Combination Mechanism of Soil Dissolved Organic Matter and Cu 2+ in Vegetable Fields, Forests and Dry Farmland in Lujiang County

Youru Yao, Jingyi Zhang, Kang Ma, Jing Li (), Xin Hu, Yusi Wang, Yuesheng Lin, Fengman Fang and Shiyin Li ()
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Youru Yao: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Jingyi Zhang: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Kang Ma: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Jing Li: Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, National Agricultural Experiment Station for Agricultural Environment, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
Xin Hu: Center for Microscopy and Analysis, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Yusi Wang: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Yuesheng Lin: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Fengman Fang: Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Province, School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China
Shiyin Li: School of Environment, Nanjing Normal University, Nanjing 210023, China

Agriculture, 2024, vol. 14, issue 5, 1-20

Abstract: Dissolved organic matter (DOM) serves as a critical link in the migration and transformation of heavy metals at the soil–solid interface, influencing the migration behaviour and transformation processes of Cu 2+ in soil. There have been studies on the combination mechanisms between DOM and Cu 2+ in paddy soils. However, the adsorption/complexation and redox processes between DOM and Cu 2+ in other agricultural soil types (such as dry farmland and vegetable fields) are unclear. In order to reveal the combination process of DOM with Cu in different agricultural soil types and the dynamic changes in chemical behaviour that occur, this study analysed the variability of DOM components and structure in three soils using three-dimensional fluorescence spectroscopy and X-ray photoelectron spectroscopy. In addition, the priority order of different DOM compounds in combination with Cu and the change process in relation to the Cu valence state in the soil of Lujiang County, Anhui Province, was revealed based on laboratory experiments. The results showed that the composition of soil DOM was mainly composed of humic-like and fulvic-like substances with a clear terrestrial origin and that the organic matter showed a high degree of decomposition characteristics. The results indicated that the composition of soil DOM is mainly composed of humic and fulvic acid-like substances, and they have obvious characteristics of terrestrial origin. In addition, the soil organic matter showed high decomposition characteristics. The complex stability constants (lgK M ) of humic acid-like substances with Cu 2+ follow the order of forest land (lgK M = 5.21), vegetable land (lgK M = 4.90), and dry farmland (lgK M = 4.88). The lgK M of fulvic acid-like substances with Cu 2+ is in the order of dry farmland (lgK M = 4.51) and vegetable land (lgK M = 4.39). Humic acid-like substances in soil DOM combine preferentially with Cu 2+ , showing a stronger chelating affinity than fulvic acid-like substances. Cu 2+ complexes mainly include hydroxyl, phenolic hydroxyl and amino functional groups are included in soil DOM, accompanied by redox reactions. In comparison to dry farmland, the soil DOM in forest and vegetable fields undergoes more intense redox reactions simultaneously with the chelation of Cu 2+ . Therefore, the application of organic fertilisers to vegetable and forest soils may lead to uncertainties concerning the fate of heavy metals with variable chemical valence. These results contribute to a deeper understanding of the interaction mechanisms between DOM and Cu 2+ in agricultural soils.

Keywords: dissolved organic matter; copper; combination mechanism; humic acid-like substances (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2024
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