底泥重金属生物有效性的控制因素研究

发布时间：2018-05-14 02:14

本文选题：太湖 + 重金属　；参考：《南京理工大学》2017年硕士论文

【摘要】：太湖流域污染问题一直是我国重点治理的环境问题,大量针对太湖流域污染问题的研究,主要集中在研究太湖流域沉积物中氮、磷的分布情况。或者研究太湖流域部分区域重金属的分布情况。本论文首先针对太湖流域进行大范围、多位点的采样研究。并对太湖流域进行潜在风险评价,有依据的总结太湖流域的污染状况。由于影响沉积物重金属生物有效性的因素有很多,研究沉积物的性质和是否含有蓝藻沉积物对重金属生物有效性的影响。实验分为三部分,三部分实验得到如下结论:太湖流域水体表层沉积物中重金属的含量分布规律为北向南降低、从东到西降低。对太湖流域重金属进行风险评价分析,太湖流域表层沉积物中重金属As、Cu、Zn、Pb、Ni、Cr、Fe、Mn污染状况不严重,重金属Hg、Cd的风险等级较高,是造成太湖流域水体表层沉积物生态风险的主要因素。不同性质的底泥沉积物对重金属生物有效性的影响表现为:重金属元素Pb、Cd在上覆水中均随着实验进行含量升高;Fe、Mn、As、Cr的含量随着时间而降低。硫化物在有机质沉积物中的含量要高于在砂质沉积物中含量。对于SEM的含量,在砂质中的含量要高于在有机质中。在不同性质沉积物中SEM-AVS的含量不同,有机质中的重金属的毒性小于砂质沉积物。不同性质的沉积物重金属的形态含量有较大的区别。总体来说,重金属的可氧化态在有机质沉积物中的含量高于在砂质沉积物。弱酸态受生物扰动的影响。可还原态的浓度除了受到沉积物种类的影响和生物扰动外,还受重金属的种类影响。生物扰动影响DGT金属通量的程度与沉积物的深度和重金属的结合情况有关。浮游植物蓝藻的存在使得重金属Cr、Mn、As、Cd的浓度要明显高于无蓝藻的沉积物。复氧期,蓝藻的数量增加。在蓝藻聚集时期,不含蓝藻的沉积物对水生生物的毒性作用高于有蓝藻存在沉积物。在死亡时期,有蓝藻存在的沉积物对水生生物的毒性作用增强。复氧期,无蓝藻存在的沉积物对水生生物的毒性低。重金属形态对生物有效性的影响很大,在有无蓝藻的沉积物中,重金属的弱酸态、可氧化态、可还原态的浓度呈现一定的规律。PEEPER测的结果可知,上覆水中的Fe的含量低于沉积物中的含量,有蓝藻存在的沉积物中Fe的含量低于没有蓝藻存在的沉积物的含量。通过DGT测定表明有蓝藻存在的沉积物在聚集期使重金属Cr的含量升高,对As、Pb、Cd、Mn、Fe等的影响不大,在死亡期,蓝藻存在对重金属Pb、Mn的浓度影响大。在蓝藻复氧期,蓝藻存在对重金属Mn、Pb的影响大。
[Abstract]:The pollution problem of Taihu Lake basin has always been an important environmental problem in China. A large number of studies on pollution problems in Taihu Lake basin are mainly focused on the distribution of nitrogen and phosphorus in sediments of Taihu Lake basin. Or study the distribution of heavy metals in some areas of Taihu Lake basin. In this paper, a large-scale, multi-site sampling study is carried out on Taihu Lake basin. The potential risk assessment of Taihu Lake basin is carried out, and the pollution situation of Taihu Lake basin is summarized. Because there are many factors that affect the bioavailability of heavy metals in sediments, the properties of sediments and the effects of cyanobacteria on the bioavailability of heavy metals are studied. The experiment is divided into three parts. The conclusions are as follows: the distribution of heavy metals in the surface sediments of Taihu Lake basin decreases from north to south and from east to west. The risk assessment of heavy metals in Taihu Lake basin showed that the pollution status of heavy metal As-CuCuZn-Zn-PbPbPbPbPbPbPbPbPbPbPbPbPbPbPbNiNiCr-FeON-Mn in the surface sediments of Taihu Lake basin was not serious, and the risk grade of heavy metal Hgn / CD was higher, which was the main factor that caused the ecological risk of surface The effects of sediment with different properties on the bioavailability of heavy metals are as follows: the content of heavy metal Pb, CD in the overlying water increases with the increase of the content of Fe, mn, as well as Cr in the overlying water, and the content of Cr decreases with time. The content of sulfides in organic matter sediments is higher than that in sandy sediments. The content of SEM in sand is higher than that in organic matter. The content of SEM-AVS in different sediments is different, and the toxicity of heavy metals in organic matter is less than that in sandy sediments. The speciation of heavy metals in sediments with different properties is different. In general, the content of oxidizable heavy metals in organic matter sediments is higher than that in sandy sediments. The weak acid state is affected by the biological disturbance. The concentration of the reducible state is affected not only by the species of sediment and biological disturbance, but also by the species of heavy metals. The extent to which DGT metal flux is affected by biological disturbance is related to the depth of sediment and the binding of heavy metals. The presence of phytoplankton cyanobacteria made the concentration of heavy metal Cr _ (mn) mn _ (C _ (2) C _ (2) was significantly higher than that of the sediments without cyanobacteria. During the reoxygenation period, the amount of cyanobacteria increased. During the period of cyanobacteria accumulation, the toxicity of cyanobacteria free sediments to aquatic organisms was higher than that of cyanobacteria sediments. At the time of death, the toxicity of sediments with cyanobacteria to aquatic organisms increased. During the reoxygenation period, the toxicity of the sediments without cyanobacteria to aquatic organisms was low. Heavy metal forms have a great influence on bioavailability. In the sediments with or without cyanobacteria, the concentrations of weak acid, oxidizable and reducible heavy metals show a certain regularity. The Fe content in the overlying water was lower than that in the sediment, and the Fe content in the sediment with cyanobacteria was lower than that in the sediment without cyanobacteria. DGT analysis showed that the presence of cyanobacteria increased the content of heavy metal Cr during the accumulation period, but had little effect on the concentration of heavy metal, such as PbPbPbCdcdMnMn-Fe, etc. At the death stage, the presence of cyanobacteria had a great effect on the concentration of heavy metal PbPb-Mn. During the period of cyanobacteria reoxygenation, the presence of cyanobacteria has a great influence on the heavy metal mn ~ (2 +) Pb.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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