Anthropogenic influences on aerosols at Ny-Ålesund in the summer Arctic

Özet

The Arctic atmosphere has been disturbed by human activities. To improve the understanding of anthropogenic influences, major ionic species and carbonaceous components were measured at NyÅlesund in July 2012. The results suggested that Naþ and Cl are the dominant water soluble inorganic species, accounting for 57 ± 17% of the mass of measuredionic species, and 61% of the variance in organic carbon can be explained by oceanic emissions. Aerosols in this area were found to be altered by secondary production involving oxides of sulfur, nitrogen and ammonia from anthropogenic activities, resulting in relative high concentrations of secondary inorganic aerosols (SIA) (such as non-sea salt (nss)SO42, NO 3 and NH4þ), with a mean concentration of 158 ng m3. SIAs were featured by a mean [NH4þ]/[nss-SO42] ratio of 0.57 and a neutralization ratio (NR) of 0.074, indicating a deficit of NH4þ. Thus, the production of particulate NH4 NO3 was strongly limited and SIAs were likely to remain in more acidic forms, NH4HSO4 or H2SO4 rather thanas (NH4)2SO4.Chloride depletion of 11%e22% occurredin the samples with high concentrations of excess acidic species (defined as [nss-SO42 þ NO3 NH4þ]) and high sea salts. The formation of SIAs and chloride depletion appeared to produce acidic aerosols with a meanpH of 4.51 and high free [H] concentrations of 3.06 ± 0.75 nmol m3 in aerosols, accounting for 77% of the total [H] concentration. This implies that anthropogenic species could be engaged efficiently in modifying of the properties of aerosols at Ny-Ålesund.