Kaschl Arno, Römheld Volker, Chen Yona
Institute of Plant Nutrition, University of Hohenheim, Stuttgart, Germany.
Sci Total Environ. 2002 May 27;291(1-3):45-57. doi: 10.1016/s0048-9697(01)01091-9.
The use of municipal solid waste (MSW) compost as fertilizer may cause increased leaching due to its high content of trace metals and thus pose a threat to groundwater quality. The effect of MSW compost application on trace metal leaching in calcareous soils has been studied in soil column experiments under laboratory conditions using three soils from the study area in the Gaza Strip and Israel. Higher levels of organic matter in solution (TOMS), nitrate, and the trace metals Cu, Ni and Zn were found in the leachates of a sandy soil and, to a lesser extent, a loamy soil, to which MSW compost had been applied at a rate of 65 Mg ha(-1) (dry weight basis). Nevertheless, the majority of water-soluble trace metal species from compost accumulated in the topsoil rather than washing out, with the exception of aqueous Ni species. Ni concentrations exceeded the maximum allowable limits for drinking water (in Germany: 50 microg l(-1)) at peak times in the leachates from sandy soil, while all other trace metals remained far below the corresponding limits. The highest absolute concentrations of trace metals were found for the leaching of Cu from compost-amended sandy soil (100 microg l(-1)). For Cd, Pb and Hg no evidence of downward movement was found in any assay. Gel filtration studies of the collected soil leachates showed that all trace metals encountered in the leachates existed mostly as organic complexes. In sandy soil most of the water-soluble organic matter added with the compost had leached from the rootzone after a year's equivalent of rainfall, while TOMS mobility was greatly reduced in the loamy soil. The makeup of the TOMS in the sandy soil and its metal-binding capacity was strongly influenced by compost-derived dissolved organic matter (DOM) as observed by FTIR spectrometry. Hence the vertical displacement of trace metals (Cu, Ni, Zn) in these calcareous soils seemed to result primarily from the presence of mobile metal-organic complexes in the soil solution after compost addition. Further studies are required to validate these findings in the field, especially to assess the risk of Cu and Ni leaching in sandy soil.
将城市固体废弃物（MSW）堆肥用作肥料可能会因其高含量的痕量金属而导致淋溶增加，从而对地下水质量构成威胁。在实验室条件下，利用来自加沙地带和以色列研究区域的三种土壤进行了土柱实验，研究了MSW堆肥施用对石灰性土壤中痕量金属淋溶的影响。在以65 Mg ha⁻¹（干重基准）施用MSW堆肥的砂土以及程度稍轻的壤土的渗滤液中，发现溶液中的总有机物质（TOMS）、硝酸盐以及痕量金属铜、镍和锌的含量较高。然而，除了水溶态镍物种外，堆肥中大部分水溶性痕量金属物种积累在表层土壤中而非被冲走。在砂土渗滤液的峰值时刻，镍浓度超过了饮用水的最大允许限值（在德国：50 μg l⁻¹），而所有其他痕量金属仍远低于相应限值。从堆肥改良砂土中淋溶出的铜的痕量金属绝对浓度最高（100 μg l⁻¹）。在任何试验中均未发现镉、铅和汞有向下移动的迹象。对收集的土壤渗滤液进行的凝胶过滤研究表明，渗滤液中遇到的所有痕量金属大多以有机络合物形式存在。在砂土中，添加堆肥的大部分水溶性有机物质在相当于一年降雨量后已从根区淋溶出来，而在壤土中TOMS的迁移性大大降低。通过傅里叶变换红外光谱法观察发现，砂土中TOMS的组成及其金属结合能力受堆肥衍生的溶解有机物质（DOM）的强烈影响。因此，这些石灰性土壤中痕量金属（铜、镍、锌）的垂直迁移似乎主要是由于添加堆肥后土壤溶液中存在可移动金属有机络合物所致。需要进一步研究以在田间验证这些发现，特别是评估砂土中铜和镍淋溶的风险。
