Abstract. The
coastal Gulf of Mexico (GOM) and coastal sea off the Korean Peninsula (CSK)
both suffer from human-induced eutrophication. We used a nitrogen (N) mass
balance model in two different regions with different nitrogen input sources
to estimate organic carbon fluxes and predict future carbon fluxes under
different model scenarios. The coastal GOM receives nitrogen predominantly
from the Mississippi and Atchafalaya rivers and atmospheric nitrogen
deposition is only a minor component in this region. In the CSK, groundwater
and atmospheric nitrogen deposition are more important controlling factors.
Our model includes the fluxes of nitrogen to the ocean from the atmosphere,
groundwater and rivers, based on observational and literature data, and
identifies three zones (brown, green and blue waters) in the coastal GOM and
CSK with different productivity and carbon fluxes. Based on our model
results, the potential primary production rate in the inner (brown water)
zone are over 2 gC m−2 d−1 (GOM) and 1.5 gC m−2 d−1
(CSK). In the middle (green water) zone, potential production is from 0.1 to
2 (GOM) and 0.3 to 1.5 gC m−2 d−1 (CSK). In the offshore (blue
water) zone, productivity is less than 0.1 (GOM) and 0.3
(CSK) gC m−2 d−1. Through our model scenario results, overall
oxygen demand in the GOM will increase approximately 21 % if we fail to
reduce riverine N input, likely increasing considerably the area affected by
hypoxia. Comparing the results from the USA with those from the Korean
Peninsula shows the importance of considering both riverine and atmospheric
inputs of nitrogen. This has direct implications for investigating how
changes in energy technologies can lead to changes in the production of
various atmospheric contaminants that affect air quality, climate and the
health of local populations.