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Archives of Environmental Contamination and Toxicology (v.52, #3)
Time Dependence in Mixture Toxicity with Soft Electrophiles: 1. Combined Effects of Selected SN2- and SNAr-Reactive Agents with a Nonpolar Narcotic by E. M. Gagan; M. W. Hull; T. W. Schultz; G. Pöch; D. A. Dawson (pp. 283-293).
Frequently the toxicity of an organic chemical mixture is close to dose-additive, even when the agents are thought to induce toxicity at different molecular sites of action. These findings appear to conflict with the hypothesis that a strictly dose-additive combined effect will be observed for agents sharing a single molecular site of toxic action within the organism. In this study, several SN2-reactive (α-halogen) or SNAr-reactive (halogenated dinitrobenzene) soft electrophiles were tested with a model nonpolar narcotic (NPN) to determine the toxicity of the combinations. A sham combination of the model NPN (3-methyl-2-butanone) was also tested as a positive control. The study design incorporated time-dependent toxicity (TDT) determinations at 15, 30, and 45 minutes using a Microtox (Vibrio fischeri) protocol that included testing seven duplicated concentrations for each single agent and mixture per combination. Additionally, in chemico reactivity was determined for each compound using thiol in glutathione as a model nucleophile. The model NPN alone lacked reactivity and TDT. The SN2-reactive agents individually showed varying levels of both reactivity and TDT alone, while the SNAr-reactive chemicals alone were reactive and had toxicity that was fully time-dependent between 15 and 45 minutes of exposure. Data analyses indicated that the sham combination was dose additive, as expected, whereas three of four SN2:NPN combinations showed effects close to that predicted for dose addition but with some differences. The fourth SN2:NPN combination, which included an α-halogen with full TDT, showed a less-than-dose-additive combined effect as did both of the SNAr:NPN pairings. By incorporating TDT values, shapes of the dose-response curves, chemical reactivity data with thiol, reactive mechanisms for the soft electrophiles, and quantitative structure activity relationship information on whether the toxicity of the individual soft electrophiles did or did not exceeded that predicted for baseline narcosis, the results suggested that the α-halogens elicited two toxic effects at the concentrations tested (reactivity and narcotizing effects), whereas toxicity induced by the halogenated dinitrobenzenes was essentially limited to reactive effects. Collectively, these results provide experimental evidence consistent with previous explanations as to why binary mixtures of industrial organic chemicals often show combined effects that are close to dose additive, even when the chemicals are thought to induce toxicity at different molecular sites of action.
Current-Use Pesticides and Organochlorine Compounds in Precipitation and Lake Sediment from Two High-Elevation National Parks in the Western United States by M. A. Mast; W. T. Foreman; S. V. Skaates (pp. 294-305).
Current-use pesticides (CUPs) and banned organochlorine compounds (OCCs) were measured in precipitation (snowpack and rain) and lake sediments from two national parks in the Western United States to determine their occurrence and distribution in high-elevation environments. CUPs frequently detected in snow were endosulfan, dacthal, and chlorothalonil in concentrations ranging from 0.07 to 2.4 ng/L. Of the OCCs, chlordane, hexachlorobenzene, and two polychlorinated biphenyl congeners were detected in only one snow sample each. Pesticides most frequently detected in rain were atrazine, carbaryl, and dacthal in concentrations from 3.0 to 95 ng/L. Estimated annual deposition rates in one of the parks were 8.4 μg/m2 for atrazine, 9.9 μg/m2 for carbaryl, and 2.6 μg/m2 for dacthal, of which >85% occurred during summer. p,p’-DDE and p,p’-DDD were the most frequently detected OCCs in surface sediments from lakes. However, concentrations were low (0.12 to 4.7 μg/kg) and below levels at which harmful effects for benthic organisms are likely to be observed. DDD and DDE concentrations in an age-dated sediment core suggest that atmospheric deposition of DDT and its degradates, and possibly other banned OCCs, to high-elevation areas have been decreasing since the 1970s. Dacthal and endosulfan sulfate were present in low concentrations (0.11 to 1.2 μg/kg) and were the only CUPs detected in surface sediments. Both pesticides were frequently detected in snow, confirming that some CUPs entering high-elevation aquatic environments through atmospheric deposition are accumulating in lake sediments and potentially in aquatic biota as well.
