Abstract：
In situ immobilization is a widely used measure for passivating Cd-contaminated soils. Amendments need to be continuously applied to achieve stable remediation effects. However, few studies have evaluated the impact of consecutive application of amendments on soil health and the microecological environment. A field experiment was conducted in a Cd-contaminated paddy (available Cd concentration 0.40 mg kg-1) on the Chengdu Plain to investigate the changes in soil Cd availability and response characteristics of soil bacterial communities after consecutive application of rice straw biochar (SW), fly ash (FM) and marble powder (YH) amendments from 2018 to 2020. Compared with control treatment without amendments (CK), soil pH increased by 0.6, 0.5 and 1.5 under SW, FM and YH amendments, respectively, and the soil available Cd concentration decreased by 10.71%, 21.42% and 25.00%, respectively. The Cd concentration in rice grain was less than 0.2 mg kg-1 under YH amendment, which was within the Chinese Contaminant Limit in Food of National Food Safety Standards (GB2762-2022) in the second and third years. The three amendments had different effects on the transformation of Cd fractions in soil, which may be relevant to the specific bacterial communities shaped under different treatments. The proportion of Fe-Mn oxide-bound fraction Cd (OX-Cd) increased by 11% under YH treatment, which may be due to the promotion of Fe(III) and Cd binding by some enriched iron-oxidizing bacteria, such as Lysobacter, uncultured_Pelobacter sp. and Sulfurifusis. Candidatus_Tenderia and Sideroxydans were enriched under SW and FM amendments, respectively, and were likely beneficial for reducing Cd availability in soil through Cd immobilization. These results revealed the significance of the bacterial community in soil Cd immobilization after consecutive application of amendments and highlighted the potential of applying YH amendment to ensure the safe production of rice in Cd-contaminated soil.
摘要：
原位固定化是钝化Cd污染土壤的广泛使用的措施。需要不断实施修正案，以实现稳定的补救效果。然而,很少有研究评估连续施用改良剂对土壤健康和微生态环境的影响。在成都平原上的Cd污染稻田（有效Cd浓度为0.40mgkg-1）进行了田间试验，以研究连续施用稻草生物炭（SW）后土壤Cd有效性的变化和土壤细菌群落的响应特征。2018年至2020年的粉煤灰（FM）和大理石粉（YH）修正案。与未修正的对照处理(CK)相比，SW下土壤pH分别增加0.6、0.5和1.5，FM和YH修正案，分别,土壤有效Cd浓度下降了10.71%，21.42%和25.00%，分别。在YH改性下，水稻籽粒中的Cd浓度小于0.2mgkg-1，第二年和第三年均在中国食品安全国家标准（GB2762-2022）的食品污染物限量之内。三种改良剂对土壤中Cd组分的转化有不同的影响,这可能与在不同处理下形成的特定细菌群落有关。在YH处理下，Fe-Mn氧化物结合部分Cd（OX-Cd）的比例增加了11％，这可能是由于某些富集的铁氧化细菌促进了Fe（III）和Cd的结合，比如溶菌酶,未培养的_Pelobactersp.还有硫磺.念珠菌_Tenderia和Sideroxydans在SW和FM修正案下得到了丰富，分别,并可能有利于通过Cd固定化降低土壤中Cd的有效性。这些结果揭示了连续施用改良剂后土壤Cd固定化中细菌群落的重要性，并强调了施用YH改良剂以确保Cd污染土壤中水稻安全生产的潜力。
