251 



through the estuarine zone by ships, barges, pipelines, trucks, and 

 railroads present a continuing opportunity for accidental bulk spills. 

 The consequences of these spills depend on the amount and type of 

 material released and the characteristics of the receiving water. They 

 may range in magnitude from tragic loss of human life to little more 

 than economic loss for the transporter ( fig. IV.5.9 ) . 



When a significant spill occurs, the results can be dramatic. A large 

 quantity of material i& suddenly disgorged into the system ; the fate of 

 this material depends on its miscibility with water, its solubility in 

 water, and its density, stability, and volatility. The fate of the environ- 

 ment depends on what segments contact the material and the inherent 

 toxicity of the material. 



The potential magnitude of the problem is staggering. The quan- 

 tities and varieties of oils and other hazardous materials transported 

 or stored are reflected in the following statistics : 



(1) Almost 4 billion barrels of petroleum and natural gas 

 liquids are used annually in the United States, 



(2) Twenty-five billion pounds of animal and vegetable oils 

 are consumed or exported annually. 



(3) Almost 80 billion pounds of synthetic organic chemicals 

 are produced annually by some 12,000 chemical companies. These 

 chemicals, many of which are toxic or have unknown effects on 

 aquatic or human life, range from everyday food flavorings to 

 lethal pesticides. 



The damage to water uses can be demonstrated by consideration of 

 a catastrophic oil spill. Water birds are attracted by the slick on the 

 surface. Once they contact the oil, their feathers become matted and 

 oil soaked. The birds either drown, are killed by toxicosis from 

 ingested oils or by exposure from the loss of body insulation, starve to 

 death from inability to fly and search for food, or are eaten by 

 predators (fig. IV.5.10). 



Fish become coated with oil and their gills become clogged, result- 

 ing in death. If the exposure is sublethal, their flesh becomes tainted 

 rendering them unfit for human consumption for a considerable time. 

 Toxic oil fractions in the water can kill the larval and adult forms 

 of invertebrate marine life necessary for a balanced ecosystem. 

 Aquatic vegetation is destroyed. An extreme fire hazard can exist, 

 depending on the type and extent of the oil blanket. Recreational use 

 of the water is impaired. Swimmers become coated with oil which is 

 difficult to remove; boat hulls are stained; beaches with oil deposits 

 become virtually unusable. Apart from the physical damage, there 

 is also an esthetic damage. Noxious odors may permeate the shoreline 

 areas; and waterfront properties are despoiled (fig. IV.5.11). 



The direct damage is not the total economic impact. The cost of 

 cleanup must be added and is considerable. The ever-present threat 

 of a catastrophic spill places the estuarine treasure house of resources 

 in jeopardy. 



DELIBERATE PHYSICAL MODIFICATION 



Building a bridge, dredging a channel, and filling land for a hous- 

 ing development are not ordinarily regarded as forms of pollution, 

 yet they can cause damage to the biophysical environment far more 

 devastating than the most potent industrial or municipal waste. 



