The atmosphere of polar regions is a good place to study the impact of natural global phenomenon on the atmospheric environment. However, the lack of knowledge on the processes affecting the incorporation of chemical constituents is a limitation to the interpretation of the glaciochemical data from ice cores. These study has been focused on the air snow relationship for nitrate, chloride and ammonium at Summit (Greenland). We show that it is possible to sample tropospheric acidic gases at Summit. We show that denuders tubes coated with sodium fluoride could be used to collect nitric acid and hydrochloric acid in Polar regions. The other method we used gives bad results under polar conditions (Nylon filters). Our data of nitrate and chloride show these two compounds are in the gas phase at Summit. Study of fresh snow and snowpits show that HCI and HN03 are not incorporated with the same efficiency in snow flakes but they seem to have the similar behaviours at the snow surface of the polar ice sheet. We have followed a strict procedure to avoid ammonium contamination of aerosol samples. We show that atmospheric information is weil preserved in fresh snow and after snow metamorphism. So we think that the disagreement between aerosol and snow data reported in other studies is probably due to analytical artefacts.
