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Archives of Environmental Contamination and Toxicology (v.60, #2)
Evaluation of the Potential of Indigenous Calcareous Shale for Neutralization and Removal of Arsenic and Heavy Metals From Acid Mine Drainage in the Taxco Mining Area, Mexico by F. M. Romero; L. Núñez; M. E. Gutiérrez; M. A. Armienta; A. E. Ceniceros-Gómez (pp. 191-203).
In the Taxco mining area, sulfide mineral oxidation from inactive tailings impoundments and abandoned underground mines has produced acid mine drainage (AMD; pH 2.2–2.9) enriched in dissolved concentrations (mg l−1) sulfate, heavy metals, and arsenic (As): SO4 2− (pH 1470–5454), zinc (Zn; 3.0–859), iron (Fe; pH 5.5–504), copper (Cu; pH 0.7–16.3), cadmium (Cd; pH 0.3–6.7), lead (Pb; pH < 0.05–1.8), and As (pH < 0.002–0.6). Passive-treatment systems using limestone have been widely used to remediate AMD in many parts of the world. In limestone-treatment systems, calcite simultaneously plays the role of neutralizing and precipitating agent. However, the acid-neutralizing potential of limestone decreases when surfaces of the calcite particles become less reactive as they are progressively coated by metal precipitates. This study constitutes first-stage development of passive-treatment systems for treating AMD in the Taxco mine area using indigenous calcareous shale. This geologic material consists of a mixture of calcite, quartz, muscovite, albite, and montmorillonite. Results of batch leaching test indicate that calcareous shale significantly increased the pH (to values of 6.6–7.4) and decreased heavy metal and As concentrations in treated mine leachates. Calcareous shale had maximum removal efficiency (100%) for As, Pb, Cu, and Fe. The most mobile metals ions were Cd and Zn, and their average percentage removal was 87% and 89%, respectively. In this natural system (calcareous shale), calcite provides a source of alkalinity, whereas the surfaces of quartz and aluminosilicate minerals possibly serve as a preferred locus of deposition for metals, resulting in the neutralizing agent (calcite) beings less rapidly coated with the precipitating metals and therefore able to continue its neutralizing function for a longer time.
Survey of Cyclic and Linear Siloxanes in Sediment from the Songhua River and in Sewage Sludge from Wastewater Treatment Plants, Northeastern China by Zifeng Zhang; Hong Qi; Nanqi Ren; Yifan Li; Dawen Gao; Kurunthachalam Kannan (pp. 204-211).
Siloxanes are used in a wide range of industrial applications, such as fuel additives, automotive polishes and waxes, and antifoaming agents, as well as in personal care products and biomedical devices. Despite the potential for environmental occurrence, few studies have reported sources and pathways of siloxanes in the environment. In this study, we determined concentrations of four cyclic siloxanes, namely, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7) as well as 13 linear siloxanes (L4 to L16), in sediments sampled from the Songhua River and in sewage sludge sampled from treatment plants that discharge wastewater into the Songhua River in northeastern China. Siloxanes were found in all of the sediment samples at total concentrations (sum of all cyclic and linear siloxanes) as high as 2050 ng/g dry weight (dw). The respective total concentration ranges for cyclic (D4, D5, D6, and D7) and linear (L4 to L16) siloxanes in sewage sludge were 602 to 2360 and 98 to 3310 ng/g dw. Cyclic siloxanes were found at greater concentrations than linear siloxanes in sediment samples. However, the summed concentrations of linear siloxanes were higher than the summed concentrations of cyclic siloxanes in sludge samples. Among cyclic siloxanes, D7 and D5 were the dominant compounds in both sediment and sludge. Among linear siloxanes, L10 and L11 together accounted for 55% of the total concentrations in sludge samples, and L6 accounted for 30% of the total concentration in sediment samples. To our knowledge, this is the first report to document concentrations and compositions of organosiloxanes in sediments and sewage sludge from China.
