merits below the surface proceed under anaeorobic conditions, while at 

 the sediment -water interface, conditions may still be aerobic. This 

 may have a significant influence on other water quality properties. 



Under aerobic conditions, some chemical elements exist in their 

 oxidized states. Iron and manganese can be found as insoluble Fe203 

 and Mn03; phosphorus as insoluble FePOi+ ; nitrogen and sulfur as nitrate 

 and sulfate. Under anaerobic reducing conditions, the ferric ion would 

 be reduced to ferrous iron; phosphate may be released from the sediments; 

 and nitrates and sulfates will be reduced to ammonia and sulfide. The 

 chemistry of other chemical species may be also affected by oxidizing or 

 reducing conditions. Temperature, salinity and turbidity also affect 

 dissolved oxygen. The saturation levels of DO are particularly influenced 

 by the vertical and horizontal distribution of temperature and salinity, 

 and both fluctuate widely near the dumping grounds. 



During summer, the thermocline is more pronounced, and surface waters 

 contain a higher concentration of oxygen, because of reaeration, wave 

 action, and photosynthesis. Below the thermocline, lack of photo- 

 synthesis and the increased BOD of the wastes could significantly reduce 

 the dissolved oxygen. Such a drop in oxygen content of near -bottom 

 waters over the dumping area was reported by the SHL. Measurements of 

 DO taken by SHL fluctuated between 2.0 ml/liter to 7.0 ml/liter; the 

 lower values occur in bottom waters during summer. Based on these 

 measurements, the SHL report suggested that oxidation of the organic 

 matter of the wastes and bacteriological activity in the sludge beds 

 periodically depletes the overlying water of its oxygen to levels too 

 low for the support of life. Such low values occur for only limited 

 periods of time not only in the dumping grounds but also in other parts 

 of the Bight. 



The organic matter content of the Bight is extremely high, reaching 

 values of 4.4 to 81.0 mg/1 according to SHL. This organic material 

 precipitates eventually to the bottom and exerts a continuous oxygen 

 demand on the overlying waters. According to Ketchum (1970), reduction 

 in the oxygen content of bottom waters of the Bight dumping grounds has 

 occurred recently. Home et al, (1971) indicate that there is no 

 evidence that oxygen depletion observed in the Bight extends into the 

 water column for more than 5 meters off the bottom. It has also been 

 suggested that periodic drops in DO in the Bight result from intrusions 

 of offshore, oxygen-depleted waters which are generated below the 

 well-developed summer thermocline. 



In contrast, Corwin and Ketchum (1956) point out that the Hudson River 

 is a source of oxygen-depleted water, and that the oxygen content in the 

 surface waters of the Outer Harbor can be as low as 1.8 to 2.0 ppm. River 

 water, intruding into the Bight may be a more direct threat to the marine 

 environment than the dumping. 



To assess adequately the DO concentrations in the Bight, measure- 

 ments should be taken diurnal ly and seasonally, something that has not 



