PubMed | a Beijing Municipal Institute of Labor Protections
Type: | Journal: Journal of the Air & Waste Management Association (1995) | Year: 2015
In this study, we report on total gaseous mercury (TGM) field observations made in the rural area of Shanghai - Chongming Island, China, from September 2009 to April 2012. The average TGM was 2.651.73 ngm-3 in Chongming Island which is higher than the TGM background value of the Northern Hemisphere (1.5~1.7 ngm-3); this indicates that to some extent, the Chongming area has been affected by anthropogenic mercury emissions. The observed TGM follows a seasonal pattern; concentrations are highest in winter followed by autumn, summer and spring. There is also a clear diurnal variation in TGM. All peak values appear between 7:00 and 9:00 in all four seasons; this appears to be the result of the height change in the atmospheric boundary layer that occurs between day and night. TGM concentrations in Chongming remains high in the westerly wind direction, especially in the southwest direction because of its low frequency, so greatest source contribution to TGM in Chongming lies to the northwest. Wind speed is also a significant factor affecting TGM, and was negatively correlated with TGM concentrations. TGM is also closely related to carbon monoxide (CO) concentrations, indicating that TGM are impacted by human activities. The slope of the linear fitting of TGM and CO demonstrates that the contribution of non-coal source emissions to TGM in summer is greater than in autumn, mainly because the high temperature and intensive sunlight in summer increase mercury emissions from natural sources. IMPLICATIONS Except some studies in the coastal areas (e.g. Kang Hwa Island by Kim et al., 2006, AnMyun Island by Kim et al., 2002 and Okinawa by Chan et al., 2008), data specifically for coastal area are lacking. Monitoring of total gaseous mercury (TGM) in the rural area of Shanghai - Chongming Island can help us understand mercury distribution.