Showing papers on "Bioaccumulation published in 1991"

Toxicokinetics and toxicity of a mixture of sediment-associated polycyclic aromatic hydrocarbons to the amphipod Diporeia sp

Abstract: Amphipods, Diporeia sp., were exposed to a reference sediment dosed with two radio- labeled polycyclic aromatic hydrocarbons (PAHs) and sediments dosed with a mixture of PAHs at four concentrations: 21.4, 41.0, 119.6, and 327.0 nmol g-I dry sediment, as the molar sum of the PAH congeners. Diporeia sp. were sampled for mortality and toxicokinetics for up to 26 d. Signif- icant sediment avoidance was observed at the highest dose out to 6 d of exposure. The toxicity for the mixture was 38 * 3% after 19 d of exposure at the highest dose, 327 nmol g-I dry sediment as the molar sum of the PAHs. The measured organism concentration required to produce the mor- tality at day 19 was 2.9 pmol g-I as the sum of the bioaccumulated PAHs. The uptake clearance (g dry sediment g-' organism h-I) from sediments for the radiotracers increased with dose to an apparent plateau. Uptake clearance is the conditional constant relating the contaminant flux into the organism to the contaminant concentration in the referenced environmental compartment, in this case the sediment. This enhanced bioavailability with dose occurred even in the absence of overt effects and in the absence of changes in the measured partition coefficients for phenanthrene (273 + 98) and pyrene (540 + 212), between the freely dissolved radiotracers in interstitial water and the sediment particles. These changes in bioavailability with changes in PAH concentration suggest that predictions of bioaccumulation of PAH congeners from sediments under different field con- centration conditions will not be possible with standard partitioning relationships.

Modelling Bioaccumulation of Organic Pollutants in Fish with an Application to PCBs in Lake Ontario Salmonids

Abstract: A model describing passive accumulation of organic chemicals from the aqueous environment and contaminated food in fish is developed. This model considers both biological attributes of the fish and...

Relationship between chronic toxicity and bioaccumulation of cadmium in Hyalella azteca

Abstract: The chronic toxicity of Cd to Hyalella in Burlington City tap (Lake Ontario) water with additions of complexing agents, distilled water, or sediments was much more constant if toxicity was expressed as a function of Cd bioaccumulated, rather than the Cd concentrations added or measured in the water. Additions of 20 mg humic acid/L or 0.5 μM EDTA increased the 6-wk EC50 from 0.53 to 4.6 and 19 μg/L, respectively. The EC50 based on bioaccumulated Cd, however, increased from 38 to only 44 μg/g (dry weight). Addition of sediments increased the 4-wk EC50 by > 1000-, 13-, or 2.3-fold for EC50s based on nominal Cd added, Cd concentrations measured in water, or Cd concentrations accumulated by Hyalella, respectively. A 10-fold reduction in hardness caused a twofold increase in the 6-wk EC50 based on Cd accumulation. The relationship between survival and Cd bioaccumulation by Hyalella was, therefore, affected less by complexing agents, hardness, and sediments than was survival compared with concentrations in water...

Evaluation of selected lipid methods for normalizing pollutant bioaccumulation

Abstract: - Current environmental models use organism lipid concentrations to estimate maximum pollutant bioaccumulation potentials. This collaborative study has shown that significantly different lipid concentrations (3.5~) are found when using common, but different, extraction solvents and methods. Based on these variable lipid values, models that estimate tissue pollutant concentrations normalized to lipid will give significantly different bioaccumulation estimates. To reduce that vari- ability, a standard lipid method needs to be developed or adopted. Keywords - Lipid Bioaccumulation Lipid analysis Bioaccumulation modeling INTRODUCTION Tissue residues of neutral organic pollutants such as polychlorinated biphenyls (PCBs) and 1,1, I-tri- chloro-2,2-bis-( pchloropheny1)ethane (DDT) are correlated with lipid concentrations in both fish and invertebrates 11-31. As a result of this association of hydrophobic neutral organics with lipids, lipid concentration has been used to normalize tissue residues

Increased Methylmercury Contamination in Fish in Newly Formed Freshwater Reservoirs

