Abstract Structural characterization of fulvic acids (FAs) along with the essential heavy metals (Fe, Co, Zn, and Cr) was carried out in the surface soil samples of prominent mango orchards in Palakkad district, Kerala, India. The FAs were examined with the help of elemental analyzer, UV-Visible, and FT-IR spectroscopy. The heavy metal distribution in the soil was observed in the following order: Fe > Cr > Zn > Co. The statistical analysis indicated the lithogenic and agricultural origin of metals in the study area. The detected level of Fe from the sampling sites was higher than the WHO guideline, while Co and Cr concentration exceeded the USEPA guideline values. The influence of cation exchange capacity, clay content, and CaCO3 of soil over the fate of heavy metals was identified through canonical correspondence analysis. The aliphatic and oxidation degree of FAs was examined using UV-Visible absorbance ratios, atomic ratios, and elemental composition. Results revealed that aliphatic moieties and polar functional groups enrich the FAs in the study area. Pearson correlation analysis exposed the dominant role of FAs in the fate of metals along with the other soil properties. These outcomes provide necessary information that might be useful in the assessment of risk/deficiency associated with the heavy metals in agricultural soils of the study region. It emphasizes the necessity of soil constituent evaluation before crop cultivation to attain sustainable farming practices.

中文翻译：

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富里酸的结构特征及其在印度喀拉拉邦 Palakkad 农业区的影响

摘要 在印度喀拉拉邦 Palakkad 区著名芒果园的表层土壤样品中对富里酸 (FAs) 以及必需重金属 (Fe、Co、Zn 和 Cr) 进行了结构表征。在元素分析仪、紫外-可见光和 FT-IR 光谱的帮助下检查了 FA。重金属在土壤中的分布顺序为：Fe>Cr>Zn>Co。统计分析表明研究区金属的岩性和农业来源。采样点检测到的Fe含量高于WHO指南，而Co和Cr浓度超过USEPA指南值。通过典型对应分析确定了土壤的阳离子交换能力、粘土含量和 CaCO3 对重金属归宿的影响。使用紫外-可见光吸收比、原子比和元素组成检测 FA 的脂肪族和氧化程度。结果表明，脂肪族部分和极性官能团丰富了研究区域的 FA。Pearson 相关分析揭示了 FAs 在金属和其他土壤特性中的主导作用。这些结果提供了必要的信息，可能有助于评估与研究区域农业土壤中重金属相关的风险/缺乏。它强调了在作物种植前进行土壤成分评估以实现可持续耕作实践的必要性。结果表明，脂肪族部分和极性官能团丰富了研究区域的 FA。Pearson 相关分析揭示了 FAs 在金属和其他土壤特性中的主导作用。这些结果提供了必要的信息，可能有助于评估与研究区域农业土壤中重金属相关的风险/缺乏。它强调了在作物种植前进行土壤成分评估以实现可持续耕作实践的必要性。结果表明，脂肪族部分和极性官能团丰富了研究区域的 FA。Pearson 相关分析揭示了 FAs 在金属和其他土壤特性中的主导作用。这些结果提供了必要的信息，可能有助于评估与研究区域农业土壤中重金属相关的风险/缺乏。它强调了在作物种植前进行土壤成分评估以实现可持续耕作实践的必要性。