Distribution Characteristics And Health Risk Assessment Of Multi-contaminations In Drinking Water Sources Of Typical Towns

Source of drinking water is closely related to human health, but its quality is not optimistic in our country. The pollution of drinking water sources in China typical towns especially serious. In this study, different types of drinking water sources of typical towns in Jiangsu province were selected. Distribution characteristics and health risk aeeseement of total141kinds of toxic pollutions were analyzed using modern instrumental analysis methods and risk assessment tools and the priority pollutants in drinking water sources of typical towns were acquired. Through this study, it may provide the basic datas and science and technology supportions for drinking water monitoring, water supply pipeline network transformation and environmental management in typical towns.Objectives:To detect the multi-pollutants in different type drinking water sources of typical towns, obtain the pollution spectrums of toxic contaminations in drinking water sources, asessment the health risks of local residents via the drinking water pathway and screen the priority pollutants. Provide the basic datas and science and technology supportions for typical town drinking water monitoring, water supply pipeline network transformation and environmental management. Methods:(1) Typical towns selection and sample collection:with the research purposes, select four typical towns in Huai’an and Xuzhou as the study districts on the basis of information surveys and historical resources observation. Accordancing with China’s relevant sample criterions, collected different types of water samples and sediment samples in the wet and dry seasons.(2) Sample processing and testing:use solid phase extraction, the disc membrane extraction, headspace solid phase micro extraction and soxhlet extraction to process the samples including drinking water sources samples, suspended substance and sediments and utilize the high performance liquid chromatography-diode array detector-fluorescence detector, gas chromatography-electron capture detector, gas chromatography-mass spectrometry, inductively coupled plasma-mass spectrometry to analyse the target pollutants including organochlorine pesticides (OCPs), coplanar polychlorophenyls (co-PCBs), polycyclic aromatic hydrocarbons (PAHs), phthalates esters (PAEs), phenols subtances (phenols), metal elements (Metals) and volatile organic compounds (VOCs).(3) Analysis of pollutants levels:according to the established toxic pollutants determination methods, obtain the pollutants concentration levels in sources of drinking water which typical towns residents exposed. Compare the difference of toxic pollutants spectrum in selected different drinking water sources of typical towns. Preliminary understand the migration and transformation characteristics of toxic pollutants in drinking water sources by combination the residual pollutants levels in suspended substances and the sediments.(4) Health risk assessment:using USEPA classic health risk assessment model and risk assessment routes of this study, evaluate the carcinogenic and non-carcinogenic health risks of different type drinking water sources in the study districts.(5) Priority pollutants screening:by application method of potential risk index, screen the priority pollutants in sources of drinking water in study districts and obain the priority pollutants list of typical towns. Results:(1) Typical districts and samples:select two typical towns in northern Jiangsu as the study districts where water supply network are building and a variety of water supply sources co-exist. The two typical towns were Huai’an Lianshui (high incidence rates of tumor and chronic) and Xuzhou Tongshan (low incidence rates of tumor and chronic). Samples were collected in2010-2011wet and dry seasons in the study typical towns including surface water, shallow groundwater (distributed well water,10-15m), deep groundwater (centralized supplied water,100-150m) and the peripheral water for a total number of2500and related sediment samples also collected with a total number of120.