长江中下游颗粒态金属元素时空分布特征探究

发布时间：2018-05-13 02:28

本文选题：长江中下游 + 徐六泾　；参考：《华东师范大学》2017年硕士论文

【摘要】：通过对长江流域中下游大面站与河口观测相结合,对悬浮颗粒物中元素含量、元素赋存形态的时空分布规律进行分析,探讨流域大规模泥沙拦截以及人类活动重金属污染输入不断增加的大背景下,中下游干流物质来源的调整及季节调配的改变,取得了以下初步认识:长江中下游干、支流悬浮颗粒物中元素组成差异明显。相对于长江干流,清江颗粒态Al、Fe、Cr、Ni、Cu、Zn、Pb、Cd元素含量远低于干流,差异在30%以上,Mn元素含量远高于干流,约为干流的7倍。汉江Al、Fe、Mn、Cr、Ni、Cu、Zn、Cd、Pb等元素含量远低于干流,差异在50%以上。相对于清江、汉江,洞庭湖因其分泄长江水沙,其颗粒物组成与干流差异相对较小,Al、Fe、Mn、Cr、Ni、Zn元素与干流差异在10%以内,Cu、Cd、Pb元素与干流差异相对较大,在20%以上。尽管洪季悬浮颗粒物浓度沿程不断降低,但其悬浮颗粒物中金属元素含量自宜昌向下游组成非常稳定,Al、Fe、Mn、Cr、Ni、Zn、Cd、Pb.元素含量的变异系数均在 10%以内,平均值分别为 8.3%、5.2%、0.12%、108μg/g、56μg/g、191μg/g、1.06μg/g、79μg/g。与流域大规模人类活动影响之前的文献数据相比,元素组成并没有发生显著改变,基本仍代表典型的流域自然风化输入。洪季在上游大量颗粒物输入的作用下,中游河床侵蚀及支流输入对干流的贡献有限,此外,人类活动重金属污染输入的影响也并不显著。枯季颗粒物元素组成及其沿中下游干流浓度变化明显,Al、Mn、Cu、Zn、Cd、Pb等元素的变异系数较大均在20%以上,其中Mn、Cd、Pb等元素变异系数达30%以上,同时平均值远大于80年代的数据,这表明枯季流域的物源组成发生了重大调整,支流贡献与中游河床侵蚀粗化对元素组成的影响显著增加。汉江的汇入使得黄石站Cu、Zn、Cd、Pb元素相对于洪湖站有30%以上幅度的降低,鄱阳湖的汇入使得彭泽站Cu、Zn、Cd、Pb元素含量有20%以上幅度的降低。洪、枯季稀土元素的沿程分布的稳定程度也体现了其物源上的差异。洪季各稀土元素变异系数较小,多在10%以内,沿程分布极为稳定,而枯季稀土元素变异系数较大,多在30%以上。这是由洪、枯季颗粒物来源不同所致。从配分模式来看,长江颗粒物来源于大陆上地壳风化输入,其相对于球粒陨石发生一定程度的分异。经北美页岩标准化后,洪、枯季各稀土元素的相对值在1左右,颗粒物稀土组成与北美页岩相似度较高。Zn、Pb、Cd元素在枯季干流悬浮颗粒物中的含量显著高于洪季,且经A1归一化后在中游洪湖、黄石站仍高于洪季组成,表明这些元素受人类活动污染输入的影响较为显著。通过干流的洪、枯季对比发现,人类活动污染输入影响主要出现在洪湖、黄石站。自鄱阳湖向下游,由于鄱阳湖采砂扰动带来低重金属污染的老沉积物输入的稀释作用,彭泽站Cu、Zn、Pb、Cd元素含量显著下降,这种变化在元素可提取态含量中极为显著,Cu、Zn、Cd、Pb元素的可提取态含量分别有15%、60%、68%、41%幅度的降低,这对Zn、Cd元素E1态、Cu、Zn、Cd、Pb元素E2态、Cu、Zn元素E3态有一定的稀释作用。徐六泾定点站金属元素含量和赋存形态与流域有着相似的季节变化规律,但这种季节差异不如流域更为显著。枯季(10月-次年4月)Cu、Zn、Cd、Pb等大部分金属元素含量的平均值略高于洪季(5-9月),枯季Cr、Ni、Zn、Cd、Pb元素的可提取态含量不同程度的高于洪季,表明人类活动输入对金属元素含量的影响在枯季更明显,但经过中游河床侵蚀、支流汇入的稀释作用,这种洪、枯季差异有所减小。
[Abstract]:Through the combination of the large surface station and the estuarine observation in the middle and lower reaches of the Yangtze River Basin, the temporal and spatial distribution of elements and elements in the suspended particles is analyzed. The adjustment of the source of the main stream in the middle and lower reaches and the seasonal adjustment are discussed under the background of the large-scale sediment interception and the increasing input of heavy metal pollution in human activities. In the middle and lower reaches of the Yangtze River, the difference of element composition in the suspended particles in the middle and lower reaches of the Yangtze River is obvious. Relative to the main stream of the Yangtze River, the content of Al, Fe, Cr, Ni, Cu, Zn, Pb, Cd is far below the main stream, and the difference is more than 30%, the content of the Mn element is far higher than that of the main stream, which is about 7 times that of the main stream. The content of the equal elements is much lower than that of the main flow, and the difference is more than 50%. Compared with Qingjiang, the Qingjiang, the Han River, the difference in the particle composition and the main flow of the Yangtze River is relatively small because it divides the water and sediment of the Yangtze River. The difference of Al, Fe, Mn, Cr, Ni, Zn elements is within 10%, Cu, Cd, and the difference of Pb elements and the main flow is more than 20%. Although the concentration of suspended particles in the flood season along the range However, the content of metal elements in the suspended particulate matter is very stable from Yichang to the lower reaches. The variation coefficients of Al, Fe, Mn, Cr, Ni, Zn, Cd, Pb. elements are all within 10%, the average value is 8.3%, 5.2%, 0.12%, 108 micron, 56 mu, 191, g/g, 1.06 mu g/g, and 79 micron before the large-scale human activities in the basin. There is no significant change in the element composition, and it still represents