摘要
【目的】研究聚乙烯微塑料(polyethylene microplastics, PE-MPs)与铁添加(单独/联合)对镉污染稻田土壤碳氮组分及镉形态的影响,从污染物联合作用角度揭示其对稻田土壤环境行为的调控效应。【方法】以广东地区水稻土为研究对象,设置对照(CK)、聚乙烯微塑料(PE)、铁(Fe)、铁+聚乙烯微塑料(Fe-PE)4个处理,测定土壤碳氮组分和镉形态相关指标;通过主成分和相关性分析,探讨复合污染下铁元素对土壤的碳氮组分、镉形态变化特征的影响。【结果】(1)与CK相比,PE、Fe、Fe-PE处理的土壤电导率分别显著提高135.83%、204.43%、160.98%,但仅Fe-PE处理显著降低土壤pH(P<0.05)。(2)与CK相比,PE处理的土壤可溶性有机碳(dissolved organic carbon, DOC)含量显著提高37.60%,Fe处理的可溶性有机氮(dissolved organic nitrogen, DON)含量显著提高162.31%(P<0.05),而Fe-PE处理的易氧化有机碳(easily-oxidized organic carbon, EOC)、微生物量碳(microbial biomass carbon, MBC)、微生物量氮(microbial biomass nitrogen, MBN)、可溶性有机氮含量分别显著增加18.10%、17.29%、60.97%、158.60%(P<0.05),各处理的土壤碳库管理指数(carbon pool management index, CPMI)呈现FePE>PE>CK>Fe。(3)与CK相比,Fe和Fe-PE处理的全镉含量显著降低40.98%和41.18%,其弱酸提取态镉含量显著降低70.67%和77.18%,PE单独处理的可还原态镉含量显著增加16.88%。主成分分析表明CK、PE、Fe和FePE处理之间差异显著,相关性分析表明土壤pH与全镉含量、弱酸提取态镉含量呈显著正相关关系,EOC与MBC、MBN也呈显著正相关关系。【结论】PE-MPs和铁元素对土壤碳氮组分、镉形态均有一定影响,两者联合作用能有效提高土壤碳活性组分(DOC、EOC)及CPMI,增强碳库稳定性,并通过促进铁氧化物对镉的吸附和共沉淀作用固定镉,降低其生物有效性。研究有助于精准评估富铁土壤微塑料与镉的复合生态风险,为提升微塑料与镉复合污染生态风险的认知提供科学依据。
【Objective】This study aimed to investigate the effects of polyethylene microplastics(PE-MPs)and iron addition—applied individually or in combination—on carbon and nitrogen fractions and cadmium speciation in cadmium-contaminated paddy soils.The objective was to elucidate the regulatory effects of these co-occurring pollutants on soil environmental behavior from the perspective of their combined interactions.【Methods】A typical paddy soil from Guangdong Province,China,was selected as the study material.Four treatments were established:control(CK),polyethylene microplastics(PE),iron(Fe),and a combined treatment of iron and polyethylene microplastics(Fe-PE).Soil carbon and nitrogen fractions as well as cadmium speciation were measured.Principal component analysis and correlation analysis were employed to explore the effects of Fe addition under co-contamination conditions on changes in carbon and nitrogen fractions,and cadmium speciation.【Results】(1)Compared with CK,PE,Fe,and Fe-PE treatments significantly increased soil electrical conductivity by 135.83%,204.43%,and 160.98%.However,only the Fe-PE treatment significantly decreased soil pH(P<0.05).(2)PE treatment alone significantly increased the content of dissolved organic carbon(DOC)by 37.60%,while Fe treatment alone significantly increased the dissolved organic nitrogen(DON)content by 162.31%(P<0.05).In the Fe-PE treatment,easily-oxidized organic carbon(EOC),microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),and DON contents increased significantly by 18.10%,17.29%,60.97%,and 158.60%(P<0.05).The carbon pool management index(CPMI)followed the order:Fe-PE>PE>CK>Fe.(3)Compared with CK,Fe and Fe-PE treatments significantly reduced total cadmium content by 40.98%,41.18%and acid-extractable cadmium fractions by 70.67%,77.18%,while PE treatment alone significantly increased the reducible cadmium fraction by 16.88%.Principal component analysis revealed clear separations among CK,PE,Fe,and Fe-PE treatments.Correlation analysis indicated that soil pH was significantly positively correlated with both total cadmium and acid-extractable cadmium contents,while EOC was positively correlated with MBC and MBN.【Conclusion】Both PE-MPs and iron exert notable effects on soil carbon and nitrogen fractions.The combined application of PE-MPs and iron effectively enhanced the labile carbon components(DOC and EOC)and improved the CPMI,thereby contributing to greater carbon pool stability.Moreover,this combination significantly reduced the bioavailability of cadmium by promoting its adsorption and co-precipitation with iron oxides.This study facilitates a precise assessment of the composite risk from microplastics and cadmium in iron-rich soils,providing a scientific basis for improved understanding of their co-pollution ecology.
作者
杨倩楠
陈静
庞煜龚
陈发明
刘科学
YANG Qiannan;CHEN Jing;PANG Yugong;CHEN Faming;LIU Kexue(School of Resources and Planning,Guangzhou Xinhua University,Guangzhou,Guangdong 510520,China;School of Chinese Medicine and Health,Nanfang College·Guangzhou,Guangzhou,Guangdong 510970,China;Institute of South China Urban-Rural Economic and Social Development,Guangzhou,Guangdong 510642,China;The College of Natural Resources and Environment,South China Agricultural University,Guangzhou,Guangdong 510642,China)
出处
《福建农业学报》
北大核心
2026年第1期118-127,共10页
Fujian Journal of Agricultural Sciences
基金
广东省哲学社会科学规划项目(GD25WTJ01-10)
广州新华学院校级科研基金项目(2020KYQN01)。
关键词
聚乙烯微塑料
铁元素
碳组分
氮组分
镉形态
polyethylene microplastics
iron
carbon fractions
nitrogen fractions
cadmium speciation