Biotransformation of Halogenated Nonylphenols with Sphingobium Xenophagum Bayram and a Nonylphenol-Degrading Soil-Enrichment Culture by Yongmei Li; John Montgomery-Brown; Martin Reinhard (pp. 212-219).
When discharged in chlorinated wastewater, alkylphenol ethoxylate metabolites (APEMs) are often discharged in halogenated form (XAPEMs, X = Cl, or Br). The potential environmental impact of XAPEM release was assessed by studying the biotransformation of halogenated nonylphenol by Sphingobium xenophagum Bayram and a soil-enrichment culture. S. xenophagum Bayram transformed chlorinated nonylphenol (ClNP) slowly and nearly completely to form nonyl alcohol; the monobrominated nonylphenol (BrNP) and dibrominated nonylphenol were transformed cometabolically with nonylphenol (NP) as the primary substrate. The presence of either ClNP or BrNP in the S. xenophagum Bayram cultures retarded the transformation of nonhalogenated NP. NP-degrading soil cultures transformed nonhalogenated NP to a mixture of nonyl alcohols but were not capable of transforming either ClNP or BrNP. The presence of either ClNP or BrNP retarded the transformation of nonhalogenated NP in the soil cultures, as was observed in S. xenophagum Bayram cultures. Predicting the environmental fate of alkylphenol ethoxylate residues requires considering APEM halogenation during effluent chlorination and inhibitory effects as well as the refractory nature of halogenated metabolites.
Effects of Ten Antibiotics on Seed Germination and Root Elongation in Three Plant Species by Derek G. Hillis; James Fletcher; Keith R. Solomon; Paul K. Sibley (pp. 220-232).
We applied a screening-level phytotoxicity assay to evaluate the effects of 10 antibiotics (at concentrations ranging from 1 to 10,000 μg/L) on germination and early plant growth using three plant species: lettuce (Lactuca sativa), alfalfa (Medicago sativa), and carrot (Daucus carota). The range of phytotoxicity of the antibiotics was large, with EC25s ranging from 3.9 μg/L to >10,000 μg/L. Chlortetracycline, levofloxacin, and sulfamethoxazole were the most phytotoxic antibiotics. D. carota was the most sensitive plant species, often by an order of magnitude or more, followed by L. sativa and then M. sativa. Plant germination was insensitive to the antibiotics, with no significant decreases up to the highest treatment concentration of 10,000 μg/L. Compared with shoot and total length measurements, root elongation was consistently the most sensitive end point. Overall, there were few instances where measured soil concentrations, if available in the publicly accessible literature, would be expected to exceed the effect concentrations of the antibiotics evaluated in this study. The use of screening assays as part of a tiered approach for evaluating environmental impacts of antibiotics can provide insight into relative species sensitivity and serve as a basis by which to screen the potential for toxic effects of novel compounds to plants.
Assessment of Heavy Metal Pollution in Republic of Macedonia Using a Plant Assay by Darinka Gjorgieva; Tatjana Kadifkova-Panovska; Katerina Bačeva; Trajče Stafilov (pp. 233-240).
Different plant organs (leaves, flowers, stems, or roots) from four plant species—Urtica dioica L. (Urticaceae), Robinia pseudoacacia L. (Fabaceae), Taraxacum officinale (Asteraceae), and Matricaria recutita (Asteraceae)—were evaluated as possible bioindicators of heavy-metal pollution in Republic of Macedonia. Concentrations of Pb, Cu, Cd, Mn, Ni, and Zn were determined in unwashed plant parts collected from areas with different degrees of metal pollution by ICP-AES. All these elements were found to be at high levels in samples collected from an industrial area. Maximum Pb concentration was 174.52 ± 1.04 mg kg−1 in R. pseudoacacia flowers sampled from the Veles area, where lead and zinc metallurgical activities were present. In all control samples, the Cd concentrations were found to be under the limit of detection (LOD <0.1 mg kg−1) except for R. pseudoacacia flowers and T. officinale roots. The maximum Cd concentration was 7.97 ± 0.15 mg kg−1 in R. pseudoacacia flowers from the Veles area. Nickel concentrations were in the range from 1.90 ± 0.04 to 5.74 ± 0.03 mg kg−1. For U. dioica leaves and R. pseudoacacia flowers sampled near a lead-smelting plant, concentrations of 465.0 ± 0.55 and 403.56 ± 0.34 mg kg−1 Zn were detected, respectively. In all control samples, results for Zn were low, ranging from 10.2 ± 0.05 to 38.70 ± 0.18 mg kg−1. In this study, it was found that the flower of R. pseudoacacia was a better bioindicator of heavy-metal pollution than other plant parts. Summarizing the results, it can be concluded that T. officinale, U. dioica, and R. pseudoacacia were better metal accumulators and M. recutita was a metal avoider.
