The groups of nitrogen components that contribute most to the eutrophi
cation of the sea are ammonia, nitrogen oxides and their respective re
action products, The emission of ammonia is mainly from animal husband
ry, whereas the emission of nitrogen oxides is mainly from combustion
processes, Ammonia reacts in the atmosphere to form particulate ammoni
um, Nitrogen oxides react to form nitric acid, nitrous acid, particula
te nitrate and peroxy-acetyl nitrate, The various nitrogen components
have different physical and chemical properties, Therefore, their dry
and wet deposition velocities differ, The dry deposition velocity of g
as to the sea depends on its solubility, reactivity, concentration in
seawater and the wind speed, The dry deposition velocity of a particle
depends on its size and the wind speed, The wet removal rate is a fun
ction of meteorological conditions, For a gas it further depends on th
e solubility and reactivity of the gas, For a particle, it further dep
ends on the particle's ability to act as a condensation nucleus for pa
rticles, The total deposition of ammonia and its reaction products to
the North Sea is about 140 kt N a(-1). The total deposition of nitroge
n oxides and their reaction products is about 200 kt N a(-1).