Abstract: The formation of major new hydroelectric reservoirs in northern Canada in the last two decades was invariably followed by increased methylmercury concentrations in fish. Concentrations in piscivorous fish exceeded marketing limits and often approached mercury concentrations (>5 μg g−1 wet weight) in muscle formerly associated only with industrial mercury pollution. Experimental manipulations of large enclosures demonstrated that terrestrial vegetation and organic soils caused increased net methylation of mercury and bioaccumulation of methylmercury at low total mercury concentrations in water (1–2 ng L−1) and sediment (0.1–1.0 μg g−1 dry weight). Total mercury concentrations per se in water or sediments did not predict mercury concentrations in fish. Enhancement of microbial methylation relative to demethylation can be demonstrated in these new reservoirs and in reservoirs up to 60 years of age. Disruption of the natural microbially mediated mercury cycle accounts for the elevated Hg concentrations in fish, and indications are that it will be a persistent problem in boreal reservoirs. The reservoir experience emphasizes the critical role of microbial activity in mercury cycling. In natural lakes of the boreal forest, water temperaturc seems to be a critical variable controlling net mercury methylation by microbial activity.

Fundamental roles of biological barriers in mercury accumulation and transfer in freshwater ecosystems (analysis at organism, organ, cell and molecular levels)

Abstract: In the framework of an ecotoxicological approach to the processes of bioaccumulation and transfer of Hg in freshwater systems, we present a synthesis of our experimental studies concerning the interactions between inorganic Hg and MeHg and biological barriers - at organism and organ levels : three biological models are selected: fish (Salmo gairdneri), burrowing mayfly nymphs (Hexagenia rigida) and rooted macrophytes (Elodea densa, Ludwigia natans). Results show strong specificities of the biological barriers (gills, intestine, roots, ...) towards metal fixation and absorption, closely related to the chemical form of the metal, the contamination sources (water, sediments or food) and the physico-chemical characteristics of the medium ; - at cell and molecular levels : biophysical study of Hg fixation on membrane reveals a new binding site on the phospholipids, the primary amine group on serine and ethanolamine polar heads, jointly with the SH groups of proteins ; Hg(II) induces a strong rigidification of the phospholipidic bilayers. Inorganic Hg and MeHg transports through model membranes (BLM) are essentially due to diffusion of neutral chloride species. These interactions between Hg compounds and membranes are strongly dependent on Hg chemical speciation (pH and pCl effects).

Accumulation levels of organochlorine pesticides in human adipose tissue and blood

Abstract: Because of their persistence and potential for bioaccumulation, the use of organochlorine pesticides, technical hexachlorocyclohexane (HCH) and pp{prime}-DDT, has been prohibited since 1971 in Japan. Furthermore, chlordane which had been applied for termite control has the potential for bioaccumulation and the use of it has been also prohibited since 1986. These chemicals can enter human body through a food chain or by inhalation of vapors. However, few data on chlordane residue in human adipose tissue are available in Japan. The aims of the present study were to assess the levels of organo-chlorine chemicals in adipose tissue and blood of Japanese and to examine the relationship between them.

Accumulation factors for eleven polychlorinated biphenyl congeners.

Abstract: According to the fugacity approach pollutant uptake by an organism is determined by the chemical fugacity differential between the organism and its environment. The Accumulation Factor (AF) is a simple, fugacity-based model which has been shown to be useful for predicting the bioaccumulation potential of hydrophobic neutral organic compounds in sediment dwelling animals. Previously, the constancy of AFs for ten hydrophobic neutral organic compounds were tested by exposing clams (Macoma nasuta) in the laboratory for 28 days to six field-collected sediments varying widely in C{sub S}, TOC, and other chemical and physical characteristics. Sediment and tissue samples from that study were achieved and later analyzed for 11 polychlorinated biphenyl (PCB) congeners. In this paper the authors report mean and maximum AFs (AF{sub max}) for 11 PCB congeners and test the constancy of the AFs across 5 sediments (treatments) by congener and across the 11 congeners by treatment.