Acute Toxicity Tests with the Tropical Cladoceran Pseudosida ramosa: The Importance of Using Native Species as Test Organisms by Emanuela Cristina Freitas; Odete Rocha (pp. 241-249).
Cladocerans have long been used for toxicological assessments of a diverse range of substances. The use of cladocerans in toxicity tests has many advantages, such as their short life cycle, parthenogenetic reproduction (clones), and high sensitivity to toxicants, as well as the easy laboratory maintenance of cultures. The most commonly used cladoceran in ecotoxicological studies of aquatic environments is undoubtedly Daphnia magna. Standard methods using cladocerans as test organisms have been documented and adopted by major international organizations and regulatory agencies of many countries. However, today there is a growing need for improving test organisms and protocols to better reflect local species sensitivity or site-specific conditions. The present study aimed to assess the tropical species Pseudosida ramosa as a potential test organism for ecotoxicological purposes, by carrying out standard acute tests with six reference compounds. Based on the results obtained in the present study and in comparison with other cladocerans, it was found that P. ramosa was more sensitive than Daphnia magna, had a sensitivity similar to that of Daphnia similis, and was less sensitive compared to Ceriodaphnia dubia and C. silvestrii (Neotropical species), except for the salts, sodium chloride and potassium chloride. Also, when P. ramosa was compared with test organisms of other taxonomic groups, we observed that it was more sensitive than most of the others, from simple coelenterates to complex fish. Considering these results and the wide distribution of the cladoceran P. ramosa in tropical and subtropical regions, we suggest that this species can be adopted as a test organism, being a good substitute for the exotic daphnid D. magna, for monitoring of toxicants in freshwaters.
Acute and Chronic Toxicity of Copper to the Euryhaline Rotifer, Brachionus plicatilis (“L” Strain) by W. R. Arnold; R. L. Diamond; D. S. Smith (pp. 250-260).
This article presents data from original research, intended for the use in the development of copper (Cu) criteria for the protection of estuarine and marine organisms and their uses in the United States. Two 48-h static-acute toxicity tests—one with and one without added food—and a 96-h static multigeneration life-cycle test (P1–F2 generations) were performed concurrently using the euryhaline rotifer Brachionus plicatilis (“L” strain) to develop a Cu acute-to-chronic ratio (ACR) for this species. Tests were performed at 15 g/L salinity, at 25°C, and the exposure concentrations of dissolved Cu were verified. Supplemental chemical analyses were performed and reported for the development of a Cu–saltwater biotic ligand model (BLM). Supplemental analyses included alkalinity, calcium, chloride, dissolved organic carbon (DOC), hardness, magnesium, potassium, sodium, and temperature. The acute toxicity test measurement end points were the dissolved Cu median lethal concentration (LC50) values based on rotifer survival. The chronic measurement end points were the dissolved Cu no-observed-effect concentration (NOEC), lowest-observed-effect concentration (LOEC), EC25, EC20, and EC10 based on the intrinsic rate of rotifer population increase (r). The 48-h LC50Fed, 48-h LC50Unfed, 96-h NOEC, 96-h LOEC, EC25, EC20, and EC10 were 20.8, 13.4, 6.1, 10.3, 11.7, 10.9, and 8.8 μg Cu/L, respectively. The ACRs were calculated as ratios of each 48-h LC50 value [fed and unfed) and each of the 96-h chronic values (ChV; geometric mean of NOEC and LOEC)], EC10, EC20, and EC25. The ACRs ranged from 1.15 to 2.63.
