Desilification of phytolith exacerbates the release of arsenic from rice straw

Quan T Dang; Anh T Q Nguyen; Anh D Nguyen; Ngan T Nguyen; Than T N Dam; Thu T T Tran; Thu H A Ngo; Trang T H Nguyen; Tuan V Tran; Van M Dinh; Minh N Nguyen

doi:10.1016/j.chemosphere.2023.140797

Desilification of phytolith exacerbates the release of arsenic from rice straw

Chemosphere. 2024 Feb:349:140797. doi: 10.1016/j.chemosphere.2023.140797. Epub 2023 Nov 26.

Authors

Affiliations

¹ Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam; Institute of Geography, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Viet Nam.
² Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam.
³ University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Viet Nam.
⁴ Department of Ecosystem Science and Management, University of Wyoming, Laramie, Wyoming, United States.
⁵ Faculty of Chemistry, University of Science, Vietnam National University, Hanoi, 19 Le Thanh Tong, Hoan Kiem, Hanoi, Viet Nam.
⁶ Department of Integrated Sciences, Fulbright University Vietnam, Tan Phu Ward, District 7, Ho Chi Minh City, Viet Nam.
⁷ Faculty of Biology, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam.
⁸ Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam. Electronic address: minhnn@vnu.edu.vn.

PMID: 38016526
DOI: 10.1016/j.chemosphere.2023.140797

Abstract

Arsenic (As) turnover in rice paddy agro-ecosystems has received much attention because As can enter the food chain through its accumulation in rice, thereby affecting human health. Returning straw to soil is a common practice to retain nutrients for soil and crops, but it also cycles As within the rice paddy field ecosystems. However, there is still a lack of detailed understanding of the fate of As in rice straw, and how or to what extent it is recycled back into the soil environment. This study aims to elucidate the relationship between the microstructure of rice straw and the release of As during rice straw decomposition. The microstructure of rice straw was found to comprise both organic and silica (phytolith) components. These two constituents are inter-embedded to form a composite-like structure that contains up to 6.48 mg As Kg^-1. The 30-day batch experiments revealed that the biochemical release of As simultaneously depends upon the decomposition of the organic component and the desilicification of the silica component. Accompanying the release of As was the release of other elements such as Fe, Al, P and S. These elements can further interact with As to form less mobile compounds. The introduction of either Trichoderma harzianum or Bacillus velezensis was expected to accelerate the decomposition of rice straw, and enhance the silica dissolution, hence contributing to an increase in the As release. Despite these expectations, our observations showed the opposite effects. Microorganisms presumably have facilitated the change in solution chemistry or the inclusion of As into the newly-formed precipitates. The biochemical decomposition process can reduce straw particle size, while the negatively-charge surface will involve microsized straw particles in the electrostatic interaction, thereby favoring the dispersibility state. Therefore, the co-transport of micro-sized straw particles with As under field conditions should not be neglected.

Keywords: Arsenic; Bacillus velezensis; Decomposition; Rice straw; Trichoderma harzianum.

MeSH terms

Arsenic*
Ecosystem
Humans
Oryza* / chemistry
Silicon Dioxide
Soil / chemistry

Substances

Arsenic
Soil
Silicon Dioxide