Analysis of Organic Pollutants in Sewage Sludges from the Valencian Community (Spain) by M. F. Gomez-Rico; R. Font; I. Aracil; A. Fullana (pp. 306-316).
Seventeen sewage sludges were studied to analyse, with the minimum number of steps, the organic pollutants that the European Union proposes to be controlled for land application. The compounds determined were a selection of polycyclic aromatic hydrocarbons (PAHs); a selection of polychlorinated biphenyls (PCBs); di(2-ethylhexyl)phthalate (DEHP); nonylphenolic compounds, including nonylphenol (NP) and nonylphenol ethoxylates with 1 and 2 ethoxy groups (NP1EO + NP2EO); extractable organic halides (EOX); and linear alkylbenzene sulphonates (LAS) with an alkylic chain of 10 to 13 carbon atoms. The results were compared with the proposed regulatory limit values, and it was observed that NP + NP1EO + NP2EO and LAS exceeded the maximums in most samples, and DEHP exceeded some of them, whereas PAHs, PCBs, and EOX almost always went beyond the limits. The values obtained are similar to those from other countries, and it can be said that it is difficult to comply with the limits for NP + NP1EO + NP2EO and LAS in many of them, although this latter parameter was not considered in the study carried out by Leschber (2004) concerning the toxicity of sewage sludge. Statistical multivariant analysis was used to look for some relationship between the results of pollutants and the characteristics of the samples, and it was found that the ratio of NP1EO + NP2EO to NP was related to sludge treatment at the sewage plant. At the same time, it was seen that the higher values of organic pollutants belonged to digested sludges.
Dioxin and Dioxin-Like Activity in Sediments of the Belgian Coastal Area (Southern North Sea) by Hermes Sanctorum; Isabelle Windal; Vincent Hanot; Leo Goeyens; Willy Baeyens (pp. 317-325).
Dioxin and dioxin-like activity in sediments of the North Sea, along the Belgian coast, was assessed with the bioassay CALUX (Chemically Activated LUciferase gene eXpression). Crude extracts of the samples as well as the dioxin fraction (PCDD/Fs) obtained after a thorough clean-up procedure were analyzed with the CALUX method. When analyzing the cleaned extract, a general low contamination level is observed (around 0.1 pg CALUX-TEQ/g sediment), except at the mouth of the two main rivers—the Yser and the Scheldt—where concentrations measured are about 100 times higher (10–42 pg CALUX-TEQ/g sediment). Much higher potencies are measured for the crude extracts compared to the cleaned ones. In the crude extracts, the highest dioxin-like activities were again observed at the mouth and outflow of the two rivers (600–7200 pg CALUX-TEQ/g sediment). These activities are at least two orders of magnitude higher than the ones found at the coastal and sea stations (1.3–45 pg CALUX-TEQ/g sediment). The difference in activity between cleaned and crude sediment extracts is due to the presence of dioxin-like compounds such as, for example, non-ortho and mono-ortho polychlorinated biphenyls and polybrominated dioxins, but also to PAHs. The percentage of five major PAHs in the crude samples at the river mouths, when using the average activities in those samples, varies between 25% and 50%.
Using Sulfate-Amended Sediment Slurry Batch Reactors to Evaluate Mercury Methylation by S. M. Harmon; J. K. King; J. B. Gladden; L. A. Newman (pp. 326-331).