(2) Detection methods:on the basis of the physical and chemical characteristics of the target compounds, established the following test methods:Determination of20kinds of organochlorine pesticides and12kinds of coplanar PCBs in drinking water sources by solid phase extraction (HLB column)-gas chromatography; Determination of16kinds of USEPA priority control polycyclic aromatic hydrocarbons in water by solid phase extraction (HLB column)-high phase liquid chromatography-diode array detector-fluorescence detector; Determination of16kinds of phthalate esters substances without plastic contact disc by membrane extraction-gas chromatography-mass spectrometry; Determination of eight kinds of polyphenols by solid phase extraction (PSD column)-gas chromatography-mass spectrometry, Determination of53kinds of volatile organic compounds by headspace solid phase micro extraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), Determination of16kinds of metal elements in drinking water sources by inductively coupled plasma mass spectrometry (ICP-MS); Determination of a variety of semi-volatile organic pollutants in suspended matter (SPM) and sediments by reference USEPA8081extraction method and useage of the florisil column purification technology.The separation method for20kinds of OCPs was satisfactory. The detection limits for20kinds of OCPs were between0.02and0.12μg/L. Retention time was used for qualitation, with time migration range at±5%. External reference method for quantitation with curve range between2and200μg/L and the related coefficients (r) were all more than0.999. The method mean recoveries were between71.6%and110.6%with the relative standard deviation (RSD)<12%. The surrogate recoveries were between70.2%and96.8%.Separation degrees of the12co-PCBs were greater than1.2. The detection limits for12kinds of co-PCBs were between0.16and0.44μg/L. Retention time was used for qualitation, with time migration range at±5%. External reference method for quantitation with curve range between4.32and138.4μg/L and the related coefficients (r) were all more than0.99. The method mean recoveries were between75.7%and103.1%with the relative standard deviation (RSD)<12%. The surrogate recoveries were the same as OCPs.The separation method for16kinds of PAHs was satisfactory. The fluorescence detection limits for16kinds of PAHs were between0.01and0.57μg/L and the UV detection limit (Ace) was3.43μg/L; Retention time was used for qualitation, curve range between1(20) and100(2000)μg/L. Fluorescence correlation coefficient (r) were>0.99and the UV correlation coefficient r=0.9995; The method recoveries were between69.1%and90.6%with RSD<10%.The separation method for16kinds of PAEs was satisfactory. The detection limits for16kinds of PAEs were between between0.20and2.45μg/L. Retention time was used for qualitation, with time migration range at±5%. External reference method for quantitation with curve range between5(20) and2000μg/L and the related coefficients (r) were all more than0.99. The method mean recoveries were between79.8%and104.0%with the relative standard deviation (RSD)<10%. The surrogate recoveries were between78.8%and93.5%.The separation method for8kinds of Phenols was satisfactory. The detection limits for8kinds of Phenols were between0.43and1.03μg/L. Retention time was used for qualitation, with time migration range at±5%. External reference method for quantitation with curve range between2and1000μg/L and the related coefficients (r) were all more than o.99. The method mean recoveries were between85.8%and96.7%with the relative standard deviation (RSD)<5%. The surrogate recoveries were between74.7%and94.5%.53kinds of the VOCs were basic separation.The detection limits for53kinds of the VOCs were between0.001and0.130μg/L.Retention time was used for qualitation, with time migration range at±5%. External reference method for quantitation with curve range between0.1and50μg/L and the related coefficients (r) were all more than0.99. The method mean recoveries were between75.9%and107.3%with the relative standard deviation (RSD)<20%.Quality control:each batch of samples collected was equipped with the full procedure blank, each batch of reagents analyzed reagent blank and target substances in the whole procedure blank and reagent blank were below the detection limit. Each sample made the parallel sample. Every15samples did a solvent blank to check instrument pollution.16kinds of metal elements and semi-volatile organic pollutants in SPM and sediments determinated by reference the relevant literature and USEPA method.(3) Toxic pollutants distribution characters①18kinds of OCPs were detected in different type sources of drinking water in study districts, which were HCHs、DDTs、Heptachlo、Heptachlor-epoxide、 cis/trans-chlordane、Endosulfan Ⅰ/Ⅱ、Endosulfan_sulfate、Aldrin、Endrin、 Endrin_ketone and Dieldrin. The total concentrations of OCPs were between8.58and107.49ng/L, and they were in the middle pollution level compared with other surface water. The concentrations of total HCHs were between2.98-74.14ng/L and they were the main OCPs pollutants. The total HCHs also had a higher correlation with total OCPs concentration (r=0.99, p<0.01).Reference to China and WHO drinking water standards, the concentrations of Aldrin in some surface water in Lianshui and Tongshan had exceeded the standard, and the maximum exceeding time was0.52. Concntrations of other OCPs were lower than WHO drinking water standards. OCPs concentrations in surface water were