Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Archives of Environmental Contamination and Toxicology (v.33, #2)
Bacillus stearothermophilus as a Model to Evaluate Membrane Toxicity of a Lipophilic Environmental Pollutant (DDT) by M. M. Donato; A. S. Jurado; M. C. Antunes-Madeira; V. M. C. Madeira (pp. 109-116).
The thermophilic eubacterium Bacillus stearothermophilus has been used as a model system to identify DDT-promoted events in biological membranes putatively related with the insecticide toxicity. Two strategies have been approached: a) bacterial growth and viability were followed and the effects of DDT (2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane) determined; b) biophysical studies with fluorescent probes were performed to elucidate the effects of DDT on the organization of the membrane lipid bilayer. The effects of DDT on growth and physical properties of the membrane were also determined in the presence of Ca2+ to further identify the interference of the insecticide at the membrane level and its putative contribution to cell toxicity. Growth inhibition by DDT is concentration-dependent, being attenuated or removed by the addition of 2.5-mM Ca2+ to bacterial cultures. Consistently, fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its propionic acid derivative (DPH-PA) exhibited opposite effects of Ca2+ and DDT on the physical state of bacterial polar lipid dispersions. Growth and viability of bacterial cells are affected by DDT concentrations lower than those able to induce detectable bulk fluidity alterations, indicating high sensitivity of the intact bacterial system to alterations in limited membrane domains not directly probed by fluorescent probes that only report the average behavior of membrane lipid population.
Effect of the Nature of Exogenous Organic Matter on Pesticide Sorption by the Soil by E. Iglesias-Jiménez; E. Poveda; M. J. Sánchez-Martín; M. Sánchez-Camazano (pp. 117-124).
A study was carried out on the sorption of two sparingly water-soluble pesticides (diazinon and linuron) by a sandy loam soil modified with different exogenous organic materials (EOMs) containing humic-like substances: city refuse compost (CRC), peat (P), commercial “humic” acid (HA), liquid “humic” acid (LHA), and two (nonhumic) model compounds (surfactants), tetradecyltrimethylammonium bromide (TDTMA) and sodium dodecyl sulphate (SDS), before and after 2- and 8-month incubation periods with the soil. In all cases, the isotherms fitted the Freundlich sorption equation (x/m = KC e n ), generally with r 2 values greater than 0.99. The value of the sorption constant K for the natural soil was 8.81 for diazinon and 2.29 for linuron. These values increased significantly for EOM modified soils with respect to natural soil, with the exception of the samples modified with SDS and LHA, in which cases they decreased, possibly due to the micellar properties of these compounds. Incubation of EOMs with soil increased their sorption capacity: the K oc values were increased proportionally to the incubation time for both pesticides and for all treatments carried out. Accordingly, the sorption capacity of hydrophobic pesticides increases with the degree of evolution in the soil of EOMs with “humic”-type compounds, possibly due, among other causes, to the increase in the EOMs' colloidal properties and the modifications occurring in the hydrophobic-hydrophilic characteristics of the soil surfaces. The main conclusion is that application to the soil of carbon-rich wastes, especially those with a high degree of maturity, may offer an important strategy for reducing pesticide leaching and for eliminating pesticide residues from soil with the use of anionic surfactants.
Effects of Sediment Homogenization on Interstitial Water PCB Geochemistry by R. M. Burgess; R. A. McKinney (pp. 125-129).
Sediment homogenization is a common practice in many contaminated sediment toxicity testing and chemical analysis protocols. A primary goal of sediment homogenization is to reduce inter-replicate variability. In this study, the geochemical effects of sediment homogenization were evaluated by measuring the concentration and distribution of polychlorinated biphenyls (PCBs) in environmentally contaminated marine sediment interstitial waters. Sediment homogenization, prior to isolation of interstitial waters, was found to significantly increase the concentration of PCBs in the dissolved and colloidal phases—generally by a factor of two. Long-term storage (i.e., several months) of sediments following mixing appeared to allow interstitial water distributions of PCBs to return to “normal,” although a storage artifact may also be present. This study indicates that homogenization results in significant changes in the concentration of PCBs in environmentally contaminated sediment interstitial waters. Consequences of these changes on inferences made based on toxicity tests or chemical analyses using homogenized sediments need to be considered and studied further.
