Development of a terrestrial vertebrate model for assessing bioavailability of cadmium in the fence lizard (Sceloporus undulatus) and in ovo effects on hatchling size and thyroid function

In the terrestrial environment, standardized protocols are available for measuring the exposure and effects of contaminants to invertebrates, but none currently exist for vertebrates. In an effort to address this, we proposed that developing lizard embryos may be used as a terrestrial vertebrate model. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may affect hatchling size, mortality, as well as thyroid function. Toxicant-induced perturbations of thyroid function resulting from in ovo chemical exposure may result in toxicity during the critical perinatal period in reptiles. Fertilized Eastern fence lizard (Sceloporus undulatus) eggs were placed in cadmium (Cd)-spiked expanded perlite (0, 1.48, 14.8, 148, 1480, 14 800 μg Cd/g, nominal concentrations), artificially incubated at 28 °C, and examined daily for mortality. Whole lizard hatchlings as well as failed hatches were homogenized in ethanol and the homogenate was divided for Cd body residue analysis and thyroid hormone (triiodothyronine (T₃) and thyroxine (T₄)) analyses. Acute mortality was observed in the two highest doses (1480 and 14 800 μg Cd/g). Cadmium body residues showed a higher internal concentration with increasing exposure concentration indicating uptake of Cd. There was a decrease in T₃:T₄ ratio at the highest surviving dose (148 μg Cd/g), however, there were no differences observed in hatchling size measured as weight and snout-vent length, or in whole body thyroid hormone levels. In summary, this study has shown Cd amended to a solid phase representing soil (perlite) can traverse the thin, parchment-like shell membrane of the fence lizard egg and bioaccumulate in lizard embryos. We believe this study is a good first step in investigating and evaluating this species for use as a model.     

Flow rates and compositions of incinerated waste streams in the United States.

The quantity and composition of RCRA hazardous wastes incinerated during 1986 were examined using the National Hazardous Waste Survey. This Survey, collected for U.S. EPA by the Research Triangle Institute, is the most extensive examination of hazardous waste generation and management available. The survey data show that although a wide variety of hazardous wastes were treated by incineration, more than 75 percent of incinerated waste streams were from chemical manufacturing. The survey data also show that more than 90 percent of the incinerated wastes were treated by incinerators located at the facility generating the waste. Despite the predominance of a single industrial sector in generating incinerated hazardous wastes, the compositional profile of the wastes is far from uniform. To illustrate this variability, the metals and chlorine content of the wastes are reported along with the sources of the metal and chlorine loadings.     

Great Lakes monitoring results--comparison of probability based and deterministic sampling grids

The Great Lakes may be viewed as a coastal environment, affected by the same meteorological and physical forces as the coastal ocean. The U.S. EPA, Great Lakes National Program Office (GLNPO) has monitored the open waters of the lakes, annually, since 1983. As part of the U.S. EPA Environmental Monitoring and Assessment Program (EMAP), a pilot study was performed in Lake Michigan to compare the existing GLNPO deterministic sampling grid with the EMAP probabilistic grid. Results of chemical analyses of trophic status indicators (total phosphorus and chlorophyll a) as well as nutrients and conventional limnological measurements, from spring and summer surveys in 1992 indicate little difference between the grids in the offshore region of the lake. The few statistically significant differences may be due to station distribution throughout the lake, or simple chance. This might be expected due to the well mixed nature of the open waters of Lake Michigan. The detection of a long-term trend for total phosphorus in Lake Michigan benefits from an annual program: viewing cumulative frequency distributions based on a four year EMAP interval does not convey information on the decrease in phosphorus in the lake. If the EMAP sampling grid were to be used in the Great Lakes, pilots in each of the lakes would be necessary for utilization of the existing long-term record as a basis for trend detection.     

Exploring the Relationship Between Hydrologic Parameters and Nutrient Loads Using Digital Elevation Model and GIS – A Case Study from Sugarcreek Headwaters, Ohio, U.S.A.

