Does Sea Spray Aerosol Contribute Significantly to Aerosol Trace Element Loading? A Case Study From the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Atmospheric deposition represents a major input for micronutrient trace elements (TEs) to the surface ocean and is often quantified indirectly through measurements of aerosol TE concentrations. Sea spray (SSA) dominates mass concentration over much global ocean, but few studies have assessed its contribution loading, which could result in overestimates “new” inputs. Low-mineral concentrations measured during U.S. GEOTRACES Pacific Meridional Transect (GP15; 152°W, 56°N 20°S), along with concurrent towfish sampling seawater, provided an opportunity investigate this aspect biogeochemical cycling. Central Ocean seawater Al, V, Mn, Fe, Co, Ni, Cu, Zn, Pb were combined Na data calculate “recycled” SSA loading. Only vanadium was calculated averaging >1% transect (mean 1.5%). We derive scaling factors from previous on enrichments sea microlayer freshly produced assess broader potential contributions Maximum applied suggest that contribute significantly loading some (notably Pb), while others (e.g., Fe Al), largely remained <1%. Our study highlights lack focused TEs limits our ability quantify component marine associated overestimating new inputs atmospheric deposition.