APPLICATION OF NEUTRON ACTIVATION ANALYSIS IN STUDIES OF LONG-TERM EFFECTS ON SOIL AND VEGETATION OF TRACE ELEMENTS FROM REUSE OF SEWAGE EFFLUENTS AND RADIOCHEMICAL-NEUTRON ACTIVATION ANALYSIS OF MARINE SPECIES IN A STUDY OF ARSENIC AND SELENIUM IN AQUATIC FOOD CHAINS OF THE SOUTHERN CALIFORNIA ECOSYSTEMS.

摘要

Part I. The primary goal of this investigation was to evaluate the metal accumulation in soils irrigated with wastewater. By examining the sewage effluent, the irrigation water, the soil to which the effluent is being applied, and the plant materials grown in the soil, the objective was to ascertain whether trace elements accumulate in any of these components. By means of delineation of trace elements with soil depth, it was possible to draw some conclusions concerning the effect that trace elements of the effluent have on ground water, and to study the role of the soil column in filtering some of these elements.; The present investigation compared two study sites, one in Orange County and the other one in Las Virgenes, located in Ventura County. The metals examined by neutron activation analysis were arsenic, antimony, chromium, cobalt, iron, manganese, mercury, and selenium. Cadmium, copper, lead, nickel, silver, and zinc were determined in a separate study by others, using atomic absorption spectroscopy.; The results of this study provide information for formulating standards concerning trace elements in treated sewage effluents for irrigation.; Part II. The purpose of this research was to determine the degree to which southern California coastal marine ecosystems are "structured" with respect to pollutants, by determining concentrations of pollutants in tissues of marine organisms and comparing these data with trophic-level assignments determined from food habit studies.; Previous researchers have shown that toxic elements, such as mercury, can be strongly enriched from a negligibly small to a potentially hazardous level by being transported through the stages of trophic level.; In earlier studies, it was shown that arsenic, selenium, and antimony were concentrated in the upper layer of sediments of the Los Angeles County sub-marine outfalls off Palos Verdes Peninsula. The vertical and horizontal concentration profiles of these elements were similar to that of mercury, which occurs at up to 100 times the normal level in the sediments. Therefore one of the important aspects of the present research was to determine the concentrations of arsenic, selenium, and antimony, as marine pollutants, and to assess the effects, if any, of these elements from the principal sewage outfalls in southern California upon marine biological species. In this regard, the relationship between trophic level and the concentration of these elements in the food chain was studied.