Oxygen Uptake Rates of Benthal Systems
By a New Technique
N. BRUCE HANES, Associate Professor
Tufts University
Medford, Massachusetts
ROBERT L. IRVINE. Graduate Student
Rice University
Houston, Texas
INTRODUCTION
During the last five years, a greater public awareness and concern of stream
pollution and its associatea problems has been evident. This concern has resulted
in a number of new laws being passed during the 1965 legislative session and more
are now under consideration. In signing the major 1965 water pollution legislation, the Water Quality Act of 1965 (P. L. 89-234), President Johnson stated "Today, we proclaim our refusal to be strangled by the wastes of civilization. Today,
we begin to be masters of our environment ... water pollution is doomed in this
century. " With the year of 2000 as a goal and assuming there will continue to be
a large flow of federal funds into the field of water pollution, there is now a dire
leed to examine our present method of stream analysis. One important aspect of
atream analysis is the oxygen balance. It was shown by Streeter and Phelps in
1925 (1) for the simple case in which the Biochemical Oxygen Demand (BOD) from
a single polluting source and reaeration from the atmosphere are the only two
processes determining the oxygen balance in a river, the net rate of change of
oxygen deficit is given by the differential equation
$P-= KiL - K D
dt       l
which describes the combined action of deoxygenation and reaeration. This relationship has been used and modified by many authors over the intervening
years, however, it is still the basis for oxygen balance studies at the present time.
The present methods (2) used for the prediction of the oxygen balance in streams
include: 1) Effects of BOD removal by sedimentation or adsorption; 2)Removalof
oxygen by respiration of microorganisms; 3) Addition of oxygen by aeration; and
4) Addition of BOD by various pollutional loadings. In general, however, most
studies at this time do not incorporate the effects of additional oxygen by photosynthesis and the removal of oxygen by benthal deposits. This study is concerned
with the effect of benthal deposits on the oxygen balance of streams. The removal
of oxygen by benthal deposits is a result of several factors which are often interrelated. They may be summarized as follows: 1) BOD may be introduced from the
benthal deposits by scour (3,4); 2) Oxygen may be consumed by the soluble end
products of benthal decomposition which diffuse into the overlying water (5,6); 3)
Oxygen may be consumed by the gases which were produced by anaerobic decomposition and rise from the benthal layers (5, 7, 8, 9); and 4) Oxygen demand of the
sludge itself.
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