Accumulation of Lead,Zinc, and Cadmium in a Wild Population of <Emphasis Type="Italic">Clethrionomys glareolus</Emphasis> from an Abandoned Lead Mine

Lead, zinc, and cadmium were determined in a range of tissues from wild populations of bank voles (Clethrionomys glareolus) trapped on an abandoned metalliferous mine site and a reference site. Estimated dietary intakes indicated that animals were exposed to elevated levels of all three metals at the mine site, and this was generally reflected in metal residues in body tissues. Lead concentrations were significantly higher in all tissues of animals from the mine compared to the reference site, while Cd was higher only in the kidney. There was evidence of age-accumulation (using total body weight as an index of age) of Cd in both the liver and kidney of mine site animals but no evidence of such accumulation of lead in bone. In contrast to Cd and Pb, Zn was lower in the tissues of mine site animals compared to the reference site. Based on critical tissue concentrations, the ecotoxicological risk to a wild population of bank voles (Clethrionomys glareolus), associated with total substrate levels of 1 μg g⁻¹ dry weight Cd and 700 μg g⁻¹ dry weight Zn at this mine site is negligible, but that associated with 4000 μg g⁻¹ dry weight Pb may be considered significant. Received: 28 January 2002/Accepted: 29 July 2002     

Comparison of Sensitivity of Grasses (<Emphasis Type="Italic">Lolium perenne</Emphasis> L. and <Emphasis Type="Italic">Festuca rubra</Emphasis> L.) and Lettuce (<Emphasis Type="Italic">Lactuca sativa</Emphasis> L.) Exposed to Water Contaminated with Microcystins

The effects of aqueous extracts from Microcysts aeruginosa strains (both microcystin-producers and non-microcystin producers) on germination and root growth were investigated for three economically important plant species: Festuca rubra L., Lolium perenne L., and Lactuca sativa L. There was a clear inhibition of root growth for L. sativa exposed to strains containing microcystins (5.9–56.4 μg L⁻¹). The strain that produced the most pronounced effects contained the lowest concentration of microcystin suggesting that other cellular compounds may also affect growth.     

Toxicity of Four Herbicide Formulations with Glyphosate on <Emphasis Type="Italic">Rhinella arenarum</Emphasis> (Anura: Bufonidae) Tadpoles: B-esterases and Glutathione <Emphasis Type="Italic">S</Emphasis>-transferase Inhibitors

In this study, amphibian tadpoles Rhinella arenarum were exposed to different concentrations of Roundup Ultra-Max (ULT), Infosato (INF), Glifoglex, and C-K YUYOS FAV. Tadpoles were exposed to these commercial formulations with glyphosate (CF-GLY) at the following concentrations (acid equivalent [ae]): 0 (control), 1.85, 3.75, 7.5, 15, 30, 60, 120, and 240 mg ae/L for 6–48 h (short-term). Acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferase (GST) activities were measured among tadpoles sampled from those treatments that displayed survival rates >85%. Forty-eight-hour LC₅₀ for R. arenarum tadpoles exposed to CF-GLY in the static tests ranged from ULT = 2.42 to FAV = 77.52 mg ae/L. For all CF-GLY, the LC₅₀ values stabilized at 24 h of exposure. Tadpoles exposed to all CF-GLY concentrations at 48 h showed decreases in the activities of AChE (control = 17.50 ± 2.23 nmol/min/mg/protein; maximum inhibition INF 30 mg ae/L, 71.52%), BChE (control = 6.31 ± 0.86 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 78.84%), CbE (control = 4.39 ± 0.46 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 81.18%), and GST (control = 4.86 ± 0.49 nmol/min/mg/protein; maximum inhibition INF 1.87 mg ae/L, 86.12%). These results indicate that CF-GLY produce a wide range of toxicities and that all enzymatic parameters tested may be good early indicators of herbicide contamination in R. arenarum tadpoles.     

