辽东湾入海河口潮间带沉积物及邻近土壤氮素转化及重金属特性

发布时间：2018-03-08 17:40

本文选题：沉积物　切入点：硝化强度　出处：《大连交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：潮间带处于海陆交错地带,是连接陆地和大洋生态系统的纽带,其中氮素污染物和重金属污染物是河口潮间带地区沉积物中的主要污染物。本文以小凌河、大凌河、双台子河、辽河四条河流入河河口处沉积物、大凌河口附近的水稻田土、玉米旱地和芦苇湿地和双台子河河口附近的玉米旱地和芦苇湿地为研究对象,电位法测定土壤p H值,重量法测定土壤可溶盐含量,悬浮液培养法测定土壤的硝化强度,厌氧泥浆培养法测定土壤的反硝化强度,气体抑制法确定土壤的氮素转化过程,原子吸收光谱测定重金属。研究结果如下:不同沉积物及其邻近土壤的硝化强度和反硝化强度研究显示,四种不同河口沉积物的硝化强度和反硝化强度差异显著,硝化强度表现为小凌河双台子河辽河大凌河,反硝化强度表现为辽河双台子河小凌河大凌河。大凌河口不同利用方式的土壤中,水稻田土、玉米旱地和芦苇湿地的硝化强度均高于河流沉积物,水稻田土反硝化强度大于其他区域的反硝化强度。双台子河口不同利用方式的土壤中,玉米旱地的硝化强度最大,芦苇湿地和玉米旱地的反硝化强度要大于河流沉积物,土壤p H值和可溶盐含量与硝化和反硝化强度存在相关性,其中硝化强度与p H值呈正相关,与可溶盐含量呈负相关,反硝化强度与p H值和可溶盐含量均呈正相关性。对辽河沉积物氮素转化过程研究显示,在空气,氧气和氩气存在的情况下,会有硝化作用、反硝化作用、厌氧铵氧化作用和硝态氮异化还原成铵作用的发生,空气和好氧条件下更易于硝化作用的发生,而且沉积物的硝化作用要大于反硝化作用,同时硝化作用对底物铵氮(NH4+-N)的竞争作用要强于厌氧铵氧化作用,好氧条件和底物NH4+-N含量的增加有助于硝化强度的增强,厌氧条件更有利于反硝化作用的发生,NH4+-N和NO3--N同时存在更有利于厌氧铵氧化作用的发生。对不同沉积物及其附近土壤的重金属污染评价研究显示,Cu和Zn含量均小于国家土壤环境质量标准值(GB15618-1995)的二级标准,Cr含量除了双台子河玉米旱地外均小于国家二级标准。用单因子污染指数法评价可以得出Cu、Zn和Cr还未达到污染水平。采用内梅罗综合污染指数对研究区进行了评价,得出只有大凌河口区芦苇湿地、双子河口区玉米旱地和辽河口沉积物属于轻度污染区,其余地区属于无污染区。通过潜在生态风险指数得出单个重金属的潜在生态风险程度由大到小依次为CrCuZn,辽东湾采样地区潜在生态风险很低;地累积指数评价法得出重金属污染程度由大到小是Cr、Zn、Cu,评价辽东湾地区采样点的潜在生物毒性可以得出Cr金属的潜在生物毒性很大,而Cu和Zn潜在生物毒性很小,三种金属毒性大小依次为CrZnCu,与地累积指数评价结果相一致。
[Abstract]:The intertidal zone is located in the intertidal zone, which is the link between land and ocean ecosystem. Nitrogen pollutants and heavy metal pollutants are the main pollutants in the sediments of estuarine intertidal zone. The sediment in the estuary of four rivers of Liaohe River, paddy soil near Daling River mouth, corn dryland and Reed wetland and maize dryland and Reed wetland near Shuangtaizi River estuary were studied. The pH value of soil was measured by potentiometric method. The content of soluble salt in soil was measured by gravimetric method, nitrification intensity by suspension culture method, denitrification intensity by anaerobic mud culture method, nitrogen conversion process of soil by gas inhibition method. Determination of heavy metals by atomic absorption spectrometry. The results are as follows: the nitrification and denitrification intensity of different sediments and adjacent soils show that the nitrification intensity and denitrification intensity of four different estuarine sediments are significantly different. The nitrification intensity was shown as Daling River in Shuangtaizi River and Daling River in Shuangtaizi River in Liaohe River. The denitrification intensity of maize dryland and Reed wetland was higher than that of river sediment, and the denitrification intensity of paddy soil was higher than that of other regions. Denitrification intensity of Reed wetland and corn dry land was higher than that of river sediment. Soil pH value and soluble salt content were correlated with nitrification and denitrification intensity, and nitrification intensity was positively correlated with pH value and negatively correlated with soluble salt content. Denitrification intensity was positively correlated with pH value and soluble salt content. Studies on nitrogen conversion process in Liaohe sediment showed that nitrification and denitrification occurred in the presence of air, oxygen and argon. The anaerobic ammonium oxidation and the dissimilatory reduction of nitrate to ammonium are more likely to occur in air and aerobic conditions, and the nitrification of sediment is greater than that of denitrification. At the same time, the competitive effect of nitrification on the substrate NH _ 4-N was stronger than that on the anaerobic ammonium oxidation. The increase of aerobic conditions and substrate NH4 -N content contributed to the enhancement of nitrification intensity. Anaerobic conditions are more conducive to the occurrence of denitrification and the presence of NH _ 4-N and NO3--N at the same time. The evaluation of heavy metal pollution in different sediments and adjacent soils shows that the contents of Cu and Zn are small. The second class standard Cr content of the national soil quality standard GB15618-1995 was lower than that of the national second class standard except for the Shuangtaihe corn dry land. The results of single factor pollution index evaluation showed that Cu Zn and Cr had not reached the pollution level. The comprehensive pollution index of Nemero was used to evaluate the study area. It is concluded that only Reed wetland in Daling River estuary, corn dryland and sediment in Liaohe estuary in Shuangzi River estuary belong to light polluted area. The potential ecological risk degree of single heavy metal is CrCuZn. the potential ecological risk of sampling area in Liaodong Bay is very low by the index of potential ecological risk. The results showed that the degree of heavy metal pollution was from large to small, and the potential biotoxicity of Cr and Zn was very high, but the potential toxicity of Cu and Zn was very small, when evaluating the potential biotoxicity of sampling sites in Liaodong Bay, the results showed that the potential biotoxicity of Cr was very high, and that of Cu and Zn was very small. The toxicity of the three metals is followed by CrZnCu, which is consistent with the results of the geoaccumulation index evaluation.
【学位授予单位】：大连交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X55

【参考文献】