城市污泥土地利用对作物的重金属污染风险

Pollution Risk of Heavy Metals to Crops after Sewage Sludge Land Application

城市污泥中的重金属是否会在作物中富集是人们最为关心的问题之一。通过总结国内外大量的研究结果,发现短期施用城市污泥,作物中重金属含量都没有超出各国的食品质量和安全标准,没有发现超标现象。对于长期施用污泥对农产品中重金属含量的影响,部分研究结果则显示长期大量施用城市污泥的农产品中出现重金属超标的现象。考虑到国外过去污泥中重金属的含量普遍偏高,相关研究的污泥施用量非常大[60～510 t/(hm2.a)],而现在中国城市污泥中重金属的含量普遍低于国外当年城市污泥中的重金属含量,因此国外过去的部分研究即长期施用污泥对作物重金属污染风险的结果不适用于中国现在的情形。

Whether heavy metals can be enriched in crops after sewage sludge land application is a significant cbncern. By summarizing a large number of studies undertaken at home and abroad, it was found that the contents of heavy metals in crops did not exceed the agricultural products quality and safety standards adopted by different countries if the sewage sludge was applied for a short period. However, if large quantity of sewage sludge was applied for a long period, the contents of heavy metals in some crops exceeded those agricultural quality standards. Nevertheless, the conclusion that sewage sludge land appli- cation for a long period could lead to the heavy metals pollution to crops does not necessarily apply to Chi- na because the quantities of sewage sludge application [ 60 to 510 t/（hm^2·a）] and the concentrations of heavy metals in the sewage sludge are notably higher abroad.