Nitrogen turnover during the spring outflows of the nitrate-rich Curonian and Szczecin lagoons using dual nitrate isotopes

摘要: Abstract Coastal zones that receive high nitrogen loads from rivers often suffer intense eutrophication. This is the case in Baltic Sea, where nutrient concentrations decrease rapidly offshore, but uptake and turnover processes highly eutrophic near-shore areas are not well understood. The Oder Nemunas Rivers, second third largest contributors (70 45 kt N y −1 ), drain into Szczecin Curonian lagoons, respectively, thus coastal waters of Baltic. In this study, nitrate Sea were determined March 2009 by measuring concentrations, rates, dual isotopes (δ 15 N-NO 3 − δ 18 O-NO ) lagoon outflows. While mixing dominated outflow lagoon, a phytoplankton spring bloom largely accounted for lagoon. Here, assimilation surface was evidenced parallel enrichment N O. near-bottom deviation 1:1 relationship between , typical denitrification, suggested coupling nitrification triggered presence organic material bloom. particulate may be sequestered sandy sediments off generate isotope signal nitrate. enriched values (up to 28‰) layer implied impact isotopic sediment water column higher than muddy sediments.