Relationship Between Gonad Maturation and Heavy Metal Accumulation in the Clam, <Emphasis Type="Italic">Galatea paradoxa</Emphasis> (Born 1778) from the Volta Estuary,Ghana

The relationship between gonadal development and the concentrations of four heavy metals Mn, Zn, Fe and Hg in the tissues of the clam Galatea paradoxa was evaluated at the Volta estuary, Ghana, over an 18-month period. Metal concentrations in the clam tissues were highly variable over the sampling period and seemed to be influenced by the reproductive cycle of the clam. Mn concentrations varied over a wide range from 49 to 867 μg/g and exhibited a significant positive correlation with gonadal development (p = 0.0146, r² = 0.3190). Zn and Fe concentrations ranged from 13 to 59 μg/g and 79 to 484 μg/g, respectively and both revealed negative relationships between gonad development and metal accumulation (Zn (p = 0.0554, r² = 0.0554) and Fe (p = 0.1040, r² = 0.1567)). Hg concentrations ranged from 0.026 to 0.059 μg/g over the sampling period and exhibited a slight positive relationship between gonadal development and metal accumulation (p = 0.0861, r² = 0.1730).     

Soil <Emphasis Type="Italic">Pseudomonas</Emphasis> Community Structure and Its Antagonism Towards <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> Under the Stress of Acetochlor

In a microcosm experiment, the amplified ribosomal DNA restriction analysis was adopted to investigate the Pseudomonas community structure in soils applied with different concentrations (0, 50, 150, and 250 mg/kg) of acetochlor, and an in vitro assay was made to examine the antagonistic activity of isolated Pseudomonas strains acting on soil-borne pathogen Rhizoctonia solani. The results showed that acetochlor application changed the community structure of Pseudomonas in aquic brown soil. The diversity of Pseudomonas and the amount of isolated Pseudomonas strains with antagonistic activity decreased with an increasing acetochlor concentration, and the toxic effect of acetochlor reached to a steady level at 150–250 mg/kg.     

Effects of Lead Pollution Against Juvenile <Emphasis Type="Italic">Achatina achatina</Emphasis> Fed on Contaminated Artificial Diet

We investigated juvenile Achatina achatina snails by feeding graded levels of inorganic lead metal contaminated artificial diet in plastic snaileries in the laboratory. Snails were tolerant of all levels of lead contamination with no mortalities. Results indicated significant (p < 0.05) transfer of lead from diet to snail with high positive (r ² = 0.98) relationship. Our data suggests that decreased feed intake and growth were found at elevated lead levels. Tissue lead accumulations were lower than dose in artificial diet.     

Accumulation of Lead,Chromium, and Cadmium in Muscle of <Emphasis Type="Italic">capitán</Emphasis> (<Emphasis Type="Italic">Eremophilus mutisii</Emphasis>), a Catfish from the Bogota River Basin

Heavy metal accumulation of lead (Pb), chromium (Cr), and cadmium (Cd) in the muscle of the catfish Eremophilus mutisii was studied in 47 specimens, captured by anglers in the Bogotá River at two sampling sites (Chocontá and Suesca) during May–October 2005. Water samples were processed for physicochemical and metal analyses. Metal accumulation in muscle (wet weight) of specimens at Chocontá and Suesca showed high levels of Pb (3.4 and 3.1 ppm, respectively), Cr (1.8 and 2.1 ppm, respectively), and Cd (0.35 and 0.48, respectively). Metal levels in waters (ppm) indicated that average Pb (0.028 Chocontá, 0.029 Suesca), Fe (0.462 Chocontá, 1.1 Suesca), and Cr (0.113 Chocontá) were above the maximum levels (MCLs) allowed in drinking waters. No extreme average values were found for pH, nitrites, alkalinity, and hardness in the waters. This study showed the importance of benthic and nonmigratory species like the capitán to evaluate the effects of heavy metals pollution. Further public health implications could be derived in the region where this investigation took place due to consumption of capitán by people in the area.     

Effects of Temperature on the Sensitivity of <Emphasis Type="Italic">Gammarus</Emphasis><Emphasis Type="Italic">aequicauda</Emphasis> (Martynov, 1931) to Cadmium

Gammarus aequicauda, collected at different times of the year was used to assess the mortality rates and the sensitivity to cadmium (96 h LC50), at different laboratory temperatures (10, 15, 20, 25°C). The survival in 10 days sediment control test, was high at all tested temperatures, ranging from 4 ± 1% at 10°C (winter collection) to 13.3 ± 2.1% at 25°C (spring collection). The 96 h-LC50 values recorded, ranged from 1.50 mgCd/L in winter at 10°C to 0.10 mgCd/L in spring and summer at 25°C. The results showed that temperature and season of collection influenced mortality rates and G. aequicauda sensitivity to cadmium.     

