Release of mercury from intertidal sediment to atmosphere in summer and winter

The release of mercury from intertidal sediment to atmosphere was studied based on the simulated experiment. The experiment samples were collected from the Haibo Estuary (S1) and the Licun Estuary (S2) of the Jiaozhou Bay in China, which are seriously polluted with mercury. The results show that the mercury in sediment releases rapidly to atmosphere under solar radiation. After 8 hours of solar radiation, mercury concentrations decrease from 5.62 μg/g and 2.92 μg/g to 2.34 μg/g and 1.39 μg/g in S1 and S2 sediments respectively in summer, and decrease from 5.62 μg/g and 2.92 μg/g to 4.58 μg/g and 2.13 μg/g respectively in winter. The mercury species in the sediment change markedly under solar radiation. The concentrations of mercury bound to organic matter decrease significantly from 2.73 μg/g to 0.31 μg/g in S1 and from 2.07 μg/g to 0.31 μg/g in S2, and the released mercury mainly comes from mercury bound to organic matter. Mercury flux shows distinguishing characteristic of diurnal change, and it increases rapidly in the morning with the rising of solar radiation intensity, but decreases in the afternoon. The mercury flux increases with sediment temperature and solar radiation intensity. The rapid release of mercury in intertidal sediment plays an important role in the regional mercury cycle.