江苏富硒土壤元素地球化学特征及主要来源

有关生态地球化学调查工程的成果应用已经受到高度关注。本文以江苏区域生态地球化学调查工程所获取的土壤、岩石等元素含量数据为基础，探讨了富硒土壤的分布特点、元素地球化学特征、物质来源与成因类型。研究结果显示：（1）全省富硒土壤的Se含量一般介于0.3~15 mg/kg，同时伴有S、TOC、Zn、Sb、Cd、Pb、As、Cr、Ni、Fe等相对富集；（2）富硒土壤可分为原岩风化残积型、煤矸石风化迁移型、湖相沉积型、粉煤灰型、污染叠加型、多金属矿化伴生型等6个成因类型，以产于苏南酸性土壤环境的原岩风化残积型富硒土壤利用价值最高，该类富硒土壤也是天然富硒农产品的主要产地；（3）富硒土壤物质来源具有多源复合性，表现为先天性物质来源（自然）、后天性物质来源（人为）及复合性物质来源（自然与人为叠加）等3种形式；（4）在先天性物质来源所形成的富硒土壤中，Se与S、TOC等呈显著正相关性，且Cd、Zn、Pb、As等未超标，富硒土壤厚度不受耕作层限制、深度可超过2 m。

Element geochemistry of selenium-enriched soil and its main sources in Jiangsu Province

The problem of how to use geological results or data, especially from the eco-geochemical survey engineering, has been an issue attracting extensive attention since the 21^th Century. By studying the regional eco-geochemical survey and some petrogeochemical survey data of Se distribution in soil, the authors investigated and summarized relevant selenium-rich soil space distribution characteristics in Jiangsu Province, element geochemistry, material sources and genetic types, and some other problems. The main research results are as follows:1) The proportion of selenium-enriched soil is less than 3% in Jiangsu Province, and Se concentration in the selenium-enriched soil is generally 0.3-15.0 mg/kg. In addition,, there are restively higher element values of S, TOC (total organic carbon), Zn, Sb, Cd, Pb, As, Cr, Ni, Fe, etc., in the soil; 2) the above selenium-enriched soil can be divided into 6 genetic types,i.e., the original rock weathering residual type, coal gangue weathering migration type, local lacustrine sediments Se-rich type, coal flyash type, superposition type of some heavy metals pollution, and polymetallic mineralization associated type. Meanwhile, the utilization values of the original rock weathering residual type selenium-rich soil are the highest and it is mainly from acid soil environment in southern Jiangsu Province, and this type Se-rich soil is the main production area of Jiangsu''s natural selenium-rich agricultural products; 3) the material sources present multi-origin compound attributes in the Se-rich soil, and they are manifested as three main material forms in the Se-rich soil, namely the congenital materials sources of natural origin, acquired materials sources of man-made origin, and compound materials sources of natural and man-made common origin; 4) there exist significant positive correlation between Se and S, TOC, etc., in the Se-rich soil formed by congenital materials sources of natural origin, and the values of some heavy metals such as Cd, Zn, Pb and As rarely exceed the standards of national farmland security utilization in this kind of Se-rich soil. Moreover, the category or thickness of this kind of Se-rich soil are not restricted by the cultivated layer, and the most thick soil of Se-rich areas can exceed 2 meters in depth.