In the methylated form, mercury represents a concern to public health primarily through the consumption of contaminated fish tissue. Research conducted on the methylation of mercury strongly suggests that the process is microbial in nature and facilitated principally by sulfate-reducing bacteria. This study addressed the potential for mercury methylation by varying sulfate treatments and wetland-based soil in microbial slurry reactors with available inorganic mercury. Under anoxic laboratory conditions conducive to the growth of naturally occurring sulfate-reducing bacteria in the soil, it was possible to evaluate how various sulfate additions influenced the methylation of inorganic mercury added to overlying water as well as the sequestration of dissolved copper. Treatments included sulfate amendments ranging from 25 to 500 mg/L (0.26 to 5.2 mM) above the soil’s natural sulfate level. Mercury methylation in sulfate treatments did not exceed that of the nonamended control during a 35-day incubation period. However, increases in methylmercury concentration were linked to bacterial growth and sulfate reduction. A time lag in methylation in the highest treatment correlated with an equivalent lag in bacterial growth. The decrease in dissolved copper ranged from 72.7% in the control to 99.7% in the highest sulfate treatment. It was determined that experimental systems such as these can provide some useful information but that they also have severe limitations once sulfate is depleted or if sulfate is used in excess.
Estimation of Biologic Gasification Potential of Arsenic from Contaminated Natural Soil by Enumeration of Arsenic Methylating Bacteria by S. M. A. Islam; K. Fukushi; K. Yamamoto; G. C. Saha (pp. 332-338).
Volatile arsenic species are found in gases released from natural environments as a result of natural ambient-temperature biomethylation of arsenic conducted by yeast, fungi, and bacteria. This process is part of arsenic transport in the arsenic geocycle. It is important to determine the flux of gasified arsenic released by microorganisms to determine the quantitative flux of arsenic cycle clearly and also to understand the effect of microorganisms on the transport and distribution of arsenic in the contaminated environment. In this study, biologic gasification potential of natural soil was determined by enumeration of arsenic methylating bacteria (AsMB). Enumeration of AsMB was conducted for 10 contaminated sites in Bangladesh where AsMB concentration varies from 0.2 × 104 to 7.8 × 104 most probable number (MPN) kg–1 dry soil. The specific gasification rate of arsenic by microorganisms was estimated as 1.8 × 10–7 μg As MPN–1d–1 by incubation of soil in a laboratory soil column setup. Natural biologic gasification potential of arsenic was then calculated by multiplying the specific rate by the number of AsMB in different soils. The attempt of this study is a fundamental step in determining the volatilization flux of arsenic from land surface contributed by microorganisms.
Distribution of Metals and Arsenic in Soils of Central Victoria (Creswick-Ballarat), Australia by K. Sultan (pp. 339-346).
A soil-sampling campaign was conducted to identify and map heavy-metal contamination in the Ballarat-Creswick area of Central Victoria, Australia, with respect to mining activities and natural background levels in soils. The distribution and concentrations of both lithology- (Fe, Al, and Mn) and pollution-sensitive elements (Zn, As, Pb, Cu, Cr, Ni, and Co) were documented in surface soils (approximately 0 to 10 cm, fraction <2 mm, n = 85). The total heavy-metal and metalloid contents in soils decreased in the order Fe >> Al >> Zn > Mn >> As > Pb > Cu ≈ Ni ≈ Cr > Co. Mean levels of Zn (273 mg/kg) and As (39 mg/kg) in soils were well above normal global ranges and could be of local importance as a source of contamination. Extreme soil levels of Ni, Cr, Pb, and Fe were found in old mining waste material and pointed to the anthropogenic influence on the environment. Most of the measured elements showed marked spatial variations except Co. As contents were significantly higher than the tolerable level (ANZECC (1992) guidelines), with values up to 395.8 mg/kg around the mine tailings site. Mn soil contents were strongly associated with Co and Ni contents in most soils. High Fe contents (average approximately 41,465 mg/kg) in soils developed on basalt bedrock were correlated with Zn contents (average 400 mg/kg), and it is highly likely that Fe-oxides serve as sinks for Zn under near-neutral soil pH (6.3) conditions. Between the two major bedrock lithologic units, Ordovician sediments and Tertiary basalt, a clear enrichment of metals was found in the latter that was reflected in high background levels of elements. Among the various size fractions, silt (average approximately 45.1%) dominated most of the soils. In general and with a few exceptions, the concentrations of measured elements did not show significant correlations to other measured soil parameters, e.g., clay, silt and sand size fractions, organic matter, soil pH, and cation exchange capacity.