Distribution of Selected PCB Congeners in the Babcock Street Sewer District: A Multimedia Approach to Identify PCB Sources in Combined Sewer Overflows (CSOs) Discharging to the Buffalo River, New York by B. G. Loganathan; K. N. Irvine; K. Kannan; V. Pragatheeswaran; K. S. Sajwan (pp. 130-140).
To evaluate sources of PCBs in combined sewer overflows (CSOs) to the Buffalo River, New York, combined sewage, sanitary flow, atmospheric wet and dry depositions, and street dust samples were collected from the Babcock Street sewer district and analyzed. Total PCB concentrations (sum of the PCB congeners quantitated) in particulate and dissolved phases of sanitary flow were 101–269 ng g-1 dry weight and <0.2 ng L-1, respectively. PCBs in the atmospheric dry and wet deposition samples were close to the method detection limit (a few pg/cm2 day-1 and <0.2 ng L-1, respectively). Average concentrations of total PCBs were noticeable in both dissolved (64 ng/l-1) and particulate (907 ng g-1 dry weight) phases in CSOs. Total PCBs in aggregates of street dust samples were between 53 and 1,700 ng g-1 dry weight, with the highest concentrations at sites nearest an industrial area that was previously remediated for PCB contamination. PCB congeners 153, 138, 101, 118, and 180 contributed >50% of the total PCB load in street dust samples. PCB congener composition in the particulate phase of CSOs reflects the congener pattern of the street dusts. In this context, it can be suggested that the local contaminated street dusts are one of the potential sources of PCBs in CSOs, which is a source of PCBs to the Buffalo River.
Recalcitrance of 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) to Cometabolic Degradation by Pure Cultures of Aerobic and Anaerobic Bacteria by M. Megharaj; A. Jovcic; H. L. Boul; J. H. Thiele (pp. 141-146).
Pure cultures of aerobic and anaerobic bacteria capable of oxidation and reductive dehalogenation of chloroethylenes, and aerobic bacteria involved in biodegradation of polychlorinated biphenyls (PCBs) were screened for their ability to cometabolize the persistent pollutant 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE). Bacterial cultures expressing methane monooxygenase (Methylosinus trichosporium), propane monooxygenase (Mycobacterium vaccae) and biphenyl 2,3-dioxygenase enzymes (Pseudomonas fluorescens and Rhodococcus globerulus), as well as bacteria reductively dechlorinating chloroethylenes (Acetobacterium woodii and Clostridium butyricum) could not degrade DDE. Cell-free extracts of M. trichosporium, M. vaccae, P. fluorescens and R. globerulus were also unable to transform DDE, indicating that cell wall and membrane diffusion barriers were not biodegradation limiting. These studies suggest that these bacteria can not degrade DDE, even when provided with cosubstrates that induce chlorophenyl- and dichloroethylene-group transforming enzymes.
Ultrastructural and Electron Energy Loss Spectroscopy Studies of Sequestration Mechanisms of Cd and Cu in the Marine Diatom Skeletonema costatum by Y. Nassiri; J. L. Mansot; J. Wéry; T. Ginsburger-Vogel; J. C. Amiard (pp. 147-155).
The marine diatom Skeletonema costatum was used to study mechanisms of detoxification when submitted to cadmium and copper contamination. After 96 h of growth, concentration corresponding to 50% growth inhibition (IC50, 96 h) was 0.224 mg/L for cadmium and 0.045 mg/L for copper, indicating that copper is more toxic for S. costatum than cadmium. Heavy cellular damages were observed for cadmium and copper concentrations close to the IC50. Exposure to these concentrations induced a migration of inclusions from the peripheral cytoplasm to the vacuole. Electron energy loss spectroscopy (EELS) investigations demonstrated that Cd and Cu were specifically trapped in these inclusions. However, Cu was less sequestered than cadmium in the vacuole. EELS determination of oxidation states evidenced that trace metals were sequestered as Cd2+ and Cu2+. Nitrogen and sulfur are involved in metallic storage, especially in the case of cadmium contamination.
