Showing papers on "Bioaccumulation published in 2011"

Pollution Threat of Heavy Metals in Aquatic Environments

Abstract: 1 Introduction.- 1.1 Mercury.- 1.2 Cadmium.- 1.3 Other Metals.- 1.4 Sources and Controls.- 2 Toxicity Testing Techniques.- 2.1 Introduction.- 2.2 Terminology.- 2.3 Physical Factors in Toxicity Tests.- 2.4 Biological Factors in Toxicity Tests.- 2.5 Numbers of Test Animals.- 2.6 Chemical Conditions of Tests.- 3 Toxicity of Metals to Freshwater Fish.- 3.1 Arsenic.- 3.2 Cadmium.- 3.3 Chromium.- 3.4 Copper.- 3.5 Lead.- 3.6 Mercury.- 3.7 Nickel.- 3.8 Selenium.- 3.9 Silver.- 3.10 Vanadium.- 3.11 Zinc.- 4 Toxicity of Metals to Freshwater Invertebrates.- 4.1 Arsenic.- 4.2 Cadmium.- 4.3 Chromium.- 4.4 Copper.- 4.5 Lead.- 4.6 Mercury.- 4.7 Nickel.- 4.8 Selenium.- 4.9 Silver.- 4.10 Vanadium.- 4.11 Zinc.- 5 Toxicity of Metals to Marine Life.- 5.1 Arsenic.- 5.2 Cadmium.- 5.3 Chromium.- 5.4 Copper.- 5.5 Lead.- 5.6 Mercury.- 5.7 Nickel.- 5.8 Selenium.- 5.9 Silver.- 5.10 Vanadium.- 5.11 Zinc.- 6 Factors Affecting Toxicity.- 6.1 Interspecies Variations in Freshwater Fish.- 6.2 Interphyletic Variations.- 6.2.1 Freshwater.- 6.2.2 Saltwater.- 6.3 Life Stage.- 6.4 Water Hardness.- 6.5 Temperature.- 6.6 pH.- 6.7 Salinity.- 6.8 Acclimation.- 6.9 Fluctuating Exposure Concentrations.- 6.10 Mixtures of Metals.- 7 Freshwater Field Studies.- 7.1 Introduction.- 7.2 Biological Assessment.- 7.2.1 Zooplankton.- 7.2.2 Benthos.- 7.2.3 Fish.- 7.3 Water Quality.- 7.4 Case Studies.- 8 Tidal Water Field Studies.- 8.1 Introduction.- 8.2 Physical Factors.- 8.3 Chemical Factors.- 8.4 Biology.- 8.5 Case Studies.- 9 Bioaccumulation.- 9.1 Biomagnification of Metals.- 9.2 Factors Affecting Bioaccumulation.- 9.2.1 Physiological Condition.- 9.2.2 Growth.- 9.2.3 Salinity and Temperature.- 9.2.4 Age.- 9.2.5 Sex.- 9.2.6 Position Relative to Shoreline and Water Depth.- 9.2.7 Pollutant Interactions.- 9.3 Monitoring.- 10 Environmental Standards.- 10.1 Introduction.- 10.2 Derivation of Standards.- 10.3 Statistical Expression of the Standard.- 10.4 The Relationship between Field and Laboratory Information.- 10.5 Effluent Controls from Environmental Standards.- 11 International Controls.- References.

Cyanotoxins: bioaccumulation and effects on aquatic animals.

Abstract: Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of cyanobacteria and their toxins over a wide range of aquatic organisms, including invertebrates and vertebrates, have reported acute effects (e.g., reduction in survivorship, feeding inhibition, paralysis), chronic effects (e.g., reduction in growth and fecundity), biochemical alterations (e.g., activity of phosphatases, GST, AChE, proteases), and behavioral alterations. Research has also focused on the potential for bioaccumulation and transferring of these toxins through the food chain. Although the herbivorous zooplankton is hypothesized as the main target of cyanotoxins, there is not unquestionable evidence of the deleterious effects of cyanobacteria and their toxins on these organisms. Also, the low toxin burden in secondary consumers points towards biodilution of microcystins in the food web as the predominant process. In this broad review we discuss important issues on bioaccumulation and the effects of cyanotoxins, with emphasis on microcystins, as well as drawbacks and future needs in this field of research.

