Dissolved organic matter differentially influences arsenic methylation and volatilization in paddy soils

• Published in: Journal of hazardous materials Vol. 388; p. 121795
• Main Authors: Yan, Mengmeng, Zeng, Xibai, Wang, Ji, Meharg, Andy A., Meharg, Caroline, Tang, Xianjing, Zhang, Lili, Bai, Lingyu, Zhang, Junzheng, Su, Shiming
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.04.2020
• Subjects: Arsine; arsM; Biotransformation; High-throughput sequencing; Pig manure; Pig manure; Arsine; High-throughput sequencing; Biotransformation; arsM
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121795

[Display omitted] •DOM characteristics influence As methylation and biovolatilization in paddy soils.•Arsine production is markedly enhanced following pig manure DOM application.•Among DOMs, Pig manure DOM addition yields much higher As-methylation in paddy soil.•Pig manure DOM addition increases the OTU number of arsM-carrying bacteria.•High labile C amount is responsible for the enhanced As-methylation in paddy soils. The effect of dissolved organic matter (DOM), derived from composted pig manure or rice straw, on arsenic methylation and subsequent biovolatilization in paddy soils was investigated. Arsine production following pig manure DOM application was 2.7- and 9.6-fold higher than that of soils treated with rice straw DOM and the control, respectively. Trimethylarsine was the dominant arsine at 54 %, followed by dimethylarsine at 22 %, arsine at 21 %, and monomethylarsine at 3 %. The copy numbers of the total and As-methylating bacteria were significantly enhanced in paddy soils treated with DOM. Pig manure DOM altered soil bacterial profile by increasing the OTU number of As methylation-inducing bacteria, such as Proteobacteria, Bacteroidetes, Geobacter, Sphingomonas, Streptomyces, and Rhodopseudomonas, thereby promoting As volatilization and methylation in paddy soils. The higher relative content of alkyl-C, N-alkyl C, and carboxyl-C in pig manure DOM was responsible for the increase in total and arsM-carrying bacteria in paddy soils, leading to enhanced As methylation. These observations will promote a better understanding of the role of DOM in mediating As methylation and volatilization, along with how organic fertilization affects straighthead disorder of rice, a condition caused by methylated arsenic species.