Multi-element fingerprinting of soils can reveal conversion of wetlands to croplands

Xiaoyan Zhu; Yuxiang Yuan; Ming Jiang; Changchun Song; Yuncong Li; Guodong Wang; Marinus L Otte

doi:10.1016/j.scitotenv.2020.141997

Multi-element fingerprinting of soils can reveal conversion of wetlands to croplands

Sci Total Environ. 2021 Jan 15:752:141997. doi: 10.1016/j.scitotenv.2020.141997. Epub 2020 Aug 25.

Authors

Xiaoyan Zhu¹, Yuxiang Yuan², Ming Jiang³, Changchun Song⁴, Yuncong Li⁵, Guodong Wang³, Marinus L Otte⁶

Affiliations

¹ Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Xincheng St., Dist. 5088, Changchun 130118, China; Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
² Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; Wet Ecosystem Research Group, Biological Sciences, Dept. 2715, North Dakota State University, PO Box 6050, Fargo, ND 58108-6050, USA. Electronic address: yuanyuxiang06@163.com.
³ Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; Jilin Provincial Joint Key Laboratory of Changbai Mountain Wetland and Ecology, Changchun, Jilin 130102, China.
⁴ Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
⁵ Tropical Research and Education Center, University of Florida, 18905 SW 280th Street, Homestead, FL 33031-3314, USA.
⁶ Wet Ecosystem Research Group, Biological Sciences, Dept. 2715, North Dakota State University, PO Box 6050, Fargo, ND 58108-6050, USA.

PMID: 32889293
DOI: 10.1016/j.scitotenv.2020.141997

Abstract

Little is known about the influence of conversion of wetlands to farmlands on concentrations and distribution of elements other than those most commonly studied, partly because of the lack of stratification in wetland soils. In this study, in the Sanjiang Plain in northeastern China, we determined the concentrations of 63 elements along soil profiles at three depths: 0-20 cm, 20-40 cm, and below the depth to which farmers would plow, at 40-60 cm, under four land uses: natural wetland, drained wetland, wetland converted to soybean field and subsequently to rice paddy field. Based on our previous work, we expected that changes in organic matter content would be an important factor affecting element concentrations, but that changes in land uses also led to decoupling of the influence of organic matter on elements. This would lead to other factors, such as changes in redox conditions, changes in hydrology and mixing of soils due to plowing, becoming more important factors affecting element distributions. Our study confirmed these expectations. Changes in organic matter content directly or indirectly affected many elements, explaining 67% of variation. Arsenic, cobalt, iron and nickel concentrations were dramatically higher and sulfur concentrations lower when wetland was converted to paddy field. Co and Ni were identified as potential chemical indicators of wetland conversion. Our research is the first to use multi-element fingerprinting to study effects of conversion of wetlands to croplands in China and showed that this relatively simple approach highlights the complexity of the many interacting factors in reclamation of wetland soils for agricultural uses.

Keywords: Biogeochemistry; Element distribution; Organic matter; Restoration; Sanjiang Plain.