长江水系沉积物重金属含量空间分布特征研究——地统计学方法

SPATIAL DISTRIBUTION CHARACTERISTICS OF HEAVY METALS IN THE SEDIMENTS OF CHANGJIANG RIVER SYSTEM ——GEOSTATISTICS METHOD

本文利用地统计学方法研究了长江水系沉积物１１种重金属元素含量的空间分布特征。采用变异函数定量描述空间分布结构特征和克立格法进行最优插值，并制作出含量分布图。结果表明：所研究的重金属在长江水系沉积物中均有显著的空间结构性特点，其变异函数均可用有块金效应的球状模型进行拟合。多数元素变异函数的变程在１０００ｋｍ左右，这种长距离的变程与分布图上同性质斑块平均距离相当。在约５００ｋｍ以上，多数元素的变异函数表现出一定的方向性特点，大多在ＮＥ～ＳＷ或ＮＷ～ＳＥ向相关较好，此方向性与含量的空间分布走向一致。

The spatial distribution characteristics of 11 heavy metals (Cu, Pb, Zn, Cd, Hg, Co, Ni, As, Cr, Mn, and Fe) in the sediments of Changjiang River system were studied using geostatistics method. The spatial distribution features were quantitatively described by variogram. Based on the variograms, Kriging interpolation was performed, and distribution maps were produced. The results show that all of the heavy metals being studied have good spatial structures, and their variograms could be fitted by spherical models with nuggets. Most of the ranges of variograms are around 1 000 km, which are consistent with average distances among patches with the same feature in the distribution maps. Over about 500 km, most elements show some directional features, and most of them have relatively good correlations in the directions of NE-SW or NW-SE, which are consistent with the trends of their spatial distribution.