Geochemical baseline values of elements in soil of Jiangsu Province

Abstract：Geochemical baseline values of elements mean their normal concentrations within the natural environmental soils and belong to a kind of inherent chemical compositions and structural characteristics related to primitive matter. The whole 1∶250 000 multi-target regional geochemistry survey of Quaternary sediments had been accomplished in Jiangsu Province by 2007, and a lot of geochemical data of soil samples were obtained. In this paper, data of 6 127 natural environmental soil samples containing total contents of 52 elements and total organic carbon (TOC) from Jiangsu were studied by statistical calculation, and the new geochemical baseline values about element contents in soil of Jiangsu are equivalent to the mean concentration ±1.5 or 2 Std. Deviation of every element from the above stated 6 127 samples by eliminating abnormal data is reported. The 6 127 samples cover about 102 600 km2 of the whole land of Jiangsu, and a soil sample per 16km2 was measured at the chemical laboratory, with every measured sample consisting of 4 samples collected from a unit of 4 km2 like a chessboard lattice, and all sampling depths being 150～200 cm or so. Some conclusions have been reached：First, most element contents are not in normal distribution, and the mean content from these elements does not change obviously after eliminating abnormal data. Second, anthropogenic input has apparently increased a part of contents of Cd, Hg, Se and N , etc. in topsoil above the depth of 20 cm, and it is necessary to exclude disturbance of anthropogenic activity to establish geochemical baseline value of soils. Third, parent matter, genetic classification of soils and topographic units are main factors affecting element content distribution within soil of Jiangsu, and the difference of normal concentrations of some elements are very obvious in soil of different areas. The information obtained by the authors will provide new clues and bases for assessing eco-environmental quality and establishing local standard of soil environment.