Heavy metal accumulation and calcium content in the bivalve Donacilla cornea

Abstract: Accumulation of heavy metals (Cu, Cd and Mn) and their effects on total Ca content were studied under laboratory conditions in sandy-bottom bivalves Donacilla cornea from a n unpolluted shore in northern Sardinia. The bivalves were found to accumulate the 3 metals. Exposure at 2 different temperatures (18 and 25°C) showed significant differences only for Cu accumulation. Following decontamination in clean seawater, the body content of Cu and Mn decreased strongly, whereas that of Cd remained practically unchanged. Among organs, gills contained the highest metal concentrations. A net increase of total Ca concentration in the body was observed during metal accumulation, and the digestive gland seems the most suitable organ for studies on the effects of heavy metals on calcium homeostasis.

Effect of pH on the bioaccumulation of low level, dissolved methylmercury by rainbow trout (Oncorhynchus mykiss)

Abstract: An inverse relationship has been observed between pH and McHg concentration in freshwater fish. Many hypotheses exist regarding the mechanisms which lead to elevated levels of organic Hg in fish from low pH lakes. To determine if pH has a direct effect on the rate of McHg bioaccumulation in fish, rainbow trout fingerlings (Oncorhynchus mykiss) were exposed to a low concentration of aqueous methylmercuric chloride (1.38 ± 0.49 ng·L−1) at four pH-levels (8.2, 7.0, 6.3, 5.8) for eight weeks. McHg and total Hg were specifically determined on whole fish homogenates and water samples. The pH was found to have a significant: inverse effect on the rate of McHg bioaccumulation in the fish only in the lowest exposure level. Fish held at pH 5.8 had an uptake rate of 1.11 ± 0.07 ng·g−1·d−1, while those at pH ≥ 6.3 had a MeHg tissue uptake rate of ≤ 0.64 ± 0.07 ng·g−1·d−1. Total body burden of MeHg in the fish held at pH 5.8 also showed an elevated level of MeHg when compared with fish held at higher pH-levels, but the difference was less dramatic. These results suggest that a portion of the Hg burden in fish from low pH systems may be due to the direct effects of low pH on bioaccumulation, but that a threshold may exist above which pH does not play a significant role.

Bioaccumulation kinetics and organ distribution of lead in a fresh water teleost, colisa fasciatus

Abstract: The study of bioconcentration, kinetics of accumulation and tissue distribution of lead, in a teleost fish, Colisa fasciatus was undertaken in a laboratory ecosystem. The system was exposed to test water with sublethal concentrations of lead. Variability of lead in tissue (gills, liver, muscles) was evaluated and is presented here. Measurements of lead contained in individual organs expound high concentrations of lead in gills and muscles, explicating gills and muscles as major sites for concentration. The uptake rate kinetics show an initial rapid phase and later slow phase responsible for net accumulation.

Bioaccumulation of metals by the southern mouthbrooder, Pseudocrenilabrus philander (Weber, 1897) from a mine-polluted impoundment

Abstract: The bioaccumulation of Fe, Mn, Zn, Cu, Ni and Pb by the cichlid Pseudocrenilabrus philander from a mine-polluted impoundment in the Transvaal was investigated. With the exception of Fe, all the other metals were accumulated in higher concentrations in the tissues of the fish than those in the sediments of the lake, with the highest bioconcentration factor being 8.54 for Zn. Results also showed that there was an inverse relationship between metal concentration and body mass of the fish, with the smaller juvenile fish being better able to concentrate all the metals per equivalent body mass than was the case for the larger, adult fish. This phenomenon is linked to a superior bioregulation mechanism for metals by the larger older fish, as well as the relatively higher metabolic rate of the younger juvenile fish

Bioaccumulation of organic micropollutants in different aquatic organisms. Sublethal toxic effects on fish

Abstract: Bioaccumulation of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) was investigated in plankton, crustaceans, and fish from two relatively small Amsterdam lakes, with different levels of contamination. Ratios between contaminant concentrations in organisms and sediments ranged from 0.1 to 41.7. The accumulation of pollutants could not be explained as a simple partitioning between sediment, water, and organisms. Probably, both biomagnification (PCBs and OCPs) and biotransformation (PAHs) affect the bioaccumulation in aquatic organisms. These effects were more pronounced in organisms of the higher trophic levels of the aquatic food-chain. Mixed function oxygenase (MFO) activity of liver microsomal fractions was determined in three fish species (roach, ccl, and pike) and compared with those of similar fish taken from a less contaminated lake that served as a reference. Despite the low level of contaminants present in the two lakes, an induction of both cytochrome P-450 and ethoxy-resorufin-O-deothylase (EROD) activity was observed in all three fish species involved. Pentoxyresoufin-O-depentylase (PROD) activity was induced in pike and eel only. Both the 3-methylcholan-threne-type inducible isozymes (P-450IA) and the phenobarbital-type inducible isozymes (P-450IIB) seem to be induced in the fish. These findings suggest that MFO enzyme activity in fish liver may be a suitable and sensitive indicator for the presence of trace organics in the aquatic environment. Despite the enzyme induction, no significant liver enlargement was observed in the fish species investigated, which can be interpreted as the absence of some pathological changes.

