不同土地利用方式对土壤铜积累的影响——以北京市为例

通过对北京市菜地、稻田、果园、绿化地、麦地以及自然土壤6种土地利用类型共609个土壤样品的调查分析,探讨了不同土地利用方式下土壤铜的积累特征。结果表明,果园土壤的平均铜浓度最高,达到29.1mg/kg,显著高于菜地、麦地和自然土壤。不同果园土壤样品之间的差别较大,铜浓度的空间分异比较明显。与北京市土壤铜的背景值相比,除自然土壤外其它5种土地利用类型的土壤铜浓度均显著高于背景值。以基线值作为评价标准,不同土地利用类型下土壤铜浓度的总体超标率为5.6%;其中,土壤铜浓度超标的果园、菜地、稻田、绿化地、麦地样品数分别占其调查样品数的29.2%、4.7%、4.2%、8.3%、4.6%。超标样点主要分布在昌平、朝阳、大兴、密云、石景山、顺义、通州7个区县,尤其以昌平和朝阳区最为集中。

Soil Copper Accumulation under Different Land Use Types--The Case of Beijing

To investigate soil copper accumulation under different land use types,Cu concentra-tions of 609 soil samples from vegetable field,paddy field,orchard,greenbelt,cornfield and natural soils in Beijing were taken and analyzed.It was found that the concentrations of Cu with geometric mean 20.9mg/kg were much higher than the background concentration (18.7mg/kg),which indicated that atmospheric transportation was an important factor influencing the accumulation of Cu in the soils at large scale.Furthermore,some human activities,such as pesticides,livestock manures and landfill,would increase the concentrations of Cu in the soils rapidly at local scale.Combined with ANOVA analysis,Cu in the orchard showed the highest geometric mean concentration in 6 types, which was significantly higher than the mean concentrations of Cu in vegetable field,cornfield and natural soils.And the differences among the samples of orchard were also obvious,indicating the inhomogeneity of the spatial distribution and differences of the way and time of cultivation in different areas.Using the baseline (37.1mg/kg) as the criterion,the ratio of total samples beyond the limit was 5.6%.Compared with the total sample numbers of each land use type,the percentages of soil samples with the Cu concentrations over the baseline of Beijing soils were 29.2%,4.7%,4.2%,8.3% and 4.6% for orchard,vegetable field,paddy field,greenbelt and cornfield,respectively.The samples over the baseline of Beijing soils are mainly distributed in Changping and Chaoyang district.How to avoid the areas with serious pollution is an important problem in land use planning,especially in agricultural land use planning.