Preliminary Study of the Use of Terrestrial Moss (Pleurozium schreberi) for Biomonitoring Traffic-Related Pt and Rh Deposition by M. Niemelä; J. Piispanen; J. Poikolainen; P. Perämäki (pp. 347-354).
The use of Pt and Rh as active components in automobile catalytic converters has led to increasing concentrations of these elements in several natural matrices. Because of this, the suitability of the use of a terrestrial moss (Pleurozium schreberi) for the passive biomonitoring of traffic-related Pt and Rh deposition was studied. The moss samples collected from Finland in and around areas with heavy traffic had increased Pt and Rh concentrations, with maximum values of 12.2 and 4.5 ng g–1, respectively. In addition, the concentrations of commonly used catalytic converter additives (Al, Ce, La, Y, and Zr) and some elements related to traffic or mineral dust (Cd, Cu, Fe, Hf, Pb, and Zn) were also measured to obtain more information about the sources of Pt and Rh. Multivariate principal component analysis and cluster analysis were applied for identification of the emission sources of the elements. The results indicated a common traffic-related source of Pt and Rh. However, the results also showed that Pt and Rh concentrations in mosses are increased only in areas located close to traffic lanes.
Environmental Contamination of Chrysotile Asbestos and Its Toxic Effects on Antioxidative System of Lemna gibba by A. K. Trivedi; I. Ahmad; M. S. Musthapa; F. A. Ansari (pp. 355-362).
Asbestos was monitored in various plant samples around an asbestos cement factory. Asbestos residue was found on the surface of all plant samples monitored. Based on asbestos concentration found in different plant samples during monitoring and on the property of asbestos to cause reactive oxygen species-mediated oxidative stress in animal models, laboratory experiments were conducted to assess the toxicity of chrysotile asbestos on an aquatic macrophyte, duckweed (Lemna gibba.). L. gibba plants were exposed to four concentrations (0.5, 1.0, 2.0, and 5.0 μg/mL) of chrysotile asbestos under laboratory conditions, and alterations in the glutathione and ascorbate antioxidative system were estimated at postexposure days 7, 14, 21, and 28 in order to assess changes in their level as suitable biomarkers of chrysotile contamination. Chrysotile exposure caused a decrease in total and reduced glutathione and an enhancement in the oxidized glutathione as well as the reduced/oxidized glutathione ratio. An increase in ascorbate pool size, and reduced as well as oxidized ascorbate was found to be accompanied by a decrease in the ratio of reduced/oxidized ascorbate. Alteration in the glutathione and ascorbate level might be considered as a biomarker of exposure to an unsafe environment because these are essential compounds of the general antioxidative strategy to overcome oxidative stress due to environmental constraints. Because an increase in the oxidation rate of antioxidants weakens cellular defenses and indicates a precarious state, they could constitute indicators of toxicity.
Growth and Reproduction of Earthworms in Ultramafic Soils by R. Maleri; S. A. Reinecke; J. Mesjasz-Przybylowicz; A. J. Reinecke (pp. 363-370).
