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紫色土丘陵区农业小流域水体大肠杆菌污染特征研究
Alternative TitleFecal bacteria pollution characteristic in an agricultural watershed in hilly areas of purple soil
薛菲
Subtype硕士
Thesis Advisor唐家良
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline环境工程
Keyword紫色土丘陵区 农业小流域 大肠杆菌
Abstract近年来,世界各地由于不洁净水体中的病原菌引发的水传播疾病时有发生,并且爆发频率有明显上升的趋势,对人类健康构成了严重威胁。而由于经济发展的限制和卫生条件的落后,这种水体病原菌污染状况在发展中国家尤为突出。我国大部分农村,特别是西部山地丘陵区的农村区域,由于资金缺乏和技术限制等原因,缺少生活污水处理基础设施设备,生活污水通常直接排放入河道,除此之外,区域内频繁的农业活动(如畜禽养殖和有机肥施用)所引发的水体面源污染也尤为严重。而区域内水体的微生物污染状况还未知,因此针对农业小流域水体病原菌污染特征调查和自然防控机理研究迫在眉睫。本研究选取亚热带气候区紫色土丘陵区域的一个典型农业小流域(1236公顷)进行综合监测,选取常见的指示微生物总大肠菌群(TC)和大肠埃希氏菌(E.coli)作为常规监测的对象,监测区域包括不同位置的河道水、沟渠水和堰塘水等地表水体以及流域内饮用水井和自然山泉等地下水体。采用固定酶底物法检测大肠杆菌数量,探讨大肠杆菌在地表水和地下水中出现的时间规律、空间分布的特点、相对移动路径、运移驱动机制和环境影响因子。综合国内外现有水环境微生物基准对小流域水体进行微生物水质评价,为进一步完善我国的水环境大肠菌群指标体系提供参考依据,最后探讨建立自然生态管理条件下紫色土丘陵区农业小流域大肠杆菌污染防治方法的可能性。主要结果和结论如下:1) 紫色土丘陵区农业小流域污染源分布及水体致病菌多样性万安小流域污染源类型主要为居民区生活污水、畜禽养殖废水、粪肥堆积物以及大面积农田,污染物输入方式主要为点源和面状输入。流域上游截流村、流域中部广庭村区域、各种畜禽养殖场是受微生物污染的脆弱区;细菌群落多样性分析以及潜在病原菌分析结果表明研究流域细菌种类多样性高,致病菌种类多且普遍,主要为变形菌门、放线菌门和拟杆菌门。2) 紫色土丘陵区农业小流域水体大肠杆菌时空分布特征万安小流域地表水体中大肠杆菌普遍存在;且几乎所有的地下水井中都检测出了总大肠菌群,大肠埃希氏菌检出率在90%以上,即使是在冬季流域水体中仍然检测出了较高的总大肠菌群,在整个流域呈现出一种常态污染的特点。小流域内水体大肠杆菌季节差异明显(P<0.05),呈现出春夏季高秋冬季低且在夏季末达到峰值的特点,在同一季节,不同水源水体大肠杆菌数量也存在明显差异(P<0.05),地表水中的大肠杆菌数量是地下水体的2-3倍。大肠杆菌浓度与人类活动范围及强度密切相关,受人为活动影响较大的水体(居民点附近的地表水和地下水)含有较高大肠杆菌数量;尽管受地形因素及农耕活动的干扰,河道水体中大肠杆菌浓度波动较大,在干扰相对较小的区域大肠杆菌浓度呈现明显的沿河道衰减的趋势。3) 紫色土丘陵区农业小流域水体大肠杆菌运移驱动力及影响因子研究流域水体中大肠杆菌主要受到水体地球化学状态(温度、ph、湿度、盐度、电导率等)、降雨、水文条件、土地利用和污染源位置等一系列因素的影响。在研究期内,河流水体中大肠杆菌浓度对降雨事件响应速度较快(1个小时),特别是对侵蚀性降雨事件的响应。而地下水中大肠杆菌对降雨驱动造成的浓度变化响应则存在一定的滞后效应。研究流域全年输出的总大肠菌群和大肠埃希氏菌总负荷分别为2.79E+16和1.08E+15 MPN,其中丰水期(5月-9月)输出总量分别是枯水期(11月-3月)的60和25倍。通过分析地表和地下途径大肠杆菌输出浓度的变化特征,确认污染源区域与目标区域(如地下水和集水出口)之间存在定量联系。此外,大肠杆菌浓度与电导和浊度呈正相关, 与泥沙或胶体物质相结合是病原菌迁移的重要方式;而温度是影响地下水中大肠杆菌存活的重要因子。 4) 紫色土丘陵区农业小流域水体微生物水质评价研究流域地表水地下水微生物水质状况较差,70%的地表水样品总大肠菌群数超过了每100毫升1000个MPN值的标准,而90%的地下水样品大肠埃希氏菌超过了世界卫生组织所推荐的每100毫升10个MPN值的安全饮用水健康风险标准。流域上游生态沟渠对总大肠菌群和大肠埃希氏菌的去除效果仍十分明显,去除效率分别为84.37%和95.66%。典型对应分析结果表明由于林山乡的生活污水出口(L1)和下游屠宰废弃物排放区(L11)在整个检测期排放量高且稳定被识别为大肠杆菌关键污染源,而位于肉羊养殖场的地下水井(W7)和养鸡场下游区域的地下水井(W9)则分别被识别为总大肠菌群和大肠埃希氏菌的关键污染源。本研究将有助于揭示区域内小流域水体病原菌污染状况及其机理,为实施病原菌污染的防治措施与优化管理策略提供科学依据,从而保护区域内饮用水安全和居民健康。
Other AbstractRecent years,there has been a significant increase of the infectious diarrhea and other diseases caused by the pathogenic bacteria in unclean water, which has posed serious threats to human health. In most developing countries access to clean drinking water and adequate sanitation remains a problem due to poor economic situation and sanitary conditions. In most rural areas of China, the domestic sewage is discharged into natural environment due to ineffective infrastructure. These areas also have serious non-point sources pollutions caused by poultry feeding and organic fertilizer application. Therefore, the investigation of water-borne pathogen pollution in agricultural watershed is key to develop pathogen removal system and maintain sustainable development of the rural region. The study was conducted in a typical agricultural watershed named Wanan (1236 hectors) in hilly areas of purple soil in the subtropical region. Two normal indicator bacteria including total coliform (TC) and Escherichia coli (E.coli) were selected as monitoring parameters to investigate water microbial contamination levels considering transport characteristics and patterns of pathogen. The surface water monitoring sites included farmland ditch water, ecological ditch water, pond water, sub-watershed outlets and watershed outlet in the nested watershed. The seasonal and spatial distribution, migration pathways and environmental impact factors of fecal bacteria were studied respectively based on a series of sampling campaigns and Defined Substrate Technology (DST). Moreover, microbial water quality and water pollution risk in study watershed were assessed based on water environmental microbial benchmarks in China, developed countries and WHO. This study provided a scientific basis for the government to reajust the water quality standards. Finally, the possibility of establishing the prediction method of fecal bacteria contamination in an agriculture watershed under traditional