Mechanism-Based Quantitative Structure-Phytotoxicity Relationships Comparative Inhibition of Substituted Phenols on Root Elongation of <Emphasis Type="Italic">Cucumis sativus</Emphasis>

Phytotoxicity of selected substituted phenols to Cucumis sativus (log1/RC₅₀, root elongation half inhibition concentration [mol/L] in logarithmic form) was determined by using a root elongation inhibition method and quantitative structure-activity relationships (QSARs) were developed. Hydrophobicity, described by 1-octanol/water partition coefficient in logarithmic form (log K _ow) and electronic effect (characterized by the energy of the lowest unoccupied orbital, E _lumo) proved to contribute mainly to the phytotoxicity of phenols in this study. Log K _ow was used as a probe to classify the tested chemicals into subsets according to the modes of toxic action. The result indicated that the substituted phenols fell into two classes in general: narcotic phenols and bioreactive phenols. Most phenols elicited their toxic response via a polar narcosis mechanism and an excellent log K _ow–dependent QSAR was developed (log1/RC₅₀= 0.94 log K _ow+ 2.04, n = 22, r ² _adj= 0.89). Selected phenols with bioreactive substructures exhibited elevated bioreactive toxicity and a strong E _lumo-dependent correlation was achieved (log1/RC₅₀=−0.91 E _lumo+ 2.73, n = 6, r ² _adj= 0.81). This implied that their reactive toxicity involved mainly their in vivo electrophilic reactions. In an effort to model all chemicals without regard to their mechanisms, a highly predictive response-surface was developed with the phytotoxicity, hydrophobicity, and electrophilic reactivity (log1/RC₅₀= 0.66 log K _ow− 0.57 E _lumo+ 2.31, n = 28, r ² _adj= 0.88). Received: 9 January 2001/Accepted: 20 July 2001     

The Extent of Arsenic and of Metal Uptake by Aboveground Tissues of <Emphasis Type="Italic">Pteris vittata</Emphasis> and <Emphasis Type="Italic">Cyperus involucratus</Emphasis> Growing in Copper- and Cobalt-Rich Tailings of the Zambian Copperbelt

The extent of arsenic (As) and metal accumulation in fronds of the As hyperaccumulator Pteris vittata (Chinese brake fern) and in leaves of Cyperus involucratus, which grow on the surface of an old flotation tailings pond in the Zambian Copperbelt province, was studied. The tailings consist of two types of material with distinct chemical composition: (1) reddish-brown tailings rich in As, iron (Fe), and other metals, and (2) grey-green tailings with a lower content of As, Fe, and other metals, apart from manganese (Mn). P. vittata accumulates from 2350 to 5018 μg g⁻¹ As (total dry weight [dw]) in its fronds regardless of different total and plant-available As concentrations in both types of tailings. Concentrations of As in C. involucratus leaves are much lower (0.24–30.3 μg g⁻¹ dw). Contents of copper (Cu) and cobalt (Co) in fronds of P. vittata (151–237 and 18–38 μg g⁻¹ dw, respectively) and in leaves of C. involucratus (96–151 and 9–14 μg g⁻¹ dw, respectively) are high, whereas concentrations of other metals (Fe, Mn, and zinc [Zn]) are low and comparable with contents of the given metals in common plants. Despite great differences in metal concentrations in the two types of deposited materials, concentrations of most metals in plant tissues are very similar. This indicates an exclusion or avoidance mechanism operating when concentrations of the metals in substrate are particularly high. The results of the investigation show that Chinese brake fern is not only a hyperaccumulator of As but has adapted itself to high concentrations of Cu and Co in flotation tailings of the Zambian Copperbelt.     

Investigation of the Multixenobiotic Resistance Mechanism in the Freshwater Fishes Western Mosquitofish, <Emphasis Type="Italic">Gambusia affinis</Emphasis>, and Bluegill Sunfish, <Emphasis Type="Italic">Lepomis macrochirus</Emphasis>

The purpose of the study was to evaluate multixenobiotic resistance mechanism expression as a biomarker for contaminant exposure in freshwater fishes. Exposure to a known mammalian inhibitor (verapamil, 10 μM) and inducer (rhodamine 123, 3 μM) on the transport protein P-glycoprotein (Pgp) was investigated in the liver of the western mosquitofish and bluegill sunfish. No differences in the activity or expression of Pgp were measured in either species using a fluorometric accumulation assay and western blot analyses. The preliminary results from this study indicate that this detoxification mechanism may not be a sensitive indicator of contaminant exposure in certain teleost species.     

