Determination And Distribution Of Trace Mercury In The Global Core Samples In Qaidam Basin

Qarhan Salt Lake located in the central Qaidam Basin is the largest salt lake in China, and it has various mineral in salt lake. The vertical distribution of mercury records the earth's geological information in Qaidam Basin. It would not only demonstrate traces back on the region's history for mercury migration, but also reflect the geological processing and fluctuation in the palaeoclimate information. The results could reveal the effect of the earth recycling, ecological and the environmental evaluation. Under the joint financial supports from the National Natural Science Foundation of China (Grants 20836009 and 40773045), the vertical distributions of mercury in Qarhan Salt Lake was carried out.The researching contents include:①Establish a sensitive mercury analysis method for high saline brines and core samples from the salt lake;②The core example includes (expressed as THg), total iron(expressed as TFe), total manganese(expressed as TMn), were extracted determined and then were analyzed. It reveal the vertical distribution of the THg, TFe and TMn.③The Hg-H2O,Hg-oxal,Hg-H2O2 and Hg-pyrite in core samples from the salt lake, were extrated determined and then were analyzed and it reveals the various forms of mercury in the core samples in the vertical distribution and the migation regular pattern.Solutions in this study can be summerized as following:①The hydride generation-atomic fluorescence spectrometry (HG-AFS) for mercury analysis established by our group is suits for mercury analysis in the high salinity sample.②There are different lithology examples of contents in the salt lake as follows: clay > silt > salt containing mealy sand > arenaceous salt with silt particles > pure salt particles. The results showed that salt minerals does not have significant influence for mercury distribution.③In the Qarhan global core samples, the content of mercury in the section of 0.00～ -10.04m is high, -10.04～-40.27 m is inhomogeneous, -40.27～-49.65 m is low, and -49.65～-82.64 m shows quickly increase, but -82.64～-103.15 m is in reduce trend.④The geochemical statistical correlations (r) among THg, TFe and TMn in the vertical distribution global core samples with depth 0.00 ~ -47.07 m in the character of salt mineral deposit type in Qaidam Basin are 0.41 and 0.36, respectively. Those results demonstrate that the effect of TFe and TMn in core samples for THg vertical distribution plays is obverious. However, the geochemical statistical correlations (r) among THg, TFe and TMn in the vertical distribution global core samples with depth -47.07 ~ -103.15 m in the character of clay mineral deposit type in Qaidam Basin are 0.41 and 0.36, respectively, and it demonstrates that the effect of iorn and manganese oxidates existed in clay for the vertical distribution of mercury is minor. For vertical distribution of mercury, generally, the effect of iorn oxidates existed core samples between 0.00 and -103.15 m is higher that that of manganese oxidates.⑤The concentrations of different mercury species in the core of the salt lake is in the order of Hg(oxal) > Hg (pyrite) > Hg(H2O) > Hg(H2O2). it explains that the two main mercury speciations are Hg(oxal) and Hg (pyrite),and the concentrations of dissolved mercery and organic mercury existed in core samples are in minor levels.