Cl. Mcneil et al., IN-SITU MEASUREMENT OF DISSOLVED NITROGEN AND OXYGEN IN THE OCEAN, Deep-sea research. Part 1. Oceanographic research papers, 42(5), 1995, pp. 819-826
Motivated by the need to separate changes in dissolved gas concentrati
ons due to air-sea fluxes from biological production, a novel method o
f inferring dissolved nitrogen in the ocean is described. The method r
equires a local measurement of gas tension, dissolved oxygen, water te
mperature and salinity. Such instrumentation has been developed and te
sted at sea. Preliminary open ocean data are presented. The measuremen
ts during periods of low wind speed show a clear diurnal dissolved oxy
gen signal, incorporating biological photosynthetic response, solar he
ating and nocturnal convective mixing. The diurnal variability of the
inferred nitrogen signal is approximately 10% that of the measured oxy
gen diurnal variability. The nitrogen diurnal variability is attribute
d to a 10 m separation between the primary measurements of gas tension
and dissolved oxygen rather than any intrinsic change in dissolved ni
trogen. These results are, however, consistent with the relative insen
sitivity of dissolved gaseous nitrogen to biological activity compared
to that of dissolved oxygen. The open ocean results give good evidenc
e for the integrity of the measurement scheme and indicate the potenti
al for simultaneous measurement of dissolved nitrogen and oxygen in th
e study of biological cycling as well as gas transfer in the upper oce
an.