Cadmium Bioaccumulation in Tetraselmis suecica: An Electron Energy Loss Spectroscopy (EELS) Study by Y. Nassiri; J. Wéry; J. L. Mansot; T. Ginsburger-Vogel (pp. 156-161).
Electron energy loss spectroscopy (EELS) was used to study the distribution of cadmium within the microalga Tetraselmis suecica when submitted to cadmium contamination. This analytical technique, which is associated to transmission electron microscopes, demonstrated that cadmium was stored specifically in the osmiophilic vesicles of T. suecica. The EELS study of the oxidation states revealed that cadmium was stored as Cd2+. In addition, the EELS quantification showed a significant relationship between cadmium, nitrogen, and sulfur concentrations. The toxic element is probably bounded to organic molecules via S-Cd bounds.
Bioindication of Heavy Metals in Soil by Liverworts by A. Samecka-Cymerman; A. Marczonek; A. J. Kempers (pp. 162-171).
Studies were made of the accumulation of the heavy metals Ba, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, Sr, V, and Zn and the macroelements N, P, K, Ca, and Mg in liverworts Conocephalum conicum, Marchantia polymorphia, and Pellia epiphylla collected from 57 microhabitats in Poland (Lower Silesia, Tatry Mts., and Puszcza Augustowska forest) and one microhabitat in the Czech Republic (Moravsky Kras).Ecological differentiation of Conocephalum conicum, Marchantia polymorpha and Pellia epiphylla populations is closely correlated with the soil chemistry. The evidence for this assumption are the significant positive correlations between concentrations of elements in soil and in the examined liverworts. In particular, correlations between contents of chromium and cobalt in soil and in Conocephalum conicum and between nickel, chromium, copper, and barium in soil and in Pellia epiphylla prove that these plants can be useful in monitoring of contamination of soil with elements mentioned above. Concentrations of cobalt in almost all the examined liverworts surpass the average background values of this element established for terrestrial bryophytes what proves that these plants tolerate increased accumulated amounts of this element and may therefore act as bioindicator for this heavy metal.Cationic equilibrium of Conocephalum conicum, Marchantia polymorpha and Pellia epiphylla examined according to Czarnowski (1977) pointed to the existence of some disturbances in ionic balance of these plants caused probably by elevated concentrations of microelements (especially iron, cobalt, lead, and copper) in their tissues.
Environmental Impact of Trace Element Emissions from Geothermal Power Plants by R. Bargagli; D. Cateni; L. Nelli; S. Olmastroni; B. Zagarese (pp. 172-181).
Concentrations of several trace elements were determined in mosses, higher plants and organs of small mammals from a geothermal area in Tuscany (central Italy). Increased deposition of Hg, As, B, and Sb was detected in biological samples collected within a few hundred meters of geothermal power plants. Among the species considered, the moss Hypnum cupressiforme was the most efficient accumulator of trace elements. Contamination levels in a fodder-plant (Hedysarum coronarium) and vegetables grown in the geothermal field did not seem to pose health risks for consumers. However, a statistically significant increase in Hg, B, and As concentrations was found in the kidney and muscle of small mammals living close to geothermal installations. Biological effects of B pollution were detected in two sensitive plant species.In view of plans to increase the exploitation of geothermal resources in the area, adequate measures to monitor the environment should be taken. Mosses are the most suitable accumulative biomonitors for a surveillance network, and studies on small mammal populations should be intensified. Available technologies should be used to diminish atmospheric emissions from geothermal power plants.
Effects of pH and Sulfate on Insects and Protozoans Inhabiting Treeholes by C. J. Paradise; W. A. Dunson (pp. 182-187).
