不同种植年限设施菜地土壤养分、重金属含量变化及主导污染因子解析

摘要

In order to study the effects of different cultivation years on soil nutrient and heavy metal ac-cumulation,and also the main pollution factors in greenhouse,the experiments were conducted to investigate the variation of soil available nitrogen,phosphorus and potassium contents,organic matter content,pH value and heavy metal accumulation quantity in different cultivation -year greenhouses.The correlations between cultivation years and soil physicochemical properties and heavy metal accumulation were also analyzed.The results showed that with the increase of cultivation years,the contents of available nitrogen,phosphorus and potassium and organic matter were significantly increased,and the available nitrogen,phosphorus and potassi-um contents were 2.5 ~3.5,33.9 ~70.3 and 4.5 ~5.6 times of those before the construction of greenhouses respectively.The pH value reduced significantly,and fell about 0.038 units per year.The contents of Cd,Cu and Zn increased significantly,and the Cd content seriously exceeded the grade II level of GB 15618 -1995 (6.5 H <7.5),while the Cu and Zn contents were higher than the background values.The soil available nitrogen,available phosphorus and organic matter contents had significantly positive correlations with the Cd, Cu and Zn contents,which suggested that they might have the similar sources.In conclusion,the problems such as unbalance of soil nutrient,acidification and heavy metal accumulation appeared in all the greenhouses with different cultivation years;the available nitrogen,phosphorus and potassium,and Cd were the main pol-lution factors,while Cu and Zn were the potential ones.The rational scientific fertilization methods should be advocated to protect the ecological enviroment of greenhouses.%为探讨不同种植年限对设施大棚土壤养分、重金属累积量的影响及主要污染因子，研究了不同种植年限的大棚土壤速效氮磷钾含量、有机质含量、pH 值及重金属累积量的变化，并对种植年限与土壤理化性状和重金属累积量之间的相关性进行了统计分析。结果表明，随种植年限延长，土壤速效氮磷钾、有机质含量均大量累积，速效氮磷、钾含量分别是未建大棚时的2．5～3．5倍、33．9～70．3倍、4．5～5．6倍；pH 值明显下降，每年约下降0．038个单位；而重金属 Cd、Cu、Zn 元素则显著升高，其中 Cd 超标现象严重，Cu、Zn 含量均超土壤背景值；土壤速效氮磷、有机质含量与 Cd、Cu、Zn 含量均呈显著正相关关系，由此推测土壤中重金属 Cd、Cu、Zn 与速效氮磷、有机质有相似的来源，这说明不同种植年限的设施菜地土壤中均出现养分失衡、土壤酸化、重金属累积等环境问题，其中主导污染因子为速效氮磷钾及重金属 Cd 元素，Cu、Zn 元素为潜在污染因子。为保证设施大棚土壤的生态环境安全应提倡合理科学施肥方式。