Bioaccumulation of some heavy metals in tilapia fish relevant to their concentration in water and sediment of Wadi Hanifah, Saudi Arabia

Abstract: Concentrations of some heavy metals (Pb, Cd, Hg, Cu and Cr) were determined in water, sediment and tissues of tilapia fish collected from Wadi Hanifah during summer 2010. The concentrations of the heavy metal in water were within the international permissible level. Cu had the highest accumulating level in fish whilst Hg had the lowest. The transfer factors of all metals in fish from water were greater than those from sediments. This led to the conclusion that fish bioaccumulation with these metals was from water. Heavy metals under study in the edible parts of tilapia were within the safety permissible level for human use.

Bioaccumulation of Metals in Tissues of Marine Animals, Part I: the Role and Impact of Heavy Metals on Organisms

Abstract: Heavy metals contribute to the anthropogenic contamination of marine ecosystems. Some of them are essential to the life processes of organisms; others are toxic, even at low concentrations. They penetrate organisms via food, respiratory pathways or the skin. The extent to which metals penetrate organisms is measured by bioconcentration and bioaccumulation factors and also by their transport between organisms at different trophic levels of an ecosystem. These factors define the course of metal bioaccumulation in the environment or in organisms, their organs, and tissues. Our paper discusses the role of heavy metals in organisms at different levels of the trophic pyramid (food web) and their influence on life processes. The levels of some elements, like Zn and Cu, are regulated by metabolic processes and are important constituents of enzymes and other compounds. Other such elements, e.g. Hg, Pb, and Cd, are toxic and may adversely affect DNA and enzymatic processes, hence interfere with life processes, even though organisms possess mechanisms for the detoxification and excretion of metals. An important role in metal detoxification is performed by metallothionein (MT), which binds to toxic metals, thereby preventing organisms from harmful effects. Information about the increasing level of a metal is transmitted by the MT gene as it initiates expression regulated by zinc in order to bind MT with the metal. Elements like cadmium, copper, or mercury have a greater affinity for ligands than zinc, and will tend to displace it at MT binding sites. Structures from which zinc has been displaced take part in detoxification, thereby limiting the toxicity of such metals as Cd, Cu, or Hg.

Bioaccumulation and translocation factors of cadmium and lead in 'Aeluropus littoralis'

Abstract: Phytoremediation is an eco-friendly and low cost potential strategy for cleaning up of heavy metals from contaminated soils. Selection of promising plant is an important approach for successful phytoremediation. In two separate pot culture experiments, five levels of soil cadmium (Cd) concentrations as 15, 30, 60, 120 and 240 mg Cd kg-1 soil and five levels of lead (Pb) including 500, 1000, 2000, 4000, 8000 mg Pb kg-1 soil were tested. Plant growth, bioaccumulation and translocation factors of Cd and Pb in A. littoralis were investigated. Cd and Pb reduced the A. littoralis dry matter production significantly. Bioaccumulation factor of Pb was <1, which shows A. littoralis could be an excluder of Pb. Our results also showed translocation factor of Cd was more than one and hence, A. littoralis could be considered as accumulator of Cd. The incremental translocation of Cd to the shoots of A. littoralis, when exposed to the higher Cd in soil, indicates a great performance of this plant for Cd phytoextraction and might be introduced as Cd- hyperaccumulator plant.

