economic trends gives only the grossest indication of the activities and 

 expected pressures of population and economic activity on all of the 

 Nation's environment. Analysis of these indicators can only provide 

 a general indication of the magnitude of the demands which will be 

 generated by these forces in the near future on the estuarine zone. 



Pollution : The Impact of Human Society on the Estuakine 



Environment 



Man has always used the biophysical environment as he needed it for 

 survival and thrown back into it his waste products and anything else 

 he did not need. As long as civilization was limited to small towns and 

 villages the impact of such treatment on the estuarine environment 

 was not noticeable and apparently insignificant. With the development 

 of a civilization based on a complex socioeconomic environment, how- 

 ever, his impact on the natural environment has increased until now 

 the most accurate term to express the relationship of man to his bio- 

 physical environment is pollution. 



Pollution is the degradation of the biophysical environment by 

 man's activities ; it is no longer limited to the discharge of sewage and 

 industrial wastes, but now includes direct or indirect damage to the 

 environment by physical, chemical, or biological modification. 



Environmental degradation is the result of often minute changes in 

 water quality, water circulation, or other conditions which are part of 

 the biophysical estuarine environment. There are brightly colored or 

 otherwise visible waste materials which have obvious poUutional im- 

 plications, but by far the deadliest pollutants are those which are in- 

 visible and often unsuspected until the damage is done. These pol- 

 lutants can be found only by the most delicate and sensitive tests and, 

 even then, the presence of some highly dangerous materials or condi- 

 tions can only be inferred by indirect evidence. 



materials and conditions which degrade the environment 



One of the major constituents of municipal and many industrial 

 wastes is decomposable organic material. Such materials consist pri- 

 marily of carbohydrates from plants and paper, proteins from animal 

 matter, and miscellaneous fats and oils. The decomposable organics 

 are not necessarily detrimental by themselves but exert a secondary 

 effect by reducing dissolved oxygen in the water. The level of dissolved 

 oxygen is one direct index of the healthiness of the system. High levels 

 are generally indicative of a healthy system which will support a 

 diverse biota and multiple use. The lower the concentration of dis- 

 solved oxygen becomes, the sicker the system is, and the less desirable it 

 is for habitat or use. 



Another class of materials, primarily organic, that can have con- 

 siderable impact on the estuarine ecosystem are the fesh-tainting sub- 

 stances. Generally these materials are contained in industrial waste 

 effluents and they result in offensive tastes, odors, and colors of fish and 

 shellfish. 



The salts of heavy metals are fairly soluble and stable in solution. 

 Consequently, they will persist for extended lengths of time. Many of 

 these are highly toxic to the aquatic biota, and since many marine 

 organisms exhibit the ability to accumulate and concentrate sub- 



