The Carbon-Oxygen Distribution In New York Bight
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Date
1979-08
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Abstract
Description
The steady-state analysis presented in this report provides a basis for
assessment of dissolved oxygen in the New York Bight, particularly in the
apex area. The analysis indicates that the discharge of carbonaceous and
nitrogenous wastes does not materially affect the dissolved oxygen levels
through bacterial oxidation. Furthermore, the discharge of solids (sludge
disposal, dredge spoils and construction debrisj do not influence these
concentrations on a bight-wide scale. The localized sludge disposal area
is evidently affected in this regard, but this area is restricted to a
relatively limited extent. On the other hand, the depression of dissolved
oxygen, particularly in the hypolimetic waters, is affected by phytoplankton
respiration and decay and the vertical transport structure. It is probable
that the discharge of wastewater from the treatment plants and urban runoff
has some effect on the growth of phytoplankton and the subsequent decay
tbrough the inorganic nutrient route. The degree to which water quality
conditions are affected by these inputs may be quantified by the development
and validation of a model defining these kinetic interactions. The analysis, developed in this second phase, will be extended to incorporate the kinetic
routes, relating the growth and decay of the phytoplankton to the nutrient
concentrations resulting from these wastewater inputs. Thus, the effect; of
the discharges will be defined, providing a basis for areawide water quality
planning, particularly with respect to the relative influence of the point
sources from treatment plants and the distributed sources from urban runoff
by contrast to the effects of other inputs such as the disposal practices
and atmospheric inputs.
The present analysis is directed to the definition of a transport
structure in accordance with the original contract to provide the Brookhaven
investigators with a reasonable transport field for summer conditions.
The transport equations included advective and dispersive terms in a multi--segmented horizontal system with two vertical layers. The advective terms were developed by a minimum energy principle, which yield the general observed flow pattern in the Bight. The overall transport field also included consistent values of the various disperation coefficinents. It is recognized that advective-dispersive models of this nature do not necessarily
result in a unique solution for the transport. However, its validity to
represent average summer conditions is demonstrated by its ability to reproduce
the salinity distribution for the two years. The analysis further indicates that the dissolved oxygen concentration
in the hypolimnetic waters is particularly sensitive to the respiration and
decay rates of the phytoplankton and the vertical dispersion coefficients.
Relatively small changes of these paremeters, within the range of measured
values, cases significant changes in the dissolved oxygen levels. Thus, from both a transport and kinetic viewpoint, the present analysis
reasonably reproduces observed water quality conditions and permits assussment
of the effect of wastewater inputs. In view of the potential significance of
these aischarges on dissolved oxygen and other water quality parameters this
analysis had indicated the analytic direction on which to proceed and provide
a valid basis for the more definitive time variable analysis.
Keywords
Carbon-Oxygen Distribution, New York Bight