Table 7. Sewage Derived Inorganic Nitrogen (NO3 + NOi + NH 3 ) in the 

 Hudson River Estuary 



Mean daily sewage input (10 6 m 3 /day~')* 

 Mean daily nitrogen input (10 6 g N/day 1 )* 

 Nitrogen content of sewage (g m 3 = ppm) 



Mean river flow (10 6 m 3 /day-')t 

 Sewage dilution 



Expected N in river water (g m -3 = Dpm) 

 Expected N in river water (mg at m 3 ) 



Nitrogen in seawater source (mg at m- 3 )§ 6.31 ± 2.8 



In surface 



Observations In upper bayj coastal water** 



Annual mean salinity 20.60 ± 5.85 28.78 i 1.59 

 Annual mean fraction fresh 0.36 0.10 



Calculated N content (mg at m- 3 )ft 47.59 17.78 



Observed mean N content (mg at m" 3 ) 50.51+10.81 18.36+16.22 



Calculated as % of observed 94.2% 96.8% 



•Malone, 1976, 1977. 

 fKetchum, et al., 1951. 



§From Malone, 1976. Observed N in the near-bottom water at Station P^ off 

 the entrance to New York Harbor; location 40°28.6'N, 73°54.0'W. 

 |From Malone, 1 976, Station A3: 40°40.3'N to 40°38.5'N; 74°0.2'1 8"W. 

 **From Malone, 1976, Station Pi off the entrance to New York Harbor. 

 ftExpected N in river water (1 20.9 mg at m" 3 ) x fraction fresh (f) plus observed 

 N in source seawater (6.31 mg at m 3 ) x fraction salt water (1-f>. 



Nutrients in the New York Bight 



The pollution load of the Hudson River is only one of several sources of nutrients 

 to the offshore waters of the New York Bight. The Raritan River pollution is added 

 to that of the Hudson, and sewer outfalls empty directly into the Bight along the 

 coasts of New Jersey and Long Island. There are also nutrients in the runoff both 

 from rivers and from urban areas. Dumping at sea includes both sewage sludge and 

 dredged spoils that are barged to the Bight for sea disposal. Mueller et al. ( 1976) dis- 

 cuss the various sources of organic carbon, nitrogen, and phosphorus to the waters 

 of the New York Bight. Their results are summarized in Figure 2. The N:P ratio of 

 the total inputs to the New York Bight is 9. 12 (by atoms). This suggests that the 

 phytoplankton productivity is nitrogen-limited as Malone (1977) concluded from 

 direct observations in the Bight apex area. 



In the coastal waters of the apex of the New York Bight, the sewage-introduced 

 nutrients are rapidly assimilated by the growing phytoplankton. Malone ( I976) esti- 

 mated that the annual production in an area of about 600 km 2 (232 mi : ) was about 

 370 g C/ m~\ which is approximately equal to the rate of productivity in upwelling 

 systems, the richest marine areas in the world (Ryther, 1969).* From his 1 2 observa- 

 tions throughout the year, Malone estimated that it would take between 0.4 and I0.9 

 days (mean = 3.22 days) for the phytoplankton to assimilate the available dissolved 

 inorganic nitrogen in the water. He also estimated that it would take between 2.6 and 

 1 3.8 days (mean = 4.94 days) to double the standing stock of detrital carbon. 



The sewage sludge disposal from barges is of particular interest in terms of this dis- 

 cussion since this is the material removed from the sewage in the treatment plants. 

 Mueller et al. (1976) list the sewage sludge characteristics of 28 different plants, 12 of 



•This rate of production would require 61 4 g N m ; yr ' at the normal C:N weight ratio of 6.03. For an area of 600 km 2 this 

 would utilize 60 4 percent of the nitrogen additions to the Hudson Estuary (Table 7) or 19 2 percent of the total anthropogenic 

 nitrogen supply to the Bight (Figure 2) The remaining nitrogen is presumably assimilated over a wider area. 



80 



