改良剂调控下水稻镉累积和土壤溶解性有机质光谱特征的响应

研究土壤中溶解性有机质(DOM)的化学组成和特征差异对理解改良剂对Cd的稳定机制具有重要意义.土壤改良剂被广泛应用于受污染农田以缓解重金属在农作物中的累积，但改良剂调控下土壤DOM的光谱特征却鲜见报道.采集南方典型Cd污染水稻土为研究对象，通过投加三大类改良剂(有机类、无机类和石灰类，共11种)进行水稻种植盆栽试验，研究了不同改良剂对土壤DOM的影响.利用紫外-可见光谱、三维荧光光谱和平行因子分析法(PARAFAC)对比分析了不同改良剂调控下根际土壤DOM的光谱特征.结果表明，石灰类改良剂提高土壤pH,促进土壤固相中有机质的溶解，从而显著提高了土壤DOM的质量分数.与对照相比，有机类改良剂提高了土壤DOM的相对分子量和新生自生源贡献率，无机类改良剂提高了土壤DOM的芳香性和疏水性组分，石灰类改良剂提高了土壤DOM的显色组分和腐殖化程度.通过PARAFAC分析和OpenFluor数据库验证，解析出了4个荧光组分C1(255/465)、 C2(325/400)、 C3(275/390)和C4(240/460),均为类腐殖质.两种光谱相互印证，表明土壤DOM来源以陆源输入的类腐殖质为主.相关...

Responses of Cd Accumulation in Rice and Spectral Characteristics of Soil Dissolved Organic Matter Regulated by Soil Amendments

Studying the chemical composition and characteristic differences of soil dissolved organic matter (DOM) is significant for understanding the mechanism of Cd immobilization by soil amendments. Soil amendments have been widely applied to contaminated farmlands to reduce the accumulation of heavy metals in crops, but the spectral characteristics of DOM in soils under amendment regulation have rarely been studied. Typical Cd-contaminated paddy soil from South China was collected, three categories of amendments (organic-based, inorganic-based, and lime-based, a total of 11 types) were applied, rice planting pot trials were done, and the effects of different amendments on soil DOM were investigated. The spectral characteristics of rhizosphere soil DOM under the regulation of different amendments were comparatively analyzed using UV-Vis spectroscopy, 3D fluorescence spectroscopy, and parallel factor analysis (PARAFAC). The results showed that the lime-based amendments increased the soil pH and promoted the dissolution of organic matter from the soil solid phase, resulting in a significant increase in soil DOM content. Compared with that of the control, organic-based amendments increased the relative molecular weight and recent autochthonous origin contribution of soil DOM, inorganic-based amendments increased the aromatic content and hydrophobic components of soil DOM, and lime-based amendments increased the chromogenic components and the degree of humification of soil DOM. Four fluorescence components, C1 (255/465), C2 (325/400), C3 (275/390), and C4 (240/460), were identified using PARAFAC and verified with the OpenFluor database, all of which were humic-like. Two types of spectra corroborated with each other, indicating that soil DOM dominated by humus-like matter originated from terrestrial source input. The correlation analysis showed that the fluorescent component C4 of soil DOM could be used to predict Cd accumulation in brown rice in the red limestone soil-rice system. These results will provide a reference for the selection of the appropriate soil amendments.