Electricity from fossil fuels without CO2 emissions: assessing the costs of carbon dioxide capture and sequestration in U.S. electricity markets.

The decoupling of fossil-fueled electricity production from atmospheric CO2 emissions via CO2 capture and sequestration (CCS) is increasingly regarded as an important means of mitigating climate change at a reasonable cost. Engineering analyses of CO2 mitigation typically compare the cost of electricity for a base generation technology to that for a similar plant with CO2 capture and then compute the carbon emissions mitigated per unit of cost. It can be hard to interpret mitigation cost estimates from this plant-level approach when a consistent base technology cannot be identified. In addition, neither engineering analyses nor general equilibrium models can capture the economics of plant dispatch. A realistic assessment of the costs of carbon sequestration as an emissions abatement strategy in the electric sector therefore requires a systems-level analysis. We discuss various frameworks for computing mitigation costs and introduce a simplified model of electric sector planning. Results from a "bottom-up" engineering-economic analysis for a representative U.S. North American Electric Reliability Council (NERC) region illustrate how the penetration of CCS technologies and the dispatch of generating units vary with the price of carbon emissions and thereby determine the relationship between mitigation cost and emissions reduction.     

Assessment of the photochemistry of OH and NO3 on Jeju Island during the Asian-dust-storm period in the spring of 2001

In this study, we examined the influence of the long-range transport of dust particles and air pollutants on the photochemistry of OH and NO3 on Jeju Island, Korea (33.17 degrees N, 126.10 degrees E) during the Asian-dust-storm (ADS) period of April 2001. Three ADS events were observed during the periods of April 10-12, 13-14, and 25-26. Average concentration levels of daytime OH and nighttime NO3 on Jeju Island during the ADS period were estimated to be about 1x10(6) and 2x10(8) moleculescm(-3) ( approximately 9 pptv), respectively. OH levels during the ADS period were lower than those during the non-Asian-dust-storm (NADS) period by a factor of 1.5. This was likely to result from higher CO levels and the significant loading of dust particles, reducing the photolysis frequencies of ozone. Decreases in NO3 levels during the ADS period was likely to be determined mainly by the enhancement of the N2O5 heterogeneous reaction on dust aerosol surfaces. Averaged over 24 h, the reaction between HO2 and NO was the most important source of OH during the study period, followed by ozone photolysis, which contributed more than 95% of the total source. The reactions with CO, NO2, and non-methane hydrocarbons (NMHCs) during the study period were major sinks for OH. The reaction of N2O5 on aerosol surfaces was a more important sink for nighttime NO3 during the ADS due to the significant loading of dust particles. The reaction of NO3 with NMHCs and the gas-phase reaction of N2O5 with water vapor were both significant loss mechanisms during the study period, especially during the NADS. However, dry deposition of these oxidized nitrogen species and a heterogeneous reaction of NO3 were of no importance.     

Heterotrophic community-level physiological profiles of domestic wastewater following treatment by small constructed subsurface flow wetlands.

Seasonal treatment performance of small-surface flow wetlands was evaluated during their second operational year and compared with community-level physiological profiles (CLPP) of the heterotrophic bacterial community obtained from sole-carbon source utilization patterns in BIOLOG GN (Haywood, California) microplates. The CLPP patterns varied significantly by season, indicating reduced functional diversity in the heterotrophic community during warmer months of active plant growth (April through October). Principal component analysis (PCA) suggested that the functional community differed in planted versus unplanted wetlands during the growing season. Wetlands generally improved wastewater quality; however, treatment performance was reduced in the second year. Despite differences in the heterotrophic community suggested by CLPP, treatment efficiency with respect to removal of five-day biochemical oxygen demand or reduction in fecal indicator organisms generally was not significantly changed as a function of growing season or plant treatment.     

Distribution and diet of juvenile Patagonian toothfish on the South Georgia and Shag Rocks shelves (Southern Ocean)

The distribution and diet of juvenile (<750 mm) Patagonian toothfish are described from four annual trawl surveys (2003–2006) around the island of South Georgia in the Atlantic sector of the Southern Ocean. Recruitment of toothfish varies inter-annually, and a single large cohort dominated during the four years surveyed. Most juveniles were caught on the Shag Rocks shelf to the NW of South Georgia, with fish subsequently dispersing to deeper water around both the South Georgia and Shag Rocks shelves. Mean size of juvenile toothfish increased with depth of capture. Stomach contents analysis was conducted on 795 fish that contained food remains and revealed that juvenile toothfish are essentially piscivorous, with the diet dominated by notothenid fish. The yellow-finned notothen, Patagonotothen guntheri, was the dominant prey at Shag Rocks whilst at South Georgia, where P. guntheri is absent, the dominant prey were Antarctic krill and notothenid fish. The diet changed with size, with an increase in myctophid fish and krill as toothfish grow and disperse. The size of prey also increased with fish size, with a greater range of prey sizes consumed by larger fish.     

Sorption of metal ions from aqueous solution using bone char

The sorption of cadmium, copper and zinc from aqueous solutions onto bone char has been studied in both single and binary multi-component systems. Equilibrium experimental studies have been performed to determine the sorption capacity of bone char for each metal ion. The isotherm results have been analysed using single and multi-component equilibrium models. The rate of sorption of the metal ions onto bone char has been studied using an agitated batch adsorber. The concentration versus time decay curves have been measured and a number of mass transfer models have been developed and tested based on diffusion controlled sorption. The results of the equilibrium and rate studies are presented and discussed in the paper. The possible mechanisms of metal sorption are also discussed. Finally a series of fixed bed column studies have been performed and analysed using a diffusion mass transport model. The experimental results show a displacement effect for the binary metal ion breakthrough curves.     