higher than it in the underground water based on the study of water in Lianshui and Tongshan. And the representative pollutant HCHs, the total concentration also showed the same phenomenon (surface water>shallow ground water> deep ground water). Concentrations of the total OCPs in different sources of drinking water showed that wet season was higher than dry season. Distribution characters of the total OCPs concentrations in study districts showed Lianshui were higher than Tongshan. And the representative HCHs also showed the same distribution characters. α-HCH and β-HCH had a stronger vertical migration ability and meanwhile a-HCH and β-HCH were the main kinds of OCPs residues in the two study districts’ drinking water sources. Analysis on HCHs origin found that HCHs mainly came from industrial pollution (except that Lindane was the main OCPs pollutant in agricultural irrigation area) in Lianshui, while in Tongshan the pollution source mainly came from agricultural pollution.②In Lianshui all the12kinds of co-PCBs were detected in wet season, while in dry season, only8kinds of co-PCBs deteced (PCB81、PCB126、PCB157and PCB167not detected). In Tongshan,3kinds of co-PCBs including PCB81, PCB15and PCB157were detected in wet season, while in dry season10kinds of co-PCBs were detected (PCB114and PCB189not detected). The total concentrations of co-PCBs in drinking water sources all did not exceed the China’s drinking water standard. Mean concentration of the total co-PCBs (14.43ng/L) in surface water of Lianshui in wet season exceeded the USEPA standard (14.0ng/L). Co-PCBs distribution in different type sources of drinking water showed that surface water>shallow underground water> deep ground water. PCBs in peripheral water were generally the same with deep gounder water. Mean concentrations of the total co-PCBs in Lianshui showed wet season was higher than dry season. While mean concentrations of the total co-PCBs in Tongshan showed wet season was lower than dry season. Study districts comparison showed the concentrations of the total co-PCBs in Lianshui were higher than Tongshan. In dry season, concentrations of the total co-PCBs in underground water showed Lianshui were higher than Tongshan. For surface water, it showed that Lianshui was lower than Tongshan. PCB169was very obvious in SPM and sediments.③7kinds of PAEs in surface water of Lianshui in wet and dry season were detected. DNBP was the most representative one and its concentrations in wet season and dry season reached to14264.62ng/L and2606.0ng/L respectively, with detection rates reaching to100%and96.7%respectively. DMP in underground water and peripheral water of Lianshui in both wet and dry season was not detected and of the detected PAEs, DNBP was also the main detected PAE (detection ratios>33.3%and average concentrations>4.38ng/L). DNBP in different drinking water sources of Tongshan that both in wet season and dry season was also the main residual PAE. The concentrations of DEP in some surface were high. In underground water and peripheral water DIOP and DNOP were not detected. PAEs concentrations in sources of drinking water of Tongshan did not exceed China’s drinking water standards while in Lianshui DNBP concentrations in surface water and deep ground water in wet and dry season exceeded the standard. In wet season, concentration of the DNBP in deep underground water exceeded1.31times as the maximum and the maximum over-limit rate reached to16.7%. In wet season concentration of the DNBP in surface water exceeded7.41times as the maximum and the maximum over-limit rate reached to73.3%. In dry season concentration of the DNBP in deep underground water exceeded4.41times as the maximum and the maximum over-limit rate reached to33.3%. In dry season concentration of the DNBP in surface water exceeded2.03times as the maximum and the maximum over-limit rate reached to73.3%. In dry season of deep water source, it exceeded4.41times at most and the over-limit ratio reached to30%. Concentrations of the total PAEs in different type sources of drinking water in study districts sources in wet and dry season both showed that surface water> underground water. Total PAEs residuals in different type sources of drinking water in Lianshui showed that wet season> dry season while in Tongshan it showed wet season<dry season. Distribution character of the total PAEs residual showed Lianshui> Tongshan.High concentrations of DNBP in deep groundwater of Lianshui in wet and dry season showed it may relate to the drill equipments. In dry season PAEs residual in SPM showed surface water SPM higher than shallow groundwater and the main pollutants DNBP and DEHP also showed surface water SPM higher than shallow groundwater while DEP distribution was opposite with DNBP and DEHP. Pollution kinds of PAEs in sediments in the two study districts showed some difference. In sediments, the main PAE in Lianshui was DNBP while the main PAE in Tongshan was DEHP. Total PAEs concentrations in sediments of Lianshui showed surface sediments a little higher than sub-surface sediments. It suggested that PAEs pollutant was getting serious in recent years. Total PAEs concentrations in sediments of Tongshan showed surface sediments did not higher than sub-surface sediments. It showed that PAEs pollutant did not get more serious in recent years or get better than before. DIBP (DNBP’s isomer) which was inspected additionally in water showed positive relation with DNBP.