次生季节性河流底泥元素的分布特征分析
发布时间：2019-01-26 20:23
【摘要】：在水资源相对匮乏且季节分配不均的淮河流域修建了大量的小型水坝,改变了河流流态,形成了大量的次生季节性河流。在半湿润、半干旱区,由于基流相对较少,河流水体更易受到污染,特别是不易转化的重金属污染,往往易在河流中累积,造成生态危害。底泥是重金属、有机碳及其他营养元素的重要聚集处,也是营养盐再生的主要场所。淮河流域作为我国社会经济发展较为重要的地区之一,也面临着严重的底泥污染问题。在水资源相对匮乏且季节分配不均的淮河流域修建了大量小型水坝,对河流流态影响显著,改变了河道沉积环境,催生了大量的次生季节性河流,也将影响各种重金属元素及N、P等营养元素在河流底泥中的分布。本文以位于河南省荥阳市的淮河4级支流索河为研究对象,应用实测值与环境背景值比较及冗余分析(平均粒径、分选系数、平均曲率、植被生物量、盖度等环境影响因子)等方法对河道沉积物中重金属元素、N、P及有机碳含量等在河道不同区段的分布特征进行了研究。结果发现：(1)河道中不同采样点间沉积物中各元素含量存在较大差异,且不同元素间的富集程度不同。Cd、Hg、Zn等重金属元素及N、有机碳等的含量均高于环境背景值；As、Cr、Cu、Mn等重金属含量总体上均低于环境背景值,Cd、Zn两种重金属含量显高于国家一级标准值。Cd、Hg、Zn等重金属元素及N、有机碳的含量变异系数相对较大(0.401-0.550),这些元素及有机碳在研究区河道内不同采样点间变化差异较大；而As、Cr、Cu、Pb、Mn、Ni等重金属元素及P的含量的变异系数相对较小(0.087-0.215),其分布特征受河道微生境条件异质性的影响相对较小。河道不同区段间的生境异质性影响元素在底泥中的富集效应,但不同元素的响应强度及响应模式存在一定差异。(2)河道不同区段间沉积物粒级结构存在较大差异,在库塘相,沉积物平均粒径较大的采样点主要位于凸型岸线区段,沉积物分选系数较大的采样点主要位于凹型岸线区段；沉积物平均粒径变化较大的采样点主要位于库塘段；而在河流相,沉积物平均粒径变化较小的采样点多位于植被生长状况较为良好的区段,河道段沉积物分选系数变化较小。(3)冗余分析结果显示,植物生长状况良好河段其沉积物中重金元素含量相对较小,而岸线相对曲折,有利于沉积过程的河段的底泥中的重金属元素、有机碳等的含量相对较高。沉积物平均粒径越小,沉积物分选性越好,底泥中重金属含量相对较高。
[Abstract]:A large number of small dams have been built in the Huaihe River basin, where water resources are relatively scarce and the seasonal distribution is uneven, which has changed the river flow pattern and formed a large number of secondary seasonal rivers. In semi-humid and semi-arid areas, the river water is more vulnerable to pollution, especially the heavy metal pollution, which is difficult to transform, because of the relatively small basic flow, which often accumulates in the river and causes ecological harm. Sediment is an important accumulation of heavy metals, organic carbon and other nutrients, and is also the main place for nutrient regeneration. As one of the most important social and economic development areas in China, Huaihe River Basin is also faced with serious sediment pollution. A large number of small dams have been built in the Huaihe River basin, where water resources are relatively scarce and the seasonal distribution is uneven, which has a significant impact on the flow pattern of the river, which has changed the sedimentary environment of the river and created a large number of secondary seasonal rivers. It will also affect the distribution of various heavy metals and nutrient elements such as Nu P in river sediment. In this paper, the Huaihe River, a grade 4 tributary of the Huaihe River, located in Xingyang City, Henan Province, is taken as the research object. The comparison between the measured value and the environmental background value and redundant analysis (mean particle size, sorting coefficient, mean curvature, vegetation biomass) are applied. The distribution characteristics of heavy metal elements, NBP and organic carbon in river sediment were studied by means of environmental impact factors such as coverage and so on. The results are as follows: (1) the contents of elements in sediments of different sampling sites are different, and the enrichment degree of different elements is different. The contents of heavy metals such as Cd,Hg,Zn, N and organic carbon are higher than those of environmental background. The contents of As,Cr,Cu,Mn and other heavy metals were all lower than the environmental background values, and the contents of Cd,Zn and Cd,Zn were higher than those of the first class national standard. The coefficient of variation of organic carbon content is relatively large (0.401-0.550). However, the coefficient of variation of heavy metal elements such as As,Cr,Cu,Pb,Mn,Ni and P was relatively small (0.087-0.215), and its distribution was influenced by the heterogeneity of microhabitat conditions. Habitat heterogeneity affects the enrichment effect of elements in sediment, but the response intensity and response mode of different elements are different to some extent. (2) there are great differences in sediment grain structure among different sections of river. In the reservoir and pond facies, the sampling points with larger average sediment diameter are mainly located in the convex shoreline section, and the sampling points with higher sediment sorting coefficient are mainly located in the concave shoreline section. The sampling point of the sediment with great variation of average particle size is mainly located in the reservoir section. However, in the fluvial facies, the sampling points with little change in the mean grain size of the sediment are mostly located in the section where the vegetation growth condition is better, and the variation of the sediment sorting coefficient is relatively small. (3) the results of redundancy analysis show that, The content of heavy gold elements in sediment is relatively small, while the coastline is relatively tortuous, which is favorable to heavy metal elements and organic carbon in sediment of the reach where plant growth is good. The smaller the average grain size of sediment, the better the separation of sediment, and the higher the content of heavy metals in sediment.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X143