We used laboratory microcosms designed to simulate treeholes to study the effect of changing levels of chemicals found in precipitation in central Pennsylvania (H+ and SO4 =) on the treehole insects Aedes triseriatus (a mosquito), Helodes pulchella (a helodid beetle), and Culicoides guttipennis (a ceratopogonid midge), and treehole protozoans. Protozoans were tested in both the presence and absence of insects. We hypothesized that the individual insect species would have differential tolerances to abiotic stresses, and that effects of low pH on protozoans would be especially strong. Survival of helodids was higher than mosquitoes and midges. Emergence and survival of mosquitoes and midges were lower at low pH. Densities of ciliates increased the most at high pH in the absence of insects. Densities of flagellates increased the most at low pH in the absence of insects. The presence of helodids, mosquitoes, and protozoans was associated with higher final [SO4 =], as was low pH. Mosquitoes at low pH caused the largest increases in cation concentrations, and protozoans at high pH caused the largest decreases in cation concentrations. It appears that the biota of treeholes are affected by ionic changes in simulated tree stemflow that can be caused by anthropogenic atmospheric deposition. The species studied here were sometimes differentially affected by the common pollutants, [H+] and [SO4 =]. The resulting changes in these discrete treehole communities may allow them to be useful bioindicators of the status of forest ecosystems altered by changing atmospheric chemistry.
Experimental Factors That May Affect Toxicity of Cadmium to Freshwater Organisms by B. C. Suedel; J. H. Rodgers, Jr.; E. Deaver (pp. 188-193).
The effects of exposure duration, test organism, and test endpoint on the toxicity of cadmium to a variety of freshwater species were evaluated. Toxicity of cadmium was assessed by monitoring the survival and reproduction of Ceriodaphnia dubia Richard; the survival of Daphnia magna Straus; and the survival and growth of Hyalella azteca Saussure, Chironomus tentans Fabricius, and Pimephales promelas Rafinesque. Organisms were exposed in static systems for 48 h, 96 h, 7 d, 10 d, and 14 d to determine acute and chronic toxicity. Relative sensitivities of test organisms exposed to aqueous cadmium varied with test duration and test endpoint. In general, H. azteca was the most sensitive organism tested, followed in decreasing sensitivity by P. promelas, C. dubia, D. magna, and C. tentans. Mortality of C. dubia and D. magna was consistent up to 7 d, after which little additional mortality occurred. Effects of test duration on cadmium toxicity were most pronounced for H. azteca and C. tentans, with mortality and growth becoming increasingly sensitive with increasing test duration.
Salinity Tolerance of Daphnia magna and Potential Use for Estuarine Sediment Toxicity Tests by G. S. Schuytema; A. V. Nebeker; T. W. Stutzman (pp. 194-198).
Daphnia magna Straus, a common organism used for freshwater sediment toxicity tests, was evaluated to determine its tolerance to salinity and suitability for tests with estuarine water and sediments. Daphnids were exposed for 2 to 21 days to salinity in a variety of water-only tests, in tests with freshwater sediment overlain by salt water, and in tests with estuarine sediments overlain by freshwater. Daphnid age, test length, and temperature seemed to have little effect upon the range of LC50, NOAEL, and LOAEL values. LC50s for all tests ranged from 5.10 to 7.81 g/L, with a mean of 6.6 g/L salinity (measured conductivity 10.0 mS/m). The mean NOAEL and LOAEL values based on production of young were 4.6 and 6.9 g/L salinity (measured conductivity 7.1 and 10.5 mS/m), respectively. The results indicate that D. magna will survive and reproduce well in water with salinities below 4 g/L and demonstrate the potential usefulness of this organism in monitoring sediment toxicity from both freshwater and estuarine wetland sites.
Acute and Chronic Toxicity of the Herbicide Stam®M-4 in Field and Laboratory Exposures by M. T. Moore; J. L. Farris (pp. 199-202).
