[Challenges Regarding the Co-emission of Emerging Pollutants to Eco-environmental Monitoring and Management].

Emerging pollutants have drawn global concerns under rapid urbanization and industrialization. However, research has been relatively independent on specific groups of pollutants due to the limitation of the discipline. In this study, from the perspective of interdisciplinary research, taking the fluorochemical industry as an example, two major categories of emerging pollutants, per-and polyfluoroalkyl substances (PFAS) and ozone-depleting substances (ODS), were discussed regarding their co-emission. The co-production mechanism of the two types of pollutants were discussed from the production processes to reveal their internal relationship; their differences and cross-processes in the emission routes were analyzed, as well as the technical approaches and challenges required in sample collection, pretreatment, and instrumental analysis. The eco-environmental effects, including ecological and human health risks, ozone depletion, and global warming effects caused by the two types of pollutants in different media were comprehensively summarized. We also further expanded the perspectives of stakeholder analysis, life cycle analysis, and mass balance analysis to provide suggestions for further research and management of emerging pollutant co-emissions.

[Estimating Methane Fugitive Emissions from Oil and Natural Gas Systems in China].

To achieve its carbon peaking and carbon neutrality objectives, China is committed to promoting a decarbonized energy transition, which has strengthened the shift from coal to oil and gas resources. As a result, methane (CH4) fugitive emissions from China's oil and gas systems are of increasing concern. Fugitive emissions include equipment leaks, venting, and flaring and involve exploration, production, transportation, storage, and distribution of oil and gas resources. However, there is no uniform accounting method for methane fugitive emissions from oil and gas systems, and fugitive emissions have not been included in the national greenhouse gas inventory statistics. Using the relevant methods, methane fugitive emissions from China's oil and gas systems were estimated for the period from 1980-2020. The results showed that CH4 fugitive emissions from oil and gas systems increased rapidly with the growth of production and consumption of oil and gas resources, from less than 0.6 million tons in 1980 to more than 2.6 million tons in 2020. CH4 fugitive emissions from oil and gas systems reached approximately 0.6 million tons and 2.0 million tons, which were 1.38 and 16.6 times larger than those in 1980, respectively. Fugitive emissions from oil and gas systems originated primarily from gas production, oil production, gas transportation, and storage, accounting for 41%, 20%, 18%, and 13% of total emissions, respectively. Gas pipelines were the main fugitive facilities. The emission intensity of unconventional oil and gas resource exploration was higher compared to conventional resource exploration. This study improved the CH4 fugitive emission inventory, which could provide solid scientific data for CH4 reduction.

[Distribution, Sources, and Ecological Risks of Polyfluoroalkyl Substances in the Surface Water of the Wuliangsuhai Watershed].

Polyfluoroalkyl substances (PFASs) enter the environment through multi-media diffusion and long-distance migration during the long-term manufacture and use of products containing PFASs. This study analyzed 17 PFASs in surface water samples collected from the Wuliangsuhai watershed in the wet and dry seasons, and investigated the temporal and spatial distribution characteristics, potential sources, and ecological risks of PFASs in the study area. PFASs were detected in all surface water samples at concentrations ranging from 4.00 to 263.45 ng·L-1. The spatial distribution of PFASs was affected by local human activities and showed two main types of characteristics. The first type was associated with Yellow River and canal water, which had relatively low concentrations of PFASs and was dominated by perfluorobutanoic acid (PFBA). The second type was associated with drain and lake water receiving industrial, agricultural, and domestic wastewater from the Hetao irrigation area, which had relatively high levels of PFASs and was dominated by perfluorooctanoic acid (PFOA). The PFAS concentrations in water samples collected during the dry season were higher than those collected in the wet season, being affected by the increased production of short-chain PFASs and seasonal changes in the amount of water from the Yellow River. The results of PFOS/PFOA, PFOA/PFNA, and PFHpA/PFOA indicated that the PFASs in the study area originate from atmospheric deposition and point source pollution. The risk assessment results showed that the current risk level from PFOA and PFOS in the study area is relatively low but their long-term cumulative effects cannot be ignored due to the cumulative characteristics and long-distance migration ability of PFASs.

