【作者】 王昭；

【导师】 石建省； 张兆吉；

【作者基本信息】 中国地质科学院 ， 地质工程， 2008， 博士

【摘要】 华北平原是我国北方严重缺水的地区。地下水是本区的主要供水水源,随着人类活动的增加,各种污染造成地下水中有害物质逐年增加,地下水水质逐渐下降,严重危及了饮用水安全。国内外对于无机污染物的迁移转化规律已开展了大量研究工作,并且取得了大量成果。自上世纪70年代后期,地下水有机污染已引起人们的高度重视。到目前为止,华北平原尚未系统开展针对供水安全的地下水污染调查评价工作,对地下水污染（特别是有机污染）总体状况还缺乏了解,对地下水污染的潜在危害认识不足。如何用适当的方法对主要调查点（如地下水水源地）的地下水水质及其饮用适宜性做出评价,如何从有机污染物本身性质来预测它们向地下水的淋溶迁移性,对于系统地评价区域地下水水质和有机污染状况,对有效保护地下水资源及污染防治、保障饮水安全具有重大意义。本次研究以“华北平原地下水有机污染调查”项目为依托,在充分收集和分析以往在该区的相关研究成果的基础上,结合本课题组对重点地区进行的实地野外地下水污染调查和采样分析结果,以及计划项目中其它工作项目的野外调查和水样分析资料,通过数理统计和GIS图件分析、模型模拟计算等方法,对研究区的地下水水化学特征进行了综合分析,对区内主要调查点地下水质量、饮用适宜性、有机污染特征进行了评价和分析。本次研究主要进行了以下三方面的研究:1、研究简单可行的评价方法或对原有的方法进行改进,对研究区内主要调查点地下水的质量和饮用适宜性进行评价。2、对地下水的有机污染进行评价,分析地下水中的主要有机污染物的种类、分布特征及其可能的污染来源。在资料充分的条件下,结合有机污染检测结果和水文地球化学资料,分析有机污染与典型无机指标间的关系,并进行规律性分析。3、根据有机污染物的物理化学性质,用适宜的参数和模型,研究调查的有机污染物在水土系统中的淋溶迁移性,以预测有机物对地下水的污染风险（污染物向地下水系统的迁移性能）,为今后的污染防治提供科学的依据。通过上述研究,得到以下成果:1.依据水样测试结果评价了主要调查点地下水的水质,修订了内梅罗指数评价标准。分别采用单因子评价法和国标中的综合评价法（内梅罗指数法）对研究区的地下水水质进行了评价。为了使两种评价结果有机地联系起来,以使内梅罗指数法的评价结果物理意义更加明确,对内梅罗指数评价标准进行了修订。修订后,评价结果与单因子评价结果完全一致,同时有利于同一类别的地下水进行质量对比。依据该评价结果,华北平原决定地下水质量的大多为无机指标,如总硬度、总溶解性固体、氟、硝酸盐等。在采集的水样中,只有4.4%的样品的水质类别是由有机指标（苯并[a]芘、挥发性酚类、四氯化碳）决定的。2.尝试拟定了适合我国具体情况的饮用水适宜性评价标准,并对研究区水样的饮用适宜性作出了评价。结合我国的生活饮用水标准及美国环保局的饮用水标准与健康咨询资料,对水质指标的致癌性分级进行了整理。在此基础上,尝试拟定了生活饮用水适宜性评价标准,并依据水样的测试资料对采样点地下水及部分地表水的饮用适宜性进行了评价。评价结果为:适宜饮用的占42.4%,基本适宜饮用的占18.4%,一般不宜饮用的占4.9%,不宜饮用的占34.2%,其中因为氟化物超标导致不宜饮用的多达19.2%。在此评价基础上,根据当地的具体地质、水文地质条件进行了分析,例如,对于一些地区地下水中的氟离子、铁等的超标,提出了加强水质监测并进行相应的水处理建议。因含砷、铅、苯并（a）芘、四氯化碳四种致癌指标导致评价结果为不宜饮用的水样点占9.0%,应进一步采样监测有关指标随时间的变化趋势、查明水质的成因并采取一定的措施。3.分析了华北平原主要调查点地下水中有机物的检出情况。依据所采样品的测试数据,在华北平原所采集的245组水样（含地表水3组）中,有93组样品检出了有机污染物。在检测的38种有机指标中,除氯乙烯、1,1-二氯乙烯、二氯甲烷、1,2-二氯乙烯、1,1,1-三氯乙烷、六氯苯六种有机物外,其他项目均有不同程度地检出,占检测有机物总数的84.2%,单点最多检出11种。检出率较高（大于4.5%）的有氯仿、甲苯、四氯乙烯、苯并[a]芘、氯苯、苯和1,2-二氯苯。从超标情况来看,依据目前的地下水质量标准报批稿（中国地质调查局,2007）,有四氯化碳和苯并[a]芘、挥发性酚类三项超标,超标率分别为1.22%、2.45%和1.90%。本次研究中,深层地下水样中也检出了微量有机污染物,这可能与取样井的混合开采、止水不佳有关。由于有机样品在时间和空间上差异较大,且易在取样等环节受到污染,建议在今后的工作中,对已发现的异常点进行重复取样测试,通过数据和有关资料的积累,以得到较为可靠的结论。从区域上来看,在人类活动相对强烈的城镇地区的地下水中的有物检出率相对较高,特别是在渗透性好的山前地带,污染物较易进入到地下水中。通过分析发现,地下水有机物的高检出率与地下水硬度的升高有一定相关性。4.利用地下水污染指数法研究了91种有机污染物的淋溶迁移性,探讨了检出的主要有机物与其淋溶迁移性的关系。本文针对我国地下水污染调查规范中所列的91中有机污染物（包括“中国水中优先控制污染物”名单中的58种有机毒物）,利用EPI Suite软件进行了有关参数的计算,利用地下水污染指数法研究了91种有机污染物的淋溶迁移性。结果表明,其中多数具有高淋溶和迁移性,当这些污染物进入到环境中时,易对含水层造成较大范围的污染。对于所研究的污染物,它们的地下水污染指数（GUS）与其有机碳分配系数(K_oc)有着很好的相关性,在土壤中的关系式为:GUS=-1.924*logK_oc+7.437,在含水层中的关系式为GUS=-2.578*logK_oc+10.050。这为评价地下水中主要有机污染物的污染指数（淋溶迁移性）提供了一个简易方法。GUS与有机化合物的其它性质(如辛醇—水分配系数K_ow、溶解度S等)的相关性不明显。对水样中有机物检出情况的统计结果与基于有机污染物本身性质的淋溶迁移性计算表明,华北平原地下水中的有机污染检出率与其淋溶迁移性有较好的相关性。更多还原

【Abstract】 The North China Plain has been suffering from the water shortage for many years. In this area, groundwater is the main source for water supply. With the development of society and economy, impacts of human activities on the evolution of groundwater are becoming more and more significant. Releasing of hazardous substances into environment, to a great extent, endangers the groundwater quality. This problem is more pronounced in the place where groundwater is used as the only drinking water source in the North China Plain. Since the late 1970s, many studies have been carried out on the inorganic hydrogeochemical aspects of groundwater in this region and great achievements have been made. However, to date, there is no investigation on groundwater organic contamination that has been systematically done in a regional scale. Little information is available on organic contamination of groundwater using as water supply source. Since most of the organic compounds