Processes controlling the concentrations of SO(4)(=), NO(3)(-), NH(4)(+), H(+), HCOO(T) and CH(3)COO(T) in precipitation on Bermuda

The composition of precipitation on Bermuda can be characterized as a slightly acidic, dilute seawater solution. The acidity of the solution is controlled by H(2)SO(4), HNO(3), HCOOH and CH(3)COOH in a 67 : 20: 8: 3 mixture, respectively. CaCO(3) and NH(3) have reduced the potential acidity of the solution by 24% and 13%, respectively. The concentrations of non-sea-salt (nss) SO(4)(=) and NO(3)(-) in precipitation on Bermuda are about a factor of three greater than those in remote marine areas of the world. These differences are attributed in part to anthropogenic activities. NH(4)(+), HCOO(T) and CH(3)COO(T) concentrations in Bermuda precipitation more closely resemble remote areas, although there are distinct events where transport from North America is evident. Precipitation associated with air masses from the central Atlantic Ocean is enriched relative to remote marine areas by about a factor of two in nss SO(4)(=). This appears to be caused by anthropogenic emissions in North America, Europe and Africa. There are higher volume-weighted average concentrations of nss SO(4)(=) and NO(3)(-) in storms on Bermuda associated with the NW airflow sector (from North America) compared to the SE airflow sector. These higher concentration are in part due to the influence of North America and in part due to lower amount of precipitation in the NW storms. An analysis of deposition differences between the two sectors confirms that there is at least a factor of two impact of North American anthropogenic activities on nss SO(4)(=) and NO(3)(-) in precipitation on Bermuda