management was evaluated. The main conclusions are as follows.1) Pollutant sources distribution and diversity of bacteria community and potential pathogen The study showed pathogenic bacteria can be delivered to water bodies from a variety of sources including humans, many species of livestock, sewage septic tank and farmland manure through point and non-point sources patterns. These areas including Jieliu village of upstream areas, Guangting village of middle areas and livestock raising farming areas are vulnerable to pathogen bacteria contamination. The diversity analysis demonstrated the study watershed water bodies had high diversity and abundance of bacteria community and potential pathogens.2) Temporal-spatial distribution of fecal bacteriaOur study proved that high concentrations of TC and E.coli were frequently detected in surface waters and almost all groundwater samples have been detected with high TC at any sampling time. Total coliform counts still maintained high levels in winter which displayed chronical pollution in whole watershed. Fecal bacteria counts significantly differed from season to season at every water sources sites (P<0.05), as well as form site to site within same season (P<0.05), the fecal bacteria concentrations in surface water were 2-3 times than in groundwater. Fecal bacteria concentrations in waterbodies were higher in warmer months than cold months (P<0.05), peaking in late summer. Fecal contamination levels were higher at areas where human activities were intensive like L1, L11, residential wells (F). Spatial distribution and presence of fecal bacteria in river showed a patchy pattern instead of homogeneous due to landscape and human activities intervention, however, we still observed bacteria descending trend along waterways in some natural regions.3) Drivers and influence factors of the presence and transport of fecal bacteria in an agricultural watershed in the hilly areas of purple soliThe persistence of fecal bacteria in study watershed was determined by a number of factors such as geochemical status of water (changes in temperature, pH, humidity, salinity, EC…), rainfall, hydrologic conditions, landuse and pollution sources location. We detected rapid responses (one hour) of fecal bacteria numbers to rainfall events in river especially for erosion rainfall events, while the changes of fecal bacteria numbers in groundwater displayed a delayed effect respond to rainfall events. The study watershed discharged TC and E.coli of 2.79E+16 MPN and 1.08E+15MPN respectively a year, while the output load of TC and E.coli in high flow condition was sixty times and twenty five times that of the drought period. The possible linkages between source area and targets (e.g. groundwater and catchment outlet) were ascertained through both surface and subsurface pathways. E.coli and TC were positively correlated with EC and Turbidity, indicating that mixture of organic colloids and sediment is the most important transport vector of bacteria in this catchment. Furthermore, temperature was the critical influence factor of fecal bacteria in groundwater.4) Microbial water quantity in an agricultural watershed in the hilly areas of purple soliBacteriological quality is poor both in groundwater and surface water in this catchment, since 70% surface water samples exceeded the guideline of 1000 TC per 100ml in the catchment. Also, 90% of groundwater samples exceeded the guideline of 10 E. coli per 100ml for safe drinking water. While the ecological ditch still showed distinct removing effects for TC of 84.37% and E. coli of 95.66%. The CCA result showed the L1 and L11 were the critical fecal bacteria pollution sites due to stable and intensive emissions within study period, moreover, the W9 and W7 were sensitive to changes of TC and E.coli in groundwater.This study will provide the scientific basis for designing pathogen removal technology and management strategy for preventing pathogen contamination. 
Pages71
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24615
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
薛菲. 紫色土丘陵区农业小流域水体大肠杆菌污染特征研究[D]. 北京. 中国科学院大学,2017.
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