摘要
所研究的１１种重金属元素在长江水系沉积物中均有较显著的空间自相关性；沉积物细粒中重金属含量空间自相关性好于沉积物原样；正相关尺度达５００ｋｍ左右，与空间分布斑块大小对应；研究区沉积物重金属含量空间分布分形存在于约１０００ｋｍ以内，分维数处于２．７６～２．９５之间，分维数的大小与空间自相关指标大小在各元素间的变化趋势相反，表明这两种指标具有一致性；多数元素在ＮＷ－ＳＥ向和ＮＥ－ＳＷ向相关性较好，与变异函数所揭示的方向性特征一致。
The spatial distribution characteristics of 11 heavy metals (Cu, Pb, Zn, Cd, Hg, Co, Ni, As, Cr, Mn and Fe) in the sediments of the Changjiang River system were studied with methods of spatial autocorrelation and fractal. Moran's I indices were calculated to quantitatively describe the significance and the directional characteristics of their spatial autocorrelations, and spatial correlograms were drawn to show the variation of spatial autocorrelation along with the changes of distance. Fractal dimensions were calculated to reveal the complication degrees of the spatial distributions. Significant spatial autocorrelations are detected for all of the elements studied. The spatial autocorrelations of heavy metals in fine grained sediments are better than those in raw sediments. The positive autocorrelations extend to about 500 km, which is consistent with the sizes of patches in the distribution maps. Fractals exist in about less than 1 000 km , and fractal dimensions are around 2.76~2.95. The variation of fractal dimension among elements has negative trend against Moran's I, which shows consistence of the two indices. Most of the elements have relatively good autocorrelations in the directions of NE SW or NW SE, which are consistent with the results from variogram method.
出处
《地理学报》
EI
CSSCI
CSCD
北大核心
1998年第1期87-96,共10页
Acta Geographica Sinica
关键词
长江水系
沉积物
重金属含量
空间分布
分形法
spatial autocorrelation, spatial correlogram, spatial distribution, fractal, sediments, heavy metals
