基于场地重金属污染特性及生物可利用性的风险评估研究

发布时间：2018-01-24 16:44

本文关键词： 场地重金属污染特性生物可利用性风险评估　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代工业生产技术的不断更替以及城市化建设进程的不断推进,近年来,城市周边地区工业企业大量搬迁或停产,遗留下大量污染场地。由于过去环保观念不强且技术水平落后,工业企业在生产运营中存在污染泄漏、废物堆放等情况,容易对土壤及地下水造成污染,其中场地重金属污染已经成了不可忽视的环境问题,亟待进行污染场地风险评估与修复。弄清场地内重金属污染特性,掌握重金属形态与生物可利用态变化规律,有利于更科学的对场地风险进行表征,更合理的指定场地修复计划,一定程度上能避免场地的过度修复。因此,本文通过对场地重金属形态分布进行模拟分析,研究了本场地土壤重金属形态分布特征,进行了基于场地污染特性的场地分区,并通过体外模拟消化实验研究了场地重金属的生物可利用性特征。在试验的基础上探索基于场地重金属生物可利用性的风险评估与基于场地重金属污染特性的分区风险评估,并评估其可行性。主要研究结论如下:(1)本场地存在严重重金属污染,其中土壤主要关注污染物为总铬、六价铬、铅、镉、锌、砷,污染深度约为4m;地下水中主要关注污染物为铅、六价铬、锌、镉、砷。场地内土壤污染情况总体较为严重,且场地土壤污染主要集中于0-3m,自上至下土壤中污染物浓度呈现降低趋势,污染主要分布在铬渣堆场及生产车间附近,其中铬、镉、砷、铅、锌污染分布具有较大相关性。4m以下土壤中污染物不超筛选值,本场地需启动风险评估。(2)以场地污染土壤为研究对象,展开场地污染特征分析。发现在场地横向与纵向水平上,场地土壤重金属活性形态如可交换态分布与重金属总量和有机质含量均有相关性。对场地重金属生物可利用态进行研究,发现本场地其中铬、铅、镉生物可利用态含量与总量有显著正相关关系,铬、镉生物可利用态含量与有机质含量有显著正相关关系,铅生物可利用态含量与有机质含量有显著负相关关系。铬、铅、镉、砷在场地内平均生物可利用率分别为20.70%、14.38%、9.36%、18.53%,生物可利用率最大值分别为42.11%,29.52%,28.88%,32.35%,保守起见,选用最大值作为场地各重金属生物可利用率,可以进行基于重金属生物可利用态含量的风险评估,更真实的反映场地健康风险。另外,根据场地污染特性将场地分为A区、B区分开进行评价,,相对选择同一个生物可利用率进行全场地健康风险评估,进行分区评价的话各区生物可利用率变异系数更低。分别选用A区、B区生物可利用率最大值作为各区生物可利用率,可以更科学的进行基于重金属生物可利用态含量的分区健康风险评估。(3)以污染场地为研究对象,在场地调查的基础上,根据本场地的污染特征,进行场地健康风险评估与环境风险评价,并确定场地修复目标与修复范围。结果表明,场地土壤中六价铬、铬、镉、砷、锌存在健康风险。在常规健康风险评估的基础上探索了基于重金属生物可利用性的健康风险评估与基于场地污染特性的分区健康风险评估应用的可行性。结果表明,与常规健康风险评估相比,基于重金属生物可利用性的健康风险评估与场地分区健康风险评估得到的总致癌风险与总危害商更小,能更真实的反映场地的人体健康风险,并能制定更合理的修复目标,防止场地过度修复,在思路与计算应用上有一定的可行性。
[Abstract]:With the continuous change of modern industry production technology and continue to promote the city construction process in recent years, industrial enterprises around the city and a large area of relocation or stop production, left a large number of contaminated sites. In the past the concept of environmental protection is not strong and the backward technology, industrial enterprises are pollution leakage in production operations, waste dumps, easy to cause the pollution of soil and groundwater, including ground heavy metal pollution has become the environmental problems can not be ignored, the need for risk assessment and remediation of contaminated sites. The pollution characteristics of heavy metal in get clearance, grasp the heavy metal forms and bioavailable state changes, is conducive to a more scientific characterization of site risk, designated site remediation plan reasonable, to a certain extent, can avoid excessive repair site. Therefore, this paper through the simulation analysis of the heavy metal speciation site research Study the soil heavy metal speciation, the pollution characteristics of the area based on the site, and the site of heavy metals through in vitro simulation of bioavailability characteristics. On the basis of the experiment site exploration heavy metals based on available risk assessment and risk assessment of heavy metal pollution partition based on the properties of the site. And to evaluate its feasibility. The main conclusions are as follows: (1) serious heavy metal pollution exists in this field, the main concern for six pollutants of soil total chromium, hexavalent chromium, lead, cadmium, zinc, arsenic pollution depth is about 4m; the main concern of pollutants in groundwater for Pb, six chromium, zinc and cadmium. In the field of soil pollution. Arsenic overall situation is more serious, and soil pollution is mainly concentrated in 0-3m, since to the concentration of pollutants in soil decreased, pollution is mainly distributed in chromium slag and production of the car Between near the chromium, cadmium, arsenic, lead and zinc pollution distribution of pollutants with larger correlation below.4m in soil does not exceed the value in this field need to start screening, risk assessment. (2) in soil as the research object, analysis of soil pollution characteristics. Found in the field of horizontal and vertical level, soil heavy metals the activity forms such as exchangeable distribution and total amount of heavy metals and organic matter content were correlated. On the site of heavy metals was studied by the state, found the site of chromium, lead, cadmium bio available content and quantity has significant positive correlation between chromium and cadmium bio available content had significant positive correlation with organic matter content, lead bio available content have a significant negative correlation with organic matter content. Chromium, lead, cadmium, arsenic in the field and average biomass utilization rate were 20.70%, 14.38%, 9.36%, 18.53%, bioavailability The maximum values were 42.11%, 29.52%, 28.88%, 32.35%, conservative, using the maximum value as the site of the heavy metal bioavailability, can evaluate the risk of heavy metal bio available content based on the health risks of more real reflection of the site. In addition, according to the pollution characteristics of the field area is divided into A zone, B zone separate evaluation, choose the same relative bioavailability of the health risk assessment, evaluation of the partition coefficient of variation can lower words district biological utilization rate. We select A District, B District bioavailability as district maximum bioavailability, can be more scientific division of health risk assessment the bioavailable heavy metal content. Based on (3) in contaminated sites as the research object, on the basis of site investigation, according to the pollution characteristics of this site, the site of health risk assessment and environmental risk assessment The price, and to determine the target site remediation and repair areas. The results showed that six chromium, chromium in soil, cadmium, arsenic, zinc. Health risk assessment based on conventional health risk on heavy metal bioavailability health risk assessment of health risk assessment application and feasibility of partition based on the characteristics of contaminated sites based on the results show that compared with the conventional health risk assessment of heavy metals using the health risk assessment of health risk assessment and zoning of the site to get the total cancer risk and total harm business based on smaller, can truly reflect the site of human health risk, and make the repair target more reasonable, to prevent excessive site repair. It has certain feasibility in thinking and computing applications.

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;X820.4

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