[Distribution Characteristics and Risk Assessment of PPCPs in Surface Water and Aquatic Organisms in Chaoshan Coastal Area along the South China Sea].

To investigate the occurrence, distribution, and potential risks of pharmaceuticals and personal care products (PPCPs) in the South costal area of China, a total of 20 PPCPs in water and aquatic organisms (fish, crab, and shellfish), obtained from 7 coastal rivers of the Chaoshan area, were determined using solid-phase extraction (SPE) and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The results showed that up to 16 to 18 kinds of PPCPs could be detected in the rivers and aquatic organisms of the Chaoshan area, and the concentrations of PPCPs in the rivers and organisms ranged from 0.30-2223 ng ·L-1 to 0.143-80.3 ng ·g-1, respectively, with a high detection rate for many pollutants. Significant differences were observed in the samples of water and organisms. The total concentration of PPCPs in the rivers of the Chaoshan area was in the order of Huanggang River > Lianjiang River > Huangjiang River > Longjiang River > Luohe River > Rongjiang River > Hanjiang River, with the dominance of sulfamethoxazole (SMX) and caffeine (CAF). The total concentrations of PPCPs in the aquatic organisms from the Huanggang River, Hanjiang River, Lianjiang River, and Luohe River were higher than the concentrations of PPCPs in the aquatic organisms from the Longjiang River and Rongjiang River, with a dominance of trimethoprim (TMP), SMX, and CAF. The total concentration of PPCPs in fish was significantly higher than that in crab and shellfish. The results of bioconcentration factor (BCF) showed that a variety of PPCPs were accumulated in the organisms from the Chaoshan rivers; among them, the BCF value in fish was higher, which was more likely to bioaccumulate than crabs and shellfish. The ecological risks in terms of risk quotient (RQ) for 12 typical PPCPs were assessed in the Chaoshan area. It was discovered that the risk for fleas and algae was significantly higher than that for fish. The RQ values of SMX, erythromycin (ERY), and sulfadiazine (SDZ) were all greater than 1, which posed potential ecological risks for algae in the Huanggang River and Lianjiang Rivers and for fleas in the Huangjiang River.

[Fate Simulation of 2,4,4'-Trichlorobiphenyl in the Bohai Rim Using the Multimedia Model].

To study the multimedia transfer and fate of polychlorinated biphenyls (PCBs) in the Bohai Rim, we used the BETR-Urban-Rural model to simulate and calculate the concentration distribution, fate distribution, and transfer processes of 2,4,4'-trichlorobiphenyl (PCB28) in nine environmental compartments under a steady-state assumption. The input parameters and output results of the model underwent sensitivity analysis and uncertainty analysis, respectively. The results showed that the simulated concentrations of PCB28 in fresh water, rural soil, urban soil, and sediment could fit the measured concentrations well, thus verifying the reliability of the model. The concentration of PCB28 in urban soil was the highest, and the average concentration was 5.26×10-6 mol·m-3. In contrast, the concentration of PCB28 in rural air was the lowest, and the average concentration was 5.79×10-14 mol·m-3. When the environmental system reached equilibrium, the largest sink of PCB28 in the Bohai Rim was soil, accounting for approximately 96.45% of the total amount remaining in the system. The mutual transfer processes between air and other environmental compartments were the dominant pathways for PCB28 inter-media transport in the Bohai Rim. Most PCB28 entering the Bohai Sea was transferred by airflow, and the fluxes from rural air to coastal water accounted for approximately 97.22% of the total fluxes of PCB28 entering the sea. According to the result of sensitivity analysis, the emission rates, grid dimensions, and transport velocity were the key parameters affecting the model output. Uncertainty analysis showed that the distributions of PCB28 concentrations in rural air and urban air fitted well with lognormal distributions, and the coefficients of variances (CVs) were 0.44 and 0.41, respectively.

