UMR ECOSYS, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
Departamento de Edafoloxía e Química Agrícola, Universidade de Santiago de Compostela, Facultade de Farmacia, Praza Seminario de Estudos Galegos s/n, 15782 Santiago de Compostela, Spain.
Sci Total Environ. 2019 Feb 15;651(Pt 2):2961-2974. doi: 10.1016/j.scitotenv.2018.10.013. Epub 2018 Oct 9.
Recycling organic residues in agrosystems presents several benefits but faces the question of contaminants, among them a few trace metals which eventually accumulate in soils following regular applications of organic waste products (OWP) and represent an ecological risk. The increase of total trace metal contents in amended topsoils can be predicted by a mass balance approach, but the evolution of their available fractions is a more intricate issue. We aimed at modelling this evolution by using the dataset of a long-term field experiment of OWP applications (manure and three urban waste composts). Two operationally-defined fractions of 6 trace metals have been quantified in the OWP and amended topsoils between 2002 and 2015: the soluble and potentially available metals, extracted in 0.01 M CaCl and 0.05 M EDTA solutions, respectively. The potentially available metals have progressively increased in amended topsoils, at rates depending on elements and types of OWP. For Zn, these increases corresponded in average to inputs of potentially available Zn from OWP. But the soil stocks of potentially available Cu increased faster than from the inputs of EDTA-extractable Cu, showing linear regression slopes between 1.4 and 2.5, depending on OWP type. The influence of OWP has been provisionally interpreted in the light of their efficiency to increase soil organic matter and their inputs of reactive oxides. Soluble copper has increased with repeated amendments. But soluble cadmium, nickel and zinc have generally decreased, as they are influenced by changing soil variables such as pH and organic matter. Statistic models were used to unravel the relationships between soluble and EDTA-extractable metals and other soil variables. For Cu, the most satisfactory models just relate soluble and potentially available Cu. Developing such models could contribute to predict the long-term effects of a precise scenario of agricultural OWP recycling upon available trace metals in soils.
农业系统中有机残留物的再利用有许多好处，但也存在污染物的问题，其中一些痕量金属在经常施用有机废物（OWP）后最终会在土壤中积累，并构成生态风险。通过质量平衡方法可以预测增施土壤中总痕量金属含量的增加，但可用部分的演变则是一个更为复杂的问题。我们旨在通过使用 OWP 应用（粪肥和三种城市废物堆肥）长期田间试验的数据来模拟这种演变。在 2002 年至 2015 年间，已在 OWP 和增施土壤中定量了两种操作定义的 6 种痕量金属的分数：可溶和潜在可用金属，分别用 0.01 M CaCl 和 0.05 M EDTA 溶液提取。潜在可用金属在增施土壤中的含量逐渐增加，增加的速率取决于元素和 OWP 的类型。对于 Zn，这些增加的量平均相当于 OWP 中潜在可用 Zn 的输入。但是，潜在可用 Cu 的土壤储量增加速度快于 EDTA 可提取 Cu 的输入速度，这表明不同 OWP 类型的线性回归斜率在 1.4 到 2.5 之间。根据其增加土壤有机质的效率和提供的反应性氧化物，对 OWP 的影响进行了初步解释。可溶性铜随着反复增施而增加。但是可溶性镉、镍和锌通常会减少，因为它们受土壤变量（如 pH 和有机质）的影响。统计模型被用来揭示可溶性和 EDTA 可提取金属与其他土壤变量之间的关系。对于 Cu，最令人满意的模型仅与可溶性和潜在可用 Cu 相关。开发这种模型可以有助于预测在精确的农业 OWP 再利用情景下，土壤中可用痕量金属的长期影响。
