A Primary Study On The Geological Environment And Contamination Condition Of The Eastern Jiaozhou Bay And The Nearshore Zone Of Qingdao

Based on the investigations of acoustic sounding and acoustic sub-bottom profile,and grain size , contents of heavy metal (Cd,Cr,Zn,Hg,Pb,Cu and As) and organic carbon in 274 suface sediment samples, The sedimentary environment and characteristics, and pollution conditions in the eastern Jiaozhou Bay and nearshore zone of Qingdao (12015 - 12030E , 3600 -3610N) were studied. The relationship between pollution and sedimentary process was primarily discussied.According to the grain size analyses data, the sediments in the study area can be divided into four types, conlomeratic sand, silty sand, sandy silt and clayey silt. Their distributions of the sediment are control led by hydrological dynamics in the studied area.The tidal current plays a dominant role in the sedimentary processes and formed the submarine morphologic pattern of the eastern Jiaozhou Bay and the near offshore zone of Qingdao. However the wave is considered to be effective confined within the offshore area. Since that, there exists heavily-erosivesea-bed area over the depth of 20m and no sediment observed, corrosion-sedimentation-balanced area from the depth of 20 to 10m, minor siltation area from the depth of 10 to 5m,siltation area from 5 to 2m and strong siltation area in the depth less than 2m.As compared with the national standards and the heavy metal concentration of the coastal rock show that the concentrations of Cu and Cd in sea water of Jiaozhou Bay meet the first-class standard, while the Hg and Pb failed, of which the Pb was a most serious contamination element. As for the heavy metal concentration of the sediment, such as Cd,Cr,Zn,Hg and Pb, has violated the national first-class sediment standard, and the area located within 3km off the coast dagang to licun estuary, is a main pollution region. The environment conditions are desirable for the heavy metal concentration in the middle part of Jiaozhou Bay and nearshore of Qingdao, due to the lower concentrations compared with the national standards. The pollution sources of the heavy metals are derived from terrigenous materials, which were inputed into the sea by rivers.The study of the relationship between the pollution and sedimentation process show, that concentration distribution of heavy metals are dominated by the sedimentary process in the Jiaozhou Bay andnearshore of Qingdao, and given the apparent relationship between sedimentation and hydrological dynamics. In the nearshore region where higher-energy wave action is strong, pollutants are more easily transported and dispersed, and formed better environmental conditions. On the contrary, a weak hydrodynamics in the eastern Jiaozhou Bay where was control led by tide, the terrigenous pollutants were deposited and resulted contamination in the shallow water areas.