f. Dissolved Oxygen . The water quality criteria, used by EPA, 

 recommended a minimum dissolved oxygen (DO) concentration of 5 milligrams 

 per liter Cmg/l) ii^ open coastal waters, and 4 mg/1 in estuarine and tidal 

 tributaries excepting waters with naturally despressed DO (EPA, 1972). 

 Similarly, both New York and New Jersey have a lower limit of 5 mg/1 for 

 ocean waters at any time, while the lower permitted limit for the waters 

 of the New York harbor is 2.5 mg/1. These values however, do not differ- 

 entiate between the DO of bottom and surface water and are average values 

 for the water column. 



Dissolved oxygen is a water quality property that can also affect the 

 quality of the sediments. Dissolved oxygen enters seawater through atmo- 

 spheric re-aeration and algal photosynthesis. Its concentration is in- 

 fluenced by a number of variables, such as mixing conditions, primary 

 production, the vertical and horizontal distributions of temperature and 

 salinity, and the biochemical oxygen demand. Certain minimum concentrations 

 of DO are required to support populations of aerobic organisms at all life- 

 development stages. Oxygen is also important in the aerobic decomposition 

 of organic materials. In the presence of oxygen organic matter undergoes 

 biological decompisition to yield CO2 and H2O which are substances necessary 

 to sustain life. Changes in the dissolved oxygen of the water may result 

 in changes in photosynthesis and the primary productivity of an area. Re- 

 duction in DO, for example, can result in the development of anaerobic 

 conditions with associated water odor problems, and the destruction of 

 aerobic marine animal life, such as commerically valuable finfish and 

 shellfish. 



Decay of organic matter in the sea may release H2, H2S, CH^ and NH3, 

 which are undesirable substances. The organic materials in the sediments 

 of the Bight dumping grounds exert a biochemical oxygen demand (BOD) which 

 reduces the DO near the bottom. According to Torpey (1967) oxygen depletion 

 can occur in the following sequence. 



a. When oxygen demand of pollutants reaches 20 lbs 02/day/acre, 

 instability develops, the oxygen level drops sharply, and fish migrate. 



b. When the pollution loading level demands 20 to 132 lbs 02/day/ 

 acre the dissolved O2 remains substantially constant at between 25 to 50 

 percent of saturation. This plateau is homeostatic because symbiotic algae 

 and bacteria are able to maintain this O2 level . 



c. At extremely high loading rates when demand exceeds 132 lbs 

 02/day/acre, the O2 is exhausted and anaeorobic conditions develop. 



A BOD range from 16 to 330 gm 02/kg of volatile solids has also been 

 determined by Isaacs (1962). The BOD of highly polluted sediments can be, 

 therefore, several orders of magnitude above the DO saturation level. More- 

 over this demand can be continuous or deferred for some future time when 

 oxygen again becomes available. Such demand probably removes all the 

 oxygen from the interstitial water so that chemical reactions in the sedi- 



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