Role of Vegetation in a Constructed Wetland on Nutrient–Pesticide Mixture Toxicity to Hyalella azteca by Richard E. Lizotte Jr.; Matthew T. Moore; Martin A. Locke; Robert Kröger (pp. 261-271).
The toxicity of a nutrient–pesticide mixture in nonvegetated and vegetated sections of a constructed wetland (882 m2 each) was assessed using Hyalella azteca 48-h aqueous whole-effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple superphosphate, diazinon, and permethrin simulating storm-event agricultural runoff. Aqueous samples were collected at inflow, middle, and outflow points within each section 5 h, 24 h, 72 h, 7 days, 14 days, and 21 days postamendment. Nutrients and pesticides were detected throughout both wetland sections with concentrations longitudinally decreasing more in vegetated than nonvegetated section within 24 h. Survival effluent dilution point estimates—NOECs, LOECs, and LC50s—indicated greatest differences in toxicity between nonvegetated and vegetated sections at 5 h. Associations of nutrient and pesticide concentrations with NOECs indicated that earlier toxicity (5–72 h) was from permethrin and diazinon, whereas later toxicity (7–21 days) was primarily from diazinon. Nutrient–pesticide mixture concentration–response assessment using toxic unit models indicated that H. azteca toxicity was due primarily to the pesticides diazinon and permethrin. Results show that the effects of vegetation versus no vegetation on nutrient–pesticide mixture toxicity are not evident after 5 h and a 21-day retention time is necessary to improve H. azteca survival to ≥90% in constructed wetlands of this size.
Feeding and Growth Responses of the Snail Theba pisana to Dietary Metal Exposure by K. S. El-Gendy; M. A. Radwan; A. F. Gad (pp. 272-280).
The effects of dietary exposure to copper (Cu), lead (Pb), and zinc (Zn) on feeding activities, growth response, and mortality of Theba pisana snails were studied in 5-week feeding tests. Snails were fed on an artificial diet containing the following Cu, Pb, or Zn concentrations: 0, 50, 100, 500, 1000, 5000, 10,000, and 15,000 μg/g dry food. At the end of 5 weeks, the food consumption rate was decreased with increasinges in both metal concentrations and time of exposure. The estimated concentrations of metals that reduces food consumption to 50% (EC50) after 5 weeks were 56, 118, and 18 μg/g dry food for Cu, Pb, and Zn, respectively. All tested metals in the diet were found to inhibit growth of the snails in a dose-dependent manner. The toxic effect on growth of the tested metals could be arranged in the order Cu > Zn > Pb. The cumulative percentage mortality among snails fed a Cu- or Zn-contaminated diet was 73.3% and the respective value for a Pb-contaminated diet was 13.3%. There was a positive correlation between growth coefficient and food consumption for all tested metals.
Acute Toxicity and Effects Analysis of Endosulfan Sulfate to Freshwater Fish Species by John F. Carriger; Tham C. Hoang; Gary M. Rand; Piero R. Gardinali; Joffre Castro (pp. 281-289).