[Selection of Priority Contaminants in a Watershed Using Risk Ranking Methodology].

The present study focuses on the risk rankings of different contaminants from Daling River in Liaoning Province, China, for categorizing the environmental risk levels in the river. Eighteen surface water samples were collected from Daling River, which has been polluted by the surrounding fluorine industries for years. Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and heavy metals were analyzed, and relevant eco-toxicity data obtained from literatures were considered. The median concentrations of PFOS and PFOA were observed as 0.77-3.57 ng·L-1 and 82.93-344 ng·L-1, respectively, which were lower than the standard limits of the United Kingdom. The concentrations of heavy metals and organochlorine pesticides (OCPs) were found to be lower than level Ⅳ of the Chinese national environmental quality standards for surface water. The maximum concentrations of mercury (Hg) and arsenic (As) were higher than the standard level Ⅲ. The environmental risks ranged from 1.42×10-6 to 2.3×10-2. The order of the risks by potential environmental contaminants was Cu > Zn > As > p,p'-DDE > p,p'-DDT > Cd > Pb > Hg > PFOA > γ-HCH > Cr > Ni > α-HCH > PFOS. The present findings revealed that the environmental risks of PFOS and PFOA were relatively low and these were not taken as priority contaminants, but the accumulation risks could not be overlooked for a long time. Among the contaminants, copper (Cu) was the priority contaminant of Daling River. Hence, necessary measures are recommended to reduce the potential effects of contaminants on the environment.

[Risk Assessment and Risk Management of Chemicals in China].

Risk assessment and risk management have been increasingly approved as an effective approach for appropriate disposal and scientific management of chemicals. This study systematically analyzed the risk assessment methods of chemicals from three aspects including health risk, ecological risk and regional risk. Based on the current situation of classification and management towards chemicals in China, a specific framework of risk management on chemicals was proposed by selecting target chemicals, predominant industries and related stakeholders as the objects. The results of the present study will provide scientific support for improving risk assessment and reasonable management of chemicals in China.

[Effects of Eliminating Backward Production Capacities on Reduction of Dioxin Emissions in Key Industries].

Phase-out of backward production facilities can significantly reduce the emissions of unintentional persistent organic pollutants from the industrial thermal process. An estimation of reduced dioxin emissions due to closure of backward production capacities is valuable to objectively evaluate China's efforts in and contribution to performing the Stockholm Convention on Persistent Organic Pollutants. Our group previously evaluated environmental effects of the phase-out of backward production facilities on dioxin emissions from 2006 to 2009. Based on the above study, due to the phase-out of backward production capacities from 2010 to 2013, the reductions in dioxin emissions to air from power generation sector, coke sector, and iron & steel (including ferroalloy) sector were estimated to be 86.13, 133.94 and 78.78 g · a⁻¹, respectively. Because the emission factors used in this paper are a little bit conservative, the actual reduced emissions may be greater than the estimated values. Besides the industrial sectors mentioned above, reduced dioxin emissions can also be estimated in more industrial sectors such as cement, calcium carbide, metal smelting and papermaking sectors. The paper also provided methods for the future comprehensive evaluation of dioxin reduction.

Responses of growth inhibition and antioxidant gene expression in earthworms (Eisenia fetida) exposed to tetrabromobisphenol A, hexabromocyclododecane and decabromodiphenyl ether.

Tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) and decabromodiphenyl ether (BDE 209), suspected ubiquitous contaminants, account for the largest volume of brominated flame retardants (BFRs) since penta-BDE and octa-BDE have been phased out globally. In this paper, the growth inhibition and gene transcript levels of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT)) and the stress-response gene involved in the prevention of oxidative stress (Hsp70) of earthworms (Eisenia fetida) exposed to TBBPA, HBCD and BDE 209 were measured to identify the toxicity effects of selected BFRs on earthworms. The growth of earthworms treated by TBBPA at 200 and 400 mg/kg dw were inhibited at rate of 13.7% and 22.0% respectively, while there was no significant growth inhibition by HBCD and BDE 209. A significant (P<0.01) up-regulation of SOD expression level was observed in earthworms exposed to TBBPA at 50 mg/kg dw (1.77-fold) and to HBCD at 400 mg/kg dw (2.06-fold). The transcript level of Hsp70 gene was significantly up-regulated (P<0.01) when earthworms exposed to TBBPA at concentration of 50-200 mg/kg (2.16-2.19-fold) and HBCD at 400 mg/kg (2.61-fold). No significant variation of CAT gene expression in all the BFRs treatments was observed, neither does all the target gene expression level exposed to BDE 209. Assessed by growth inhibition and the changes at mRNA levels of encoding genes in earthworms, TBBPA showed the greatest toxicity, followed by HBCD and BDE 209, consistent with trends in molecular properties. The results help to understand the molecular mechanism of antioxidant defense.

Growth inhibition and altered gene transcript levels in earthworms (Eisenia fetida) exposed to 2,2',4,4'-tetrabromodiphenyl ether.

The toxic effects of the ubiquitous pollutant 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on the earthworm Eisenia fetida were assessed by determining growth-inhibition and gene transcript levels of superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), and transcriptional changes of the stress-response gene (heat-shock protein 70 [Hsp70]). Somatic growth and growth-inhibition rates in all BDE-47-treated groups were significantly different from those of the controls. The SOD gene transcripts were upregulated at all exposure doses and reached the maximum at the concentration of 400 mg/kg dry weight (dw) (3.84-fold, P < 0.01), which protected earthworms from oxidative stresses. However, downregulation of CAT and Hsp70 was present in all exposure doses and reached to the minimum at concentrations of 400 mg/kg dw (0.07-fold, P < 0.01 and 0.06-fold, P < 0.01, respectively). Upregulation of GST gene transcript level presented significant changes at concentrations of 10 (2.69-fold, P < 0.05) and 100 mg/kg dw (2.55-fold, P < 0.05). SOD maintained a dynamic balance to upregulate SOD expression to eliminate superoxide radicals in all dosage treatments, but downregulation of CAT decreased the ability to eliminate hydrogen peroxide. These changes could result in biochemical and physiological disturbances in earthworms.

[Assessment of Emission and Co-Reduction of PCDD/Fs and PCNs in the Secondary Copper Production Sector].

Polychlorinated naphthalenes (PCNs) could he generated and discharged unintentionally in the secondary copper production industry with similar mechanisms as PCDD/Fs during high-temperature industrial processes. Therefore, measures that reduce the release of PCDD/Fs will also reduce PCNs emissions. Analysis of the technical process and correlation with their emissions will provide theoretical basis for co-mitigation of PCNs and PCDD/Fs. The production process of secondary copper was analyzed, with key production stages of discharge identified through monitoring the emissions of two kinds of pollutants. Co-reduction technologies were screened and specified. Three recommendations on co-mitigation of the two pollutants were provided to support the implementation of Stockholm Convention and UPOPs reduction in the secondary copper production sector in China. Key words:secondary copper industry; smelting; PCNs; PCDD/Fs; co-mitigation

[Risk assessment and countermeasures of BTEX contamination in soils of typical pesticide factory].