detected in the groundwater are toxic and carcinogenic, there is a need to systematically assess the groundwater quality and its suitability for drinking in the North China Plain. Therefore, it is of great significance to acquire knowledge on the current condition of groundwater quality and contamination, to access the groundwater quality and its suitability by proper methods, and to predict the leachability of target organic compounds detected in groundwater.The objectives of this work are (1) to select simple and feasible methods or modify the existing methods for groundwater quality and drinking suitability evaluation; (2) to investigate the organic contamination of groundwater, based on the available data to classify the main classes of organic contaminants and briefly discuss the contamination source and their possible relationship with typical inorganic components (e.g., total hardness) in groundwater; and (3) according to the physical and chemical properties of organic compounds, to predict their leachability from soil s and sediments by suitable model, in order to provide scientific evidence for further risk assessment.As a part the project Investigation of Groundwater Organic Contamination in the North China Plain, the author has availability of data for the huge region from collaborating institutions. In the field, the water samples were collected according to the standard sampling procedure issued by China Geological Survey and the relating information about the sampling sites were careful investigated. Based on the analytical data from the nationally qualified laboratories and available hydrogeological data, GIS mapping, multivariate statistics and modeling approaches were applied for data processing. The main works carried out are described as follows:1. Groundwater quality assessmentAccording to the analyzed results of the water samples, the groundwater quality was assessed by single index method and comprehensive assessing method (i.e., Nemerow index). In order to make the assessment results to be easily interpreted in a practical sense and closely relate to the drinking water standards, in this work, the criteria of Nemerow index classification were adjusted. The assessed results indicated that the groundwater quality in the North China Plain is controlled by the inorganic items, such as total hardness, total dissolved solids (TDS), fluoride, and nitrate. The organic compounds including benzo[a]pyrene, volatile phenols, and carbon tetrachloride determine the quality assessment results of 4% water samples due to their high concentrations.2. Assessment of suitability of water for drinkingAccording to the actual hydrogeological and economic condition, and the toxicity (e.g., carcinogenicity) of investigated compounds, a more feasible method to assess the suitability of water (including groundwater and surface water) for drinking purpose was put forward. By using this method, the suitability of waters for drinking were evaluated. The results showed that 60.8% of waters are suitable for drinking purpose. Among these, 18.4% waters have certain compound concentrations classified as Class IV, which does not meet the national standard for drinking water. However, these compounds are not quite harmful to human health at this concentration range. A few waters (4.9% of the total samples) need to be simply treated to meet the quality requirement for drinking due to the high concentration of some compounds, even they do not have high risk to human health.Analyzed results of 84 samples indicated