Ultramafic soils are characterized by high concentrations of heavy metals of natural origin—such as chromium, cobalt, manganese, and nickel—as well as a shortage of primary nutrients. This can result in extremely disadvantageous living conditions for all soil-dwelling organisms. Responses to these conditions were addressed by studying growth, cocoon production, and fecundity of earthworms as endpoints of sublethal effects and how this influences the reproductive system and, consequently, population development. Mature specimens of two ecophysiologically different species of earthworms, Eisenia fetida (Savigny) and Aporrectodea caliginosa (Savigny), were exposed for 56 days to an uncontaminated soil and ultramafic soils collected from six ultramafic sites in the Barberton greenstone belt. In all ultramafic soil samples, the specimens of both species grew slower than those in the control soil. In A. caliginosa, an autotomization of the tail section was observed at higher concentrations of heavy metals. At high levels of heavy metals such as manganese, chromium, nickel, and cobalt, a significantly lower cocoon production was recorded for E. fetida, and at medium levels, a time delay in cocoon production was found. A. caliginosa showed an increase in production at medium levels and a decrease at high levels of heavy metals. In both species, no correlation between growth and cocoon viability was found, indicating different target levels for toxicants present in ultramafic soils. To determine effects of these soils on population dynamics, hatching success may be a more useful endpoint of reproduction.
Role of cAMP in Tissues of Mussel Mytilus galloprovincialis As a Potent Biomarker of Cadmium in Marine Environments by Stefanos Dailianis; Martha Kaloyianni (pp. 371-378).
The present study investigated the signal transduction molecule cAMP as a biomarker of exposure to cadmium in mussels Mytilus galloprovincialis. Mussels were exposed to 10 and 100 μg/l cadmium for 3, 6, and 9 days, and cAMP content in three tissues—digestive gland, gills and mantle–gonad complex—was estimated. The results showed significantly increased levels of cAMP in all tissues at all time points tested. In support of our results, cAMP levels were positively correlated with the established metal biomarker, metallothionein. Therefore, we could suggest that mussels exposed to cadmium respond by increasing cAMP content in digestive gland, gills and mantle–gonad complex, thus indicating that cAMP could constitute a promising biomarker of exposure to cadmium.
Polycyclic Aromatic Hydrocarbons and Ecotoxicological Characterization of Seawater, Sediment, and Mussel Mytilus galloprovincialis from the Gulf of Rijeka, the Adriatic Sea, Croatia by Nevenka Bihari; Maja Fafanđel; Vanda Piškur (pp. 379-387).
The pattern of spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in seawater, sediment, and mussels, potential toxicity of different matrices, and mussel anoxic survival from six sampling sites of the Gulf of Rijeka, the Adriatic Sea, Croatia was examined. The total concentrations of 10 PAHs vary from below detection limit to 305 ng/L in seawater, from 213 to 695 μg/kg dry weight in sediment and from 49.2 to 134 ng/g wet weight in mussel tissue. Combustion is the principal source of PAH contamination in seawater and sediment samples. Sediment samples are distinguished from the majority of seawater and mussel samples by the presence of high molecular weight PAHs, whereas mussels from majority of sampling sites tend to accumulate PAHs of lower molecular weight. The PAH dynamic between different matrices is complex and site specific. Toxicity of seawater and sediment organic extract is correlated with PAH content, indicating that PAHs are the predominant toxic compounds. There is no correlation between toxicity of mussel biological fluids and toxicity of seawater and sediment, or between toxicity of mussel biological fluid and PAH content in mussel, seawater, or sediment. There is a positive correlation between potential toxicity of mussel biological fluids and reduction of anoxic survival time. Mussel anoxic survival is influenced by the presence of complex mixture of toxic contaminants, not only PAHs. The relationship between PAH contents in different marine matrices and their ability to affect mussels revealed specific interactions between an organism and complex mixture of toxic contaminants present in the marine environment.
Acute and Sublethal Toxicities of Rotenone in Juvenile Rainbow Trout (Oncorhynchus mykiss): Swimming Performance and Oxygen Consumption by W. W. Cheng; A. P. Farrell (pp. 388-396).