Ohio is typical among the Midwestern and Eastern United States with high levels of water pollutants, the main sources being from agriculture. In this study, we used a digital elevation model in conjunction with hydrological indices to determine the role of landscape complexity affecting the spatial and temporal variation in pollutant levels, in one of the most impaired headwater streams in Ohio. More than eighty five percent of the study area is dominated by agriculture. Spatial distribution of slope (S), altitude and wetness index along with other watershed parameters such as flow direction, flow accumulation, stream networks, flow stream orders and erosion index were used within a Geographic Information Systems framework to quantify variation in nitrate and phosphate loads to headwater streams. Stream monitoring data for nutrient loads were used to correlate the observed spatial and temporal patterns with hydrological parameters using multiple linear regressions. Results from the wetness index calculated from a digital elevation model suggested a range of 0.10–16.39, with more than 35% having values less than 4.0. A Revised Universal Soil Loss Equation (RUSLE) predicted soil loss in the range of 0.01–4.0 t/ha/yr. Nitrate nitrogen levels in the study area paralleled precipitation patterns over time, with higher nitrate levels corresponding to high precipitation. Atmospheric deposition through precipitation could explain approximately 35% of total nitrate levels observed in streams. Among the different topographic variables and hydrological indices, results from the step-wise multiple regression suggested the following best predictors, (1) elevation range and upstream flow length for nitrate, (2) flow direction and upstream flow length for ammonia-nitrogen and slope, and (3) elevation range for phosphate levels. Differences in the landscape models observed for nitrate, phosphate and ammonia-nitrogen in the surface waters were attributed partly to differences in the chemical activity and source strengths of the different forms of these nutrients through agricultural management practices. The results identify geomorphologic and landscape characteristics that influence pollutant levels in the study area.     

Method for determining toxicologically relevant cadmium residues in the earthworm Eisenia fetida

In the present study, we investigated the contribution of methylsulfonyl metabolite derived from 1,2,4-trichlorobenzene (1,2,4-TCB) on the delta-aminolevulinic acid (ALA) synthetase induction by the parent compound in rats. The time courses of increasing of hepatic microsomal total cytochrome P450 content after a single i.p. administration of 1,2,4-TCB (1.36 mmol/kg), and 2,3,5- and 2,4,5-trichlorophenyl methyl sulfones (2,3,5- and 2,4,5-TCPSO2Mes) (50 micromol/kg each) were in parallel with those of increasing of the total heme content in liver microsomes. 1,2,4-TCB significantly increased the heme oxygenase activity, but 2,3,5- and 2,4,5-TCPSO2Mes did not. On the other hand, 1,2,4-TCB and 2,3,5-TCPSO2Me markedly enhanced the ALA synthetase activity. No change was observed in this enzyme activity after the administration of 2,4,5-TCPSO2Me. After the administration of 1,2,4-TCB to the rats treated with DL-buthionine-(S,R)-sulfoximine (BSO) and to the non-BSO-treated rats, the concentrations of both 2,3,5- and 2,4,5-TCPSO2Mes were significantly lower in liver of the BSO-treated rats than in liver of the non-BSO-treated rats. Additionally, the 1,2,4-TCB did not elevate the ALA synthetase activity in the BSO-treated rats. On the other hand, the administration of 2,3,5-TCPSO2Me to BSO-treated rats resulted in induction of ALA synthetase. The results strongly suggest that the methyl sulfone derived from 1,2,4-TCB, i.e., 2,3,5-TCPSO2Me, contributes highly to the induction of the ALA synthetase activity by the parent compound.     

Multi-species interactions impact the accumulation of weathered 2,2-bis (p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) from soil

The impact of interactions between the earthworms Eisenia foetida and Lumbricus terrestris and the plants Cucurbita pepo and Cucurbita maxima on the uptake of weathered p,p'-DDE from soil was determined. Although some combinations of earthworm and plant species caused significant changes in the p,p'-DDE burden in both organisms, the effects were species specific. Contaminant bioconcentration in C. pepo was increased slightly by E. foetida and by 3-fold when the plant was grown with L. terrestris. E. foetida had no effect on the contaminant BCF by C. maxima, but L. terrestris caused a 2-fold reduction in p,p'-DDE uptake by the plant. Contaminant levels in E. foetida and L. terrestris were unaffected by C. pepo. When grown with C. maxima, the concentration of p,p'-DDE decreased by approximately 4-fold and 7-fold in E. foetida and L. terrestris, respectively. The data suggest that the prediction of contaminant bioavailability should consider interactions among species.     

