ENVIRONMENTAL CHARACTERISTICS OF RARITAN BAY, A POLLUTED ESTUARY1

Abstract

Temperature, salinity, dissolved O₂, PO₄‐P, and NO₃‐N in Raritan Bay, N. J. were determined over a 16‐month period. Each reflects the circulation pattern in which sea water floods along the northern shore, enters a region of mixing with river discharge in the head of the bay, and then ebbs out along the southern shore.At the mouth of the bay, salinity was higher on the northern than on the southern side. The mean annual monthly difference at the surface was 1.27‰; departures from the mean were related to river flow.Surface and bottom dissolved O₂ content were minimal in August and highest during winter. Low concentrations occurred in the Raritan River, especially during the summer preceding operation of a trunk sewer.The primary source of NO₃‐N was outflow from the Raritan River. Prior to operation of a trunk sewer, the river may have discharged significant quantities of PO₁‐P into the bay.Throughout spring and summer, PO₄ concentrations rose and NO₃ decreased. It is postulated that the resultant low N:P ratio was partially due to an efficient nutrient regeneration mechanism that favored the rate of P renewal.A combination of rich nutrient supplies arising from natural and domestic sources, plus a sluggish circulation, efficient nutrient regeneration mechanism, and scarcity of macroscopic algae combine to form an estuarine environment capable of supporting extremely dense plankton populations.