皖江经济区基本农田地球化学特征及成因

The Character and Influencing Factors of Geochemical Distribution in Basic Farmland of Economic Zone along Yangzte River in Anhui

皖江经济区的基本农田分布区是我国国家商品粮生产基地，该区基本农田的土地地球化学特征与粮食质量安全密切相关。本文以皖江经济区的南陵一泾县国家商品粮基地为重点研究区，以野外实地调查资料和采集的0～20cm深度土壤样的化学组分检测分析数据作为研究基础，应用地学数理统计学方法和GIS空间特征分析技术，通过该农田区土壤元素组成、含量、空间分布和异常变化特征及其成因研究，发现：南陵一泾县基本农田的土壤中重金属Fe、Mn和Hg等含量存在异常，Fe、Mn变异系数呈现区域性异常，Hg含量表现为局部异常；Ca、Mg和Na元素呈现显著空间分布相关性，与成土母质影响相关。在区域分布上，南陵一泾县基本农田区土壤中重金属元素和盐分含量呈现南高、北低的趋势性分布特征，这与当地水文地质条件、地下水水位埋藏状况和矿化度之间存在一定的相关性。从南陵一泾县基本农田区土地地球化学分布特征来看，南部地区不利于高品质稻谷、小麦等粮食生产。

The basic agricultural farmland which distributed in economic zone along Yangtze river in Anhui is the principle grain producing area. The grain security is closely related to the soil geochemical characteristics in this area. Selecting the marketable grain producing farmland in Nanling-Jing county as the study area, basing on the field survey and the chemical contents data of top soil（0-20cm）, using geo-statistic methods and GIS technology, this paper analyzes the contents, spatial distribution and variation, impact factors of basic elements in farmland soil. The results show that some heavy metal elements displayed regional abnormal distribution （Fe and Mn） and localized anomaly （Hg）. Correlation analysis indicates that the elements Ca, Mg and Na significantly correlated each other and have high concentration in topsoil which shows the controlling of parent materials. Generally, the spatial distribution character of heavy metal elements and salinity presents that southern area has higher contents than northern area in Nanling-Jing county farmland. This phenomenon is related to hydrogeological condition, groundwater depth and groundwater salinity. Thus farmland located in southern area may in bad condition for high quality grain products.