Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland.
Federal Office for Agriculture, Mattenhofstrasse 5, 3003 Bern, Switzerland.
Environ Pollut. 2017 Feb;221:85-93. doi: 10.1016/j.envpol.2016.11.035. Epub 2016 Nov 28.
Mineral phosphorus (P) fertilizers contain contaminants that are potentially hazardous to humans and the environment. Frequent mineral P fertilizer applications can cause heavy metals to accumulate and reach undesirable concentrations in agricultural soils. There is particular concern about Cadmium (Cd) and Uranium (U) accumulation because these metals are toxic and can endanger soil fertility, leach into groundwater, and be taken up by crops. We determined total Cd and U concentrations in more than 400 topsoil and subsoil samples obtained from 216 agricultural sites across Switzerland. We also investigated temporal changes in Cd and U concentrations since 1985 in soil at six selected Swiss national soil monitoring network sites. The mean U concentrations were 16% higher in arable topsoil than in grassland topsoil. The Cd concentrations in arable and grassland soils did not differ, which we attribute to soil management practices and Cd sources other than mineral P fertilizers masking Cd inputs from mineral P fertilizers. The mean Cd and U concentrations were 58% and 9% higher, respectively, in arable topsoil than in arable subsoil, indicating that significant Cd and U inputs to arable soils occurred in the past. Geochemical mass balances confirmed this, indicating an accumulation of 52% for Cd and 6% for U. Only minor temporal changes were found in the Cd concentrations in topsoil from the six soil-monitoring sites, but U concentrations in topsoil from three sites had significantly increased since 1985. Sewage sludge and atmospheric deposition were previously important sources of Cd to agricultural soils, but today mineral P fertilizers are the dominant sources of Cd and U. Future Cd and U inputs to agricultural soils may be reduced by using optimized management practices, establishing U threshold values for mineral P fertilizers and soils, effectively enforcing threshold values, and developing and using clean recycled P fertilizers.
矿物磷 (P) 肥料含有对人类和环境潜在有害的污染物。频繁施用矿物 P 肥料会导致重金属在农业土壤中积累并达到不理想的浓度。人们特别关注镉 (Cd) 和铀 (U) 的积累，因为这些金属是有毒的，会危及土壤肥力、淋滤到地下水，并被作物吸收。我们测定了从瑞士 216 个农业地点获得的超过 400 个表土和底土样本中的总 Cd 和 U 浓度。我们还研究了自 1985 年以来，在瑞士六个国家土壤监测网络站点的土壤中 Cd 和 U 浓度的时间变化。可耕地表土中的 U 浓度比草地表土中的 U 浓度平均高 16%。可耕地和草地土壤中的 Cd 浓度没有差异，这归因于土壤管理实践和除矿物 P 肥料以外的 Cd 来源掩盖了矿物 P 肥料的 Cd 输入。可耕地表土中的 Cd 和 U 浓度分别比可耕地底土中的 Cd 和 U 浓度平均高 58%和 9%，这表明过去向可耕地土壤中输入了大量的 Cd 和 U。地球化学质量平衡证实了这一点，表明 Cd 积累了 52%，U 积累了 6%。在六个土壤监测点的表土中，Cd 浓度仅发现了较小的时间变化，但三个站点的表土中 U 浓度自 1985 年以来显著增加。过去，污水污泥和大气沉降是农业土壤中 Cd 的重要来源，但如今矿物 P 肥料是 Cd 和 U 的主要来源。通过优化管理实践、为矿物 P 肥料和土壤建立 U 阈值、有效执行阈值以及开发和使用清洁的回收 P 肥料，未来农业土壤中的 Cd 和 U 输入可能会减少。