Rotenone, a natural insecticide and piscicide, was shown to have an extremely small margin between no lethality (5.0 μg/L) and 100% mortality (6.6 μg/L) for static-renewal 96-hour toxicity tests with juvenile rainbow trout (Oncorhynchus mykiss). Dissolved organic carbon (DOC) at concentrations of 3.0 and 4.0 mg/L significantly increased the rotenone 96-hour LC50 (median lethal concentration) from 5.80 μg/L (confidence interval (CI) 5.51 to 6.10) to 6.55 μg/L (CI 6.28 to 6.83) and 7.75 μg/L (CI 7.29 to 8.24), respectively, probably as a result of rotenone adsorption onto DOC, which decreased its bioavailability. Using concentrations of 0, 3.0, 4.0, and 5.0 μg/L rotenone and exposure periods of 2, 4, 6, 12, 16, 24, and 48 hours, the threshold concentration of rotenone for impairment of critical swimming performance (Ucrit) was 3.0 μg/L (P = 0.029), with no further impairment at higher concentrations and no time-dependent effect on Ucrit. Using continuous measures of oxygen uptake for 48 hours before and 48 hours during rotenone exposure (0, 1.5, 2.5, 3.0, and 3.5 μg/L), rotenone significantly decreased peak active oxygen uptake at all rotenone concentrations tested without affecting routine oxygen uptake. Fish were individually chased and then placed in rotenone concentrations of 0, 1.0, 3.0, 4.0, 5.0, and 6.0 μg/L to monitor initial postexercise oxygen uptake (Mo2Max) and excess postexercise oxygen consumption (EPOC) during a 40-minute recovery period. Rotenone significantly decreased Mo2Max (P = 0.002) after exposures to 4.0 and 5.0 μg/L, but not 6.0 μg/L, without affecting EPOC.
Concentrations of Metals in Water, Sediment, Biofilm, Benthic Macroinvertebrates, and Fish in the Boulder River Watershed, Montana, and the Role of Colloids in Metal Uptake by Aïda M. Farag; David A. Nimick; Briant A. Kimball; Stanley E. Church; David D. Harper; William G. Brumbaugh (pp. 397-409).
To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 μg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 μg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.
Bioremediation of Tetrachloroethylene-Contaminated Groundwater in a Model Aquifer: Effects on Green Frogs (Rana clamitans) and Xenopus laevis as Potential Wetland Receptors by Tana V. McDaniel; Nathalie Ross; Pamela A. Martin; Helena Steer; Ann-Marie Irwin Abbey; Suzanne Lesage (pp. 410-417).
Recent regulations require that the ecological effects of microorganisms introduced into the environment, such as for groundwater bioremediation, be assessed prior to their utilization. A native anuran (Rana clamitans) and a model anuran (Xenopus laevis) were used as potential wetland receptors of tetrachloroethylene (PCE)-contaminated groundwater, undergoing three bioremediation treatments: natural attenuation (NA), biostimulation (ST), and bioaugmentation (AU). Eggs of both species were exposed acutely (96 h) to remediated effluents. Xenopus tadpoles were chronically exposed to the effluents for 100 days and were screened for the presence of bacterial pathogens. There was no impact on the survivorship of the frogs exposed either acutely or chronically to the NA, ST, or AU effluents; nor was there any evidence of bacterial infection found, with the exception of control individuals. The results of these exposures suggest that bioremediation with KB-1™ culture poses a minimal threat to anuran development and survivorship.
Trace Elements in Three Marine Birds Breeding on Reunion Island (Western Indian Ocean): Part 1—Factors Influencing Their Bioaccumulation by J. Kojadinovic; M. Le Corre; R. P. Cosson; P. Bustamante (pp. 418-430).
