Showing papers on "Bioaccumulation published in 1979"

Bioaccumulation of marine pollutants.

Abstract: Bioaccumulation of pollutants can occur from sea water, from suspended particles, from sediments and through food chains. The rate at which accumulation occurs in an organism depends not only on the availability of the pollutant but also on a whole range of biological, chemical and environmental factors. The ultimate level which is reached is governed by the ability of the organism to excrete the pollutant or, alternatively, store it. This latter course often leads to the attainment of very high concentrations and sometimes no equilibrium level is ever reached. Two particular topics which are considered are the biological amplification of pollutants along food chains and the development of tolerance which sometimes occurs.

Estimating rate constants for the uptake and clearance of chemicals by fish

Abstract: Presented are mathematical models developed to predict the uptake of chemical residues by fish. Predictions made with the models are compared with actual bioaccumulation of di-2-ethylhexyl phthalate, chlorpyrifos, and TCDD observed in fish. The new models, which were designed to consider both the physiological characteristics of the fish and chemical properties, provide acceptable predictions of actual bioaccumulation rates. (2 graphs, 16 references, 4 tables)

Bioaccumulation of cadmium in marine organisms.

Abstract: A general review of cadmium concentrations in marine organisms and studies of cadmium bioaccumulation is presented. Factors which influence cadmium concentrations, such as regional differences, seasonal fluctuations and salinity, are discussed and species which are likely to accumulate cadmium identified. Experimental studies designed to investigate the influence of some of these factors on cadmium bioaccumulation in a filter feeding bivalve mollusk, the American oyster (Crassostrea virginica), are presented. Field studies of seasonal dynamics of cadmium in oysters indicate patterns which may be correlated with seasonal physiological activity. The bioaccumulation of cadmium following input to estuarine systems by natural phenomena is observed. Cadmium concentrations in oysters collected from regions of different salinity suggest an inverse relationship between cadmium concentration and salinity. Laboratory experiments designed to investigate mechanisms of cadmium accumulation demonstrate that an inducible cadmium binding protein, similar to metallothiomein, is present in the American oyster.

Degradation of Selected Organophosphate Pesticides in Water and Soil

Abstract: Laboratory studies on the breakdown of several organophosphate pesticides both in aqueous solution and moist soil were conducted. The hydrolysis rates of phosmet, dialifor, malathion, methyl chlorpyrifos, dicapthon, chlorpyrifos, and parathion were measured at 20 and 37.5 "C (pH 7.4) in an aqueous system. A similar study was carried out at 20 "C and pH 6.1. The half-lives at 20 "C (pH 7.4) range from 7.1 h for phosmet to 130 days for parathion; the corresponding rates at 37.5 "C are approximately fiveseven times greater than those at 20 "C. The rate equations at pH 7.4 were calculated from the 20 and 37.5 "C data in an Arrhenius form: k = A exp(-Ea/RT). In moist soil (pH 6.2), degradation rates were measured at pesticide concentrations of approximately 1.0 and 0.1 ppm in a Willamette clay loam soil at a moisture level of 50% of field capacity. A comparison of the 20 "C half-lives for phosmet and dialifor in water and in moist soil at comparable pH indicates an appreciable increase in persistence for these two compounds, but little for the others in the soil-water system. This study was intended to evaluate the stabilities of several agricultural pesticides. In recent years, there has been an increasing concern over the effects of residual pesticides on man and his environment. This concern has led to the prohibited use of the less toxic but more persistent organochlorine pesticides. There has been an increasing use of organophosphates and carbamates which are regarded to be less persistent and consequently less likely to bioaccumulate. However, an assessment of the bioaccumulation potential through measurement of the octanol/water partition coefficient (Chiou et al., 1977) showed that some organophosphates have partition values comparable to those of the organochlorine compounds (e.g., DDT, DDE). This study deals with structural variables and environmental factors such as temperature and solution pH as related to persistence. Information on the persistence of these compounds will provide a better base on which to evaluate future use.

Cadmium bioaccumulation assays. Their relationship to various ionic equilibria in Lake Superior water.

Abstract: Bioaccumulation by Daphnia magna could be used as an analytical tool in studying properties of various aqueous cadmium forms. Selected aquatic chemical factors affecting cadmium residues were determined for organisms exposed to cadmium in the absence and presence of various organic and inorganic chemicals. Without any added complexing agents, steady state relationships between total aqueous cadmium concentrations and bioaccumulated cadmium within 2-4 days of exposure were observed. Residues were a nonlinear function of the concentration. Presence of humic acid, pyrophosphate, or aminopolycarboxylic acids, at sufficient concentrations to maximize complexation, was effective in reducing cadmium uptake. However, cadmium in the presence of diethyldithiocarbamate bioaccumulated to a greater degree than in its absence. (1 graph, 26 references, 4 tables)

Toxic substances in the Great Lakes

Abstract: The origins and distributions of heavy metals and organic wastes in the Great Lakes are reviewed. PCB's, mercury, and pesticide residues pose the greatest threat to aquatic organisms in the Great Lakes. Studies that have been conducted to determine sediment content of toxic substances and bioaccumulation of substances by fish in the Great Lakes are surveyed. The need for an effective federal program to improve water quality of the Great Lakes is stressed. (1 diagram, 1 map, 2 tables)

The uptake and release of petroleum hydrocarbons by the marine mussel mytilus edulis

Abstract: Mussels, Mytilus edulis, were exposed to seawater solutions of four radiolabelled hydrocarbons. The aromatic hydrocarbons were rapidly accumulated. Bioaccumulation factors were determined to about 4 for toluene, about 30 for naphthalene, and more than 70 for phenanthrene. The bioaccumulation factors were found independent of the water concentration level. When transferred to clean seawater, the hydrocarbons were released, toluene and naphthalene very rapidly, phenanthrene more slowly. Hexadecane was taken up and released very slowly. During 8 hours' exposure to hexadecane the concentration in the mussels did not reach the concentration in the water. The coefficients of variation of hydrocarbon accumulation between individual mussels were determined and found between 18 and 32%. The results support the theory that uptake and release of hydrocarbons are passive processes dependent on partitioning between the water and the tissue lipids.