Novel Perspectives on the Bioaccumulation of PFCs – the Concentration Dependency

Abstract: The effects of exposure concentration on the bioaccumulation of four perfluorinated chemicals (PFCs): perfluorooctanesulfonate (PFOS), perfluoroocanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), was investigated using green mussels, Perna viridis. Mussels were exposed to concentrations of 1 μgL–1 and 10 μgL–1 of each PFC for 56 days, and the bioaccumulation factors (BAF) were found to range from 15 to 859 L/kg and from 12 to 473 L/kg at 1 μgL–1 and 10 μgL–1, respectively. For all compounds, the BAF was larger at the lower dosage. Results suggest that the bioaccumulation of PFCs is concentration dependent. This concentration dependency can be explained by a nonlinear adsorption mechanism, which was further supported by the experimental results. The sensitivity of BAF to exposure concentration was found to be positively related to perfluorinated chain length and the binding affinity of the compounds. Bioaccumulation of long chain carboxylates and sulfonates are more easil...

Strain-Dependent Norovirus Bioaccumulation in Oysters

Abstract: Noroviruses (NoVs) are the main agents of gastroenteritis in humans and the primary pathogens of shellfish-related outbreaks. Some NoV strains bind to shellfish tissues by using carbohydrate structures similar to their human ligands, leading to the hypothesis that such ligands may influence bioaccumulation. This study compares the bioaccumulation efficiencies and tissue distributions in oysters (Crassostrea gigas) of three strains from the two principal human norovirus genogroups. Clear differences between strains were observed. The GI.1 strain was the most efficiently concentrated strain. Bioaccumulation specifically occurred in digestive tissues in a dose-dependent manner, and its efficiency paralleled ligand expression, which was highest during the cold months. In comparison, the GII.4 strain was very poorly bioaccumulated and was recovered in almost all tissues without seasonal influence. The GII.3 strain presented an intermediate behavior, without seasonal effect and with less bioaccumulation efficiency than that of the GI.1 strain during the cold months. In addition, the GII.3 strain was transiently concentrated in gills and mantle before being almost specifically accumulated in digestive tissues. Carbohydrate ligand specificities of the strains at least partly explain the strain-dependent bioaccumulation characteristics. In particular, binding to the digestive-tube-specific ligand should contribute to bioaccumulation, whereas we hypothesize that binding to the sialic acid-containing ligand present in all tissues would contribute to retain virus particles in the gills or mantle and lead to rapid destruction.

Bioaccumulation of Heavy Metals in Fish (Tilapia Zilli and Clarias Gariepinus) Organs from River Benue, North - Central Nigeria

Abstract: Heavy metals concentrations were determined in fish organs of Tilapia zilli and Clarias gariepinus from River Benue along Makurdi metropolis using atomic absorption spectrophotometer. The results indicated that Tilapia zilli gills contained the highest concentration (52.2%) of all the detected heavy metals, followed by the intestine (26.3%), while the muscle tissues appeared to be the least preferred site for the bioaccumulation of metals as the lowest metal concentration (21.5%) were detected in this tissue. Similarly, the Clarias gariepinus gills contained the highest concentration (40.3%) of all the detected heavy metals, followed by the intestine (31.6%), while the muscle tissue (28.1%) was the lowest. The trend of heavy metals concentration can be represented as: Cr > Zn > Cu > Fe > Mn > Cd > Pb for Tilapia zilli, while that of Clarias gariepinus was Cr > Zn > Fe > Cu > Mn > Cd > Pb. Tilapia zilli showed high bioaccumulation factors of 244, 229 and 178 for Cr, Zn and Cu, respectively. Claria gariepinus showed 232, 226 and 151 for Cr, Zn and Fe, respectively. This suggests that the fish samples could be used to monitor Cr and Zn pollution levels in the River Benue.

Field-Scale Reduction of PCB Bioavailability with Activated Carbon Amendment to River Sediments

Abstract: Remediation of contaminated sediments remains a technological challenge because traditional approaches do not always achieve risk reduction goals for human health and ecosystem protection and can even be destructive for natural resources. Recent work has shown that uptake of persistent organic pollutants such as polychlorinated biphenyls (PCBs) in the food web is strongly influenced by the nature of contaminant binding, especially to black carbon surfaces in sediments. We demonstrate for the first time in a contaminated river that application of activated carbon to sediments in the field reduces biouptake of PCBs in benthic organisms. After treatment with activated carbon applied at a dose similar to the native organic carbon of sediment, bioaccumulation in freshwater oligochaete worms was reduced compared to preamendment conditions by 69 to 99%, and concentrations of PCBs in water at equilibrium with the sediment were reduced by greater than 93% at all treatment sites for up to three years of monitoring....