This work aimed to use seabirds as bioindicators of trace element levels in the tropical waters and food webs of the Western Indian Ocean. The accumulation patterns of selected toxic (Cd and Hg) and essential (Cu, Fe, Mn, Se, and Zn) elements were determined in liver, kidney, and pectoral muscle of 162 marine birds belonging to 3 species collected in Reunion Island between 2002 and 2004. These pelagic seabirds belong to the following species: Barau’s Petrel (Pterodroma baraui), Audubon’s Shearwater (Puffinus lherminieri bailloni), and White-Tailed Tropicbird (Phaethon lepturus). Hg levels were also measured in breast feathers. Highest mean kidney Cd and liver Hg levels (respectively, 27.79 ± 13.78 μg.g −1 dry weight (dw) and 24.31 ± 14.13 μg.g −1 dw) were found in the squid-eating Barau’s Petrel. Barau’s Petrel feather Hg levels fell in the range of 0.6 to 2.7 μg.g−1 dw previously reported for other petrels and shearwaters. The values of the other elements were also in the same range as those previously reported in the published literature concerning related seabirds, although Se and Zn burdens in the Reunion birds were among the highest values. Levels of Zn, Fe, and, to a lesser extent, Cu appeared to be regulated in seabird tissues. Uptake and pathways of metabolism and storage seemed to be similar for the five essential elements. The reproductive status of the bird did not seem to affect element levels, which, moreover, were not significantly different between male and female birds. However, trace elements in sampled birds varied according to the tissue considered, the age of the animal, and its species. Diet was seemingly a major influencing factor. Health status also appeared to have an impact on element levels.
Trace Elements in Three Marine Birds Breeding on Reunion Island (Western Indian Ocean): Part 2—Factors Influencing Their Detoxification by J. Kojadinovic; P. Bustamante; M. Le Corre; R. P. Cosson (pp. 431-440).
Seabird tissues collected between 2002 and 2004 from Barau’s Petrel (Pterodroma baraui), Audubon’s Shearwater (Puffinus lherminieri bailloni), and White-Tailed Trop icbird (Phaethon lepturus) colonies on Reunion Island were analyzed for metallothioneins (MTs) and trace element content. The subcellular distribution between soluble and insoluble fractions of Cd, Cu, Fe, Mn, Se, and Zn was determined in liver and kidney. In both, the soluble fraction of the cell concentrated most of the Cd and Se, whereas Fe, Mn, and Zn were preferentially accumulated in the insoluble fraction. The distribution of these elements varied with the tissue, age of the bird, and species. Furthermore, the distributions of Fe and Mn were somewhat influenced by the bird’s physical condition. MT levels were measured in the soluble fraction after heat denaturation. The levels of these proteins varied from 5.5 ± 2.7 mg.g−1 dry weight (dw) to 11.4 ± 6.2 mg.g−1 dw depending on the species and the tissue considered. MT levels were significantly different between liver and kidney only in the White-Tailed Tropicbird. In the three species, MT levels in kidney were significantly higher in adult than juvenile birds. The bird’s weight also had an influence on hepatic and renal MT levels, but not the sex nor the reproductive status. The implication of MTs in Cu and Zn homeostasis and Cd and Hg detoxification are discussed. In addition, clues on Hg regulation by Se were found, especially in Barau’s Petrel, where the levels of these two elements were significantly correlated.
Mercury and Methylmercury Accumulation and Excretion in Prairie Voles (Microtus ochrogaster) Receiving Chronic Doses of Methylmercury by G. P. Cobb; A. W. Moore; K. T. Rummel; B. M. Adair; S. T. McMurry; M. J. Hooper (pp. 441-449).
Methylmercury cation (MeHg) and divalent mercury (Hg++) accumulation in liver, kidney, and brain were quantified in prairie voles (Microtus ochrogaster) at 0, 3, 6, and 12 weeks during chronic exposure to aqueous MeHg. Dose groups received deionized water or aqueous solutions containing 9, 103, or 920 ng MeHg/ml. Our study presents temporal patterns of Hg++ and MeHg concentrations in organ tissues and makes inter-tissue comparisons at each time point to illustrate the accumulation and distribution of Hg species during the study. MeHg was accumulated in tissues for 3 weeks and then concentrations plateaued. Mercury accumulated in brain, liver, and kidney to average concentrations of 510 ng/g, 180 ng/g, and 3400 ng/g, respectively. MeHg and Hg++ concentrations were roughly equivalent in liver, kidney, and urine. MeHg concentrations in brain tissue were 2 to 20 times the concentrations of Hg++. Regression analysis was also used to demonstrate the utility of urinalysis as an indicator of Hg++ and MeHg concentrations in organ tissue (p < 0.001).