Soil samples around three representative pesticide factories were collected in Zhangjiakou City, Hebei Province, and analyzed to identify their pollution characteristics and health risk of BTEX by purge-and trap and gas chromatography/mass spectroscopy method. Total concentrations of BTEX in soils in Plant A, B and C ranged from 673.50 to 32 363.50 ng x g(-1), nd to 6 461.80 ng x g(-1) and 461.70 to 8 740.80 ng x g(-1), respectively. Concentrations of detected toluene (4 619.50-7 234.30 ng x g(-1)) and ethylbenzene (364.60-7 944.60 ng x g(-1)) had exceeded the Canadian guidelines for industrial land (370 ng x g(-1) and 82 ng x g(-1)), and concentration of xylene (19 799.40 ng x g(-1)) in dust in production area of Plant A was larger than the Dutch soil intervention value (17 000 ng x g(-1)). While concentrationsn of BTEX around Plant A (Region I ) and Plant B and C (Region II) ranged from nd to 645.81 ng x g(-1), and nd to 309.13 ng x g(-1), respectively, which were below the Canadian guidelines for agricultural land. The non-carcinogenic risk of BTEX in Plant A (2.90E-06 -1.32E-04), B (nd -4.30E-05) and C (1.29E-06 -5.64E-05) were all below 1, which suggested that no obvious health risk existed in each plant. The non-carcinogenic risks in Region I (nd -2.02E-06) and Region II (nd -1.10E-06) were below than 1, and also lower than those in factories. High risk areas were mainly concentrated in the downwind, moreover, soils around villages and towns were also with higher risk. In conclusion, soils and dusts in each factory had been polluted and the quality of agricultural land had been partly deteriorated. Finally, environmental management and occupational protection countermeasures were proposed based on the research results.

[Risk assessment and countermeasures of heavy metals pollution in Wanquan segment of Yanghe River].

In order to investigate heavy metals contamination status in Wanquan segment of Yanghe River, Zhangjiakou, 9 water and sediments samples were collected respectively for analyzing Cu, Ni, Cd, Zn, Cr, Pb, Hg and As, with water quality indicators determined at the same time. The potential ecological risk index (PERI) was then employed to evaluate potential ecological risk of heavy metals in sediments. Results indicated that the concentrations of Cu, Ni, Cd, Zn, Cr, Pb, Hg and As in water samples ranged from 1.28-24.13, 1.13-16.84, 0.08-0.11, 1.80-10.65, 1.40-19.12, 0.13-2.05, 0.06-0.99, 0.46-4.22 microg x L(-1), respectively, which are all below the national water quality standard for the demands of industrial use and agricultural irrigation. Principal component analysis (PCA) was conducted to reveal the relationship between water quality indicators and heavy metals pollution in water samples. Concentrations of Cu, Ni, Cd, Zn, Cr, Pb, Hg and As in sediments ranged from 5.90-110.11, 17.34-56.04, 0.07-0.31, 38.71-116.74, 40.39-85.77, 18.65-22.74, nd-0.047, 0.85-9.98 mg x kg(-1), respectively. The descending order of potential ecological risk intensity caused by different heavy metals was: Cd > Cu > Hg > Ni > As > Pb > Cr > Zn, and the average value of each heavy metal was low, while middle-grade risk level of Cd and Hg were also found in several sites. Among all monitoring sites, the descending order of PERI of all target heavy metals was: YH-07 > YH-03 > YH-09 > YH-02 > YH-06 > YH-04 > YH-05 > YH-01, and the average value reached slight grade, while middle-grade risk level was detected in YH-07. Sampling locations in YH-02-YH-03 and YH-07-YH-09 were found with relatively high ecological risk level because of agricultural and anthropogenic activities, respectively. Finally, three risk management regions were figured out and corresponding countermeasures for improving the environmental quality of the watershed were proposed based on the research results.

[Construction of index system for early warning of persistent organic pollutants (POPs) pollution incidents in China].

Early warning of pollution incidents caused by persistent organic pollutants (POPs) is urgently needed for China in the circumstances of serious POPs pollution and in increasing demand for improvement in chemical risk management. Given different categories of POPs and pollution incidents, the index system for early warning of POPs pollution accidents was built based on lifecycle theory and POPs formation mechanisms. It will be helpful for decision makers to enhance the early warning management of POPs pollution incidents in China. The index system for early warning includes two parts, early warning and mechanism for system operation. The indices include risk source indicators, warning indicators and warning level indicators. To ensure the effective implementation of this system, the mechanisms for response and policy guarantee were also formulated. These mechanisms contain dynamic inventory management and periodical assessment of risk sources, timely and effective report of warning conditions, as well as coordination and cooperation among the relevant departments.