Propanil (3′,4′-dichloropropionanilide), the active ingredient in the herbicide Stam®M-4, is possibly the most extensively used herbicide for rice production in the world. Propanil and its metabolites are transported within characteristic ditch ecosystems in the production landscape of northeast Arkansas. Runoff from these ditch ecosystems is further transported to a river or other water body supplied by the Mississippi River Alluvial aquifer. Forty-eight–hour acute toxicity tests with Ceriodaphnia dubia (cladoceran) and Pimphales promelas (fathead minnow) were conducted on stormwater runoff, laboratory synthetic water, and irrigation (ground) water. No effects on survival were observed in this study following 48-h toxicity testing with the stormwater. Survival studies indicated assimilative capacity in irrigation (ground) water as opposed to laboratory synthetic water. Mean 48-h LC50s of C. dubia increased from 2.94 mg/L Stam®M-4 in laboratory synthetic water to 8.01 mg/L Stam®M-4 in irrigation water. Likewise, P. promelas mean 48-h LC50s increased from 23.76 (laboratory synthetic water) to 33.52 mg/L Stam®M-4 (ground water). In 7-d chronic tests, there was an increase in mean LC50s of C. dubia when comparing synthetic water to irrigation water (0.48 to 1.24 mg/L Stam®M-4, respectively). P. promelas, however, had less tolerance for Stam®M-4 in irrigation water (4.45 mg/L) than in synthetic water (5.93 mg/L) in 7-d chronic toxicity tests. Forty-eight–hour toxicity tests indicate that ground water affords organisms some assimilative capacity that laboratory synthetic water does not. Since herbicides and most other pesticides are manufactured to elicit rapid responses, 48-h toxicity results best describe potential nontarget organism effects in aquatic ecosystems.
Effects of Organophosphate and Carbamate Pesticides on Acetylcholinesterase and Choline Acetyltransferase Activities of the Polychaete Nereis diversicolor by P. Scaps; S. Demuynck; M. Descamps; A. Dhainaut (pp. 203-208).
A toxicity test for organophosphates (OP) and carbamates (C) was improved with the adult ragworm Nereis diversicolor. Animals were maintained in U-shaped glass tubes of 4-mm inner diameter fixed vertically on a plastic plate and placed in glass aquaria. Each tank was covered with glass in order to reduce evaporation and heat dissipation. Temperature varied between 15 and 16°C and salinity was constant (34‰) during the entire length of the experiment. Experiments were performed with a fixed day length of 12 h and seawater was gently aerated. The maintenance system allowed the administration of OP and C compounds via the seawater. An acclimatization period of 48 h was not sufficient to accomodate worms to their artificial burrows; accordingly, we chose to acclimate worms for a week before beginning the exposure.Choline acetyltransferase (ChAT) activity was very low and was not significantly modified by two OP compounds: malathion and parathion-ethyl. ChAT is not a target for these pesticides and should not be used for future studies about OP and C toxicity. On the other hand, inhibitory effects on acetylcholinesterase (AChE) activity were determined at concentrations of 10−6 M for three OP compounds—malathion, parathion-ethyl, and phosalone—and a carbamate pesticide—carbaryl. We measured only short-term effects and no cumulative effect was determined, the maximum percentage of AChE activity inhibition being between 2 (carbaryl) and 7 (OP compounds) days after exposure and then remaining stable. Mortality occured only after a period of intoxication of 14 days. N diversicolor, which can be easily maintained at the laboratory, seems to be a good candidate for future laboratory studies to test the toxicity of other pollutants.
Dose-Dependent Effects of Cadmium on the Growth of Snails in Toxicity Bioassays by A. Gomot (pp. 209-216).
The effects on survival and growth of exposure to cadmium (Cd) in the food were analyzed in juvenile snails (age one month, mean weight 1 g) of the two subspecies Helix aspersa aspersa (H.a.a.) and H. aspersa maxima (H.a.m.). The experiments lasted for four weeks and the animals were fed with special snail food containing 0-, 50-, 100-, 200-, 400-, and 800 μg Cd/g of dry food. No significant adverse effect (NOEC) was noted at 50 μg/g for three weeks. A negative effect of Cd on growth was noted from 100 to 800 μg/g and plotting the growth coefficient variation against the Cd concentration led to an estimate of the EC75 at day 14 of 370 μg/g in H.a.a. and 470 μg/g in H.a.m. and at day 28 of 290 μg/g in H.a.a. and 330 μg/g in H.a.m. Juvenile snails are thus a suitable material for use as bioindicators in the assay of contamination of food.
