The Arctic environment is transforming rapidly due to climate change, which induces several feedback processes such as retreating sea ice, changing atmospheric transport patterns and cloud formation. In addition, more local pollution due to shipping and resource extraction occurs, affecting the atmospheric chemical composition and therefore the radiation budget of the Arctic. While the overall seasonality of aerosol mass concentrations and chemical compositions at Arctic ground-based surface observatories is relatively well known, short extreme events such as storms, warm air mass intrusions or intense pollution spikes from shipping have been less studied, mostly due to a lack of comprehensive, high time-resolution chemical composition datasets. This is particularly true for the central Arctic. Here, we present the annual cycle in aerosol chemical composition retrieved with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). Fresh pollution from local sources is detected using the cosine similarity of the dataset with a chosen reference polluted spectrum. The chemical composition of such polluted periods, used as a proxy for the future Arctic, and other extreme events (i.e., warm air mass intrusions) is then compared to cleaner periods and seasonal means. Finally, preliminary results of source apportionment using Positive Matrix Factorization (PMF) during spring are also presented.