Sdudy On Topographic Geochemistry Feature Of The Hebei Plain

At the end of the twentieth century, China began to carry out the multi-purposegeochemical surveys, mainly in the plains, basins, lakes, coastal lines, beaches,grasslands, wetlands, etc., carrying out soil survey, measuring the seabed and lakebedsediments. By studying geochemistry of the earth surface system, it evaluated, assessedand warned eco-geochemical on the earth surface, and promoted the research ofecological environment in China.This research was based on the project in Hebei Province to carry outmulti-purpose geochemical surveys, and the main purpose was to find out the distributionof soil characteristics and migration and transformation of the elements on Hebei plain,providing the basic data in the region for evaluation of soil and environment quality. Theresults could be used in the environment, agriculture, industrial, medical and other area.This paper was studying geochemical characteristics of the soil based on thedifferent geomorphological units of Hebei Plain. First, topographic features of the HebeiPlain was studied, and landscape data and the Hebei Plain latest research results werecollected, classifying the Hebei plain into three units: the piedmont sloping plain, centralalluvial-lacustrine flood plain and the eastern coastal plain, respectively, and these threeunits were further subdivided, including the micro-topography study. A mass of soilgeochemical data （shallow:20029; deep:5056） were extracted and analyzed by differentgeomorphological units, studying the distribution of52elements, and the migration andtransformation of unusual elements was also discussed. The following results weregained:1.Elements in the surface soil on the Hebei Plain were influenced by humanactivities and some natural factors, however, it originated from the soil maternal material.The natural geological background of the natural elements was the main factor for thedistribution of element content.2.The contents of Halogens （F,Cl,Br,I）,heavy metal elements （Cu,Pb Zn,Ni,Cd,Hg，As，Se）， CaO, MgO, P and S had large changes in Hebei Plai. The distribution of soilelement was influenced obviously by landform. Because Taihang and YanshanMountains had different components of parent rock elements Geochemistry, thedistribution of element in haihe river basin and the luanhe river basin had area differences. Distribution of a few elements in soil were influenced by human activities,Hg and Se were obvious.3.Soil element in Hebei Plain varied regularly traversing different geomorphologicalunits. The element of Si and Al in the piedmont sloping plain mainly deposited in mineralfragments,and both of them had high value distribution. The central of the Hebei Plaindeveloped flood plain and channel facies,the content of SiO₂was high and the Al₂O₃waslow. In lacustrine facies and flood depressions,the sediment was mainly clay, thecontent of Al₂O₃was high. The distribution of heavy metal elements（Ni,Cu,Pb,Zn）, F andI in both horizontal and vertical direction were influenced obviously by the changes ofAl₂O₃and the type of soil, but Se and Hg were not obvious4. The factors affected element migration were the distribution of elements, land usestrategies, soil pH, soil organic matter and clay content.