During Arctic spring, reactive halogens are released from snow, ice and aerosols over Arctic Ocean, which drastically changes the chemical cycles within the lowest part of the atmosphere. This includes reduction in the amount of ozone and mercury present, especially over the Arctic Ocean near the surface. This affects that extend beyond the central Arctic Ocean as air is transported to other regions. Halogens and other radicals in the atmosphere react with mercury to form oxidized mercury, which is quickly removed from the atmosphere via loss to ice, snow, and the open ocean. Once deposited to the Arctic Ocean, mercury can undergo transformation to more toxic forms, which poses risks to ecosystems and human health.

CRiceS researchers Shaddy Ahmed and Jennie Thomas have published a new paper including a description of coupling between snow, ice and aerosols for the Arctic mercury cycle, which has been developed within the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). They examined the impacts of surface processes on sea ice/snow on atmospheric chemistry near the over Arctic Ocean and surrounding regions. This new model has been used to predict Arctic atmospheric chemistry during the spring season on an hourly timescale during the MOSAiC expedition. Ultimately, this advancement has the potential to improve predictions of the long-term consequences of climate change and sea ice loss on atmospheric chemistry and the links to the impacts of mercury on Arctic ecosystems.