Endosulfan sulfate is a persistent environmental metabolite of endosulfan, an organochlorine insecticide–acaricide presently registered by the United States Environmental Protection Agency. There is, however, limited acute fish toxicity data for endosulfan sulfate. This study determines the acute toxicity (LC50s and LC10s) of endosulfan sulfate to three inland Florida native fish species (mosquitofish [Gambusia affinis]; least killifish [Heterandria formosa]; and sailfin mollies [Poecilia latipinna]) as well as fathead minnows (Pimephales promelas). Ninety-six-h acute toxicity tests were conducted with each fish species under flow-through conditions. For all of the above-mentioned fish species, 96-h LC50 estimates ranged from 2.1 to 3.5 μg/L endosulfan sulfate. The 96-h LC10 estimates ranged from 0.8 to 2.1 μg/L endosulfan sulfate. Of all of the fish tested, the least killifish appeared to be the most sensitive to endosulfan sulfate exposure. The above-mentioned data were combined with previous acute toxicity data for endosulfan sulfate and freshwater fish for an effects analysis. The effects analysis estimated hazardous concentrations expected to exceed 5, 10, and 50% of the fish species’ acute LC50 or LC10 values (HC5, HC10, and HC50). The endosulfan sulfate freshwater-fish acute tests were also compared with the available freshwater-fish acute toxicity data for technical endosulfan. Technical endosulfan is a mixture of α- and β-endosulfan. The LC50s had a wider range for technical endosulfan, and their distribution produced a lower HC10 than for endosulfan sulfate. The number of freshwater-fish LC50s for endosulfan sulfate is much smaller than the number available for technical endosulfan, reflecting priorities in examining the toxicity of the parent compounds of pesticides. The toxicity test results and effects analyses provided acute effect values for endosulfan sulfate and freshwater fish that might be applied in future screening level ecologic risk assessments. The effects analyses also discussed several deficiencies in conventional methods for setting water-quality criteria and determining ecologic effects from acute toxicity tests.
Methods for Conducting Bioassays Using Embryos and Larvae of Pacific Herring, Clupea pallasi by Paul A. Dinnel; Douglas P. Middaugh; Nathan T. Schwarck; Heather M. Farren; Richard K. Haley; Richard A. Hoover; James Elphick; Karen Tobiason; Randall R. Marshall (pp. 290-308).
The rapid decrease of several stocks of Pacific herring, Clupea pallasi, in Puget Sound, Washington, has led to concerns about the effects of industrial and nonpoint source contamination on the embryo and larval stages of this and related forage fish species. To address these concerns, the state of Washington and several industries have funded efforts to develop embryo and larval bioassay protocols that can be used by commercial laboratories for routine effluent testing. This article presents the results of research to develop herring embryo and larval bioassay protocols. Factors evaluated during protocol development included temperature, salinity, dissolved oxygen (DO), light intensity, photoperiod, larval feeding regimes, use of brine and artificial sea salts, gonad sources, collection methods, and egg quality.
Effects of Water Cadmium Concentrations on Bioaccumulation and Various Oxidative Stress Parameters in Rhamdia quelen by Alexandra Pretto; Vania Lucia Loro; Bernardo Baldisserotto; Maria Amália Pavanato; Bibiana Silveira Moraes; Charlene Menezes; Roberta Cattaneo; Bárbara Clasen; Isabela Andres Finamor; Valderi Dressler (pp. 309-318).
The effects of sublethal cadmium concentrations on oxidative stress parameters were evaluated in Rhamdia quelen. The fish were exposed to 0.44, 236, and 414 μg l−1 cadmium for 7 and 14 days, followed by the same time periods for recovery. Enzymes, such as catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST), and indicators of oxidative stress, such as thiobarbituric acid-reactive species (TBARS) and protein carbonyl, were verified in fish tissues. In addition, the accumulation of cadmium was evaluated in these tissues. Our results indicate that CAT and GST levels decreased in gills after exposure periods associated with increased TBARS levels. In hepatic tissue, CAT, GST, TBARS, and protein carbonyl levels increased after 7 days of exposure, whereas SOD activity decreased after exposure for 14 days. In the kidney, TBARS levels decreased after exposure for 7 days and increased after exposure for 14 days. During the recovery periods, some variations persisted in gills, liver, and kidney. Cadmium accumulation was most significant in liver, followed by kidney and gills. These results indicate that cadmium concentrations studied invoke a stress response in silver catfish.
Influence of a Toxic Microcystis aeruginosa Strain on Glutathione Synthesis and Glutathione-S-Transferase Activity in Common Carp Cyprinus carpio (Teleostei: Cyprinidae) by Lílian Lund Amado; Márcia Longaray Garcia; Patrícia Baptista Ramos; João Sarkis Yunes; José Maria Monserrat (pp. 319-326).