Contemporary Western Rural USA Economic Composition: Potential Implications for Environmental Policy and Research

/ The rural West of the United States is considered strongly antienvironment. The traditional economic reliance of the area on natural resources has long explained this antienvironment stance. The region consistently elects federal officials who as a group consistently vote against environmental bills and seek to undo existing federal environmental regulation. These politicians defend their antienvironment actions based on their perception of the economic composition and interests of the region. Recent studies, however, have suggested that rural residents are increasingly concerned about environmental issues. These studies, however, lack a consistent theoretical basis. This article uses an alternative economic typing system to examine the economic composition of rural Idaho and suggests that the results found using the alternative typing system might provide a theoretical basis to explain why some studies are finding increased rural environmental support. The results show that rural Idaho is much more economically diverse using this alternative typing methodology compared to the outcomes of traditional USDA economic methodologies. The policy and research implications of these findings are examined.KEY WORDS: Rural; Environmental policy; Economic composition     

Variation of pyrrolizidine alkaloids in Ithomiinae: A comparative study between species feeding on Apocynaceae and Solanaceae

Summary The primitive, Apocynaceae-feeding Ithomiine,Tithorea harmonia, incorporates dehydropyrrolizidine alkaloids (PAs) from its larval foodplant (Prestonia acutifolia), rarely visiting PA sources pharmacophagously in the adult; females show higher concentrations of PAs than males, with similar variance. The close relativeAeria olena (feeding onP. coalita, without PAs) shows similar PA concentrations in both sexes and greater variation in males, like more advanced Solanaceae-feeding Ithomiine such asMechanitis polymnia, which likeA. olena obtain PAs by pharmacophagy in the adult (mainly males). This difference is due to the dynamics of PA incorporation in these species. Little variation in PA content was found among allopatric populations of the same species, but variation in available PA sources in different months was correlated with different average storage levels in the butterflies.     

Tropane and pyrrolizidine alkaloids in the ithomiinesPlacidula euryanassa andMiraleria cymothoe (Lepidoptera: Nymphalidae)

Summary Larvae of the ithomiine butterflyPlacidula euryanassa sequester tropane alkaloids (TAs) from the host plantBrugmansia suaveolens and pass them through the pupae to freshly emerged adults. Wild caught adults also show in their tissues, variable amounts of pyrrolidizine alkaloids (PAs), probably sequestered from variable plant sources and subject to dynamics of incorporation, accumulation and utilization of PAs by ithomiine butterflies. The ratio TAs/PAs is also variable between different populations.Miraleria cymothoe, another ithomiine that feeds onB. suaveolens as larvae, does not sequester TAs from the host-plant, but sequesters PAs from plant sources visited by the adult butterflies. The main alkaloid found in both butterflies is lycopsamine, which also is the principal PA found in all genera of Ithomiinae.     

Differential parasitism of least flycatchers and yellow warblers by the brown-headed cowbird

Summary Brown-headed cowbirds (Molothrus ater) parasitized yellow warblers (Dendroica petechia) six times more frequently than least flycatchers (Empidonax minimus) nesting in the same riparian habitat in southern Manitoba. This difference was surprising because least flycatchers were higher quality hosts; flycatchers always accepted cowbird eggs while warblers did so on only about half the occasions. Both hosts were equally good foster parents, at least until fledging; thus, once an egg was accepted there was probably no further advantage in parasitizing one species over the other. The probability that a nest was parasitized decreased with increasing nest height, perhaps as a consequence of the cowbird's habit of searching for nests close to the ground. Since least flycatchers nested higher in the canopy than yellow warblers, a greater proportion of flycatcher nests probably were not detected by cowbirds. Nevertheless, nest height alone could not account fully for the lower incidence of parasitism on flycatchers. Clutch initiation in flycatchers peaked 6 days after warbler clutch initiations and 5 days after that of cowbirds. Despite the later peak in initiations, flycatcher nests were always available as potential hosts over the entire cowbird laying season and it was not until new clutch initiations by warblers declined in late summer that flycatchers were actually used as hosts. Because least flycatchers responded more aggressively than yellow warblers to a model female cowbird at the nest, we concluded that greater nest defense by flycatchers may have also reduced the rate of brood parasitism in this host. Together, our results suggest the large difference in the frequency of parasitism between these two hosts was primarily a product of nest location but that differences in host nest-defense and breeding season asynchrony may have contributed to preferential host selection.Offprint requests to: J.V. Briskie     

Evidence of immunomodulation in nestling American kestrels (Falco sparverius) exposed to environmentally relevant PBDEs

We investigated whether exposure to environmentally relevant polybrominated diphenyl ethers (PBDEs) causes immunomodulation in captive nestling American kestrels (Falco sparverius). Eggs within each clutch, divided by laying sequence, were injected with safflower oil or penta-BDE congeners-47, -99, -100, and -153 dissolved in safflower oil (18.7 microg sigmaPBDEs/egg) approximating Great Lakes birds. For 29 days, nestlings consumed the same PBDE mixture (15.6+/-0.3 ng/g body weight per day), reaching sigmaPBDE body burden concentrations that were 120x higher in the treatment birds (86.1+/-29.1 ng/g ww) than controls (0.73+/-0.5 ng/g ww). PBDE-exposed birds had a greater PHA response (T-cell-mediated immunity), which was negatively associated with increasing BDE-47 concentrations, but a reduced antibody-mediated response that was positively associated with increasing BDE-183 concentrations. There were also structural changes in the spleen (fewer germinal centers), bursa (reduced apoptosis) and thymus (increased macrophages), and negative associations between the spleen somatic index and sigmaPBDEs, and the bursa somatic index and BDE-47. Immunomodulation from PBDE exposure may be exacerbated in wild birds experiencing greater environmental stresses.