ENVIRONMENTAL CHARACTERISTICS OF RARITAN BAY, A POLLUTED ESTUARY1

Temperature, salinity, dissolved 02, PO,-P, and NO:,-N in Raritan Hay, N. J. vvere detcrmined 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 dixhargc 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 1.272,; departures from the mean were related to river flow. Surface and bottom dissolved O2 content were minimal in August arid Ilighcxt during winter. Low concentrations occurred in the Raritan River, especially. during the summer preceding operation of a trunk sewer. The primary source of NOJ-N was outflow from the Raritan River. Prior to operation of a trunk sewer, the river may have discharged significant quantities of PO,-1’ into the bay. Throughout spring and summer, PO, concentrations rose and NO:{ decreased. It is pohtulated 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 soruces, plrls a sluggish circulation, efficient nutrient regeneration mechanism, and scarcity of nnrcroscopic algae combine to form an estuarine environment capable of supporting estrernely dcbnsc pl&kton populations.