Influences on chemical distribution patterns across the west Greenland shelf: the roles of ocean currents, sea ice melt, and freshwater runoff

Abstract. The west Greenland shelf is a dynamic marine environment influenced by various physicochemical and biological processes. This study provides a comprehensive overview of the main factors affecting the distribution of macronutrients, carbonate system parameters, and dissolved trace elements during July. Key drivers include major ocean currents, melting sea ice, and terrestrial freshwater runoff, each contributing uniquely to the cycling and spatial distribution of chemical constituents. Major ocean currents, such as the southward-moving Baffin Island Current (BIC) and the northward-moving West Greenland Current (WGC), introduce water masses with distinct chemical signatures that shape the chemical composition of shelf waters. Melting sea ice serves as an important source of freshwater and dissolved constituents for the marine environment. During the study period, we were able to capture a distinct nutrient gradient following the east-to-west direction of sea ice retreat, with low nutrient levels in highly productive shelf waters and high nutrient levels in areas with prolonged ice cover. This process also influenced the carbonate system, leading to changes in pH and aragonite saturation states, both of which are is critical to the health of marine organisms. Terrestrial freshwater runoff, particularly from the Greenland Ice Sheet (GIS), replenishes macronutrients in the photic zone, stimulating primary production and creating important CO2 sinks. However, coastal surface waters become more susceptible to acidification by the input of poorly buffered glacial freshwater. Understanding these key drivers is essential for predicting future changes in the marine chemistry and ecosystem dynamics on the west Greenland shelf, especially in the context of ongoing climate change within this high-latitude region.