Li Shanshan, Fei Yang, Wang Chen, Sun Jiajun, Liang Jiahui, Feng Yao, Yang Bing, Wang Meng, Shi Huading, Chen Shibao
Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China.
State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
J Hazard Mater. 2024 Sep 15;477:135392. doi: 10.1016/j.jhazmat.2024.135392. Epub 2024 Jul 31.
Iron (Fe) oxides have a strong adsorption affinity for Cd and organic carbon (SOC). However, under alternate wet-dry (IF) condition,the influences of Fe oxides on the speciation and disrtribution of Cd and SOC in soil aggregates are unkown. In the present study, soils untreated (S), removed (S-Fe) or added (S+Fe) Fe oxide soils were blended with cadmium chloride solution and cultivated for 56 days under different moisture management practices. Compared with the S-Fe soil, the IF treatment increased the contents of Fe oxide-bound SOC (Fe-OC) and Fe/Mn oxide-bound Cd (Fe/Mn-Cd) by 18.5-29.8-fold and 1.45-2.45-fold, repectively, in the S and S+Fe soils, corresponding to a 36 %-42 % increase in the recalcitrant C pool (RCP) and a 53 %-87 % decrease in the exchangeable Cd content. These results could be attributed to soil particle aggregation and Fe redistribution. Fe addition promoted the transfer of Cd/SOC accumulated in microaggregates to macroaggregates and increased the variable negative charge content in macroaggregates and the adsorption capacity of macroaggregates for Cd/SOC. More Cd/SOC accumulated in macroaggregates in Fe oxide-bound form, which reduced the risk of Cd migration and Cd availability and increased the physical protection of SOC. Therefore, Fe oxide has great potential to simultaneously reduce carbon emissions and cadmium toxicity in paddy soil.
铁（Fe）氧化物对镉和有机碳（SOC）具有很强的吸附亲和力。然而，在干湿交替（IF）条件下，铁氧化物对土壤团聚体中镉和有机碳的形态及分布的影响尚不清楚。在本研究中，将未处理（S）、去除铁氧化物（S-Fe）或添加铁氧化物（S+Fe）的土壤与氯化镉溶液混合，并在不同水分管理措施下培养56天。与S-Fe土壤相比，IF处理使S和S+Fe土壤中氧化铁结合有机碳（Fe-OC）和铁/锰氧化物结合镉（Fe/Mn-Cd）的含量分别增加了18.5 - 29.8倍和1.45 - 2.45倍，相应地，难降解碳库（RCP）增加了36% - 42%，可交换镉含量降低了53% - 87%。这些结果可归因于土壤颗粒团聚和铁的重新分布。添加铁促进了微团聚体中积累的镉/有机碳向大团聚体的转移，并增加了大团聚体中的可变负电荷含量以及大团聚体对镉/有机碳的吸附能力。更多的镉/有机碳以氧化铁结合的形式积累在大团聚体中，这降低了镉迁移和镉有效性的风险，并增加了对有机碳的物理保护。因此，铁氧化物在同时降低稻田土壤碳排放和镉毒性方面具有巨大潜力。
