黔中地区不同污染风险等级黄壤镉形态分布特征

Distribution characteristics of cadmium in yellow soils with different pollution risk levels in central Guizhou

为探究喀斯特地区地带性黄壤的镉形态分布特征,在中国南方喀斯特中心区域--黔中地区进行了农田黄壤样品采集,并对其化学成分进行了定量分析,通过对土壤镉形态及pH、钙、镁的分析测定,探究了喀斯特背景对黄壤中镉形态分布的影响。结果表明,黔中地区黄壤全镉为0.184~3.316mg/kg,具有较大的空间差异,各形态镉含量随污染风险等级的提高而显著增加(p<0.01)。黄壤中的镉主要以残渣态及可还原态存在,可交换态镉占全镉的17.52%(质量分数,下同)~22.83%,且随着风险等级的提高,可交换态镉向更为稳定的形态转变。可交换态镉与全镁、可交换态镁均显著负相关(p<0.05),镁组分可在一定程度上降低黄壤中可交换态镉含量,对镉的生物有效性具有一定的调控作用。

In order to explore the distribution characteristics of cadmium in zonal yellow soils in karst areas,samples of farmland yellow soils were collected in the central area of karst in southern China(central Guizhou),and their chemical compositions were quantitatively analyzed.The cadmium forms in soil,pH,calcium and magnesium were analyzed.The effect of karst background on the distribution of cadmium species in yellow soil was explored.The results showed that the total cadmium content of yellow soil in central Guizhou was 0.184-3.316 mg/kg,which had a large spatial difference.The content of different forms of cadmium increased significantly with the increase of pollution risk level(p<0.01).Cadmium in the soil mainly existed in the residue and reducible state.Exchangeable cadmium accounted for 17.52%(mass fraction,the same below)-22.83% of the total cadmium,and the exchangeable cadmium changed to a more stable form with the increase of the risk level.There was a significant negative correlation between exchangeable cadmium and total magnesium,as well as exchangeable magnesium(p<0.05).The magnesium component could reduce the content and activity of exchangeable cadmium in the soil,and it had a regulating effect on the availability of cadmium.