Antagonistic Interaction of Mercury and Selenium in a Marine Fish Is Dependent on Their Chemical Species

Abstract: It is well-known that selenium (Se) shows protective effects against mercury (Hg) bioaccumulation and toxicity, but the underlying effects of Se chemical species, concentration, and administration method are poorly known. In this study, we conducted laboratory studies on a marine fish Terapon jurbua to explain why Hg accumulation is reduced in the presence of Se observed in field studies. When Se and Hg were administrated concurrently in the fish diets, different Se species including selenite, selenate, seleno-dl-cystine (SeCys), and seleno-dl-methionine (SeMet) affected Hg bioaccumulation differently. At high concentration in fish diet (20 μg g−1 normally), selenate and SeCys significantly reduced the dietary Hg(II) assimilation efficiency (AE) from 38% to 26%. After the fish were pre-exposed to dietary selenite or SeMet (7 μg g−1 normally) for 22 days with significantly elevated Se body concentrations, the Hg(II) AEs were pronouncedly reduced (from 41% to 15−26%), whereas the dissolved uptake rate const...

Bioaccumulation of Metals in Tissues of Marine Animals, Part II: Metal Concentrations in Animal Tissues

Abstract: The bioaccumulation of metals in an animal depends on a multitude of factors: biotic ones, like its body dimensions and mass, age, sex, diet, metabolism, and position in the trophic web; and abiotic ones, such as the distribution of metals in its environment, salinity, temperature, and pH of the water, habitat type, and interactions with other metals. But it is diet that has the greatest influence on the accumulation of metals in animal tissues. Bioaccumulation is a complex process, requiring the simultaneous examination of metal levels in the tissues of animals from at least two adjacent trophic levels. To illustrate the differences in metal concentrations in animals, data are presented on heavy metal levels in the tissues of different groups of animals (marine molluscs, crustaceans, echinoderms, fish, sea turtles, birds, and mammals) from various levels of the trophic pyramid. Most commonly, metal concentrations are higher in larger animals that are end members of a trophic chain than in the smaller organisms they feed on. Since to a large extent an animal’s habitat determines the level of metals in its body, these data are generally indicators of the extent of pollution of the water body in which it lives. It has been found that carnivorous species bioaccumulate far greater quantities of metals than herbivores or omnivores, and that metal levels are lower in organisms capable of detoxifying or excreting metals.

Optimal choice of pH for toxicity and bioaccumulation studies of ionizing organic chemicals

Abstract: It is recognized that the pH of exposure solutions can influence the toxicity and bioaccumulation of ionizing compounds. The present study investigates whether it can be considered a general rule that an ionizable compound is more toxic and more bioaccumulative when in the neutral state. Three processes were identified to explain the behavior of ionizing compounds with changing pH: the change in lipophilicity when a neutral compound becomes ionized, electrical attraction, and the ion trap. The literature was screened for bioaccumulation and toxicity tests of ionizing organic compounds performed at multiple pH levels. Toxicity and bioconcentration factors (BCFs) were higher for acids at lower pH values, whereas the opposite was true for bases. The effect of pH was most pronounced when pH − pKa was in the range of −1 to 3 for acids, and −3 to 1 for bases. The factor by which toxicity and BCF changed with pH was correlated with the lipophilicity of the compound (log KOW of the neutral compound). For both acids and bases, the correlation was positive, but it was significant only for acids. Because experimental data in the literature were limited, results were supplemented with model simulations using a dynamic flux model based on the Fick–Nernst–Planck diffusion equation known as the cell model. The cell model predicts that bases with delocalized charges may in some cases show declining bioaccumulation with increasing pH. Little information is available for amphoteric and zwitterionic compounds; however, based on simulations with the cell model, it is expected that the highest toxicity and bioaccumulation of these compounds will be found where the compounds are most neutral, at the isoelectric point. Environ. Toxicol. Chem. 2011;30:2395–2406. © 2011 SETAC