Assessing the Performance of a Bdelloid Rotifer <Emphasis Type="Italic">Philodina acuticornis odiosa</Emphasis> Acute Toxicity Assay

A bioassay using the bdelloid rotifer, Philodina acuticornis odiosa, was evaluated for use as a standard test method for direct toxicity assessment testing in the Australasian region. Philodina acuticornis odiosa was found to be relatively tolerant to phenol (24 h LC50, 142 mg/L). The mortality endpoint was both reliable and repeatable (the coefficients of variation for mortality at the 24 h LC50 concentration ranged from 11%–24% (n = 8)), sufficiently low to warrant further testing with a range of reference toxicants, so that this organism can be included for use as a regulatory test in Australasia.     

Use of Behavioral Responses of Rainbow Trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> in Identifying Sublethal Exposure to Hexavalent Chromium

Laboratory tests were conducted in a flow-through apparatus on 1-year-old rainbow trout Oncorhynchus mykiss to evaluate the sensitivity of a number of their behavioral responses to hexavalent chromium (Cr⁶⁺). Test fish were exposed to Cr⁶⁺ concentrations corresponding to 0.001–1 parts of the rainbow trout 96-h LC50 (0.029–28.5 mg Cr/L, respectively) in short-term (15 min) tests. Sensitivity parameter responses could be arranged into the following sequence: latent period of detection response = locomotor activity > gill ventilation frequency > coughing rate. All the rainbow trout responses were sensitive behavioral indicators of sublethal exposure. Behavioral responses meet the criteria as rapid tools for bioassay testing and could be easily standardized using Cr⁶⁺ as a reference toxicant.     

Effects of Nitrate and Ammonium on Larvae of <Emphasis Type="Italic">Rana temporaria</Emphasis> from the Pyrenees

In order to investigate the effects of nitrate and ammonium on the amphibians in a pasture zone of the Catalonian Pyrenees, larvae of Rana temporaria from several ponds were exposed to different concentrations of nitrate (0–500 mg/L) and ammonium (0–1.2 mg/L). High concentrations of nitrate in the water caused mortality and reduced larval size of R. temporaria, whereas no effects on larvae were observed in ammonium conditions. The results suggest that, if the levels of nitrate reach about 100 mg/L, the possibility of survival of R. temporaria larvae may be reduced.     

Analysis of Pyrethroid Insecticides in <Emphasis Type="Italic">Chironomus dilutus</Emphasis> Using Matrix Solid Phase Dispersion Extraction

A matrix solid phase dispersion method was developed to detect eight pyrethroid insecticides in the aquatic invertebrate, Chironomus dilutus. A mixture of silica gel, diatomaceous earth and primary/secondary amino solid absorbents were selected as the dispersion matrix, while 7% ethyl ether in hexane was used as the elution solvent. Method detection limits for the target pyrethroids ranged from 0.46 to 4.4 μg kg⁻¹, and recoveries were 63.5%–124.0%, 43.7%–116.0% and 53.1%–93.1% at spiked levels of 5, 20 and 50 μg kg⁻¹, respectively. The developed method was used to assess pyrethroid residues in laboratory-exposed and field-collected C. dilutus.     

Effects of Hypoxia and Sedimentary Naphthalene on the Activity of <Emphasis Type="Italic">N</Emphasis>-acetyl-<Emphasis Type="Italic">β</Emphasis>-Glucosaminidase in the Epidermis of the Brown Shrimp, <Emphasis Type="Italic">Penaeus aztecus</Emphasis>

The brown shrimp, Penaeus aztecus, is subject to dual stresses of environmental hypoxia and contamination of polycyclic aromatic hydrocarbons (PAHs) in the northern Gulf of Mexico. The effects of hypoxia and sedimentary naphthalene, administered alone and in combination, on epidermal activity of N-acetyl-β-glucosaminidase (NAG), a biomarker for molt-interfering effects in P. aztecus, were investigated. It was found that hypoxia and sedimentary naphthalene, when given simultaneously, significantly inhibited epidermal NAG activity, suggesting that these two environmental stressors together can have adverse effects on molting of the brown shrimp. The results of this study also show that sedimentary naphthalene potentiates hypoxia effects on epidermal NAG activity.     

