北京黑石头填埋场治理后期土壤质量评价

Soil quality assessment of Beijing Heishitou Landfill in the late treatment period

为了评价北京黑石头垃圾填埋场在好氧加速降解治理后期表层土壤质量,测定了填埋场表层土壤重金属Cd、Hg、As、Cu、Pb、Cr、Zn、Ni的含量,以及容重、孔隙度、有机质、有效磷、速效钾和碱解氮等理化性质,运用内梅罗污染指数、潜在生态危害指数对土壤重金属污染进行了评价,运用BP神经网络法对土壤宜林性进行了评价。结果表明:土壤重金属含量大多高于北京市土壤背景值,但属于较安全的范畴;容重与通气孔隙度表现良好,但毛管孔隙度与孔隙比低,水气性能不够协调;养分状况总体上属于中上等水平,在17个样点中,养分极高2个,养分高11个,养分中等4个;土壤理化性质能满足一般园林乔灌木和草坪的生长需求,土层浅薄是该填埋场建植绿化的主要限制因素。

After aerobic accelerated degradation had been employed in the Beijing Heishitou Landfill, the quality of the topsoil was evaluated, including the heavy metal pollution level and its suitability for forestry. The Nemerow pollution index, potential ecological risk index, and the BP neural network were used in the assess- ment. The topsoil evaluation was based on the bulk density data; porosity; the Cd, Hg, As, Cu, Pb, Cr, Zn, Ni and organic matter of the topsoil, as well as the available phosphorus ; rapidly available potassium ; and alkali- hydrolyzable nitrogen. The results showed that the heavy metals contents of the topsoil were higher compared with the background concentrations of Beijing, but were within the safe category. The bulk density and the aeration porosity of the topsoil were satisfactory, but the capillary porosity and void ratio were lower than the normal val- ues, which indicated disordered water-air properties. As regards the 17 sampling points, the topsoil nutrient levels of 2 points were found extremely high, 11 were high, and 4 were medium. Overall, the nutrient level was classified within the upper- to middle category. The physical and chemical properties of the topsoil were generally suitable for growing trees, shrubs, and lawns; however, the main limitation for planting was the thin covering of topsoil.