International symposium on applications of isotope techniques in studying past and current environmental changes in the hydrosphere and the atmosphere

Abstract

Radionuclides have long been in use for various measurements of coastal environment contamination. As to effluent disposal impact evaluation, its proper utilization depends on the discharge type as well as on characteristics of the receiving system. Industrial effluents, even at smaller flow rates, may be more deleterious than domestic wastewaters. Besides, their degrading effect will increase as one passes from open to confined waters; estuaries are the most sensitive coastal ecosystems. Industrial effluents also differ from waste waters in that they may eventually be denser than sea water and, not infrequently, laden with particulates. In such circumstances, multiple tracers are instrumental. In any case, tracer measurements should always be backed by hydrological observations, often in conjunction with physicochemical and biological surveys. Only then will tracers be able to deploy their full potential. However, radiotracers may not be very effective in very dynamic systems such as estuaries. In these cases, natural tracers, when properly used, may assist or even substitute artificial ones. Salinity is the most obvioyus tracer of this type. The paper briefly describes some of the work performed in Brazil, each case dealing with a special situation.