Sw. Effler et al., EFFECT OF REDUCED SALINITY INPUT ON RIVER STRATIFICATION AND DISSOLVED-OXYGEN, Water, air and soil pollution, 95(1-4), 1997, pp. 45-58
Changes in the occurrence, character, and longitudinal extent of salin
ity (S) stratification, and related impacts on dissolved oxygen (DO),
in the Seneca and Oswego Rivers, NY, in response to the abatement of i
onic pollution of inflowing Onondaga Lake, is documented. The analysis
is based on vertical profiles of specific conductance and DO collecte
d over a 20 km reach of the river system for several years before and
after the closure of the source of the ionic pollution, a soda ash man
ufacturing facility. The S difference between the lake and the Seneca
River decreased from about 2.6 to 0.7 parts per thousand (parts per th
ousand) following the closure; more than 50% of the continuing differe
nce is associated with lingering ionic waste loading from soda ash pro
duction. The occurrence and longitudinal range of the S stratification
phenomenon was, and continues to be, highly dependent on river flow.
It is most strongly manifested when river flow is low. The occurrence,
magnitude, and longtitudinal extent of S stratification have decrease
d, and vertical exchange between the stratified layers has increased,
since the closure, thereby ameliorating the coupled negative impact on
the river's oxygen resources. However, under low flow conditions (e.g
., probability of occurrence equal to 15%) S stratification continues
to extent > 2 km upstream and > 8 km downstream of the point of entry
of Onondaga Lake into the Seneca River. Severe DO depletion in the low
el river layer, representing violations of New York water quality stan
dards, continues to occur where S stratification prevails. Elimination
of the continuing ionic waste inputs from soda ash production would f
urther limit the stratification phenomenon and improve the river's DO
problem.