④PAHs detected in different type sources of drinking water in Huai’an Lianshui and Xuzhou Tongshan at different degrees. The total concentrations of PAHs (0.80-162.0ng/L) in study distrcts were at low or moderate pollution level compared to other surface water and they did not exceed China’s drinking water standards, so did the BaP concentrations. Vertical distribution of the total PAHs in different type sources of drinking water in the study districts (Huai’an Lianshui Xuzhou Tongshan County) showed that the residues concentration of PAHs in surface water was the highest, the second was in shallow underground water and the deep groundwater concentration was the lowest. Time distribution characteristics of the total PAHs in different type sources of drinking water in the study districts showed that wet season was higher than dry season. In study districts,3-ring and4-ring PAHs were the main PAHs in water sources and Phe was the representative pollutant. The average concentrations of16PAHs in the SPM dectected in dry season were greater than the corresponding water. Phe made the most contribution to the SPM in the two study districts, and it accounted for44.4%and44.8%of the total PAHs in the shallow groundwater SPM and surface water SPM. Flu also made a contribution to SPM in the two study districts, and it accounted for33.1%and42.8%of the total PAHs in the shallow groundwater and surface water SPM. By detecting the different depths of Kuihe River’s sediments, we found the same composition and amount of PAHs at surface seniments and secondary sediments. It suggestted that the PAHs pollution was relatively stable, and further analysis of the PAHs compositon in local water presented that the average levels of large rings (5-rings and6-rings) PAHs were highest in the deep groundwater (1.16ng/L), and second in the shallow groundwater (1.06ng/L), in surface water (0.46ng/L) was lowest. Compared to deep groundwater, the total PAHs of peripheral water increased (82.88%). The content of Phe increased (2.04times), but the high-ring PAHs decreased (from1.16ng/L to0.90ng/L), with a decrease of22.41%.⑤Phenol was the most obvious pollutions in water sources. Reference to the volatile phenol limits in China’s drinking water standard, the mean concentration of phenol in surface water exceeded4.48times during Huai’an Lianshui wet season with the exceeded rate of90%and in dry season exceeded0.99times with the exceeding rate of40%.2-Methylphenol also had relatively higher detection rates and concentrations. Vertical distribution of the total Phenols in different type sources of drinking water in the study districts (Huai’an Lianshui Xuzhou Tongshan County) showed that the mean residues concentration of Phenols in surface water was the highest, the second was in shallow groundwater and in deep groundwater the mean concentration was the lowest. Time distribution characteristics of the Phenols in different type sources of drinking water in study districts showed that the residues concentration of Phenols in wet season was higher than in dry season, and the total Phenols in different type sources of drinking water in the study districts was higher in dry season than in wet season. The total Phenols concentrations in surface water were greater in Huai’an Lianshui than in Xuzhou Tongshan.⑥Distribution of metal elements had some differences in study districts: excessive metal elements in Huai’an Lianshui mainly were Fe, Mn, Al and As, with the maximum exceeding times115.58、123.07、13.77and10.12respectively. Fe exceeded not only in the surface water and shallow ground water, but also in the deep groundwater. Excessive metal elements in Xuzhou Tongshan mainly were Fe and Mn, with the maximum exceeding times8.22and0.40respectively and they were mainly in the surface water and shallow groundwater. As as a carcinogen, with a10.12maximum exceeding times, most obviously in the shallow groundwater in dry season in Huai’an Lianshui and its average concentration (52.13μg/L) also surpassed the surface water (5.89μg/L) and the deep ground water (0.63μg/L); As had a low concentration in the shallow groundwater in Tongshan.