不同人工植被群落对铅锌矿废弃地径流重金属流失特征的影响

Effects of Different Artificial Vegetation Communities on Characteristics of Heavy Metal Loss in Runoff of Lead Zinc Mine Wasteland

研究不同人工植被群落及土壤改良对铅锌矿废弃地径流重金属流失特征的影响,为矿区废弃地的生态恢复提供前期修复思路。采用径流小区试验,通过混合施加有机肥和钙肥对土壤进行改良,在自然降雨条件下,分别在铅锌矿废弃地原状土及改良土上构建不同人工植被群落(草、灌—草、乔—灌—草),对地表径流的产生量与径流中泥沙、Cd、Pb、As的含量和流失量进行了分析研究。结果表明:(1)原状土下,乔—灌—草模式相较于草模式和灌—草模式,累计径流产生量分别减少11.3%和0.8%,同一人工植被群落,改良土相较于原状土累计径流产生量减少3.2%~18.8%;原状土下,灌—草模式相较于草模式、乔—灌—草模式,累计泥沙量分别减少28.9%,14.0%,同一人工植被群落,改良土相较于原状土累计泥沙量减少40.0%~63.3%。(2)原状土下,不同人工植被群落溶解态Cd、Pb、As累计流失量分别为2.7~7.2,104.3~295.1,1.4~5.4 mg/m^(2),改良土相较于原状土,不同人工植被群落溶解态Cd、Pb、As累计流失量分别减少47.7%~61.0%,43.8%~64.6%,43.8%~63.8%。(3)原状土下,不同人工植被群落颗粒态Cd、Pb、As累计流失量分别为2.5~9.0 g/m^(2),437.5~1347.2,16.2~89.9 mg/m^(2);改良土相较于原状土,不同人工植被群落颗粒态Cd、Pb、As累计流失量分别减少53.7%~72.0%,55.4%~65.8%,60.2%~71.1%。(4)颗粒态Cd、Pb、As流失量分别占总流失量的99.8%~99.9%,77.1%~84.1%,85.1%~96.7%。综上所述,人工植被群落越复杂,径流量、泥沙和重金属的流失量越低;施加改良剂能进一步强化植被群落的截流功能;重金属的流失主要以颗粒态为主。

This paper studied the effects of different artificial vegetation communities and soil improvement on the characteristics of heavy metal loss in the runoff of lead-zinc mine wasteland,in order to provide early restoration ideas for the ecological restoration of mining wasteland.The runoff plot experiment was used to improve the soil by adding organic fertilizer and calcium fertilizer.Under the condition of natural rainfall,different artificial vegetation communities(grass,shrub grass and tree shrub grass)were constructed on the undisturbed soil and improved soil of lead-zinc mine wasteland respectively.The production of surface runoff,the content and loss of sediment,cadmium,lead and arsenic in runoff were analyzed and studied.The results showed that:(1)In undisturbed soil,the cumulative runoff decreased by 11.3%and 0.8%respectively compared to grass communities and irrigated grass communities.Compared with undisturbed soil,the cumulative runoff of improved soil decreased by 3.2%~18.8%in the same artificial vegetation community.In undisturbed soil,the accumulated sediment of shrub grass community decreased by 28.9%and 14.0%respectively compared with grass community and tree shrub grass community.Compared with undisturbed soil,the cumulative sediment of improved soil decreased by 40.0%~63.3%in the same artificial vegetation community.(2)In undisturbed soil,the cumulative losses of dissolved cadmium,lead and arsenic in different artificial vegetation communities were 2.7~7.2,104.3~295.1 and 1.4~5.4 mg/m^(2) respectively.Compared with the undisturbed soil,the cumulative losses of dissolved cadmium,lead and arsenic in different artificial vegetation communities decreased by 47.7%~61.0%,43.8%~64.6%and 43.8%~63.8%respectively.(3)In undisturbed soil,the cumulative losses of particulate cadmium,lead and arsenic in different artificial vegetation communities were 2.5~9.0 g/m^(2),437.5~1347.2 and 16.2~89.9 mg/m^(2) respectively.Compared with the undisturbed soil,the cumulative loss of particulate cadmium,lead and arsenic in different artificial vegetation communities decreased by 53.7%~72.0%,55.4%~65.8%and 60.2%~71.1%respectively.(4)The losses of particulate cadmium,lead and arsenic accounted for 99.8%~99.9%,77.1%~84.1%and 85.1%~96.7%of the total loss respectively.In conclusion,the more complex the artificial vegetation community,the lower the runoff,sediment and heavy metal loss.Adding soil amendment could further strengthen the interception function of vegetation community.Under different plant communities,the loss of particulate heavy metals dominated.