Contributions Of Different Size Particles To The Heavy Metals Transport In The Changjiang Estuary And Yellow River

Biogeochemical processes of heavy metals in high turbidity estuaries areinfluenced by the rivers, oceans, and environmental. The river inputs dominate heavymetals in estuaries and continental shelf Heavy metal usually existes in the waterwith the forms of dissolved and particulate. Heavy metals mainly are adsorbed onparticulate matters, while the particle heavy metal is the main input form by rivers.The forms, contents and distributions of heavy metals are controlled by properties ofparticles, including the characteristics of the surface structure of the particles, surfacearea, particle size and surfactant adsorption potential. Particle size, which is one ofmost important factors, affects the delivery of particulate heavy metals. To betterreveal the biogeochemical behaviour of heavy metal in the rivers, the migration andtransformation of heavy metals in different size particle is studied.In this study, the suspended particle matter(SPM) was collected in the YangtzeRiver Estuary in June and August,2011,Lijin Station of the Yellow River monthlyfrom January2009to December2011and during the period of Water and SedimentRegulation(WSR). The SPM was classified using water grading device, and contentsof particle heavy metals, SSA, TOC after grading were determined.(1)During the SPM transport from land to sea, the finer particles, the moresignificant impart of heavy metal content and distribution by salinity changes inChangjiang Estuary. Geochemical behavior are apparently different in dry and wetseasons. The removal behavior of Zn, Cu, Pb in different size particle occurs at lowsalinities(<10), and at high salinities. Their concentrations increase first and thendecrease in June,2011; The distributions of Zn, Cu and Pb are roughly the same as thedry season from river to sea in August,2011. In the dry season or wet period, theconcentration of Cd with increasing salinity gradually decreased, and Cr and Fe, Mn have a higher value in the turbidity maximum.(2)The contents of heavy metals in different size particles in the Yangtze Estuaryare shown as follows: Fe> Mn> Zn> Cr> Cu> Pb> Cd. The heavy metals are mucheasier coexisted with the finer particles (size <32μm). The smaller the particle size is,the higher concentrations of Zn, Cu, Pb and Cr exist in June,2011.(3)Fe/Mn oxides and TOC in the suspended particulate matter are the majorfactors which affect the heavy metal content significantly in Changjing River. Fe/Mnoxides are mainly enriched in the fine particls, while they have not significantrelationship with Pb,Cd in August,2011. The influence of TOC changes with theseasons. The correlation between TOC and heavy metals in the dry season is moresignificant than it in the wet period.(4)The content of heavy metals are higher in2010than that in2009in the YellowRiver, transportation fluxes of heavy metal are shown as follows: Fe> Mn> Zn> Cr>Cu> Pb> Cd, both in2009and2010. The transport flux of Zn, Cu, Cr, Fe, Mn in2010is about three times than that of2009, while Pb is about four times than that of2009. The transport fluxes of heavy metals in the wet period are greater than those inthe dry season.(5)Heavy metals are mainly enriched in the fine particles (particle size <32μm).The contents of heavy metals were increased while the particle size decreases. Thereis remarkable relation between heavy metals and the particle size.(6)The content of heavy metal is mainly enriched in the fine particles (<32μm)during the period of water and sediment regulation in Yellow River, and the contentsare shown as follows: Fe> Mn> Zn> Cr> Cu> Pb> Cd. Particle size and specificsurface area have a greater impact on the content and distribution of heavy metal. Thecontent of heavy metals almost increased along with the particle size decreases. Thecontent of heavy metals in the fine particulate matter in the early water and sedimentregulation period is higher than that in the late.