Geochemical Characters Of Heavy Metals And Its Environment Record Of Jiaozhou Bay

With development of the social economy, environment pollution caused by human activities has become one of the most important research topics. The gulf is the linkage for interaction between land and ocean. A large number of pollutants are driven into the sea through different ways, so this area is always considered as the "sink", the different environment information can be documented in the marine sediment. Therefore, the study of gulf sediment, especially the study of the heavy metals, it can help us realize ecological damage and environment pollution caused by human activities and has important theory value and practical significance.In this article, the concentration of heavy metals in the surface sediment and two sediment core QDS137, QDS176were systematically analyzed in combination with210Pb data. Through these analysis we discussed the heavy metal element characteristic and the, record of the environmental evolution information of Jiaozhou bay. Results show that:Sediment types in Jiaozhou Bay include sand, silty sand、clayey sand、sandy silt and clayey silt, silty clay and sand—silt—clay. Generally, the sediment type in western region of the Jiaozhou Bay is complex, from clay to coarse sand. The sediment type fine—coarse—fine has a banding distribution along the bank to sea direction from Dagu river and by Yanghe river. Silty clay and clayey silt is prevalent in eastern deposits and the sediment appearing from fine to coarse from coast to sea.According to the result of heavy metals content of surface sediment from2surveys in Jiaozhou bay, the content of Cu、Pb and Zn in2002s survey is higher than that of1980s survey, but the value of Cd and Hg is opposite. We evaluated environmental quality of Jiaozhou bay and the result shows that:The whole environmental quality of heavy metal in Jiaozhou bay is good, but in the eastern coast area of Jiaozhou bay, the value of heavy metals is higher than the other areas. The potential ecological harm order of heavy metals in surface sediment is:Hg> As> Cd>Cu>Pb>Cr>Zn.According to the degree of heavy metal pollution, the areas of Jiaozhou Bay can be divided into three pollution level areas:there were light polluted or non-pollution in the western Jiaozhou Bay and the shallow of the central Jiaozhou Bay at the east of study area, we define this area is I; the southern areas of Jiaozhou Bay were light polluted, The pollution of Hg and Cd is medium pollute in several stations, we define this area is Ⅱ. While the eastern river mouths and central areas of Jiazhou Bay were medium polluted, the pollution caused mainly by natural processes, and the recharge of pollutants by human activities along the coast was another reason.The sediment in the core QDS137and QDS176is mainly of silt and clay, the sand is lowest. The two Cores are analized by radioisotope data, the core QDS137deposition rate is0.25cm/a, while the deposition rate of QDS176is0.3cm/a (from0-30cm) and0.55cm/a (30cm-265cm).Heavy metals in two cores were measured. The values of Cd、Cr、Cu and Hg in core QDS137are showing a slightly lower after rising trend in vertical, the value of Pb and Zn shows larger in vertical. The trend of As shows lower; However, the value of Cd and Hg in core QDS176outside of Jiaozhou Bay show rising trend, Cr、Cu and As have the lower trend, while Pb and Zn have fluctuated quite a bit in vertical, K content in the core QDS176did not change significantly. The method Igeo is used to evaluate the heavy metals in the cores and result shows that:Hg makes the intense pollution, Cd、Cu、Zn and As make the mild contamination, the pollution of other heavy metal element is no obvious.We calculate the AF of heavy metals and determine the Cd、Cr、Pb and Zn can be considered to be the proxy indexes in reconstruct the evolutionary history of human activities inside Jiaozhou Bay, outside Jiaozhou Bay Cd and Hg can be considered the proxy indexes. The vertical value of heavy metals in two cores can record the evolutionary history of human activities:In the1920s human activities and industry is just emerging, this period, China broke the feudal society which bounded the development of productive forces, the western advanced science and technology was introduced to china, the productivity is obviously improved, especially since1950s, large scale socialist construction was started. So we can see clearly the values of Cd、Cr、Pb. Zn in core QDS137and Cd、Hg in core QDS176show the rising trends. In80s and90s in the20th century, environmental protection is rapidly strengthened in our country, so we can see clearly the values of Cd. Cr、Pb、Zn in core QDS137and Cd、Hg in core QDS176show the decreasing trends...