Soil contamination by trace elements (TEs) is a major concern for sustainable land management. A potential source of excessive inputs of TEs into agricultural soils are organic amendments. Here, we used dynamic simulations carried out with the Intermediate Dynamic Model for Metals (IDMM) to describe the observed trends of topsoil Zn (zinc), Cu (copper), Pb (lead) and Cd (cadmium) concentrations in a long-term (>60-year) crop trial in Switzerland, where soil plots have been treated with different organic amendments (farmyard manure, sewage sludge and compost).The observed ethylenediaminetetraacetic acid disodium salt (EDTA)-extractable concentrations ranged between 2.6 and 27.1 mg kg⁻¹ for Zn, 4.9 and 29.0 mg kg⁻¹ for Cu, 6.1–26.2 mg kg⁻¹ for Pb, and 0.08 and 0.66 mg kg⁻¹ for Cd. Metal input rates were initially estimated based on literature data. An additional, calibrated metal flux, tentatively attributed to mineral weathering, was necessary to fit the observed data. Dissolved organic carbon fluxes were estimated using a soil organic carbon model. The model adequately reproduced the EDTA-extractable (labile) concentrations when input rates were optimised and soil lateral mixing was invoked to account for the edge effect of mechanically ploughing the trial plots. The global average root mean square error (RMSE) was 2.7, and the average bias (overestimation) was −1.66, −2.18, −4.34 and −0.05 mg kg⁻¹ for Zn, Cu, Pb and Cd, respectively. The calibrated model was used to project the long-term metal trends in field conditions (without soil lateral mixing), under stable climate and management practices, with soil organic carbon estimated by modelling and assumed trends in soil pH. Labile metal concentrations to 2100 were largely projected to remain near constant or to decline, except for some metals in plots receiving compost. Ecotoxicological thresholds (critical limits) were predicted to be exceeded presently under sewage sludge inputs and to remain so until 2100. Ecological risks were largely not indicated in the other plots, although some minor exceedances of critical limits were projected to occur for Zn before 2100.This study advances our understanding of TEs' long-term dynamics in agricultural fields, paving the way to quantitative applications of modelling at field scales.

中文翻译：

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有机改良剂施肥土壤中锌，铜，镉和铅的长期动力学模型

微量元素（TEs）对土壤的污染是可持续土地管理的主要关注点。有机修饰物可能是向农业土壤中过量添加TEs的潜在来源。在这里，我们使用金属中间动力学模型（IDMM）进行的动力学模拟来描述长期观察到的表土Zn（锌），Cu（铜），Pb（铅）和Cd（镉）浓度的趋势。 （> 60年）在瑞士进行的作物试验，其中对土壤块进行了不同的有机改良剂处理（农家粪便，污水污泥和堆肥）。观察到的可提取的乙二胺四乙酸二钠盐（EDTA）浓度范围为2.6至27.1 mg kg ^-1用于锌，4.9和29.0毫克千克^-1对Cu，6.1-26.2毫克公斤^-1用于Pb和0.08和0.66毫克千克^-1镉。金属输入速率最初是根据文献数据估算的。临时归因于矿物风化的额外的，经过校准的金属通量对于拟合观测到的数据是必要的。使用土壤有机碳模型估算溶解的有机碳通量。当优化输入速率并调用土壤横向混合以考虑机械耕作试验地块的边缘效应时，该模型充分再现了EDTA可提取的（不稳定的）浓度。全球均均方根误差（RMSE）为2.7，以及平均偏差（高估）为- 1.66， - 2.18， - 4.34和- 0.05毫克千克^-1分别用于Zn，Cu，Pb和Cd。在稳定的气候和管理实践下，使用校准后的模型来预测田间条件下的长期金属趋势（无土壤横向混合），并通过建模估算土壤有机碳并假定土壤pH趋势。预计到2100年不稳定金属的浓度将保持接近恒定或下降，除了堆肥区中的一些金属。预计目前在污水污泥输入下会超过生态毒理学阈值（临界限值），并一直保持到2100年。在其他地块中，虽然在Zn的2100年前预计会略有超出临界限值，但在其他地块中并未显示出生态风险。这项研究提高了我们对TEs在农业领域中长期动态的理解，为在田间尺度上进行建模的定量应用铺平了道路。