Advancing the analysis of volatile selenium species in high-humidity and low-volatility paddy systems: A novel...

Selenium (Se) volatilization represents a crucial component of the Se biogeochemical cycle in paddy systems. However, current existing methodologies for capturing volatile Se (VOSe) in high-humidity and low-volatility paddy systems are insufficient. This study developed an innovative approach to capture and quantify VOSe from soil and rice plants, such as DMSe (dimethylselenide) and DMDSe (dimethyldiselenide). Initially, the efficacy of preconcentration was enhanced by optimizing the sampling apparatus, which significantly reduced water vapour by 43.5 % and increased the Se concentration by 37.7 % within 6 h sampling. Subsequently, HPLC-ICPMS analysis refinements included the screening and optimizing chromatographic columns and mobile phases, achieving absolute detection limits of 1.2 pg and 1.4 pg for DMSe and DMDSe, respectively. For validation, VOSe were quantified in the paddy systems, with DMSe and DMDSe volatilized rates from soil measured at 16.55±9.94 ng·m^-2·h^-1 and 124.49±120.34 ng·m^-2·h^-1, and from rice plants at 38.38±29.85 ng·m^-2·h^-1 and 72.54±94.66 ng·m^-2·h^-1, respectively. Additionally, volatile H₂Se and potential plant-based volatile organic Se species were found. This represents the first accurate and sensitive method for the in-situ capture of trace VOSe in high-humidity, low-volatility paddy systems, providing invaluable insights into the biogeochemical processes of Se volatilization.