that necessary treatments are necessary if they are used for drink. Most of these waters have relative high fluoride concentrations. The available hydrogeological data implies that the high fluoride content is mainly caused by the natural geological conditions. This is also the reason for the high content of iron and manganese in some groundwater. Among the samples of this class, there are 22 samples with high content of arsenic, lead, benzo[a]pyrene, and carbon tetrachloride. Because these compounds are considered carcinogenic, further sampling and monitoring work should be carefully conducted for the waters with high concentration of these compounds. Based on the detail information on the origin of these hazardous substances, necessary measures should be taken.3. Assessment of groundwater organic contaminationThirty-eight organic compounds were chosen as target items for testing in the lab for totally 245 samples, in which there are three surface water samples. The analyzed data indicated that there were organic contaminants detected in 93 samples. Among the target compounds, chloroethylene, 1,1-dichloroethylene, dichloromethane, 1,2-dichloroethylene, 1,1,1 -Trichloroethane, and hexachlorobenzene were not detected in all the water samples. The maximum number of compounds detected in one site is 11. The organic compounds with a detection frequency (ratio of number of samples with organic compound(s) detected to the total number of samples) higher than 4.5% include trichloromethane, toluene, tetrachloroethlyene, benzo[a]pyrene, chlorobenzene, benzene, and 1,2-dichlorobenzene. According to the standards of groundwater quality (China Geological Survey, 2007), the concentrations of carbon tetrachloride, benzo[a]pyrene, and volatile phenols were higher that that for class III, which corresponds to the drinking water standards. It should be noted that there were organic contaminants detected in some deep groundwater samples. This suggests that further monitoring work should be carried out for these sites.From the statistic results in the large region, it can be easily found that the groundwater organic contamination is relatively more pronounced in the urban areas. There is a close relationship between the extent of groundwater organic contamination and the increase of total hardness in groundwater.4. Classification of leachability of target organic compounds and the relationship between their leachability and detection frequencyIn order to prevent organic contamination of groundwater, to predict the environmental fate of organic contaminants from their quantitative structure is a useful method. This is especially helpful under the condition that there is not enough data or it is difficult to take measurement. In this study, the leachability of 91 target organic contaminants (among them, 58 compounds are China Priority Organic Pollutants) was studied by groundwater ubiquity score (GUS). The half life (DT50) and organic carbon sorption coefficient (Koc) of the chemicals were calculated by the US EPA software EPI Suite (V3.20). The results showed that there is a close relationship between GUS and Koc of the investigated chemicals and their leachability is mainly controlled by Koc. There was no direct relationship of GUS with octanol -water distribution coefficient (Kow) and solubility (S) of the chemicals. The statistic results showed that there is a relatively close relationship between the leachability of organic compounds and their detection frequency in groundwater in the North China Plain.更多还原