[Analysis of control policy for persistent toxic substances from electronic wastes in China].

The environmental pollution and risk of persistent toxic substances (PTS) have caused extensive attention nationally and internationally in recent years. Electronic waste (e-waste) is an important emission source of PTS. Based on life-cycle management, e-waste management was divided into four major areas according to emission paths of e-waste PTS, namely source reduction, process control, end-of-pipe treatment and emergency response. Related regulations and policies of China's e-waste PTS control were analyzed. An evaluation system of regulations and policies was set up, which involves management objective, regulation availability, specific provisions, regulations coordination and policy implementation. The regulations and policies of each life-cycle phase were evaluated according to expert consultancy. The regulations and policies of source reduction are more perfect for their clear management objectives and the better regulation availability, while the response is the most imperfect, for lacking of clear management objectives and detailed rules, and poor coordination and implementation of the regulation. Recommendations for regulation and policy improvement were proposed based on the assessment results.

[Spatial distribution and composition of perfluorinated compounds in soils around the Huaihe River].

In order to analyze the occurrence and composition of perfluorinated compounds (PFCs), 18 topsoil samples were collected around the Huaihe River in October, 2008. Total fluoride (TF) and extractable organic fluorine (EOF) were determined using combustion ion chromatography (CIC), and PFCs were quantified by HPLC/MS-MS. Among the sixteen PFCs analyzed, eleven PFCs were detected. Concentrations of PFCs ranged from n. d. to 1.22 ng x g(-1), and perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorooctane sulfonate (PFOS) were the predominant PFCs. Concentrations of PFCs showed no significant difference, but compositions varied from soil to soil. PFCs mainly came from emissions of local small chemical plants and atmospheric dry and wet deposition. The results from mass balance analysis indicated that PFCs only accounted for 0.3% of EOF and EOF comprised 0.02% of TF. There was still a large amount of organic fluorine besides PFCs, and inorganic fluorine and non-extractable organic fluorine comprised the major portion of TF. Furthermore, the current analysis method could not detect all kinds of PFCs and related unknown organic fluorine.

[Risk assessment and countermeasure of BTEX in pesticide factory].

BTEX are important environmental pollutants, harmful to human through respiratory inhalation, digestive tract and skin contact, and also have teratogenic, mutagenic and carcinogenic effects. BTEX were detected in multi-media to identify their distributions and assess their human health risk in a pesticide factory in Hebei province. Purge and trap GC-MS, adsorption/thermal desorption GC chromatography and the health risk assessment model were applied, and corresponding management measures were proposed. The results showed that BTEX existed in soil, dust, air, groundwater and wastewater. The concentration of BTEX in dust of the production area was 7.33 mg x kg(-1), in particular the concentration of toluene was 5.64 mg x kg(-1), exceeding the Canadian industrial land standard. Building three scenarios for working more than 10 years, 20 years and 30 years, the total non-carcinogens index was 4.19 x10(-3), 8.25 x 10(-3) and 1.22 x 10(-2), respectively, all lower than 1; the carcinogens index of benzene was 1.70 x 10(-7), 3.34 x 10(-7) and 4.92 x 10(-7), respectively, all lower than 10(-6). It indicated that there was no significant non-carcinogens and carcinogens hazard to workers inside the factory, but they might be exposed to more health risks if their work experience increase. Finally, recommendations for improving the environmental quality and personnel security in the factory were proposed based on the research results.

[Risk communication in construction of new nuclear power plant].

