Wrocław University of Environmental and Life Sciences, Institute of Soil Science and Environmental Protection, Grunwaldzka 53, 50-357, Wrocław, Poland.
Environ Monit Assess. 2018 Dec 15;191(1):19. doi: 10.1007/s10661-018-7133-1.
The legal regulatory/action levels of trace elements in soils are established at high concentrations, at which the crucial functions of soil are at risk or are eliminated. However, concentrations below these action levels, but above presumed natural levels, may also limit particular ecosystem services, including organic food production. Thus, defining the (ambient) background concentrations is an essential part of environmental or health risk assessment, e.g., on Chernozems, which are considered to be the most productive soils and ones that should be protected against all forms of contamination. Based on 28 profiles of chernozemic soils developed from loess in an agricultural region of SW Poland presumed to be free of industrial contamination, ambient geochemical baselines have been derived for Fe and six trace metals for four standardized soil layers, including the topsoil (plow layer) and parent material layers. The median values for the plow layer (1.89% for Fe, and 537, 49, 17, 14, and 26 mg kg for Mn, Zn, Pb, Cu, and Ni, respectively) are lower than the values reported for other Chernozems in SE Poland/Europe/the world, and thus may serve as a general geochemical baseline for chernozemic soils developed from loess. The concentration of Cd, although lower than in other Chernozems around the world, is higher than in Ukrainian Chernozems and thus may serve as a local (or Central European) baseline only. The median concentrations of Fe, Cu, Mn, and Zn are very close to their concentrations in the Chernozem buried under the Neolithic kurgan. However, Pb and Cd concentrations are two times higher than in the buried soil, indicating the scale of general contamination of the topsoil horizons of arable soils. Concentrations of the elements under study, excluding Fe, in both the buried and surface soils are significantly higher in the topsoil layer compared to parent material (loess), and this justifies the separate baseline values for topsoil horizons, instead of background values derived universally for parent rock types. This is essential, in particular in soils texturally differentiated within profiles, where the subsoil material has a different origin and cannot be considered the parent material for topsoil horizons. Underlying or locally outcropped bedrock (e.g., serpentinite rocks) may naturally enhance the total concentration of trace elements in the entire soil profile by the addition of metal-rich regolith particles during the formation of surface covers, e.g., by eolian processes under periglacial conditions (Late Pleistocene). Such soils are naturally enriched with metals (with nickel in the case of serpentinite bedrock), cannot be considered contaminated, and thus require a separate legal treatment, including separate (or individually suited) background baselines for health risk assessments.
土壤中微量元素的法律监管/行动水平是在高浓度下建立的，此时土壤的关键功能处于风险之中或已被消除。然而，低于这些行动水平但高于假定的自然水平的浓度也可能限制特定的生态系统服务，包括有机食品生产。因此，定义（环境）背景浓度是环境或健康风险评估的一个重要部分，例如在黑钙土上，黑钙土被认为是最具生产力的土壤，应该防止受到各种形式的污染。在波兰西南部一个被认为没有工业污染的农业区，从黄土中发育的 28 个黑钙土剖面中，得出了 Fe 和六种痕量金属在四个标准化土壤层中的环境地球化学基线，包括表土层（耕层）和母质层。耕层的中值（Fe 为 1.89%，Mn、Zn、Pb、Cu 和 Ni 分别为 537、49、17、14 和 26mgkg）低于波兰东南部/欧洲/世界其他黑钙土报告的值，因此可作为黄土发育的黑钙土的一般地球化学基线。Cd 的浓度虽然低于世界各地的其他黑钙土，但高于乌克兰的黑钙土，因此只能作为当地（或中欧）基线。Fe、Cu、Mn 和 Zn 的浓度非常接近埋藏在新石器时代古墓下的黑钙土中的浓度。然而，Pb 和 Cd 的浓度是埋藏土壤的两倍，表明耕地表土层普遍受到污染。研究元素的浓度，除了 Fe，在埋藏和表层土壤中的含量都显著高于母质（黄土），这证明了需要为表土层分别建立基线值，而不是为母岩类型普遍推导背景值。这是必要的，特别是在剖面中具有不同质地的土壤中，其中亚土层物质具有不同的来源，不能被视为表土层的母质。潜在的或局部露头的基岩（例如蛇纹岩岩石）可能会在形成地表覆盖物期间通过添加富含金属的风化壳颗粒来自然增加整个土壤剖面中痕量元素的总浓度，例如在冰缘条件下的风成过程（更新世晚期）。这些土壤自然富含金属（蛇纹岩基岩的镍），不能被视为污染，因此需要单独处理，包括单独的（或单独适合的）健康风险评估背景基线。