本文编号：2415874
[Abstract]:A large number of small dams have been built in the Huaihe River basin, where water resources are relatively scarce and the seasonal distribution is uneven, which has changed the river flow pattern and formed a large number of secondary seasonal rivers. In semi-humid and semi-arid areas, the river water is more vulnerable to pollution, especially the heavy metal pollution, which is difficult to transform, because of the relatively small basic flow, which often accumulates in the river and causes ecological harm. Sediment is an important accumulation of heavy metals, organic carbon and other nutrients, and is also the main place for nutrient regeneration. As one of the most important social and economic development areas in China, Huaihe River Basin is also faced with serious sediment pollution. A large number of small dams have been built in the Huaihe River basin, where water resources are relatively scarce and the seasonal distribution is uneven, which has a significant impact on the flow pattern of the river, which has changed the sedimentary environment of the river and created a large number of secondary seasonal rivers. It will also affect the distribution of various heavy metals and nutrient elements such as Nu P in river sediment. In this paper, the Huaihe River, a grade 4 tributary of the Huaihe River, located in Xingyang City, Henan Province, is taken as the research object. The comparison between the measured value and the environmental background value and redundant analysis (mean particle size, sorting coefficient, mean curvature, vegetation biomass) are applied. The distribution characteristics of heavy metal elements, NBP and organic carbon in river sediment were studied by means of environmental impact factors such as coverage and so on. The results are as follows: (1) the contents of elements in sediments of different sampling sites are different, and the enrichment degree of different elements is different. The contents of heavy metals such as Cd,Hg,Zn, N and organic carbon are higher than those of environmental background. The contents of As,Cr,Cu,Mn and other heavy metals were all lower than the environmental background values, and the contents of Cd,Zn and Cd,Zn were higher than those of the first class national standard. The coefficient of variation of organic carbon content is relatively large (0.401-0.550). However, the coefficient of variation of heavy metal elements such as As,Cr,Cu,Pb,Mn,Ni and P was relatively small (0.087-0.215), and its distribution was influenced by the heterogeneity of microhabitat conditions. Habitat heterogeneity affects the enrichment effect of elements in sediment, but the response intensity and response mode of different elements are different to some extent. (2) there are great differences in sediment grain structure among different sections of river. In the reservoir and pond facies, the sampling points with larger average sediment diameter are mainly located in the convex shoreline section, and the sampling points with higher sediment sorting coefficient are mainly located in the concave shoreline section. The sampling point of the sediment with great variation of average particle size is mainly located in the reservoir section. However, in the fluvial facies, the sampling points with little change in the mean grain size of the sediment are mostly located in the section where the vegetation growth condition is better, and the variation of the sediment sorting coefficient is relatively small. (3) the results of redundancy analysis show that, The content of heavy gold elements in sediment is relatively small, while the coastline is relatively tortuous, which is favorable to heavy metal elements and organic carbon in sediment of the reach where plant growth is good. The smaller the average grain size of sediment, the better the separation of sediment, and the higher the content of heavy metals in sediment.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X143
【参考文献】
相关期刊论文 前1条
1 宁建凤;邹献中;杨少海;陈勇;巫金龙;孙丽丽;;广东大中型水库底泥重金属含量特征及潜在生态风险评价[J];生态学报;2009年11期
，本文编号：2415874
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