⑦Volatile organic compounds mainly detected in study districts were methylene dichloride and chloroform, but there are differences in concentrations. The average concentration, detection rate and maximum exceeding times of methylene dichloride in the surface water and the shallow groundwater in dry season in Tongshan were significantly greater than in Huai’an Lianshui while the concentration of chloroform was significantly higher in Lianshui than in Tongshan.(4) Health Risk AssessmentShallow groundwater, deep groundwater and peripheral water as the direct source of drinking water in the study districts showed that carcinogenic and non-carcinogenic health risks in different type sources of the drinking water in Lianshui were greater than Tongshan. In dry season non-carcinogenic risk in shallow groundwater of Lianshui was313.78times larger than Tongshan and the carcinogenic risk Lianshui was3.54times larger than Tongshan. Non-carcinogenic risk in deep groundwater was702.56times larger than Tongshan and the carcinogenic risk lianshui was4.40times larger than Tongshan. Non-carcinogenic risk in Lianshui peripheral water was366.36times larger than Tongshan and the carcinogenic risk Lianshui was1.41times larger than Tongshan. The shallow groundwater both performed the largest risk in carcinogenic and non-carcinogenic health risks in study districts and made a clear difference in deep groundwater source and peripheral water. Health risks level in deep groundwater and peripheral water were much the same and did not exceed the relevant standards. Non-carcinogenic risk in shallow groundwater in Lianshui in dry season was6.15E+00which had over the limit value of the USEPA and displayed as an unacceptable risk. The main pollutants that producing the non-carcinogenic risk were As and Fe. Carcinogenic risk in shallow groundwater in Lianshui in dry season was3.96E-03which exceeded the acceptable risk (10-6-10-4) of USEPA. The calculated annual carcinogenic risk with70a was5.66E-05which had exceeded the acceptable risk limits of the IRPC (5.00E-00). Carcinogenic risk in shallow groundwater in Tongshan in dry season was1.12E-03, slightly exceeded the USEPA acceptable risk, the calculated annual carcinogenic risk with70a was 1.60E-05and did not surpass the acceptable risk limits of the IRPC. The major pollutants producing the carcinogenic risk in Xuzhou Tongshan mainly were PCB126and PCB169. In Huaian Lianshui, addition to the above two, but also including As.(5) Priority pollutants62kinds of priority pollutants were screened out from the141target pollutants in Lianshui. They were14kinds of OCPs,12kings of PCBs,6kinds of PAEs,2kinds of Phenols,12kinds of PAHs,2kinds of VOCs and12kinds of Metals.53priority pollutants were screened out from the141target pollutants in Tongshan. They were11kinds of OCPs,10kings of PCBs,5kinds of PAEs,2kinds of Phenols,12kinds of PAHs,1kinds of VOCs and12kinds of Metals.Conclusions:(1) Methodology research:determination parameters of sensitivity, accuracy and stability all met the analysis requirements of trace organic pollutants.(2) Pollutants distribution:multi-pollutants in different type sources of drinking water in study districts were detected in different degree. The kinds and concentrations of multi-pollutants in the two study districts had some difference. The total concentrations of pollutants in drinking sources of Huan’an Lianshui were higher than Xuzhou Tongshan. The concentrations of pollutants in different type sources of drinking water showed that the surface water was higest, the deep ground water was the lowest and the shallow groundwater was between them and pollutants concentrations in deep ground water was much the same of. The concentrations of pollutants in drinking water sources of Huan’an Lianshui showed the wet seaon higher than the dry season while in Xuzhou Tongshan it showed the wet seaon lower than the dry season.(3) Health risk assessment:carcinogenic and non-carcinogenic health risks both showed Huai’an Lianshui (high incidence rates of tumors and chronic diseases) higher than Xuzhou Tongshan (low incidence rates of tumors and chronic diseases). Carcinogenic and non-carcinogenic risk levels in shallow groundwater of Huai’an Lianshui were unacceptable. It might produce some potential influence on local resident health. Carcinogenic and non-carcinogenic health risks in deep groundwater and peripheral water were lower, and this suggested that current water supply transformation in typical towns reduces the health risks of local residents. The effect is obvious.(4) Priority control pollutants:The method screening rate was approximately56%-62%. Priority pollutants species in Lianshui and Tongshan were62and53respectively and the compositions were similar. The obtained priority pollutants list may provide a reference for further environmental management of sources of drinking water of typical towns.