基于环境容量的污泥产品土地安全施用量研究

Land Safe Application Amount of Sludge Products Based on Environmental Capacity

以北京的土壤重金属背景值、2021年中心城区污泥产品质量均值为基础,从环境管理的角度,通过对标法、静态环境容量法和动态环境容量法分析了采用不同方法核算的污泥产品最大安全施用量、优缺点以及土地利用防控要求。结果显示:污泥产品以对标法核算,符合林地、园林绿化、土地改良、农用B级用途,具体用量按对应标准执行。静态环境容量法不考虑重金属衰减,其一次最大安全施用量为830.9 t/(hm2·a),10、30、50 a周期的最大安全施用量分别为83.1、27.7和16.6t/(hm2·a);动态环境容量法考虑重金属衰减,其5、10、30、50 a周期的最大安全施用量分别为247.3、163.6、118.3和114.7 t/(hm2·a)。基于环境容量法可知,北京地区污泥产品施用于土壤的重金属污染风险低、土地利用潜力大,重金属风险度依次为锌>汞>铜>镉>砷>铬>镍>铅。汞为安全风险防控关键元素,锌为生态风险防控元素。并提出了“以标准限值为底线,以环境容量为基线”的动态安全核算法,旨在指导不同土地利用方向的污泥产品施用。

Based on the soil background value of heavy metals in Beijing and the average quality of sludge products in central urban area in 2021,this paper analyzed the maximum safe application amount of sludge product,advantages and disadvantages of different calculation methods and the requirements of land use prevention and control by benchmarking method,static environmental capacity method and dynamic environmental capacity method from the perspective of environmental management.According to the benchmarking method,sludge products were suitable for forest land,landscaping,land improvement and agricultural level B purposes.The specific application amount should be implemented according to the corresponding standards.The static environmental capacity method did not consider the attenuation of heavy metals,the maximum safe application amount for one time was 830.9 t/(hm~2·a),and those for 10 years,30 years and 50 years were 83.1 t/(hm~2·a),27.7 t/(hm~2·a) and 16.6 t/(hm~2·a),respectively.The dynamic environmental capacity method considerd the attenuation of heavy metals,the maximum safe application amount for 5 years,10 years,30 years and 50 years were 247.3 t/(hm~2·a),163.6 t/(hm~2·a),118.3 t/(hm~2·a) and 114.7 t/(hm~2·a),respectively.According to the environmental capacity method,the heavy metal pollution risk of sludge products applied to soil in Beijing area was low and the land use potential was large,and the heavy metal risk in descending order was zinc,mercury,copper,cadmium,arsenic,chromium,nickel and lead.Mercury was the key element for safety risk prevention and control,and zinc was the element for ecological risk prevention and control.The dynamic safety calculation algorithm of“taking the standard limit as the bottom line and the environmental capacity as the baseline”was proposed to guide the application of sludge products in different land use directions.