Bioaccumulation Kinetics: Experimental Data and Modelling

Abstract: Organic micropollutants which tend to accumulate in aquatic organisms can be taken up from water, food or sediments. For most contaminants which bioaccumulate, uptake from water is the predominant route. Because aquatic organisms have to ventilate very large amounts of water to satisfy their oxygen requirements, exposure to extremely low concentrations in water can lead to high concentrations in the organisms.

Experimental ecosystems: Comparative study of two methods of contamination of the water column by mercury compounds in relation to bioaccumulation of the metal by rooted macrophytes (Ludwigia notons).

Abstract: In the context of work on bioaccumulation and transfer of mercury compounds within a multicompartment model (water, natural sediment, rooted macrophytes) a study was set up to select from several methods of water column contamination the one which best matched our experimental objectives. After some theoretical considerations based on a simulation using simple mathematical models, an experiment was carried out to compare two methods of water column contamination, with specific reference to the bioaccumulation of total mercury by one species of rooted macrophyte (Ludwigia natans): these were: 1) continuous additions of Hg in order to maintain a constant concentration in the water, and 2) twice daily additions of a constant quantity of Hg into all experimental units. For a better appreciation of the effect of each method, the experimental protocol considered several factors: photoperiod, temperature, chemical form of mercury and length of observation period. In view of the overall objectives of our...

Study of accumulation of copper by carp (Cyprinus carpio L.) ‐ adaptation analysis of bioconcentration by the gills

Abstract: Experimenta were carried out with a cyprinid, Cyprinus carpio, adopting a semi‐static type of test during 3 weeks and using 2/10 of previously determined 48 h copper LC 50 at three different water hardness (50, 100, 300 mg.l‐1 as CaCO3). Bioaccumulation was studied using a sample of gills from three fish that were kept overnight in toxic free water for elimination of the metal adsorbed on surface being samples taken at the start of experimenta and every week. Adaptation assays were also performed submitting fish to increasing proportions of LC50. Bioconcentration factor (BCF) and pollution factor (PF) were determined and a relationship between copper concentrations in water and in the gills was found. Although considering only an external transtegumentary route, it can be admitted that copper concentration in gills might be used as a first approach for a bioindicator of chronic contamination. Thus, if the concentration of copper in water is known, the concentration in aquatic organisms can be cal...

Bioaccumulation of Nonylphenol in Caged Mussels in an Industrial Coastal Area on the Swedish West Coast

Abstract: In a field test with caged mussels (Mytilus edulis), bioaccumulation of nonylphenol (NP) and its short-chained ethoxylates was measured after a 7-week exposure along a transect away from the wastewater outlet of a chemical plant on the west coast of Sweden. The highest tissue residue concentration of NP was found in mussels from the deep cages close to and just north of the outlet, which is the main direction of the water current. In a test performed at the same time, mussels were exposed to known concentrations of wastewater. The degree of bioaccumulation of NP could then be estimated and compared with that obtained in the field.

Toxicity of selected chromium compounds in microbial bioassay system

Abstract: The short term acute toxicity of potassium chromate, potassium dichromate and chromium sulphate has been compared in a simple microbial bioassay. The test parameters were, decrease in viability, genotoxicity and metal uptake. The LC50 values of Cr(III), dichromate Cr(VI) and chromate Cr(VI) for Escherichia coli were 16, 10 and 1.2 μg mL−1, respectively. Among the test substances potassium chromate was most toxic and showed no bioaccumulation while potassium dichromate was less toxic but resulted in significant bioaccumulation. Chromium sulphate was least toxic. As evident from loss of plasmid, genotoxicity was exhibited only by Cr (VI).