IV-352 



the metabolism of this food. BOD is generally expressed as 

 (milligrams per liter) mg/1 of 5-day BOD at 68°F. while natural 

 waters have values around 1, untreated domestic sewage may average 

 around 300. 



The flow of oxygen resources in an estuary is analogous to the flow 

 of money in a bank if the estuarine system is viewed as a dissolved 

 oxygen bank. There is a certain amount of oxygen in the system just 

 as there are certain assets in a bank; the oxygen is invested in 

 supporting and renewing the biota, while the bank assets are invested 

 to earn money. There is a constant flow of oxygen into and out of the 

 estuarine system, both to and from the atmosphere and the ocean. In 

 the bank there is a cash flow to and from the depositors. Large 

 waste discharges may exert an abnormal demand on the oxygen resources 

 such as an embezzler exerts on the cash resources of a bank. If 

 enough dissolved oxygen is utilized in stabilizing wastes the system 

 goes bankrupt. 



The amount of organic wastes that can be assimilated in the estuarine 

 system without stressing the biota is dependent on the oxygen balance 

 or the flow of oxygen in the system. The rate of oxygen renewal is 

 dependent on the tidal driving force causing new oceanic water to 

 flood into the system, the fresh water inflow, the wind, the surface 

 area and the amount of turbulence generated by the fresh-oceanic 

 water mixing. The more turbulent the system the greater opportunity 

 for atmospheric exchange with the attendant ability to assimilate 



