Zhang H.,Shanghai JiaoTong University |
Zhang H.,The Chinese Academy of Science |
Zhang N.,Shanghai JiaoTong University |
Zhong L.,Shanghai JiaoTong University
Environmental Chemistry Letters | Year: 2011
Measuring Hg levels of water sediments is one of the primary routes to assess the trend of the contamination. Little work has been carried out in the Yangtze Delta to track the trend of mercury contamination caused by Shanghai, which is one of the fastest growing economies in the world today. The mercury concentration in the sedimentary cores from Dianshan Lake, Shanghai is studied here. Results show that mercury transported to Dianshan Lake from emissions of coal combustion and non-coal sources in the Yangtze Delta was greater after 1979. We found also that before 1979 mercury levels changed less with time than after 1979. Before 1967 Hg levels were more variable than in the 1970s. Moreover, the mercury dissolved in river water and bound to particles of water that flow past downtown Shanghai is different from that observed in Dianshan Lake, which is located in upper Shanghai. This indicates that atmospheric Hg deposition is probably the main source of mercury in Dianshan Lake. These results are important for the establishment of environmental protections and pollution treatment proposals for mercury in similar areas of the world, as well as in Shanghai. © 2010 Springer-Verlag.
Xu Y.,The Chinese Academy of science |
Xu Y.,University of Chinese Academy of Sciences |
Huang Z.,The Chinese Academy of science |
Zhu D.,The Chinese Academy of science |
Luo T.,The Chinese Academy of science
Ore Geology Reviews | Year: 2014
In the western Yangtze Block, southwest China, there are many hydrothermal native copper ore deposits and Zn-Pb ore deposits. All of these hydrothermal ore deposits are spatially associated with the Permian Emeishan flood basalts (EFBs), although they are much younger than the EFB. The maximum time interval between the hydrothermal ore deposits and the EFB is over 100. Ma. During this time interval, there is no documented magmatism in this region, and many studies indicate that magmatic fluids played important roles in the formations of these deposits. Thus, the origin of these hydrothermal deposits has long been controversial. In this study, we present a model that considers the underplated Emeishan basalts at the base of the crust as the main source of the ore-forming metals and fluids and present thermal simulation results of the evolution of the underplated Emeishan basalt. The results indicate that the underplated basalts begin to release metal-bearing fluid at 30. Ma after the onset of the underplating, consistent with age data of the oldest hydrothermal deposits in this region, such as the Huize Pb-Zn and native Cu ore deposits. The simulation results also indicate that the releasing ore-forming fluid from the crystallising underplated basalts can last over 100. Ma, which almost covers the entire age data available for the hydrothermal deposits, and thus successfully demonstrates the lack of temporal association between the hydrothermal deposits and the EFB. The model is developed primarily for the origin of the hydrothermal mineralisation in the SYG province, but it has general applicability to other sediment-hosted Pb-Zn deposits around the world. © 2014 Elsevier B.V.