College of Environment and Ecology, Hunan Agricultural University, Changsha, 410128, Hunan, China.
College of Environment and Ecology, Hunan Agricultural University, Changsha, 410128, Hunan, China.
J Environ Manage. 2023 Oct 15;344:118477. doi: 10.1016/j.jenvman.2023.118477. Epub 2023 Jun 24.
Despite the potential importance of the removal of contaminated straw for heavy metal output from agricultural soils, previous studies have primarily focused on the variation in the metal concentration without considering the impact input of heavy metals from atmospheric deposition. Here, rice was grown under field conditions, and, as a reference, in a deposition-free environment, and exposed to different ambient air Cd levels. Two consecutive years of pot experiments were conducted in two study areas (ZZ and LY) to examine the changes in soil physicochemical properties as well as Cd accumulation in the soil-rice (Oryza sativa L.) system in response to straw return or removal. The results showed that rice straw return enhanced the soil pH and organic matter (OM) content, but reduced the soil redox potential (E); and the variation in amplitude increased with number of cultivation years. After two years of cultivation, the concentrations of soil total Cd and extractable Cd in the straw-removal treatments reduced by 9.89-29.49% and 4.88-37.74%, respectively, whereas those in the straw-return treatments exhibited a slight decrease, or even an increase. This indicated that straw removal could effectively reduce the concentration and bioavailability of Cd in contaminated farmland, which was further confirmed by the results for accumulation of Cd in rice tissues. In addition, the contribution from atmospheric deposition was confirmed by the greater variation in Cd concentration in soils and rice tissues under deposition-free conditions. A major implication of our findings is that the adoption of reasonable straw-treatment measures and proper control over ambient air heavy metals can promote the remediation efficiency of Cd-contaminated fields.
尽管去除受污染的秸秆对于减少农业土壤中重金属的输出具有重要意义，但先前的研究主要集中在金属浓度的变化上，而没有考虑大气沉降输入重金属的影响。在这里，水稻在田间条件下种植，并作为参考，在无沉积环境下种植，同时暴露于不同的环境空气 Cd 水平。在两个研究区（ZZ 和 LY）进行了为期两年的盆栽实验，以研究秸秆还田或去除对土壤理化性质以及土壤-水稻（Oryza sativa L.）系统中 Cd 积累的变化。结果表明，秸秆还田会提高土壤 pH 值和有机质（OM）含量，但降低土壤氧化还原电位（E）；并且振幅的变化随种植年限的增加而增加。经过两年的种植，秸秆去除处理的土壤总 Cd 和可提取 Cd 浓度分别降低了 9.89-29.49%和 4.88-37.74%，而秸秆还田处理的浓度则略有下降，甚至有所增加。这表明秸秆去除可以有效降低污染农田中 Cd 的浓度和生物可利用性，这一点从 Cd 在水稻组织中的积累结果得到了进一步证实。此外，无沉积条件下土壤和水稻组织中 Cd 浓度的更大变化证实了大气沉降的贡献。我们研究结果的一个主要含义是，采用合理的秸秆处理措施和对环境空气重金属的适当控制，可以促进 Cd 污染农田的修复效率。
