Environmental Engineering Reference
In-Depth Information
minima seen in the region 250-350 m and peaks in chemoautotrophic production
within the redox gradient as discussed above and in [34] (this volume).
6. CONCLUSIONS
Nutrient distributions in oxic waters of the Cariaco Basin vary seasonally
with fluctuations in rates of upwelling and primary productivity as well as in
variations in the intensity of intrusions. In the suboxic zone, there appears to
be at least occasional overlap of ammonium and nitrite, which could allow
the growth of anammox bacteria. Although our sample spacing has not been
sufficiently fine to always resolve these features, we also have evidence for
phosphate removal above the sulfidic layer as is seen in the Black Sea. Intrusions
of oxygenated water into deep, sulfidic layers occur intermittently but not
infrequently, also influencing distributions of nitrite and phosphate. In the
upper part of the anoxic zone, sulfide concentrations are lower than would be
predicted by the amounts of inorganic nitrogen and phosphorous present. This is
likely due to sulfide removal during intrusions of water containing oxidant. The
deepest waters of the Cariaco Basin continue to have nutrient concentrations,
which have increased at a roughly constant rate for the past 50 years.
Figure 9. Alk/TCO 2 plot for CARIACO cruises between Dec 1995 and May 2003 for depths
greater than 250 m. The equation of the line is Alk = 0.76 TCO 2 + 664 and the r 2
= 0.976.
Search WWH ::




Custom Search