珠江三角洲区域地下水酸化机理研究

发布时间：2018-04-11 07:40

本文选题：珠江三角洲 + 酸化机理　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：随着珠江三角洲地区经济建设的快速发展,不恰当的排放所引发的环境问题逐渐显现,地下水环境污染问题日益突出,尤其是地下水酸化问题严重。调查研究显示,区域地下水pH超标率为68.6%,pH6.5的偏酸性地下水已占全区面积的3/4。以往的研究多是对酸性地下水的分布状况以及主要成因进行了简略的讨论,其最重要的酸化机理并未指明。所以,研究珠江三角洲地区地下水酸化的问题时,机理的研究尤为重要。本研究从酸性地下水分布规律入手,从机理角度剖析影响酸化的各个因素。分别以区域尺度(整个珠江三角洲地区)、剖面尺度(典型研究区剖面)以及微观尺度(土壤构成组分)开展研究,得出的结论可以为珠江三角洲区域地下水污染的防治提供科学的指导。本研究取得了如下主要成果：在区域尺度上,以2005-2008年珠江三角洲地区的地下水污染调查评价为基础,从地下水中S042-的来源反推引起地下水酸化的主要因素,分析每个可能的来源,最终确定酸雨为导致地下水酸化的主要因素。引入酸雨危害指数(AHI)的概念,以表征酸雨的危害程度,并应用主成分分析(PCA)方法研究珠江三角洲地下水的水化学组分以及酸雨的影响。在剖面尺度,以包气带为主要研究对象,研究了典型酸化区剖面上的pH、土壤盐基离子以及A1的变化。包气带为砂砾石,渗透性好,地势高坡度大,径流条件良好,酸化现象不显著。表层为粘土或粉质粘土,渗透性很差,部分区域地势凹陷,径流条件较差,酸化较为严重。按照土壤中酸缓冲体系的三个阶段(游离碳酸盐溶解-沉淀阶段、盐基离子交换阶段、铝硅酸盐矿物溶解-沉淀阶段)分析其变化特征。采用酸缓冲曲线法进行实验,测定典型研究区未酸化的水稻土和红壤的缓冲容量,进而计算该土壤对酸沉降的临界负荷值,并预测其达到酸害所需的时间分别为：86.5年和45.5年。采用土壤固相组分顺序提取的方法研究了区内典型土壤的三种土壤(未酸化水稻土、已酸化水稻土、红壤)的缓冲能力差异。由于土壤固相组分的差异,三种土壤所具有的缓冲能力大小为：未酸化的水稻土红壤酸化的水稻土。
[Abstract]:With the rapid development of economic construction in the Pearl River Delta region, the environmental problems caused by improper discharge gradually appear, and the problem of groundwater environmental pollution is becoming increasingly prominent, especially the serious problem of groundwater acidification.The investigation shows that the partial acid groundwater whose pH exceeds the standard rate of 68.6% and pH 6.5 has accounted for 3 / 4 of the total area of the region.The most important acidification mechanism of acid groundwater has not been pointed out.Therefore, it is very important to study the mechanism of groundwater acidification in Pearl River Delta.This study starts with the distribution of acidic groundwater and analyzes the factors affecting acidification from the point of view of mechanism.The regional scale (the whole Pearl River Delta region), the profile scale (typical study area section) and the micro scale (soil composition) were studied, respectively.The conclusions can provide scientific guidance for the prevention and control of groundwater pollution in the Pearl River Delta region.The main results of this study are as follows: on a regional scale, based on the investigation and evaluation of groundwater pollution in the Pearl River Delta region from 2005 to 2008, the main factors causing groundwater acidification are derived from the source of S042- in groundwater.Each possible source was analyzed and acid rain was identified as the main factor leading to groundwater acidification.The concept of acid rain hazard index (AHI) was introduced to characterize the damage degree of acid rain. The method of principal component analysis (PCA) was used to study the hydrochemical composition of groundwater in the Pearl River Delta and the influence of acid rain.The changes of pH, soil base ions and A1 in typical acidified zone were studied at the profile scale, taking the aeration zone as the main research object.The aeration zone is sandy and gravel with good permeability, high slope, good runoff condition and no significant acidification.The surface layer is clay or silty clay, the permeability is very poor, some regional topography sag, runoff condition is poor, acidification is more serious.According to the three stages of acid buffer system in soil (free carbonate dissolution-precipitation stage, base-based ion-exchange stage, aluminosilicate mineral dissolution-precipitation stage), the change characteristics were analyzed.The buffer capacity of unacidified paddy soil and red soil in typical study area was measured by acid buffer curve method. The critical loading value of the soil to acid deposition was calculated, and the time required to reach acid damage was predicted as 86.5 years and 45.5 years, respectively.The buffer capacity of three typical soils (unacidified paddy soil, acidified paddy soil and red soil) was studied by sequential extraction of soil solid components.Because of the difference of soil solid composition, the buffer capacity of the three soils is as follows: unacidified paddy soil, red soil, acidified paddy soil.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X523

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