The radiological impact of atmospheric emissions from oil shale retorts

The radionuclide content of various oil shales, shale oils, and retorting waste products has been studied to determine the extent to which the development of this energy resource may perturb the natural radiation environment. Nearly all of the radioactivity in the raw shale is found in the spent shale after retorting. A primary exposure pathway to the public from this radioactivity will be through the release of particulate matter to the atmosphere during various mining, crushing, and retorting operations. Since the activity of this material is close to that of normal soil, however, the expected radiological impact is small.     

Mapping large areas of radioactively contaminated land with a self adapted, handheld, GPS coupled, scintillation detector

In Belgium, during several decennia, a phosphate plant discharged radium chloride containing waste water into two small rivers. One of those is part of a hydrographically very complex ecosystem with lots of small tributaries and hundreds of hectares of flooding zones. Hence, the river banks and large parts of these flooding zones have become contaminated with radium, heavy metals and chlorides. During a foot campaign, using a home made portable data logging system, consisting of a commercial 2.5 kg NaI detector, a computer mouse sized GPS, and a small pocket PC, the radioactive contamination of about 600 ha of sometimes very rough terrain was measured and mapped. The resulting very detailed radium contamination maps shed a whole new light on the water flow patterns of the ecosystem. The apparatus can also be used for efficiently guiding sampling campaigns for investigating other types of contamination. The ground maps are also compared to existing maps from helicopter measurements, evaluating strengths and weaknesses from both methods.     

Freshwater Mussel Population Status and Habitat Quality in the Clinch River,Virginia and Tennessee,USA: A Featured Collection

The Clinch River of southwestern Virginia and northeastern Tennessee is arguably the most important river for freshwater mussel conservation in the United States. This featured collection presents investigations of mussel population status and habitat quality in the Clinch River. Analyses of historic water‐ and sediment‐quality data suggest that water column ammonia and water column and sediment metals, including Cu and Zn, may have contributed historically to declining densities and extirpations of mussels in the river's Virginia sections. These studies also reveal increasing temporal trends for dissolved solids concentrations throughout much of the river's extent. Current mussel abundance patterns do not correspond spatially with physical habitat quality, but they do correspond with specific conductance, dissolved major ions, and water column metals, suggesting these and/or associated constituents as factors contributing to mussel declines. Mussels are sensitive to metals. Native mussels and hatchery‐raised mussels held in cages in situ accumulated metals in their body tissues in river sections where mussels are declining. Organic compound and bed‐sediment contaminant analyses did not reveal spatial correspondences with mussel status metrics, although potentially toxic levels were found. Collectively, these studies identify major ions and metals as water‐ and sediment‐quality concerns for mussel conservation in the Clinch River.     

Does need matter? Needs assessments and decision‐making among major humanitarian health agencies

Disasters of physical origin, including earthquakes, floods, landslides, tidal waves, tropical storms, tsunamis, and volcanic eruptions, have affected millions of people globally over the past 100 years. Proportionately, there is far greater likelihood of being affected by such disasters in low‐income countries than in high‐income countries. Furthermore, low‐income countries are in need of international assistance following disasters more often than high‐income countries. The funding of international humanitarian assistance has increased from USD 12.9 billion in 2006 to an estimated USD 16.7 billion in 2010. The majority of this funding is channelled through humanitarian agencies and is supposed to be distributed based on the need of those affected, as assessed using needs assessments. Such needs assessments may be used to inform decisions internally, to influence others, to justify response decisions, and to obtain funding. Little is known about the quality of needs assessments in practical applications. Consequently, this paper reports on and analyses the views of operational decision‐makers in major health‐related humanitarian agencies on needs assessments.     

