珠江三角洲典型区农业土壤镍的空间结构及分布特征

 通过对东莞市118处农业表层土壤和5处典型土壤纵剖面的取样调查，利用常规统计学和地统计学方法研究了土壤中镍的空间结构和分布特征。结果显示，东莞市农业土壤镍含量为2.29~58.00 mg·kg^-1，平均值为21.22 mg·kg^-1，远高于广东省土壤背景值；镍的空间结构表现为明显的几何各向异性，各向异性比约为1.7，长、短轴分别在118°和28°方向；指数模型对于实验变异函数的拟合效果较好，变异函数表现出明显的块金效应，块金值在基台值中所占的比例约为40%，表明东莞市农业土壤中镍具有较强的空间相关性；镍的空间分布具有明显西部高、东部低的地域特征，其空间分布主要受成土母质和地形的控制，镍主要来源于成土母质，另外人为活动对镍的空间分布也有显著的影响。

Spatial Structure and Distribution of Ni Contents in Agricultural Soils in a Typical Area of the Pearl River Delta, China

Spatial variations and distribution of Ni contents in agricultural soils of Dongguan city, Guangdong Province are studied using geostatistical and geographic information system (GIS) techniques.118 surface samples and 5 vertical sections of agricultural soil were collected from Dongguan city. Spatial structure is described with Variogram. Well defined structure with nonzero nugget effect, distinct sill and range can be fitted with exponential model (R²=0.75, P<0.01), which is mainly influenced by soil parent materials and landform,with the relative range of 19.2 km. Variogram analysis shows that spatial structure of Ni contents is in obvious geometric anisotropy with a ratio of 1.7,and the major axis in the 118° direction and the short axis in the 28° direction. Ni contents of agricultural soils are high in west and low in east.The spatial distribution of Ni contents is mainly controlled by soil parent materials,landform, and anthropogenic factors.