Arsenic accumulation by <Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis> and its response to some thiol chelators

Objective  The aim of this study is to examine arsenic accumulation by Pseudomonas stutzeri and its response to some thiol chelators, DMPS and MiADMSA. Methods   Determination of arsenic accumulation by Pseudomonas sp. was carried out using an atomic absorption spectrophotometer, a TEM and an EDAX. Arsenate reductase enzyme assay was carried out from a cell-free extract of Pseudomonas sp. The effect of chelating agents on arsenite accumulation was analyzed. Total cellular proteins were analyzed using 1-D SDS-PAGE. Results   Pseudomonas sp. exhibited a maximum accumulation of 4 mg As g⁻¹ (dry weight). TEM and EDAX analysis showed the presence of As-containing electron-dense particles inside the cells. Data on arsenate reductase enzyme kinetics yielded a K _m of 0.40 mM for arsenate and a V _max of 5,952 μmol arsenate reduced per minute per milligram of protein. The chelating agents MiADMSA and DMPS were found to reduce the arsenic accumulation by 60 and 35%, respectively, whereas the presence of both chelating agents in medium containing cells pretreated with arsenite reduced it by up to 90%. The total protein profile of the cellular extract, obtained by 1-D SDS-PAGE, indicated five upregulated proteins, and three of these proteins exhibited differential expression when the cells were grown with MiADMSA and DMPS. Conclusion  This study shows a new approach towards arsenic detoxification. A combination treatment with MiADMSA and DMPS may be useful for removing intracellular arsenic. The proteins that were found to be induced in this study may play an important role in the extrusion of arsenic from the cells, and this requires further characterization.     

Toxicokinetics of Organic Contaminants in <Emphasis Type="Italic">Hyalella azteca</Emphasis>

Uptake, biotransformation, and elimination rates were determined for pentachlorophenol (PCP), methyl parathion (MP), fluoranthene (FU), and 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCBP) using juvenile Hyalella azteca under water-only exposures. A two-compartment model that included biotransformation described the kinetics for each chemical. The uptake clearance coefficients (k_u) were 25.7 ± 2.9, 11.5 ± 1.1, 184.4 ± 9.3, and 251.7 ± 9.0 (ml g⁻¹ h⁻¹) for PCP, MP, FU, and HCBP, respectively. The elimination rate constant of the parent compound (k_ep) for MP was almost an order of magnitude faster (0.403 ± 0.070 h⁻¹) than for PCP and FU (0.061 ± 0.034 and 0.040 ± 0.008 h⁻¹). The elimination rate constants for FU and PCP metabolites (k_em) were similar to the parent compound elimination 0.040 ± 0.005 h⁻¹ and 0.076 ± 0.012 h⁻¹, respectively. For MP, the metabolites were excreted much more slowly than the parent compound (0.021 ± 0.001 h⁻¹). For PCP, FU, and MP whose metabolites were measured, the biological half-life (t_1/2p) of the parent compound was shorter than the half-life for metabolites (t_1/2m) because the rate is driven both by elimination and biotransformation processes. Thus, H. azteca is capable of metabolizing compounds with varying chemical structures and modes of toxic action, which may complicate interpretation of toxicity and bioaccumulation results. This finding improves our understanding of H. azteca as a test organism, because most biomonitoring activities do not account for biotransformation and some metabolites can contribute significantly to the noted toxicity. Received: 13 June 2002/Accepted: 21 October 2002     

A modified version of Moran's <Emphasis Type="Italic">I</Emphasis>

Background  

Investigation of global clustering patterns across regions is very important in spatial data analysis. Moran's I is a widely used spatial statistic for detecting global spatial patterns such as an east-west trend or an unusually large cluster. Here, we intend to improve Moran's I for evaluating global clustering patterns by including the weight function in the variance, introducing a population density (PD) weight function in the statistics, and conducting Monte Carlo simulation for testing. We compare our modified Moran's I with Oden's I * _pop for simulated data with homogeneous populations. The proposed method is applied to a census tract data set.