Gray tree frogs, Hyla versicolor, give lower-frequency aggressive calls in more escalated contests

As animal contests escalate, variation in the performance of aggressive signaling behaviors can give important insights into contest dynamics. In anuran amphibians, males of numerous species utilize distinctive aggressive vocalizations during disputes over calling spaces. Little is known, however, about the causes and consequences of variation in aggressive-call characteristics. We analyzed recordings of calls made during staged aggressive interactions between male gray tree frogs, Hyla versicolor, to determine how variation in a key aggressive-call characteristic, dominant frequency, was affected by increasing contest escalation. We found that dominant frequencies of aggressive calls were lower than those of advertisement calls used to attract females. Furthermore, we found that males lowered their aggressive-call frequencies with increases in escalation. Winners tended to have lower-frequency aggressive calls than losers. We conclude that aggressive calls in H. versicolor are similar to the graded aggressive calls that have been described in several other species. This gradation may allow males to balance the energetic costs of producing lower-frequency calls with the benefits of efficiently repelling rival males. Other processes related to motivation and the physiological effects of participating in contests may also be responsible for the observed variation in aggressive-call frequency with contest escalation. Our results demonstrate that detailed experimental studies of aggressive calling behavior in anurans, which to this point have rarely been performed, are feasible and generate important insights relating to general problems in animal contest behavior and animal communication.     

Hierarchical Bayesian strategy for modeling correlated compositional data with observed zero counts

This article proposes a hierarchical multivariate conditional autoregressive model applied to a compositional response vector. We particularly focus on situations when the composition is discrete occurring when observations are based on small multinomial counts. We address drawbacks that exist in current modeling approaches for such data. Our hierarchical model will be demonstrated with data used to help manage a commercial sockeye salmon fishery in the Fraser River of British Columbia.     

Morphological adaptations to chronic hypoxia in deep-sea decapod crustaceans from hydrothermal vents and cold seeps

Animals inhabiting hydrothermal vents and cold seeps face conditions that are challenging for survival. In particular, these two habitats are characterized by chronic hypoxia, sometimes reaching complete anoxia. The characteristics of the scaphognathite and gills were studied in four species of shrimp and three species of crabs from hydrothermal vents and cold seeps, in order to highlight potential adaptations that could enhance oxygen acquisition in comparison with shallow-water relatives. All the vent and seep species studied here exhibit significantly larger scaphognathites, likely allowing more water to flow over their gills per stroke of this appendage. This is probably more energetically efficient that prolonged hyperventilation. In contrast to annelids, vent and seep decapods usually do not possess enlarged gills, a phenomenon likely due to the physical limitations imposed by the size of the gill chamber. In the vent shrimp Rimicaris exoculata and the vent crab Bythograea thermydron, however, there is a significantly higher specific gill surface area linked to a higher number of lamellae per gram of gill. Again in contrast to annelids, the diffusion distance through the gills is not strikingly different between the vent shrimp Alvinocaris komaii and the shallow-water species Palaemon spp. This may indicate that the epithelium and cuticle of the decapod gills are already optimized for oxygen uptake and that reducing the thickness of these compartments is not physically possible without affecting the physical integrity of the gills.     

Monitoring, modeling, and management impacts of bivalve filter feeders in the oligohaline and tidal fresh regions of the Chesapeake Bay system

Populations of bivalve filter feeders are distributed throughout the oligohaline waters of the Chesapeake Bay system and, to a lesser extent, in tidal fresh waters as well. Previous studies indicate these bivalves significantly diminish phytoplankton concentrations in one major tributary, the Potomac River, and observed chlorophyll concentrations suggest bivalve influence on phytoplankton in other oligohaline reaches. We incorporated a model of these bivalves into an existing eutrophication model of the system. The model indicated that bivalves may reduce phytoplankton concentrations in oligohaline and tidal fresh waters throughout the system but the most significant effects were noted in the Potomac and Patuxent tributaries. Bivalve impacts were related to hydraulic residence time. The greatest phytoplankton reductions occurred in the regions with the longest residence time. Model carbon and nutrient budgets indicated bivalves removed 14% to 40% of the carbon load, 11% to 23% of the nitrogen load, and 37% to 84% of the phosphorus load to the regions where their impact on computed chlorophyll was greatest.