We evaluated the effects of aqueous extracts of the cyanobacterium-producing microcystin (MC), Microcystis aeruginosa (strain RST9501), on detoxification capacity and glutathione (GSH) synthesis in liver, brain, gill, and muscle—as well as apoptotic protease (calpain) activity in liver and brain—in the common carp Cyprinus carpio (Teleostei: Cyprinidae). Experimental groups were defined as follows: (1) control (CTR); (2) carp treated with an aqueous extract from the toxic cyanobacteria M. aeruginosa in a final MC concentration of 25 μg/kg (MC 25); and (3) carp treated with an aqueous extract from the toxic cyanobacteria M. aeruginosa in a final MC concentration of 50 μg/kg (MC 50). Carp were gavaged with a cyanobacterial aqueous solution or MilliQ water (CTR group). The experiment was conducted for period of 48 h comprising two gavages with a 24-h interval between them. Some of the parameters analyzed in liver, brain, gill, and muscle included activity of the enzymes glutathione-S-transferase (GST), glutamate cysteine ligase (GCL), glutathione reductase (GR), and GSH concentration. We also evaluated GST pi concentration by Western blot as well as calpain activity in liver and brain samples. In carp liver from the MC 50 group, we observed a decrease in GST and GCL activity, which was accompanied by a decreased GSH concentration. In addition, liver calpain activity was highly induced in carp at both MC doses. Thus, MC ingestion affected the liver antioxidant status through decreasing the GSH concentration and the activity of the enzyme involved in its synthesis (GCL). It also decreased the MC detoxification capacity of the liver because total GST activity decreased, a result that cannot be ascribed to GST pi levels. Because GSH acts as an uncompetitive inhibitor of calpain, its decrease should explain the higher activity of this apoptotic enzyme. The main goal of this study was to show that a decrease in GSH concentration is related to decreased activity of GCL, the limiting enzyme involved in GSH synthesis. Because MCs are phosphatase inhibitors and GCL is allosterically inhibited by phosphorylation, the cellular hyperphosphorylation state induced by MC exposure could act as a modulator factor for antioxidant defenses.
Differential Effects of Malathion and Nitrate Exposure on American Toad and Wood Frog Tadpoles by Geoffrey R. Smith; S. V. Krishnamurthy; Anthony C. Burger; Leonard B. Mills (pp. 327-335).
Organisms living in aquatic ecosystems are increasingly likely to be exposed to multiple pollutants at the same time due to the simultaneous use of several pesticides and fertilizers. We examined the single and interactive effects of environmentally realistic concentrations of nitrate and malathion on two species of tadpoles common in agricultural regions of the United States—the American Toad (Bufo americanus) and the Wood Frog (Rana sylvatica)—using a fully factorial mesocosm experiment that crossed four concentrations of malathion ranging from 0 to 1000 μg/l and two concentrations of nitrate (0 or 8 mg/l). In both B. americanus and R. sylvatica, malathion delayed metamorphosis compared to controls, even at the lowest concentration of malathion. Malathion did not affect survivorship in either species. B. americanus metamorphs were smaller in malathion treatments, whereas R. sylvatica were larger in malathion treatments. Nitrate did not affect survivorship or metamorph size in either species, but did accelerate time to metamorphosis in R. sylvatica. The interaction between nitrate and malathion had no effects in B. americanus and had no effect on R. sylvatica survivorship or metamorph size. However, in the 250 μg/l and 500 μg/l malathion treatments, nitrate reduced the negative effect of malathion on time to metamorphosis in R. sylvatica such that there was little if any delay in metamorphosis compared to the controls in these treatment combinations. This observation suggests that the presence of nitrate might ameliorate the effects of malathion on R. sylvatica. Our results suggest that malathion could have significant effects on anuran populations and communities and that nitrate might potentially mediate such effects in some species.
