State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Environ Sci Process Impacts. 2021 Mar 1;23(3):417-428. doi: 10.1039/d0em00501k. Epub 2021 Mar 2.
The heavy metal pollution induced by agricultural land use change has attracted great attention. In this study, the divergent response of the bioavailability of heavy metals in rhizosphere soil to different agricultural land uses was analyzed using sequential extraction, and possible influence paths were constructed. The results show that land use change can affect the heavy metal bioavailability by influencing the soil organic matter and redox potential (Eh). The average concentrations of N, P, K, Ca, Mg, S, and Fe in the soil showed no significant differences. However, the conversion direction and extent of chemical speciation of heavy metals were different across land use changes from paddy fields to various drylands. After conversion from paddy to wheat field, the bioavailability of heavy metals decreased due to an increase in permanganate oxidizable carbon (KMnO-C) and a decrease in Eh. The transformation from paddy to celery soil is accompanied by a change in the soil's KMnO-C content, increasing the proportion of the bioavailable states of heavy metals. However, the response of bioavailability to changes in the soil KMnO-C varied among heavy metals. In contrast, when land use changed to grapevine culture, the bioavailability of heavy metals increased due to a change in the KMnO-C content. Moreover, the dissolved organic carbon (DOC) content increased, which positively affected the Eh and, in turn, increased the bioavailability of heavy metals. This research is of great significance for understanding the impact of land use change on the heavy metal migration and activity in the rhizosphere microenvironment of soil.
农业土地利用变化引起的重金属污染受到了极大关注。本研究采用连续提取法分析了不同农业土地利用方式下根际土壤中重金属生物有效性的差异响应，并构建了可能的影响途径。结果表明，土地利用变化可以通过影响土壤有机质和氧化还原电位（Eh）来影响重金属的生物有效性。土壤中 N、P、K、Ca、Mg、S 和 Fe 的平均浓度没有显著差异。然而，重金属化学形态的转化方向和程度在从水田到各种旱地的土地利用变化中是不同的。从水田转化为麦田后，由于高锰酸盐可氧化碳（KMnO-C）增加和 Eh 降低，重金属的生物有效性降低。从水田到芹菜地的转化伴随着土壤 KMnO-C 含量的变化，增加了重金属生物有效态的比例。然而，生物有效性对土壤 KMnO-C 变化的响应因重金属而异。相比之下，当土地利用方式转变为葡萄种植时，由于 KMnO-C 含量的变化，重金属的生物有效性增加。此外，溶解有机碳（DOC）含量增加，这对 Eh 产生了积极影响，从而增加了重金属的生物有效性。本研究对于理解土地利用变化对土壤根际微环境中重金属迁移和活性的影响具有重要意义。
