Characteristics Of Water Quality And Heavy Metals In Guangdong Section Of The Pearl River Basin

River is the major source for production and human living. River is also the main tiebetween mainland and ocean, plenty of matters migrate to delta area along with river water,and flow into the sea eventually. The Pearl River is the largest river in south China, supplyingfresh water for the Pearl River Delta. In recent years, water quality deterioration, especiallyfor heavy metals pollution, leads to varying degrees of lack of water in Zhuhai, Macau andother cities, which has attracted wide-ranging attention in China.Water samples at13sampling sites were collected quarterly during the peoriod of June,2009to June,2010along the Pearl River Basin. The content of13key ions,7heavy metalsand suspended particulate matters was determined; the key ions in rivers were then categories;the origin, the relation between geology, the content of heavy metals and the types of waterquality were investigated; the time-space distribution of heavy metals was studied, Principalcomponent analysis was applied to studied the origin and interactions of heavy metals, thefluxes of the upstream and downstream of the Pearl River was estimated; a comparison studywas also conducted to investigate the contribution of key ions and heavy metals in Pearl Riverbasin to the world ocean. The results are as follow:The River water quality can be classified into Ca-HCO₃, Ca-Na-HCO₃, Ca-HCO₃-SO₄,Na-Cl and Ca-Na-HCO₃-SO₄, among which Ca-HCO₃water was the dominant one. Waterquality type was mainly affected by the interaction between water and minerals in geologicalrocks. The amounts of dissolved substances and heavy metals in Na-Cl water affected by seatide, were higher than those in other types of water, while SO₄and Na water were related topyrite mine, human activities as well as the length of river path.The average concentrations of dissolved and parculate Cr、Ni、Cu、Mn、Zn、Cd、Pbwere1.695,1.892,1.092,1.061,3.611,0.042,0.077and2.178,1.398,2.761,41.779,8.742,0.061,3.915μg/L, respectively. The concentrations of dissolved Cr, Ni, Cu, Mn at mostsampling sites were greater in dry season than those in rainy season, while the concentrationsof dissolved Cd, Pb, Zn and all the above metals in particulate phase in June were greater thanother months; the vertical changes of heavy metals concentrations in Beijing River andXijiang River were smaller than that in Liuxihe River and Suijiang River, surface erosion wasthe main source of particulate heavy metals in Pearl River Basin. The concentration of heavymetal in upstream and downstream was controlled by mine waste water and agriculturalactivities, industrial activity and sea tide, respectively. While geology affect theconcentrations of heavy metals in both upstream and downstream. Particulate heavy metals are of great correlation, dissovled heavy metals were followed the opposite way. Dissolved Zn,Cd, Pb and particulate elements showed positive correlation, which explain why it isconsistent with seasonal distribution.The annual flux of key ions in upstream and dowmstream of the Pearl River were18304×103and37908×103tons/year, respectively. The outputs of suspended particulate matter inthat two sections were1990×103,13292×103tons/year. The key ions in the downstream ofthe Pearl River outputs accounted for0.56%to2.12%of the world’s rivers outputs and thecontribution of suspended particulate matter is less than0.9%. The annual fluxes of Cr, Ni, Cu,Mn, Zn, Cd and Pb in upstream and downstream were445,256,241,3293,1279,12,317tons/year and1823,1144,1786,15634,6183,74,2017tons/year, respectively. Thecontribution of dissolved Pb, Cr and Zn in the upstream were46%,42%and38%,respectively. In addition to some elements, heavy metals in the downstream of the Pearl Riveroutputs were less than1%of the world’s rivers outputs.