河道底泥重金属检测及潜在生态风险评估

发布时间：2017-12-31 06:21

本文关键词：河道底泥重金属检测及潜在生态风险评估　出处：《中国计量学院》2015年硕士论文　论文类型：学位论文

【摘要】：河道底泥重金属具有毒性持久、难分解、易在水生生物体内积累、能破坏生物体正常生理代谢活动、会对生态环境造成极大危害等性质,已经成为影响水体环境质量的重要污染物,因此有必要检测河道底泥中重金属的含量,研究河道底泥中重金属的分布特征和污染水平,分析底泥重金属的潜在生态风险,探讨合理的风险控制方法。本文基于原子吸收光谱技术,对杭州经济技术开发区河道底泥重金属进行检测,在重金属检测方法、空间分布特征及生态风险控制方面做了一些研究。本文主要的研究内容如下:(1)河道底泥重金属检测方法研究。本文利用传统的四酸消解-原子吸收光谱法对杭州经济技术开发区18条河道底泥中重金属Cu、Zn、Pb、Cd、Ni和As的含量进行了检测。同时针对传统底泥重金属检测方法回收率低的问题以及底泥有机质含量普遍偏高的特点,提出了基于有机质梯度变化的底泥重金属检测方法,研究了四种消解体系对不同有机质含量底泥Cu、Zn、Ni的检测结果的影响,针对不同有机质含量样品,提出了回收率在90%~110%范围内、以最小酸用量为目标的Cu、Zn、Ni的最佳消解体系。结果显示,最佳消解体系提高了底泥重金属消解的回收率,且总耗酸量在2~19 ml的范围内,平均总耗酸量为10.54 ml,少于传统消解方法中的19 ml。(2)研究区域河道底泥中重金属空间分布特征及污染评价。本文分析了研究区域河道表层底泥重金属和底泥垂向重金属的空间分布特征和污染水平,并对底泥重金属进行了聚类分析和因子分析。结果表明,表层底泥中Cu、Zn、Pb、Cd、Ni及As的污染程度排序为CdCuZnAsNiPb,其中Cd、Cu污染相对严重,且重金属的空间分布不均匀;重金属在底泥垂向上的分布总体呈表层多底层少的特征,但受不同时期人为清淤疏浚的影响,导致这一特征在不同时期内有所变化;重金属聚类分析将6种重金属聚为3类,Zn、As为一类,Cd、Pb为一类,Ni、Cu为一类,被聚为一类的重金属应受到同一污染源因素影响;18个采样点聚类分析结果表明杭州经济技术开发区河道底泥重金属污染分布较为均匀,工业区重金属污染较为突出;因子分析结果表明研究区域的主要污染源有三种。(3)河道底泥重金属潜在生态风险及控制研究。本文引入Hakanson潜在生态风险指数法评估杭州经济技术开发区河道底泥重金属的潜在生态风险,基于底泥中重金属的潜在生态风险评估结果,研究并提出了临界风险控制方法,以方便和快速地确定合理的底泥环保疏浚深度,为工程疏浚提供一定指导。研究结果显示,研究区域内河道底泥以Cd污染为主,其潜在生态风险指数的平均值在234.2~973.3之间,属于高风险至极高风险,是底泥生态风险控制的决定因子;采用临界风险控制方法确定的18条河道底泥环保疏浚深度为10~110cm。
[Abstract]:Heavy metals in river sediment with persistent toxic, refractory, easy to accumulate in aquatic organisms, can destroy the normal physiological metabolic activities of organisms, will cause great harm to the ecological environment and nature, has become an important pollutant affecting the water quality of the environment, so it is necessary to detect content of heavy metals in river sediment, distribution characteristics and pollution levels of heavy metals in river sediment, analysis of the potential ecological risk of heavy metals in sediments, to explore the reasonable risk control method. In this paper, atomic absorption spectrometry based on the detection of Hangzhou economic and Technological Development Zone in the river sediment heavy metal, heavy metal detection methods, do some research on the spatial distribution characteristics and ecological risk control. The main contents are as follows: (1) research on detection methods of heavy metals in river sediments. Four conventional acid digestion atomic absorption spectrometry based on Hangzhou The heavy metal Cu, economic and Technological Development Zone 18 river sediment Zn, Pb, Cd, Ni and As content were detected. At the same time for the recovery of the traditional detection methods of heavy metals in the sediment of the problem of low rate and characteristics of sediment organic matter content is generally high, the heavy metal detection method based on gradient changes of organic matter, study four kinds of digestion system in different organic matter content in the sediment of Cu, Zn, Ni influence test results, according to different organic matter content of samples, proposed the recovery rate in the range of 90%~110%, with the minimum amount of acid as the target of Cu, Zn, the best digestion system of Ni. The results showed that the optimum digestion system to increase recovery the rate of digestion of heavy metals in sediments, and the total amount of acid consumption in the range of 2~19 ml, the average total amount is 10.54 ml, less than the traditional digestion method in 19 ml. (2) distribution characteristics and evaluation of heavy metal pollution in the study area of river sediment in space This paper analyzes the research area. The river sediment heavy metals and Sediment Heavy Metals vertical spatial distribution characteristics and pollution level of heavy metals in sediments, and the cluster analysis and factor analysis. The results show that the surface sediment in Cu, Zn, Pb, Cd, Ni and As pollution degree ranked CdCuZnAsNiPb, Cd, Cu pollution relatively serious, and the spatial distribution of heavy metals in the uneven distribution of heavy metals in the sediment; the overall vertical surface is much less the underlying characteristics, but the influence of different period for dredging, the characteristics of the changes in different periods of heavy metals; clustering analysis of 6 kinds of heavy metals were clustered into 3 groups, Zn. For a class of As, Cd, Pb, Ni, Cu as a class as a class are clustered into a class of heavy metals should be affected by the same source of pollution factors; 18 sampling points cluster analysis results show that the distribution of heavy metal pollution in sediments of Hangzhou economic and Technological Development Zone River Uniform, area of heavy metal pollution industry is more prominent; the results of factor analysis showed that the main pollution source in the study area. There are three (3) of River Sediment Heavy Metal potential ecological risk and control research. This paper introduces the Hakanson method of potential ecological risk index assessment of potential ecological risk in Hangzhou economic and Technological Development Zone of river sediment heavy metals, the potential ecological risk of sediment in the evaluation of heavy metals based on the results of research and put forward critical risk control methods to environmental dredging depth conveniently and quickly determine the reasonable, provides some guidance for the dredging engineering. The results showed that the study area of river sediment Cd pollution and its potential ecological risk index of the average value between 234.2~973.3, belongs to the high the risk to high risk, is a decisive factor of sediment ecological risk control; 18 rivers sediment ring determined by critical risk control method The depth of dredging is 10~110cm.

【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X832;X824

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