Research On Geochemical Background And Flux For Arsenic, Cadmium, Mercury And Lead In Soil Environment

With the fast development of social economy, the prominent resources and environmental problems causes the governmental and public demand of defining natural spatial materials. For the purpose of meeting such demands and cooperating with the IGCP259 and IGCP360 projects sponsored by International Union of Geological Sciences, China Geological Survey Bureau has initiated and organized a national-wide, land and resources survey, which is called "National Multi-purposes Regional Geochemical Survey". This survey uses grid sampling methods and provides subsoil and topsoil testing data with densities of 1sample per 16km2 and 1sample per 4km2 respectively, which cannot be matched by any former soil survey and providing new extension to the soil elements geochemical backgrounds. Under such background, the author carries out a systematical study on the geochemical background of As, Hg, Cd and Pb in subsoil and topsoil of Chengdu Basin and Taiyuan Basin. This study is based on the "Project of Agriculture Ecosystem Geochemical Assessment of Chengdu Economy Area, Sichuan Province"and "Project of Regional Ecosystem Geochemical Assessment for Loess Altiplano Economy Area, Shanxi Province."By virtue of "3S"and computer data processing techniques, the author adopts the traditional mathematical and geological statistic methods and uses the Regression Analysis, which is rarely used in the former soil surveys. On the basis of spatial analysis, the spatial structure characteristics of As, Hg, Cd and Pb have been analyzed and the results are incorporated into an interpolation map of such above elements. At last, with the study results of the quality of As, Hg, Cd and Pb topsail input and output, the author makes a static and dynamic analysis on the geochemical background characteristics and other effect factors of As, Hg, Cd and Pb in the topsail of Chengdu Basin and Taiyuan Basin. From the above study, the following conclusions have been drawn out: there have great differences in As, Hg, Cd and Pb contents of the topsail and subsoil between the Chengdu Basin and Taiyuan Basin. The soil in Chengdu Basin has less As contents than that in Taiyuan Basin, while the Hg, Cd and Pb contents are greater than that of Taiyuan Basin. These differences are the results of the diversity of parent materials from various soil types and the climates influences of different regions. As strongly affected by the Human production activities, Hg, Cd and Pb concentrate in the city surroundings, the properties, some part of river banks, irrigating areas, etc. The factors causing such differences are specifically as follows: Chengdu Basin: mining activities, fertilizing and waste water emission and other waste discharge from city life; Taiyuan Basin: irrigating with foul water, fertilizing and the waste discharge from industry production;...