九台市不同利用方式下土壤铬含量及其空间分布特征

基于传统统计学和地统计学原理,分析了菜地、旱地和水田3种耕作方式对吉林省九台市土壤重金属铬分布的影响,并研究了整个区域铬含量的空间异质性特征。结果表明,菜地和水田土壤中铬含量明显高于背景值,存在积累现象,而旱地不明显。用球状模型来拟合整个区域铬含量的理论半变异函数效果最佳,铬分布具有较好的空间结构性,自相关范围较大,属于强空间相关。同时,各向异性分析表明该区域的铬含量分布是各向同性的。通过普通Kriging插值发现,铬含量的高值区主要分布于九台市东北部的岛状区域和西南部,这主要是受不同土地利用方式和地形的影响,使得长期以来．该区域铬的迁移方向大致为西部和东北部。总体而言。九台市土壤铬含量分布目前仍主要受母质、土壤性质等内在因素的影响,但一些外在因素如耕作方式、施肥对其影响也不容忽视。

Chromium Accumulation in Soils for Different Land Uses and Spatial Distribution of Chromium in Jiutai City of Jilin Province

Based on traditional statistics,the influence of different land uses on chromium(Cr) concentration in Jiutai city of Jilin province was compared,including vegetable field,dry land and paddy field.Geo-statistics was used to analyze the spatial distribution pattern of Cr in the whole study area.The variance analysis indicated that different land uses greatly affected the accumulation of Cr in the soils.The difference of Cr concentration between vegetable field,paddy field and background value was significant,whereas it was not the case for dry land.Semivariogram of Cr content in the whole area was fitted well using spherical mode1.The relatively small ratio of nugget variance to sill(14%) and large range(74.58 km) showed good spatial correlation of Cr content.Further analysis indicated that the spatial structure of Cr was isotropy.Through ordinary Kriging interpolation,it was found that the content of Cr was high in the southwest and island area of northeast due to different land use types and topographical factors.Although the spatial distribution of Cr content was mainly controlled by the shape,topography and soil character of the study area,some anthropogenic factors should not be ignored,including regulations of land management for different land use types and fertilization.