43 



the dissolved oxygen in the water makes it impossible for most marine organisms 

 to survive and also results in the production of hydrogen sulphide, a toxic, 

 malodorous gas. Even when the treatment methods are successful in preventing 

 excessive oxygen depletion, the ferti'izing elements remain in the effluent and can 

 stimulate excessive growth of objectionable plant populations in the process 

 known as eutrophication. This plant growth can produce as much organic mate- 

 rial as was removed at considerable cost in the treatment plant, thus partly 

 defeating the puri>oses of sewage treatment. 



Because of the biodegradability of domestic pollution, it is not persistent in 

 the environment, except for the added fertilizing elements. For the oceans as a 

 whole, therefore, domestic ixilution is not a significant problem, but it is im- 

 portant in more confined areas where the density of the human population is 

 high and the recovery capacity of the system is limited. I have computed, for 

 example, that the population of metropolitan New York discharges into the 

 Hudson estuary about 5 to 10 times as much domestic pollution as the s.vstem can 

 recycle without an adverse impact (Ketchum, 1969). Fortunately, the mixing 

 in the Hudson estuary is vigorous and by the time the water leaves the Harbor 

 and enters the New York Bight the dilution is sufficient to reduce the concentra- 

 tions of nutrients to acceptable levels. 



A corol'ary of the fertilizing effects of domestic pollution is the fact that it 

 could be used beneficially to stimulate the productivity of the sea if it were dis- 

 charged within the limits of the receiving capacity of the ecosystem. This must 

 be carefully done to avoid inifortunate side effects but it is possible, theoretically 

 at least, to use this type of pollution for beneficial purposes rather than to dispose 

 of it in ways that cause deleterious effects. 



Solid Wastes 



Solid waste disposal has become one of the most urgent and diflBcult problems 

 in crowded urban centers. The types and amounts of waste materials dumped at 

 sea in the coastal waters "of the United States in 1968 is presented in Table 2 

 (Council on Environmental Quality. 1970). Nearly 50 million tons of waste 

 material was dumped in T-nited States' coastal waters, most of which was 

 dredging spoils resulting from channel and harbor development. The Council 

 estimated that 3J% of these dredging spoils could be considered polluted. Pearce 

 (1970) has presented data to show that both the polluted dredging spoils and the 

 sewage sludge from waste treatment plants which has been dumped in the New 

 I'ork Bight have cau.sed damage to the bottom dwe'ling population in the area. 

 The Marine Protection, Research and Sanctuaries Act of 1972 regulates the 

 transportation and dumping of materials into the oceans, coastal zones and other 

 waters. A permit system is established to be administered by the Army Corps of 

 Engineers for dredging and filling and by the Environmental Protection Agency 

 for all other purposes. 



TABLE 2.— OCEAN DUMPING:' TYPES AND AMOUNTS, 1968 

 (In tons] 



Percent 

 Waste type Atlantic Gulf Pacific Total oftota. 



Dredge spoils _ 15,808,000 15,300,000 7,320,000 38,428,000 80 



Industrial wastes 3,013,200 696,000 981,300 4,690,500 10 



Sewage sludge 4,477,000 4,477,000 9 



Construction and demolition debris 574,000 574,000 



Solid waste 26,000 26,000 1 



Explosives 15,200 ' 15,200 



Total 28,887,400 15,966,000 8,327,300 48,210,700 100 



» From CEQ, 1970. 



Ocean dumping is also a subject of international concern. An intergovem- 

 inentil conference convened l)y the United Nations was held in London. 30 October 

 to 10 November, 1972. A Convention on the Dumping of Wastes at Sea was 

 adopted and will be open for signature from 29 December, 1972, until 1 December, 

 1973. It will come into force when it has been ratified by 15 nations. The Con- 

 vention prohibits the dumping of some materials ; requires a special permit for 

 the dumping of other identified substances ; and a general permit for all other 

 substances. 



