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Chinese Agricultural Science Bulletin ›› 2023, Vol. 39 ›› Issue (8): 51-62.doi: 10.11924/j.issn.1000-6850.casb2022-0239

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Evaluation of Heavy Metal Passivation in Contaminated Paddy Fields Based on Soil Quality and Rice Safety

ZHAO Shouping1(), XIAO Wendan1, CHEN De1, YE Xuezhu1(), ZHANG Qi1, WU Shaofu2, HU Jing1, GAO Na1, HUANG Miaojie1   

  1. 1 Key Laboratory of Information Traceability for Agricultural Products, Institute of Agro-product Safety and Nutrition,Zhejiang Academy of Agricultural Sciences, Hangzhou 310021
    2 Shaoxing Grain and Oil Crop Technology Extension Center,Shaoxing, Zhejiang 312000
  • Received:2022-03-29 Revised:2022-06-08 Online:2023-03-15 Published:2023-03-14

Abstract:

With the popularization and application of heavy metal passivation technology in polluted arable land, comprehensive and integrated evaluation techniques are urgently needed for the treatment and remediation effects of heavy metal polluted rice fields. In this study, the commonly used passivation application patterns, including CK, lime 4500 kg/hm2 (LM), sepiolite 12000 kg/hm2 (SEP), lime +biochar 1:1 mixed application 9000 kg/hm2 (F1), lime+ biochar + calcium magnesium phosphate 1:1:0.5 mixed application 9000 kg/hm2 (F2) and lime+ biochar + sepiolite 1:1:1 mixed application 9000 kg/hm2 (F3), were compared in typical contaminated plots in Zhuji City (ZJ) and Yuecheng District (YC) of Shaoxing City, Zhejiang Province. The emphasis was on the effect of passivation on pollution indicators and soil quality. The remediation effect was evaluated by rice yield, heavy metal content in rice and heavy metal DTPA extractable amount in soil; the soil quality was evaluated by soil physicochemical indexes (soil organic matter, CEC, available nitrogen and clay) and biological indexes (microbial biomass carbon and soil sucrose activity) to build a comprehensive evaluation system. The evaluation results showed that: compare to those of CK, DTPA extractable Cd of F1 (YC) and LM (ZJ) soil decreased by <15%, organic matter and available nitrogen of F1 (ZJ) and LM (ZJ) soil decreased by >10%, the sucrose activity of F1 (YC) decreased by 43.4%, so the comprehensive evaluation conclusion for F1 and LM was ‘poor’. For SEP (ZJ) soil, the organic matter decreased by 20%, the microbial carbon decreased by 25.7%, the comprehensive evaluation conclusion was ‘poor’. The rice yield of F2 and F3 decreased by <8%, heavy metal content in rice were lower than the limited value of GB2762, and soil DTPA extractable Cd, Cr and Pb were reduced by more than 15%, 30% and 25%, respectively; and the reduction of soil physical, chemical and biological indexes were <10%, the overall evaluation conclusion of F2 and F3 was ‘excellent’. According to the constructed comprehensive evaluation system, F2 and F3 are the most effective treatments in remediating heavy metal contaminated paddy soil in the study sites.

Key words: rice, heavy metal, remediation, evaluation, soil quality