Differential Patterns of Accumulation and Depuration of Dietary Selenium and Vanadium During Metamorphosis in the Gray Treefrog (Hyla versicolor) by Christopher L. Rowe; Andrew Heyes; Jessica Hilton (pp. 336-342).
Selenium (Se) and vanadium (V) are contaminants commonly found in aquatic systems affected by wastes derived from fossil fuels. To examine their effects on a widely distributed species of amphibian, we exposed gray tree frogs (Hyla versicolor) to Se (as SeO2) or V (as NaVO3) in their diet from the early larval period to metamorphosis. Concentrations of Se in Se-enriched food were 1.0 (Se control), 7.5 (Se low), and 32.7 (Se high) μg/g dw. Concentrations of V in V-enriched food were 3.0 (V control), 132.1 (V low), and 485.7 (V high) μg/g dw. Although we observed bioaccumulation of both metals throughout the larval period, no effects on growth, survival, metabolic rate, or lipid content were observed. Se concentrations in tissues did not vary among life stages, neither in Se low nor Se high treatments, such that maximum accumulation had occurred by the mid-larval period. In addition, there was no evidence of depuration of Se in either the Se low or the Se high treatments during metamorphosis. A strikingly different pattern of accumulation and depuration occurred in V-exposed individuals. In treatments V low and V high, maximum body burdens occurred in “premetamorphs” (i.e., animals with developed forelimbs but in which tail resorption had not begun), whereas body burdens in animals having completed metamorphosis were much lower and similar to those in larvae. These results suggest that compared with Se-exposed animals, V-exposed animals were able to depurate a substantial amount of accumulated V during the metamorphic period. In an ecologic context, it appears that amphibians exposed to Se during the larval period may serve as a vector of the metal to terrestrial predators, yet potential transfer of accumulated V to predators would largely be restricted to the aquatic habitat.
Carbaryl Concentration Gradients in Realistic Environments and Their Influence on Our Understanding of the Tadpole Food Web by Benjamin J. Bulen; Christopher A. Distel (pp. 343-350).
Although exposure to pesticides has been correlated with amphibian declines, the mechanism of their role remains enigmatic. Declines have been associated with sublethal exposure, but few outdoor studies have evaluated impacts of low pesticide concentrations. Understanding the effects of a range of pesticide concentrations on amphibians in outdoor mesocosms provides a framework for both direct and indirect effects of exposure. Indirect effects are challenging to glean from lab studies, which typically lack a food web. Our design tested direct and indirect effects of exposure to the insecticide carbaryl on the American toad (Bufo americanus) and the northern leopard frog (Rana pipiens) tadpole survival and growth. We evaluated the effects of five concentrations (2.0, 0.2, 0.02, 0.002, and 0 mg carbaryl/l). Specifically, we predicted a threshold effect in which carbaryl concentrations great enough to reduce zooplankton abundance would have negative indirect effects on tadpoles, but the degree of these effects would not be concentration-specific. Similarly, we predicted that lower carbaryl concentrations (where zooplankton abundance was not reduced) would not differ in effect from controls. We did not observe a threshold effect or any negative effect on tadpoles. The highest carbaryl concentration expedited the time to metamorphosis in the northern leopard frogs by ~4 days. The toads were unaffected by any concentration of carbaryl. Despite significant reductions in zooplankton abundance and increases in phytoplankton abundance, periphyton abundance was unaffected by carbaryl. Taken together, these results suggest that despite evidence from studies using single concentrations of pesticides, trophic cascade models do not sufficiently explain sublethal effects on larval amphibians.
Lead and Copper in Pigeons (Columbia livia) Exposed to a Small Arms–Range Soil by Desmond I. Bannon; Patrick J. Parsons; Jose A. Centeno; Simina Lal; Hanna Xu; Alan B. Rosencrance; William E. Dennis; Mark S. Johnson (pp. 351-360).