Temporal increase in organic mercury in an endangered pelagic seabird assessed by century-old museum specimens

Abstract: Methylmercury cycling in the Pacific Ocean has garnered significant attention in recent years, especially with regard to rising mercury emissions from Asia. Uncertainty exists concerning whether increases in anthropogenic emissions over time may have caused increased mercury bioaccumulation in the biota. To address this, we measured total mercury and, for a subset of samples, methylmercury (the bioaccumulated form of mercury) in museum feathers from an endangered seabird, the black-footed albatross (Phoebastria nigripes), spanning a 120-y period. We analyzed stable isotopes of nitrogen (δ15N) and carbon (δ13C) to control for temporal changes in trophic structure and diet. In post-1940 and -1990 feathers, we detected significantly higher mean methylmercury concentrations and higher proportions of samples exhibiting above deleterious threshold levels (∼40,000 ng·g−1) of methylmercury relative to prior time points, suggesting that mercury toxicity may undermine reproductive effort in the species. We also found higher levels of (presumably curator-mediated) inorganic mercury in older specimens of albatross as well as two nonpelagic species lacking historical exposure to bioavailable mercury, patterns suggesting that studies on bioaccumulation should measure methylmercury rather than total mercury when using museum collections. δ15N contributed substantially to models explaining the observed methylmercury variation. After simultaneously controlling for significant trends in δ13C over time and δ15N with methylmercury exposure, year remained a significant independent covariate with feather methylmercury levels among the albatrosses. These data show that remote seabird colonies in the Pacific basin exhibit temporal changes in methylmercury levels consistent with historical global and recent regional increases in anthropogenic emissions.

Uptake and bioaccumulation of heavy elements by two earthworm species from a smelter contaminated area in northern Kosovo

Abstract: As, Cd, Cu, Pb, Sb and Zn concentrations were determined in two earthworm species (Allolobophora rosea and Nicodrilus caliginosus) from a mining and industrial area in northern Kosovo and compared with their contents in the bulk soil and the main soil fractions. Earthworm specimens were collected at fifteen sites located at different distances from a Pb–Zn smelter along a gradient of decreasing contamination. Individuals of A. rosea and N. caliginosus showed similar tissue levels of As, Cd, Cu, Pb, Sb and Zn, suggesting that earthworm species belonging to the same eco-physiological group have a similar propensity to uptake and bioaccumulate heavy elements. Cd, Pb, Sb and Zn concentrations in both earthworm species were positively correlated with the respective total soil contents and generally decreased with distance from the smelter. The bioaccumulation factor (BAF) revealed that Cd and Zn were the only elements bioaccumulated by earthworms. The rank order of BAF values for both species was as follows: Cd > > Zn > > Cu > As = Pb = Sb. The absorption of Cd, Pb, Sb and Zn by earthworms mostly depended on the extractable, reducible and oxidable soil fractions, suggesting that the intestine is likely the most important uptake route. The extractable soil fraction constantly influenced the uptake of these heavy elements, whereas the reducible fraction was important mainly for Pb and Zn. The water soluble fraction had an important role especially for the most mobile heavy elements such as Cd and Zn, suggesting that dermal uptake is not negligible. As a whole, the analytical data indicate that soil fractionation patterns influence the uptake of heavy elements by earthworms, and the extractable fraction is a good predictor of heavy element bioavailability to these invertebrates in soil.

Cyclic volatile methylsiloxane bioaccumulation in flounder and ragworm in the Humber Estuary.

Abstract: Cyclic volatile methylsiloxanes are being subjected to regulatory scrutiny as possible PET chemicals. The investigation of bioaccumulation has yielded apparently contradictory results, with high la ...