| Marine suspended matters control the behavior of trace elements and organic matters, serving as a key of the global material cycle, and a linkage in the interaction among sea, air, and sediment. The adsorption and disadsorption of trace elements and organic matters between the suspended particles and water, as well as a number of complex physical and chemical reactions, make them enrichment or dispersion that is great significant to environmental and ecological systems in the areas. Macroscopic distribution and microscopic composition of suspended matters have a direct impact on environmental and ecological systems. The ’cleaning effect’ of suspended matters on pollution substances (heavy metals and harmful organic matter, etc.) had been studied systematically in order to achieve scientific support to the environmental and ecological assessment and prediction. The major and trace elements studies in suspended matters can investigate the effect of source and sink in oceanographic processes, and a variety of geochemical behavior of them. Therefore, the study of marine suspended matters has significant scientific value.In this paper, we select a typical estuary and shelf areas-the Yangtze River estuary, the East China Sea as study areas. Supported by the National Natural Science Foundation (40976020,41030856) and the National Major Fundamental Research Program (2010CB951202), we have sampled water and sediment samples of the Yangtze Estuary and its adjacent areas in October,2010. Water samples were filtered, therefore the suspended matters and clean seawater samples had been gotten, as well as the suspended matters concentration. Measurement of major and trace elements concentration of these samples and microscopic observation on the suspended particulate matters in the DH3section have been made. In addition, the CTD data of waters were processed to obtain data of salinity, temperature, chlorophyll, turbidity and so on. Combining of these experimental results and data, the microscopic types, geochemical composition, macro-distribution characteristics and its influencing factors of suspended matters in the Yangtze estuary and its adjacent area had been studied. At the same time, combined with the analysis of electron microscopy images of suspended matters in the DH3section, authigenic mineral phases, coupled with the elemental composition of water samples, have been researched to discuss the environmental effects of the suspended matters.The main conclusions are as follows:1. Conclusions on suspended matters and chlorophyll distribution and characteristics(1) There is a good linear relationship between content of suspended matters and turbidity in the Yangtze River estuary and its adjacent areas. Salinity has little to do with this relationship.(2) High content of suspended matters appears in the areas west of123°E. The content of TSM shows a decreasing trend from inshore to offshore, from sea bottom to sea surface. The distribution is mainly affected by the water masses, Yangtze River input, upwelling and resuspension processes.(3) A relative high content of chlorophyll located at east of123°E, and low content near-shoreward. The highest chlorophyll content was at the area between123-124°E. The distribution of chlorophyll is mainly affected by the combined effects of the water masses, phytoplankton species, seasonal variations, and nutrient conditions.(4) By comparing of two periods of previous and post Three Gorges Dam, it shows that the boundaries of high content of suspended matters moves westward nearly half longitude, and chlorophyll content is lower in post Three Gorges Dam.2. Conclusions of suspended particulate matters(1) The geochemical composition conclusions1) the characters of the major elementsTwo elements Mg, Feeach of them has a good linear relationship with Al. This shows that they are terrestrial. The changing content of Mg is also affected by the concentration of TSM and chlorophyll content, salinity, etc. The types of suspended matters and content of biology can influence the concentration of Ca. Al and Fe are mainly controlled by land-based particulate matters with a perfect linear relationship between them.2) the characters of trace elementsKnown by the correlation analysis of trace elements and major elements, the trace elements are adsorbed on the land-based suspended particles. Each of the four elements Cr、V、Co、Ni has a good linear relationship with Mn, meanwhile, Mn has a good relationship with Al and Fe.In a word, the distribution and types of suspended matter have been impacted by water mass. Consequently, both major and trace elements are controlled by water mass.3. the particulate composition in DH3section(1) In this section, the average particle size of the particles along the offshore direction gradually decreases, indicating the weakening of hydrodynamic weaken carrying capacity. The big particulates have precipitated in the near-shore. The size of the vast majority of the suspended matters in all stations are less than10microns.(2) Different types of suspended matters have different distribution. The single mineral particulates have a negative relationship with the single biological particles, and the flocculated particulates have a good linear relationship with the single organic matters, mineral particles, flocs and organic matters have high content near shore, and the biological particles have high content in the middle of this section. In addition, the DH3-6has a very high content of single mineral particulates, because of the complex hydrodynamic environment and muddy sediment.In short, the distribution and composition of suspended matters of this section are mainly controlled by water masses, as well as the impact of the bonding effects between the organic particulates and flocculated particulates. |
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