Accompanied by construction of new nuclear power plants in the coming decades in China, risk management has become increasingly politicized and contentious. Nuclear risk communication is a critical component in helping individuals prepare for, respond to, and recover from nuclear power emergencies. It was discussed that awareness of trust and public attitudes are important determinants in nuclear power risk communication and management. However, there is limited knowledge about how to best communicate with at-risk populations around nuclear power plant in China. To bridge this gap, this study presented the attitudinal data from a field survey in under-building Haiyang nuclear power plant, Shandong Province to measure public support for and opposition to the local construction of nuclear power plant. The paper discussed the structure of the communication process from a descriptive point of view, recognizing the importance of trust and understanding the information openness. The results showed that decision-making on nuclear power was dominated by a closed "iron nuclear triangle" of national governmental agencies, state-owned nuclear enterprises and scientific experts. Public participation and public access to information on nuclear constructions and assessments have been marginal and media was a key information source. As information on nuclear power and related risks is very restricted in China, Chinese citizens (51%) tend to choose the government as the most trustworthy source. More respondents took the negative attitudes toward nuclear power plant construction around home. It drew on studies about risk communication to develop some guidelines for successful risk communication. The conclusions have vast implications for how we approach risk management in the future. The findings should be of interest to state and local emergency managers, community-based organizations, public health researchers, and policy makers.

[Temporal variation of water quality and driving factors in Yanghe watershed of Zhangjiakou].

Yanghe is an important water source for Guanting Reservoir, which once supplied the Beijing city with drinking water, industrial process water and water-use in landscape. Based on the data of water quality monitored by Yanghe watershed monitoring stations from 1992 to 2009, 11 pollutants were selected for analysis. The trends of changes in water quality were figured out, and the major pollutants and driving factors were measured by the integrated standard index and grey correlation analytical methods. The results showed that there were two stages of water quality change in Yanghe watershed of Zhangjiakou. Firstly, the water was polluted seriously but recovered rapidly from 1992 to 1996. Secondly, although light pollution occurred in the watershed from 1997 to 2009, the pollution factors were still above the limits. The main pollution factors are ammonia nitrogen, petroleum, permanganate index, BOD5, Cr6+ and Cd. The main driving factor of water quality is the change of land use type, and the agricultural land showed less impact on water quality than the industrial land.

[Pollution characteristics and health risk assessment of atmospheric volatile organic compounds (VOCs) in pesticide factory].

A method for determining volatile organic compounds (VOCs) in air by summa canister collecting and gas chromatography/ mass spectroscopy detecting was adopted. Pollution condition and characteristics of VOCs were discussed in three representative pesticide factories in Zhangjiakou City, Hebei Province. Meanwhile, an internationally recognized four-step evaluation model of health risk assessment was applied to preliminarily assess the health risk caused by atmospheric VOCs in different exposure ways, inhalation and dermal exposure. Results showed that serious total VOCs pollution existed in all factories. Concentrations of n-hexane (6161.90-6910.00 microg x m(-3)), benzene (126.00-179.30 microg x m(-3)) and 1,3-butadiene (115.00-177.30 microg x m(-3)) exceeded the Chronic Inhalation Reference Concentrations recommended by USEPA, corresponding to 700, 30 and 2 microg x m(-3), respectively. Concentration of dichloromethane (724.00 microg x m(-3)) in factory B was also higher than the reference concentration (600 microg x m(-3)). Results of health risk assessment indicated that non-carcinogenic risk indexes of VOCs ranged from 1.00E-04 to 1.00E + 00 by inhalation exposure, and 1.00E-09 to 1.00E-05 by dermal exposure. Risk indexes of n-hexane and dichloromethane by inhalation exposure in all factories exceeded 1, and risk index of benzene by inhalation in factory B was also higher than 1. Carcinogenic risk indexes exposed to VOCs ranged from 1.00E-08 to 1.00E-03 by inhalation exposure and 1. oo00E -13 to 1.00E-08 by dermal exposure. Cancer risk of 1,3-butadiene by inhalation exceeded 1.0E-04, which lead to definite risk, and those of benzene by inhalation also exceeded the maximum allowable level recommended by International Commission on Radiological Protection (5.0E-05). The risks of dermal exposure presented the same trend as inhalation exposure, but the level was much lower than that of inhalation exposure. Thus, inhalation exposure of atmospheric VOCs was the dominant way of health risk in these factories.