Du Lina, Cuss Chad W, Dyck Miles, Noernberg Tommy, Shotyk William
Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2G1, Canada.
Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2G1, Canada; School of Science and the Environment, Memorial University of Newfoundland, NL A2H 5G4, Canada.
Sci Total Environ. 2024 May 10;924:171590. doi: 10.1016/j.scitotenv.2024.171590. Epub 2024 Mar 13.
The chemical species of trace elements (TEs) in agricultural soils is highly variable under diverse conditions, requiring tools with clear resolution and minimal disturbance for exploration. A novel surgical (316L) stainless steel (SS) lysimeter with a 5 μm pore size was developed to collect field soil solutions. The size-resolved distribution of TEs were characterized into total (nitric acid digestion), particulate (0.45-5 μm), dissolved (<0.45 μm), colloidal (1 kDa to 0.45 μm), and mainly ionic (<1 kDa) fractions in the lysimeter soil solutions. Total concentrations of TEs (dry weight basis) in acid digested Gray Luvisolic soils were analyzed. Most TEs in lysimeter soil solutions were present in particulate phases, relevant to their geochemical affinities and occurrences in soil minerals. Among dissolved fractions, As, Ba, Co, Li, Mn, Tl, and V existed as mainly ionic species in the soil solutions. Copper, Pb, Al, Th, and U showed variable associations with dissolved organic matter (DOM) and/or inorganic colloids among agricultural treatments. Inorganic NPKS or NKS fertilizer applications with lower pH (5.25-5.74) enhanced mobility and potential bioavailability of Ba, Co, Li, Mn, and Pb present in mainly ionic species, compared with other locations (pH 5.82-6.37). Manure application exhibited a dual effect, potentially increasing bioavailability for As, Tl, and V due to probably enhanced cation exchange capacity (CEC), while also facilitating specific adsorption of Cu and U on DOM, potentially reducing their bioavailability depending on DOM molecular weight. Colloidal and ionic Al and Th concentrations were higher in forest soils than agricultural soils, with extremely low potential bioavailability of Th attributed to strong precipitation with inorganic colloids and adsorption on DOM. The lysimeter sampling and size fractionation method provided a clear insight into agricultural effects on TE distributions and enhancing understanding of agricultural soil health in terms of TE bioavailability in situ.
在不同条件下，农业土壤中微量元素（TEs）的化学形态变化很大，这就需要使用分辨率高且干扰小的工具来进行探究。一种新型的外科手术用（316L）不锈钢（SS）渗漏计被开发出来，其孔径为5μm，用于收集田间土壤溶液。在渗漏计土壤溶液中，按大小解析的TEs分布被分为总量（硝酸消解）、颗粒态（0.45 - 5μm）、溶解态（<0.45μm）、胶体态（1kDa至0.45μm）以及主要为离子态（<1kDa）的组分。分析了酸性消解的灰化淋溶土中TEs的总浓度（以干重计）。渗漏计土壤溶液中的大多数TEs以颗粒态存在，这与其地球化学亲和力以及在土壤矿物中的赋存情况有关。在溶解组分中，砷、钡、钴、锂、锰、铊和钒在土壤溶液中主要以离子形态存在。在不同农业处理中，铜、铅、铝、钍和铀与溶解有机物（DOM）和/或无机胶体呈现出不同的结合情况。与其他地点（pH 5.82 - 6.37）相比，施用pH较低（5.25 - 5.74）的无机NPKS或NKS肥料会增强主要以离子形态存在的钡、钴、锂、锰和铅的迁移性和潜在生物有效性。施用粪肥呈现出双重作用，一方面可能由于阳离子交换容量（CEC）增强而提高了砷、铊和钒的生物有效性，另一方面也促进了铜和铀在DOM上的特异性吸附，这可能会根据DOM分子量降低它们的生物有效性。森林土壤中胶体态和离子态铝和钍的浓度高于农业土壤，钍的潜在生物有效性极低，这归因于其与无机胶体的强烈沉淀作用以及在DOM上的吸附。渗漏计采样和按大小分级的方法为农业对TEs分布的影响提供了清晰的认识，并增进了对农业土壤健康状况（就TEs原位生物有效性而言）的理解。
