The Way of Carbon: Composition and Transport of Organic Carbon in the Nearshore Zone of Herschel Island, Qikiqtaruk

Arctic permafrost coasts are greatly impacted by global climate change. Warming permafrost, decreasing sea ice extent and increasing sea temperature lead to greater coastal erosion. The carbon stored in the permafrost is then released into the nearshore zone, where it degrades, potentially leading to the release of greenhouse gas emissions (GHG) into the atmosphere. Yet, the exact pathways of organic carbon (OC) in the nearshore zone are not completely understood. In order to fill this gap, we collected dissolved and particulate OC (DOC, POC) samples in the nearshore zone of Herschel Island, Qikiqtaruk. The sampling was repeatedly carried out along a transect over a period of two weeks during the open water season in summer 2022. Water samples were collected at the surface and at several water depths. Subsequently, water samples were filtered through 47 μm fiberglass filters and examined in the laboratory for suspended particulate matter, DOC, and POC. When possible, Van Veen Grab samples and short cores were taken at each sample location. The upper six centimeters of the short cores as well as the grab samples were analyzed for grain size, mercury, carbon and nitrogen content. In addition to the water sampling, temperature, conductivity, salinity, and turbidity were measured at each sampling location with CTD and turbidity meter. Initial data shows a gradient in temperature and turbidity in the water column, especially at the beginning of the sampling period, which coincided with the sea ice breakup. Hereby, values for Turbidity range from 3.81 to 205.00 FNU. The amount of DOC and POC in the water samples will give an indication on the variability of geochemical properties in the water column over time. This will allow us to determine and quantify the link between these properties and environmental forcing.