Phosphine migration at the water-air interface in Lake Taihu, China

The diurnal atmospheric phosphine (PH₃) concentrations and fluxes at the water-air interface in Lake Taihu were reported. The results showed that the PH₃ flux at the water-air interface ranged from −69.9 ± 29.7 to 121 ± 42 ng m⁻² h⁻¹, with a mean flux of 14.4 ± 22.5 ng m⁻² h⁻¹. The fluxes were both negative and positive during the diurnal period, indicating that the lake can act as a sink and a source of PH₃. In addition, the PH₃ fluxes were positively correlated with water temperature, total soluble phosphorus and soluble reactive phosphorus, while they were negatively correlated with water redox potential. A similar diurnal variation curve of atmospheric PH₃ concentrations was observed during all four seasons, with the maximum level occurring in early morning and the minimum appearing around midday. These findings suggest that light plays an important role in the elimination of atmospheric PH₃. A significant positive correlation was also found between air temperature and atmospheric PH₃ concentration. The mean flux of PH₃ in Lake Taihu was higher than in other reported wetlands, with an estimated annual emission of PH₃ to the atmosphere of 2.94 × 10⁵ g y⁻¹.