a good fit, with R² = 0.86–0.93 for 72 data sets collected in the industrial river and R² = 0.60–0.85 for 60 data sets collected in the cleaner river. All the regression presented good linear relationship, leading to the conclusion that the occurrence of the five metals are directly related to suspended solids, and these metal concentration could be approximated using these regression equations. Thus, the linear regression equations were applied to estimate the metal concentration using online turbidity data from January 1 to June 30 in 2014. In the prediction, the WASP 7.5.2 (Water Quality Analysis Simulation Program) model was introduced to interpret the transport and fates of total suspended solids; in addition, metal concentration downstream of the two rivers was predicted. All the relative errors between the estimated and measured metal concentration were within 30%, and those between the predicted and measured values were within 40%. The estimation and prediction process of metals’ concentration indicated that exploring the relationship between metals and turbidity values might be one effective technique for efficient estimation and prediction of metal concentration to facilitate better long-term monitoring with high temporal and spatial density.

Economic Estimation of the Losses Caused by Surface Water Pollution Accidents in China From the Perspective of Water Bodies' Functions

The number of surface water pollution accidents (abbreviated as SWPAs) has increased substantially in China in recent years. Estimation of economic losses due to SWPAs has been one of the focuses in China and is mentioned many times in the Environmental Protection Law of China promulgated in 2014. From the perspective of water bodies’ functions, pollution accident damages can be divided into eight types: damage to human health, water supply suspension, fishery, recreational functions, biological diversity, environmental property loss, the accident’s origin and other indirect losses. In the valuation of damage to people’s life, the procedure for compensation of traffic accidents in China was used. The functional replacement cost method was used in economic estimation of the losses due to water supply suspension and loss of water’s recreational functions. Damage to biological diversity was estimated by recovery cost analysis and damage to environmental property losses were calculated using pollutant removal costs. As a case study, using the proposed calculation procedure the economic losses caused by the major Songhuajiang River pollution accident that happened in China in 2005 have been estimated at 2263 billion CNY. The estimated economic losses for real accidents can sometimes be influenced by social and political factors, such as data authenticity and accuracy. Besides, one or more aspects in the method might be overestimated, underrated or even ignored. The proposed procedure may be used by decision makers for the economic estimation of losses in SWPAs. Estimates of the economic losses of pollution accidents could help quantify potential costs associated with increased risk sources along lakes/rivers but more importantly, highlight the value of clean water to society as a whole.

Identification of Major Risk Sources for Surface Water Pollution by Risk Indexes (RI) in the Multi-Provincial Boundary Region of the Taihu Basin, China

Environmental safety in multi-district boundary regions has been one of the focuses in China and is mentioned many times in the Environmental Protection Act of 2014. Five types were categorized concerning the risk sources for surface water pollution in the multi-provincial boundary region of the Taihu basin: production enterprises, waste disposal sites, chemical storage sites, agricultural non-point sources and waterway transportations. Considering the hazard of risk sources, the purification property of environmental medium and the vulnerability of risk receptors, 52 specific attributes on the risk levels of each type of risk source were screened out. Continuous piecewise linear function model, expert consultation method and fuzzy integral model were used to calculate the integrated risk indexes (RI) to characterize the risk levels of pollution sources. In the studied area, 2716 pollution sources were characterized by RI values. There were 56 high-risk sources screened out as major risk sources, accounting for about 2% of the total. The numbers of sources with high-moderate, moderate, moderate-low and low pollution risk were 376, 1059, 101 and 1124, respectively, accounting for 14%, 38%, 5% and 41% of the total. The procedure proposed could be included in the integrated risk management systems of the multi-district boundary region of the Taihu basin. It could help decision makers to identify major risk sources in the risk prevention and reduction of surface water pollution.