Ecological niche suitability model with an application in Taojiang land use planning

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The cost of being an omnivore: mandible wear from plant feeding in a true bug

Evolutionary and ecological transitions from carnivorous to omnivorous feeding may be constrained by the ability of the animal to cope with disparate types of foods, even if preadaptations for such behaviour exist. The omnivorous true bug, Dicyphus hesperus (Hemiptera: Miridae) requires both animals (small, soft-bodied insects) and plants in its diet and obtains the majority of its dietary and metabolic water from plant feeding. Serrations on the lateral margins of the mandibular stylets wear with age, and this wear is exacerbated when the insects feed on plants compared to those provided free water and no plants. D. hesperus that feed on plants attack fewer prey but consumed similar amounts of prey tissue compared to individuals that were provided free water. Although others have shown mandible wear for plant-chewing animals we show for the first time that plant feeding can impose similar wear on plant-piercing animals as well.     

Analysing countries’ contribution to climate change: scientific and policy-related choices

This paper evaluates the influence of different policy-related and scientific choices on the calculated regional contributions to global climate change (the “Brazilian Proposal”). Policy-related choices include the time period of emissions, the mix of greenhouse gases and different indicators of climate change impacts. The scientific choices include historical emissions and model representations of the climate system. We generated and compared results of several simple climate models. We find that the relative contributions of different nations to global climate change—from emissions of greenhouse gases alone—are quite robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa and Latin America. Policy-related choices, such as time period of emissions, climate change indicator and gas mix generally have larger influence on the results than scientific choices. More specifically, choosing a later attribution start date (1990 instead of 1890) for historical emissions, decreases the contributions of regions that started emitting early, such as the OECD countries by 6 percentage points, whereas it increases the contribution of late emitters such as Asia by 8 percentage points. However, only including the fossil CO₂ emissions instead of the emissions of all Kyoto gases (fossil and land use change), increases the OECD contributions by 21 percentage points and decreases the contribution of Asia by 14 percentage points.     

Early succession arthropod community changes on experimental passion fruit plant patches along a land-use gradient in Ecuador

Many tropical landscapes are today characterized by small forest patches embedded in an agricultural mosaic matrix. In such highly fragmented landscapes, agroforests have already been recognized as refuges for biodiversity but few studies have investigated the potential of non-forested land-use types to contribute to overall biodiversity of functionally important taxa in the tropics. This study experimentally investigated species richness, abundance, and community similarity of arthropods on Yellow Passion fruit plants, planted in standardized patches in 30 sites along a land-use intensity gradient. The gradient comprised all major land-use types of the area: forest fragments, abandoned coffee agroforests, coffee agroforests managed under shade trees, pastures, and rice fields in Coastal Ecuador. We found a total of 2123 individuals belonging to 242 species. Overall arthropod species richness increased with light intensity and leaf-surface area and decreased with land-use intensity: forest fragments and abandoned coffee agroforests harboured significantly more species than rice or pastures. Overall diversity in managed coffee agroforests was intermediate between the intensively managed and more natural habitats. However, the three most abundant taxa of arthropods (ants, spiders, and beetles) had the highest number of species in managed coffee agroforests, while ant abundance was highest in abandoned coffee agroforests and spider abundance highest in managed coffee agroforests. Analyses of community similarity revealed that open (pasture, and rice) and shaded (forest, abandoned and managed coffee agroforests) land-use types had distinct arthropod communities. In conclusion, although open agricultural land-use types tend to have fewer species in lower numbers, all land-use types contribute to overall biodiversity of the agricultural matrix because of distinct communities in shaded vs. non-shaded land-use types.