摘要
镉(Cd)是我国农田土壤污染最严重的重金属元素之一,土壤溶解性有机质(DOM)对Cd在土壤环境中的迁移和转化具有重要影响,但稻田土壤中Cd的迁移性和生物有效性与DOM光谱特征参数的关系是否受稻虾共作模式的影响尚不明确。因此,本研究以传统稻作模式(CK)为对照,以稻虾共作模式(RS)为研究对象,通过紫外-可见光谱和三维荧光光谱,解析RS模式在水稻生育期[稻前期(T1)、分蘖期(T2)、孕穗期(T3)和黄熟期(T4)]土壤DOM光谱特征及组成变化;利用相关性与逐步回归模型,建立RS和CK模式土壤DOM与交换态镉(Cd_(ex))含量的关系。研究结果如下:1)与其他生育期相比,两种模式在T4时芳香性和疏水性DOM最多;RS模式土壤DOM分子量随水稻生长呈下降趋势,且T4时期DOM更倾向生物源。2)RS与CK模式下土壤DOM均主要由类色氨酸(C1)、腐殖质(C2和C3)和类富里酸(C4)组成,但各组分占比在生育期无显著变化规律;CK和RS模式荧光指数均>1.9,腐殖化指数(HIX)均<4;RS的自生源指数为0.70~0.76,高于CK模式(0.62~0.66),表明两种模式DOM均具有一定程度的内源性本土特征。3)两种模式下,土壤Cd_(ex)含量均随水稻生育期推进呈上升趋势,但RS模式在T2—T4时期的Cd_(ex)含量和变化幅度均低于CK模式。两种模式Cd_(ex)含量均与HIX、光谱斜率比(SR)和C4含量呈显著或极显著相关(P<0.05或P<0.01或P<0.001),表明Cd_(ex)含量与DOM腐殖化程度、分子量大小、来源及组分密切相关。逐步回归分析表明,与DOM分子量大小相关的因子(SR)对Cd_(ex)含量的预测具有重要影响。本研究结果可为理解稻虾共作模式对土壤Cd污染的潜在影响提供理论参考。
Cadmium(Cd)is one of the most severe heavy metal pollutant in farmland soils in China.Soil dissolved organic matter(DOM)significantly influences Cd migration and transformation in soil environments,however,whether the relationship between Cd mobility,bioavailability,and DOM spectral characteristics in paddy soils is affected by the rice-crayfish coculture mode(RS)remains unclear.Therefore,this study used traditional rice monoculture(CK)as the control and RS as the research object.Using ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscopy,we analyzed changes in DOM spectral characteristics and composition in RS-mode soils during different rice growing stages[early rice stage(T1),tillering stage(T2),booting stage(T3),and yellow ripening stage(T4)].Correlation analysis and stepwise regression models were used to establish the relationships between soil DOM and exchangeable Cd(Cd_(ex))content in the RS and CK modes.The results were as follows.1)Compared with other growing stages,both modes exhibited the highest aromaticity and hydrophobic DOM at T4.The molecular weight of DOM under RS mode showed a decreasing trend during rice growing,with DOM in T4 being more biogenic-oriented.2)Soil DOM in both the RS and CK modes primarily consisted of tryptophan-like components(C1),humus components(C2 and C3),and fulvic-like components(C4).However,the proportional distribution of these components showed no significant variation across different growing stages.The fluorescence index(FI)values of both CK and RS modes exceeded 1.9,whereas the humification index(HIX)values were below 4.The biological index(BIX)of RS mode(0.70–0.76)was higher than that of CK mode(0.62–0.66),indicating that DOM in both modes possessed endogenous native characteristics to some extent.3)In both modes,Cd_(ex) content increased progressively along with the rice growing.However,the RS mode exhibited a lower Cd_(ex) content and smaller fluctuations from T2 to T4 compared to CK mode.The Cd_(ex) content in both modes showed significant or highly significant correlations(P<0.05 or P<0.01 or P<0.001)with HIX,the spectral slope ratio(SR)and fulvic-like components contents(C4),demonstrating close associations between the Cd_(ex) content and the DOM humification degree,molecular weight,source,and composition.Stepwise regression analysis revealed that factors related to DOM molecular weight(SR)critically influenced Cd_(ex) content prediction providing a theoretical references for understanding the potential impacts of rice-crayfish coculture systems on soil Cd pollution.
作者
杜春朝
梁以豪
倪才英
蒋志忠
傅雪军
DU Chunzhao;LIANG Yihao;NI Caiying;JIANG Zhizhong;FU Xuejun(School of Geography and Environment,Jiangxi Normal University/Key Laboratory of Poyang Lake Wetland and Watershed Research,Ministry of Education,Nanchang 330022,China;Yingtan Agricultural Technology Extension Center,Yingtan 335299,China;Aquatic Conservation and Rescue Center of Jiangxi Province,Nanchang 330029,China)
出处
《中国生态农业学报(中英文)》
北大核心
2025年第8期1517-1528,共12页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(42167006)
江西省现代农业产业技术体系建设专项项目(JXARS-12-环境控制)资助。
关键词
稻虾共作
溶解性有机质
光谱特征
交换态镉
rice-crayfish coculture
dissolved organic matter
spectral characteristics
exchangeable cadmium