Small arms–range (SAR) soils can be contaminated with metals from spent copper (Cu)-jacketed bullets. Avian species are particularly at risk because they are exposed to lead (Pb) through ingestion of grit, soil intake from preening, or ingestion of contaminated food near ranges. Examination of the effects of Pb on birds at ranges have mainly focused on intake and toxicity of Pb shot pellets or fragments; however, Pb in soils may be an important pathway of exposure. To evaluate the uptake and effects of Pb from an actual range, the soil fraction (<250 μm) from a contaminated SAR soil was used to dose pigeons (Columbia livia) for 14 days at low (2700 μg Pb and 215 μg Cu/d) and high (5400 μg Pb and 430 μg Cu/d) doses. At the end of the study, blood Pb and erythrocyte protoporphyrin were determined, and tissues were analyzed for Pb and Cu. Results showed that Pb was absorbed in a dose–response manner in blood, tissues, and feathers, and erythrocyte protoporphyrin, a biomarker of early Pb effect, was increased at blood Pb levels >50 μg/dL. Four tissues showed differential retention of Pb, with kidney having the highest concentration followed by liver, brain, and heart, whereas Cu levels were not changed. To examine possible interactions with other metals, amendments of either Cu or tungstate were made to the soil sample. Although these amendments seemed to decrease the absorption of Pb, the results were ambiguous compared with sodium chloride controls. Overall, this study showed that intake of SAR soils contaminated with Pb and Cu causes an increase in Pb body burdens in birds and that the response can be modulated by amending soils with salts of metals.
Alterations in Vitamin A and E Levels in Liver and Testis of Wild Ungulates from a Lead Mining Area by Jaime Rodríguez-Estival; Mark A. Taggart; Rafael Mateo (pp. 361-371).
In animals, exposure to metal pollution can induce oxidative stress via several mechanisms. This stress might then cause adverse effects on functions such as male reproductive capacity. Antioxidant vitamins A and E play an important role in maintaining organism functions under stressed conditions. This study assessed the effect of different metals and metalloids on levels of vitamins A and E in livers and testis (n = 67 and 36) of red deer and in livers (n = 22) of wild boar. The study compared animals residing within and outside a polluted mining area. Red deer from mined areas showed significant reductions in liver retinyl docosahexaenoate and retinyl docosapentaenoate. Free retinol, α-tocopherol, and retinyl palmitate in the testis were also lower. This might indicate that increased internal usage of these antioxidants is occurring as deer try to maintain the integrity and function of reproductive tissue. Wild boar from mined areas also showed significant reductions in liver retinyl stearate but increased free retinol levels. This might suggest that vitamin A is being mobilized to a greater degree to cope with the induced oxidative stress caused by exposure to metal pollution. Additionally, a significant negative relationship between liver α-tocopherol and bone lead (Pb) in boar might indicate some long-term effects of Pb on antioxidant levels. Results suggest that vitamin A and E status can be altered as a consequence of exposure to Pb pollution and that complex differences in this response probably exist between species.
Monitoring Environmental Pollutants in the Vicinity of a Cement Plant: A Temporal Study by Joaquim Rovira; Montse Mari; Marta Schuhmacher; Martí Nadal; José L. Domingo (pp. 372-384).
From 2008 to 2009, we evaluated the environmental impact of a cement plant (Montcada i Reixac, Catalonia, Spain) that is located close to densely populated areas. The potential health risks for the population living in the neighborhood were also assessed. The levels of various heavy metals and the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in soil, vegetation, and air samples collected at different directions and distances from the facility. Three 6-monthly consecutive campaigns were performed to establish temporal and seasonal trends. Multivariate statistical techniques, such as principal component analysis, were used. Human exposure to metals and PCDD/Fs, as well as the associated carcinogenic and noncarcinogenic risks, were also calculated. Environmental pollutant concentrations, especially those found in urban sites, were noted to be slightly higher than those recently reported around other cement plants in Catalonia. A seasonal pattern was observed, with higher values recorded during the colder sampling periods. Despite this, the carcinogenic and noncarcinogenic risks derived from human exposure to metals and PCDD/Fs were within the ranges considered acceptable by international regulatory organisms.