Distribution Characteristics And Controlling Factors Of Heavy Metals In The Yangtze River Estuary,the Yellow River Estuary And Adjacent Sea

In this master’s thesis, the Yangtze River Estuary and the Yellow River Estuarywere main objects of study. Water and sediments samples from both of the estuarieswere collected in five surveys from2010to2011. Meanwile, various kinds of indexof hydraulic were mearsured. Some heavy metals, like Cu, Pb, Cr, Cd, Zn, As, Hg,were analysed, to research the distribution characteristics and controlling factors ofheavy metals in the Yangtze River Estuary, the Yellow River Estuary and AdjacentSea. The results also could contribute to research the behaviour of heavy metalsduring the estuarine mixing and assess the ecological risk of surface sediment. Theresearch finding can provide theoretical basis to explain the biogeochemicalbehaviour of heavy metals in estuaries, and reference to protect aquatic environmentin the estuary and nearshore. The main conclusions are as follows:⑴In the Yangtze River Estuary, the behaviour of soluble Zn, Hg was addition,and Cu, Cd showed addition behaviour in the area, whose salinity respectively was0-15,10-20. The behaviour of soluble As was removal in June in the area, whosesalinity was from10to25, nevertheless, it showed addition behaviour in June.⑵The average concentrations of Cu, Pb, Cr, Cd, Zn, As, Hg in surface water ofthe Yellow River Estuary were12.47,2.30,9.89,0.23,15.72,2.84,0.098μg/L inMay2011, while the average concentrations of Cu, Pb, Cr, Cd, Zn, As, Hg were11.62,2.17,2.09,0.24,6.95,2.51,0.047μg/L in August2011. Concentrations ofheavy metals in May were higher than in August. Compared with Cu, Pb, Cd, As, thechanges were significant for Cr, Zn, Hg.⑶The concentrations of particulate heavy metals in the Yangtze River Estuaryin June2011were higher than those in August. Salinity could not siginificantlyaffect the concentrations of particulate heavy metals in June, while the concentrations of particulate heavy metals show “SPM effect” with the change ofSPM. Salinity had remarkable negative correlation with particulate Cu, Pb, Zn inAufust2011. As for the Yellow River Estuary, the concentrations of particulateheavy metals were higher in May2011than those in August2011. The controllingfactors of particulate heavy metals were salinity and SPM in the Yellow RiverEstuary.⑷The particulate heavy metals showed notable correlation with each other inthe Yangtze River Estuary and adjacent sea, while, which mean that the source ofparticulate heavy metals had large differences in different seasons in the YangtzeRiver Estuary and adjacent sea. Particulate Cu, Pb, Cr, Cd, Zn showed siginificantcorrelation in the Yellow River Estuary in May and August,2011. These phenomenaindicated the same source and behaviour of particulate heavy metals.⑸Generally, the solid-liquid distribution coefficient was stable, and salinity andSPM were not the main factors that effect Kd.⑹The relative concentrations of heavy metals were stable in the Yangtze RiverEstuary and adjacent sea in August2011. The gain size could influence theconcentrations of heavy metals, that is, the finer of the sediment-size, the higher ofthe concentration of heavy metals.⑺Using the potential ecological risk index to assess aquatic environment of theYangtze Estuary and adjacent sea, the Yellow River Estuary, the results showed thatmost of areas were free from contamination, except some special stations, just likethe pollution of Cr, Hg in the Yangtze River Estuary and the pollution of As in theYellow River Estuary.⑻The range of concentration of soluble Cu, Pb, Cr, Cd, Zn was ND-7.15,ND-2.50, ND-1.07, ND-0.16, ND-9.64μg/L. The result showed a significantlypositive correlation between the flux of sediment concentration and water dischargein the downstream of the Yellow River in2010. The Yellow River input about46.90tons of soluble Cu,8.68tons of soluble Pb,7.56tons of soluble Cr,1.60tons ofsoluble Cd,41.74tons of soluble Zn to the Yellow River Estuary in2010. Themonthly flux of the soluble heavy metals showed the same trend with water discharge without considering the concentration of the soluble heavy metals whichwere under detection limite in some months.