Bioaccumulation and elimination of copper in the rock oyster Crassostrea cucullata

Abstract: The kinetics of copper bioaccumulation in the rock oyster Crassostrea cucullata Born showed that the initial rate of uptake was directly related to metal concentration in the medium. As the accumulation in the tissues increased, the oysters remained closed and the uptake rate fell. At the end of 7 weeks, the average copper concentrations in the tissue were 60.42 μg g-1 and 63.97 μg g-1 wet weight in the 0.01 and 0.05 ppm experimental groups, respectively. The net rate of uptake ranged from 1.76 to 1.97 μg g-1 week-1 and the rate of copper loss, measured after transferring the oysters into natural sea water, was dependent on the original cooper concentration in the soft parts. The concentration of copper in the tissues declined by 37.38 and 36.56% in the 0.01 and 0.05 ppm experimental groups, respectively. Even after a 7 week period of depuration (self-purification) there was some residual copper left in the tissue. This indicates that accumulation occurs in the tissue more rapidly than cleansing can eliminate it.

Bioaccumulation and depuration of bromoform in five marine species

Abstract: Bromoform has been identified as the major halogenated organic compound resulting from the chlorination of seawater. To test the potential for bioconcentration and subsequent return to man, 28-day uptake/28-day depuration studies were conducted with five commercially and recreationally important species (Protothaca staminea, Mercenaria mercenaria, Crassostrea virginica, Penaeus aztecus, Brevoortia tyrannus). The results indicate that for these species, the uptake and depuration is rapid (equilibrium is reached in 24 to 48 hours), and the concentration factors are relatively low (< 1 to 10 times the water concentration).

Some physical factors in toxicological assessment tests.

Abstract: Many thousand organic compounds are in common use and new ones introduced daily. With many of these materials, little is known about their toxic hazard. For years scientists have been investigating the relation of structure and properties to biological activity. Among the factors relating to toxicity are bioaccumulation and persistence in the organism. In this study, the relation of partition coefficient and solubility to bioaccumulation of some organochlorine compounds was investigated as was also the reactivity of several organophosphates. The work adds confirmation to the relation of molecular parameters to penetration, accumulation, and persistence in toxic action.

Organochlorine Contaminants in The Great Lakes

Abstract: Great Lakes sediments and biota are contaminated by persistent and toxic organochlorine compounds. Large areas of sediments are contaminated, however, much higher concentrations are observed in fish and birds due to bioaccumulation processes The estimated total load of polychlonnated biphenyls in the sediments of the Lakes Ontario, Erie and Superior is approximately 50 metric tons. Spatial and temporal changes of sediment contamination can provide useful information on contaminant sources and pathways within the basin. With increasing numbers and amounts of chemicals in use, the potential for further environmental damage is high. Environmental research, effluent limitations and public education are needed to restore and maintain high water quality in the Great Lakes.

Factors determining the bioaccumulation potential of pesticides in the individual compartments of aquatic food chains

Abstract: Representative members of aquatic food chains, i.e., algae (Scenedesmus acutus), daphnids (Daphnia magna), and catfish (Ictalurus melas), have been used to evaluate the bioaccumulation potential of 10 pesticides. The objectives of the studies were to determine the kinetics of bioacumulation and depuration of pesticides and to estimate the contribution of food chain transfer of pesticide residues to the total magnitude of bioaccumulation. Furthermore, the influence of physicochemical properties and the stability of pesticides in the aquatic environment on their final concentration in aquatic organisms and on their possible availability in the aquatic environment was investigated. In standardized experiments it was shown that bioaccumulation of nonionic organic chemicals from water can essentially be described as sorption or, as a simplification, as a distribution phenomenon which was correlated with the n-octanol/water partition coefficient of the compounds. Increasing the biomass at a given pesticide concentration caused a decrease in the bioaccumulation factor. Depuration of pesticides from aquatic organisms followed second-order reaction kinetics. The half-lives as well as the reciprocal of the rate constants of depuration were found to be highly correlated with the lipophilicity of the pesticides. Transfer of pesticide residues via food chains was found to be of lesser importance compared with direct uptake from water. It did not result in a buildup of residues so that higher residues would have been obtained in higher trophic levels of the aquatic food chains (biomagnification). Even for the highly lipophilic p, p′-DDT only 23 and 44% of the residue of the respective lower food chain organisms (algae, daphnids) were retained by the respective higher food chain organisms (daphnids, catfish). Also the transfer of residues can be estimated by means of the partition coefficient of the pesticide. The possible appearance of a soil-applied pesticide in water systems depends on its soil mobility which was found to be inversely correlated with the partition coefficient and also with the sorption constants of aquatic organisms. Consequently, a high bioaccumulation potential of a lipophilic compound is significantly reduced due to its limited transfer to the aquatic environment.