Developmental Toxicity of Three Carrier Solvents Using Embryos of the Grass Shrimp, Palaemonetes pugio by J. R. Rayburn; W. S. Fisher (pp. 217-221).
Embryos of the grass shrimp (Palaemonetes pugio) have shown sensitivity to the water soluble fraction of number 2 fuel oil. To determine the possible use of carrier solvents in grass shrimp bioassays, detailed concentration-response experiments for ethanol (EtOH), dimethylsulfoxide (DMSO), and acetone were performed and LC50 values were obtained using two test methods. The 4-d assay included development prior to the time of hatch through the time of hatch, a critical life stage of these embryos. The 12-d assay included development from the tissue cap stage embryos (late gastrula) through two days post-hatch. The average 4-d LC50s for EtOH, DMSO, and acetone were 12.07, 22.57, and 6.78 g/L, whereas the average 12-d LC50s were 3.63, 12.33, and 6.94 g/L, respectively. The coefficient of variation for each test was less than 25.2%. Based on concentration-response curves, the maximum allowable limit of EtOH, DMSO, and acetone to be used as a carrier in the grass shrimp embryo toxicity studies should be <1, <6, and <4 g/L, respectively.
Mercury Concentrations in Pond Fish in Relation to a Coal-Fired Power Plant by A. E. Pinkney; D. T. Logan; H. T. Wilson (pp. 222-229).
Many studies have reported that atmospheric mercury is the primary cause for bioaccumulation in fish from remote lakes. Few data, however, are available on the possible effects of near-field mercury deposition on mercury concentrations in fish from local waters. Mercury concentrations were surveyed in fish from 23 ponds in the vicinity of a 543-megawatt coal-fired power plant located at Dickerson, Maryland. A stratified random sampling design was used to select ponds within zones delineated by concentric arcs mapped at 3, 7, 10, and 15 km from the plant. For each pond, mercury concentrations were measured by atomic absorption spectrometry in sunfish (bluegill or green sunfish) in all ponds, and largemouth bass, which were present in 14 of the ponds. Mean mercury concentrations in the ponds ranged from 0.01 to 0.38 ppm for sunfish and 0.04 to 0.43 ppm for bass. Stepwise multiple regression identified variables related to tissue concentrations. Differences between strata were tested with analysis of covariance, after adjusting the concentrations to account for differences in water quality. The observed pattern of mercury bioaccumulation did not match the pattern predicted by a wet deposition model.
60Co Transfer from Water to the Rainbow Trout (Oncorhynchus mikiss Walbaum) by J. P. Baudin; M. P. Véran; C. Adam; J. Garnier-Laplace (pp. 230-237).
60Co uptake from natural water, release and tissue distribution were investigated in the rainbow trout (Oncorhynchus mikiss), which is representative of the third order consumers of the freshwater trophic chains. The experiments were carried out on two groups of fingerling trout placed in 0.45 μm filtered river water, maintained at 12 ± 0.5°C, contaminated with about 30 Bq ml−1 of 60Co and renewed three times a week. After a 8-week exposure phase, the fish of one group were dissected to determine the contamination of the tissues and organs and the distribution of the accumulated 60Co. The fish of the other group were placed in non-contaminated water, renewed daily, to monitor radionuclide release. After a 42-day depuration phase, the specimens were dissected to study the tissue distribution of the residual 60Co. 60Co accumulation from water by trout can be described by a one-compartment exponential model. The concentration factor, calculated from the ratio of the radionuclide concentration in filtered water and in the fish, reached a maximum value of 4.6 (w.w.) after 30 days exposure. After the 42-day depuration phase, the fish retained about 29% of the accumulated radionuclide. A single-compartment exponential model was fitted to the 60Co elimination data, and the corresponding radionuclide half-life was 21 days. At the end of the exposure phase, tissue contamination study showed 60Co accumulation by the gills, viscera (air bladder, heart and spleen) and kidneys, to be the highest. At the end of the depuration phase, the kidney was the most contaminated organ, followed by the viscera, head, gills, and liver. In both cases, 60Co concentration was by far the lowest in the muscle, which accounted for about 45% of the total body weight and only 20% of the total radionuclide body load.