Production and emission of phosphine gas from wetland ecosystems.

Phosphine is a part of an atmospheric link of phosphorus cycle on earth, which could be an important pathway for phosphorus transport in environment. Wetland ecosystems are important locations for global biogeochemical phosphorus cycle. In this study, production and emission fluxes of free phosphine from four wetlands types in southern China were observed in different seasons. The results showed that the concentration of phosphine liberated from wetlands was at pg/m3-ng/m3 level. The emission concentrations of different wetlands followed the sequence: paddy field (51.83 +/- 3.06) ng/m3 > or = marsh (46.54 +/- 20.55) ng/m3 > lake (37.05 +/- 22.74) ng/m3 >> coastal wetland (1.71 +/- 0.73) ng/m3, the positive phosphine emission flux occurred in rice paddy field (6.67 +/- 5.18) ng/(m2 x hr) and marsh (6.23 +/- 26.9) ng/(m2 x hr), while a negative phosphine flux of (-13.11 +/- 35.04) ng/(m2 x hr) was observed on the water-air interface of Lake Taihu, suggesting that paddy field and marsh may be important sources for phosphine gas in atmosphere, while lake may be a sink of atmospheric phosphine gas during the sampling period. Atmospheric phosphine levels and emission flux from Yancheng marsh and rice paddy field varied in different seasons and vegetational zones. Both diffusion resistance in aqueous phase and temperature were dominating factors for the production and transportation of phosphine to atmosphere.