碳酸盐岩地区不同种植方式下黄壤重金属含量特征及评价

The Content Characteristics and Evaluation of Heavy Metals in Yellow Soil of Different Planting Patterns in Carbonate Regions

  • 摘要: 以贵州开阳县不同种植方式下的黄壤为供试样品,对其重金属含量特征及污染水平进行探究.结果表明:不同种植方式下,单作土壤在种植前和收获后为酸性,而连作和间作在两个时期为中性;土壤重金属Cd、Cr、Cu、Zn和Pb的含量变化规律基本一致,均呈现种植前高于收获后;土壤pH与土壤重金属Cd、Cr、Cu、Zn的变异程度均不大,而Pb在连作种植前与间作收获后的变异程度较大;相关性分析显示,Cd与Cu、Pb之间、Cu和Zn、Pb之间均具有较高的同源性;综合污染指数(P)表现为单作(种植前)>间作(收获后)>连作(种植前)>单作(收获后)>间作(种植前)>连作(收获后),分别为14.20、13.67、13.62、11.38、9.89和8.04,均高于3.0,属于重度污染等级,土壤受污染相当严重,其中单作和连作在收获后污染程度较种植前有不同程度的下降,而间作则呈上升趋势.在所选定的污染评价因子中,Cd的贡献率极高,为土壤污染的主要影响因子,其次是Cr.

     

    Abstract: The environmental safety of the producing area of agricultural products has been widely concerned and the risk status of heavy metals in the soil of the producing area of agricultural products has realistic and long-term significance. Yellow soil under different planting patterns in Kaiyang county of Guizhou province was taken as sample for the studies of its heavy metal content characteristics and pollution levels. The results showed that under different planting patterns, single-cropping soil was acidic before planting and after harvest, while in continuous cropping and intercropping periods it was neutra. The contents of heavy metals including Cd, Cr, Cu, Zn and Pb in soil were basically the same, all of which were higher before planting than after harvest. The variation degrees of pH and heavy metal such as Cd, Cr, Cu and Zn in soil were not high, while the variation degree of Pb was high before continuous planting and after intercropping. Correlation analysis shows that Cd has high homology with Cu, Pb, and the same for Cu with Zn and Pb. Comprehensive pollution index(Pzong) scores from high to low: crop monoculture (before planting) > intercropping (after harvest) > continuous cropping (before planting) > crop monoculture (after harvest) > intercropping (before planting) > continuous cropping (after harvest), which were 14.20, 13.67, 13.62, 11.38, 9.89 and 8.04, and all the above were higher than 3.0, belonging to heavy pollution levels. Pollution of soil is quite serious, the pollution degree of the monoculture and continuous cropping after harvest was declined with different degree compared with those before planting, and the pollution degree of intercropping is on the rise. Among the selected pollution evaluation factors, the contribution of metal Cd is very high, which is the main influencing factor of soil pollution, followed by metal Cr.

     

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