a typical natural weathering input in the basin. In the flood season, the contribution of the river bed erosion and the tributary input to the main stream is limited under the action of a large number of particles in the upper reaches of the upper reaches. In addition, the influence of the input of heavy metal pollution in human activities is not significant. The variation of the concentration of the main stream along the middle and lower reaches is obvious. The variation coefficients of the elements such as Al, Mn, Cu, Zn, Cd, Pb are all larger than 20%, of which the coefficient of variation of elements such as Mn, Cd and Pb is above 30%, and the average value is far greater than that of the 80s data. This indicates that the source composition of the dry season basin has been greatly adjusted, the tributary contribution and the erosion of the middle reaches of the river bed have been coarsened to the element group. The remittance of the Han River makes the Cu, Zn, Cd, Pb elements of the HuangShi Railway Station lower than 30% of the Honghu station, and the remittance of Poyang Lake makes the content of Cu, Zn, Cd, Pb elements in the Pengze station lower than 20%. The stability of the distribution of rare earth elements along the flood season also reflects the difference in its source. The coefficient of variation of rare earth elements is smaller, more than 10%, and the distribution of rare earth elements is very stable, while the variation coefficient of rare earth elements in the dry season is larger than 30%. This is the result of the different sources of the grain in the flood season and the dry season. After the standardization of the North American shale, the relative value of the rare earth elements in the flood season and the dry season is about 1, the composition of the rare-earth particles and the North American shale is high.Zn, Pb and Cd in the dry season suspended particles in the dry season are significantly higher than those in the flood season, and in the middle reaches of Honghu after A1 normalization, the HuangShi Railway Station is still higher than the flood season, indicating that these elements are affected by people. In the dry season, the influence of human activity pollution input mainly appeared in Honghu, HuangShi Railway Station. From Poyang Lake to the lower reaches, the content of Cu, Zn, Pb, Cd elements in Pengze station decreased significantly from the dilution effect of the old sediment input to the low heavy metal pollution caused by the sand mining disturbance in Poyang Lake. The extractable state content of Cu, Zn, Cd, Pb is 15%, 60%, 68%, 41%, respectively. It has a certain dilution effect on Zn, Cd element E1 state, Cu, Zn, Cd, Pb element E2 state and Pb element. The metallic element content and occurrence form of the Xuzhou six jingpoint station are similar to the watershed. The seasonal variation is not as significant as that of the watershed. The average value of most metal elements such as Cu, Zn, Cd and Pb in the dry season (October - April) is slightly higher than that of the flood season (5-9 months), and the extractable state of Cr, Ni, Zn, Cd, and Pb in the dry season is high Yu Hongji, indicating the influence of human activity input on the content of metal elements in the dry season. The season is more obvious, but after the middle reaches of the river bed erosion, the dilution effect of the tributaries converge, this flood and dry season difference has decreased.

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X522;P342

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