of radioactive materials from aquatic sources and that 

 fish living in the water vi'ill not receive an injurious 

 dose of radiation. 



(3) The concentrations of radioactive materials 

 present in fresh, estuarine, and marine waters should be 

 less than those that would require restrictions on the 

 use of organisms harvested from the area in order to 

 meet the Radiation Protection Guides recommended 

 by the Federal Radiation Council. 



This recommendation assures that fish and other 

 fresh water and marine organisms will not accu- 

 mulate radionuclides to levels that would make 

 them unacceptable for human food. It also limits 

 the radiation dose that the organisms would receive 

 from internally deposited nuclides to levels below 

 those that may be injurious. Some workers (Car- 

 ritt, 1959; Isaacs, 1962; Pritchard, 1959) have 

 recommended "maximum permissible levels for 

 sea water" based on various assumptions of dis- 

 persion, uptake by marine organisms, and the use 

 of the organisms as food by people. While these 

 recommendations are most useful as a first ap- 

 proximation in predicting safe rates of discharge 

 of radioactive wastes, their applicability as water 

 quality criteria is limited and they are not intended 

 for use in fresh or estuarine waters where the con- 

 centrations of a great variety of chemical elements 

 vary widely. Because it is not practical to general- 

 ize on the extent to which many of the important 

 radionuclides will be concentrated by fresh water 

 and marine forms, nor on the extent to which these 

 organisms will be used for food by people, no at- 

 tempt is made here to specify MPC for either sea 

 water or fresh water in reference to uptake by the 

 organisms. Rather, each case requires a separate 

 evaluation that takes into account the peculiar fea- 

 tures of the region. Such an evaluation should be 

 approved by an agency of the State or Federal 

 Government in each instance of radioactive con- 

 tamination in the environment. In each particular 

 instance of contamination, the organisms present, 

 the extent to which these organisms concentrate 

 the radionuclides, and the extent to which man 

 uses the organisms as food must be determined, as 

 well as the rates of release of radionuclides must be 

 based on this information. 



Plant nutrients and nuisance 

 organisms 



All terrestrial biological processes plus the ma- 

 jority of man's activities ultimately result in waste 

 products in various stages of decomposition. A 

 portion of these sooner or later enter surface fresh- 

 waters. These waste products include a rather 



abundant amount of plant nutrients such as nitro- 

 gen, phosphorus, carbon, and other elements. 

 Subsequently, these plant nutrients are incorpo- 

 rated into organic matter by aquatic plants. 



Surface water areas are like land areas in that 

 some type of vegetation will occupy any suitable 

 habitat. Thus, the more abundant the nutrient sup- 

 ply, the more dense the vegetation, provided other 

 environmental factors are favorable. In the aquatic 

 habitat, these growths may be bacteria, aquatic 

 fungi, phytoplankton, filamentous algae, sub- 

 mersed, emersed, floating, and marginal water 

 plants. Practically all aquatic plants may be de- 

 sirable at one time or another and in one habitat 

 or another. However, when they become too dense 

 or interfere with other uses of the water or of the 

 aquatic habitat, they become nuisance growths. 



Some sheath-forming bacteria are the primary 

 nuisance-type growths in rivers, lakes, and ponds. 

 A notable problem associated with this group oc- 

 curs in areas subjected to organic enrichment. The 

 most common offenders belong to the genus Sphae- 

 rotilus. These bacteria are prevalent in areas re- 

 ceiving raw domestic sewage, improperly stabilized 

 paper pulp effluents or effluents containing simple 

 sugars. The growths they produce interfere with 

 fishing by fouling lines, clogging nets, and gener- 

 ally creating unsighdy conditions in the infested 

 area. Their metabolic demands while they are liv- 

 ing and their decomposition after death impose a 

 high BOD load on the stream and can severely 

 deplete the dissolved oxygen. It has been suggested 

 that large populations of Sphaerotilus render 

 the habitat noxious to animals and hence its 

 presence may actively exclude desirable fish and 

 invertebrates. 



The freshwater algae are diverse in shape, 

 color, size, and habitat. A description of all spe- 

 cies of algae would be as comprehensive as writing 

 about all land plants, mosses, ferns, fungi, and 

 seed plants. 



They may be free floating (planktonic) or they 

 may grow attached to the substrate (benthic or 

 epiphytic types). They may be macroscopic or 

 microscopic and are single-celled, colonial, or fila- 

 mentous. They are the basic link in the conversion 

 of inorganic constituents in water into organic 

 matter. When present in suflicient numbers, these 

 plants impart a green, yellow, red, or black color 

 to the water. They may also congregate at or 

 near the water surface and form so-called "water- 

 bloom" or "scum." 



A major beneficial role of algae is the removal 

 of carbon dioxide from the water by photosyn- 

 thesis during daylight and the production of oxy- 

 gen. Algae, like other organisms, continually 



51 



