堆肥腐殖质的形成和变化及其对重金属有效性的影响

Formation and Transformation of Humus in Composting and Its Impacts on Bioavailability of Toxic Metals

重金属污染物是限制城市污泥及畜禽粪便土地利用的重要因素,如何有效降低其中重金属的生物有效性成为研究的热点。根据有关文献资料概述了堆肥过程中腐殖质的形成、组成和结构的变化,论述了腐殖质和重金属相互作用的机理以及腐殖质对重金属有效性影响的因素。指出选择合适的堆肥原料和控制适当的堆肥条件,促使堆肥产品中腐殖质的形成并提高腐殖质组分向着稳定态和不溶态转化,可以作为利用堆肥降低有机固体废弃物中重金属污染风险的手段。

With the high contents of toxic metals in sewage sludge and livestock manure, the application of the sewage sludge and livestock manure in farmland may pose potential risks on ecological environment, crops, and human. Hence, decreasing the bioavailahility of toxic metals is critical and has become a focus of current researches. Several techniques have been developed to decrease the bioavailability of toxic metals in the sewage sludge and livestock manure, including leaching, liming, and composting etc. This paper mainly reviews and discusses the composition and formation of humus during composting of sewage sludge and livestock manure and the effect of humus on the bioavailability of toxic metals. Generally, composting of sewage sludge and livestock manure can increase the content of stable humus and thus decrease the bioavailability of toxic metals in them. However, formation of soluble hnmus may increase the mobility as well as the bioavailability of toxic metals in the composting materials. Therefore, it is critical to synthesize more stable humus instead of soluble humus during composting by selecting raw materials and controlling composting conditions, It is suggested that further studies on the bulking agents and composting conditions be necessary to enhance the formation of stable humic-metal complexes for decreasing the potential risk of toxic metals in the sewage sludge and livestock manure.