Effects of ionising radiation on aquatic organisms and ecosystems, technical report series no. 172

lume is excellent in providing a concise account for the current status of the art in the use of nuclear techniques in geochemistry and geophysics. The volume lacks any discussion of the use of naturally occurring radionuclides in geochronology; while the major methods are now very sophisticated and constitute a well-defined discipline, the volume could have dealt with the use of some of the shorter lived radionuclides, for example 2~°Pb and 2~°Po, for dating modern geological materials and some biological materials which are important in examining the record of industrial pollution as contained in modern cores. Mention, at least, could also been made of the use of radon and thoron in geochemical prospecting together with the varied use of fission track and alpha particle recording in plastics in relation to the geochemistry of uranium and thorium. This volume illustrates the very valuable contribution made by nuclear techniques in geochemistry and geophysics and is to be recommended to a wide audience. Plymouth (England) E . I . Hamilton

Effects of lonising Radiation on Aquatic Organisms and Ecosystems, Technical Report Series No. 172, International Atomic Energy Agency, Vienna, 1976, 131 pp. Price: U.S. $ 8.50. ISBN 92-0-125076-2.

This volume presents the results of discussions held in November 1971 and April 1974 and concerns the levels of dose from ionising radiation received by aquatic organisms, somatic and genetic effects and potential effects following exposure to low-level chronic irradiation of aquatic ecosystems. Chapter I present an excellent review for levels of natural and man-produced radionuclides in various components of aquatic ecosystems; data are fairly complete for natural radionuclides but there appear to be gaps in knowledge for internal dose received by organisms from man-produced radionuclides. In spite of the many problems of natural variability of aquatic ecosystems the magnitude of radiation exposure originating from man's activities are similar to those found for terrestrial ecosystems, namely 40/~ radh -~. Under normal operating conditions of nuclear facilities, it is considered unlikely that the dose rate to aquatic organisms will exceed those of natural background levels. However, it is acknowledged that in the vicinity of discharge points increases above background levels are to be expected, but are not likely to exceed 25 m radh -1. "It seems unlikely that dose rates greater than this will occur in environments receiving waste when the discharge is controlled on public health criteria"mhopefully all discharges are controlled on the grounds of public health through the method of critical path analysis and contain some additional protection in the case of defined accidents. Chapter 2 considers effects to components of aquatic ecosystems arising from exposure to ionising radiation. Mortality has been observed for exposure 195

to an acute dose of 100 rad, while for chronic exposure, physiological or metabolic effects have been observed at a dose rate in the order of 1 rad d-1. One of the major problems is the lack of data describing exposure to low close rates under conditions of realistic natural exposure. Chapter 3 highlights the problems of determining effects on aquatic organisms which arise because of the great variation of response to ionising radiation compared with those for man. However, the mortality among many aquatic species from natural causes is very high, often much less than 196 of the viable zygotes are expected to reach adulthood and reproduce. With present estimates of dose no significant deleterious effects are likely to be produced although species which are less fecund, such as the whale, shark and seal, have to be considered separately. This volume concludes with a listing of recommendations for future research, such as a need to carry out dose assessments at realistic levels, to consider species common to the natural environment rather than focus attention on a species which is amenable to laboratory work, to pay more attention to radionuclides present in coastal waters and to consider the effects of ionising radiation in terms of the stability of total aquatic ecosystems. A general conclusion, applicable to most aspects of ionising radiation as recorded by aquatic systems, is that no effects are observed and none are really expected for natural environments although many gaps in knowledge still exist. Since this publication was prepared the impact of plutonium released into the natural environment as a result of reprocessing nuclear fuels has aroused considerable attention; quite clearly some aquatic environments will be subjected to new levels of ionising radiation which because of the nature of the process are likely to be concerned with fairly large geographical distributions. Hopefully, the experience gained in such areas from past levels of discharge will be sufficient to indicate any future potential hazards; the areas of concern will centre upon the benthic communities and the manner in which radionuclides deposited on bottom sediments participate in aquatic ecosystems. Plymouth (England) E . I . Hamilton

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