Improving simulations of sulfate aerosols during winter haze over Northern China: the impacts of heterogeneous oxidation by NO<Subscript>2</Subscript>

We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are–0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s^–1). At the Beijing station, sulfur dioxide (SO₂) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO₂ emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO₂ emissions and incorporating heterogeneous oxidation of dissolved SO₂ by nitrogen dioxide (NO₂) on sulfate formation during winter haze. The results suggest that doubling SO₂ emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO₂ by NO₂ substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO₂ to sulfate conversion in the HetS (heterogeneous oxidation by NO₂) case reduces SO₂ concentrations, it is still largely overestimated by the model, indicating the overestimations of SO₂ concentrations in the North China Plain (NCP) are mostly due to errors in SO₂ emission inventory.

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Improving simulations of sulfate aerosols during winter haze over Northern China: the impacts of heterogeneous oxidation by NO2

Incorporating the missing heterogeneous oxidation of S(IV) by NO₂ into the WRF-Chem model. Sulfate production is not sensitive to increase in SO₂ emission. The newly added reaction reproduces sulfate concentrations well during winter haze. We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are -0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s⁻¹). At the Beijing station, sulfur dioxide (SO₂) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO₂ emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO₂ emissions and incorporating heterogeneous oxidation of dissolved SO₂ by nitrogen dioxide (NO₂) on sulfate formation during winter haze. The results suggest that doubling SO₂ emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO₂ by NO₂ substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO₂ to sulfate conversion in the HetS (heterogeneous oxidation by NO₂) case reduces SO₂ concentrations, it is still largely overestimated by the model, indicating the overestimations of SO₂ concentrations in the North China Plain (NCP) are mostly due to errors in SO₂ emission inventory.     

Mass mortality and slow recovery of Diadema antillarum: Could compromised immunity be a factor?

Long-spined sea urchins (Diadema antillarum-a) began dying in January 1983 and over the next year virtually disappeared from the Caribbean. Decades later, Diadema densities remain low, with only very limited recovery in some areas. Ecological extinction of Diadema is a factor in the transformation of coral to barren algae-covered rock that has occurred in the Caribbean during the past 25 years. Working with sea urchins collected from St. Croix, United States Virgin Islands, we asked whether the immune system of Diadema differs from those of other common Caribbean urchins that did not experience the die-off. Using isolated coelomocytes, we tested humoral responses of the urchins with classic stimulators in numerous humoral immune assays. All coelomocytes responded to stimulators—with one notable and statistically significant exception—D. antillarum did not respond to lipopolysaccharide. Our results indicate that Diadema may have a weakness in its humoral defense response that is independent of local stressors and may help explain why Caribbean Diadema was vulnerable to the 1983 epidemic and has shown slow and limited recovery since then.     

Mineral licks: motivational factors for visitation and accompanying disease risk at communal use sites of elk and deer

Free-ranging cervids acquire most of their essential minerals through forage consumption, though occasionally seek other sources to account for seasonal mineral deficiencies. Mineral sources occur as natural geological deposits (i.e., licks) or as anthropogenic mineral supplements. In both scenarios, these sources commonly serve as focal sites for visitation. We monitored 11 licks in Rocky Mountain National Park, north-central Colorado, using trail cameras to quantify daily visitation indices (DVI) and soil consumption indices (SCI) for Rocky Mountain elk (Cervus elaphus) and mule deer (Odocoileus hemionus) during summer 2006 and documented elk, mule deer, and moose (Alces alces) visiting licks. Additionally, soil samples were collected, and mineral concentrations were compared to discern levels that explain rates of visitation. Relationships between response variables; DVI and SCI, and explanatory variables; elevation class, moisture class, period of study, and concentrations of minerals were examined. We found that DVI and SCI were greatest at two wet, low-elevation licks exhibiting relatively high concentrations of manganese and sodium. Because cervids are known to seek Na from soils, we suggest our observed association of Mn with DVI and SCI was a likely consequence of deer and elk seeking supplemental dietary Na. Additionally, highly utilized licks such as these provide an area of concentrated cervid occupation and interaction, thus increasing risk for environmental transmission of infectious pathogens such as chronic wasting disease, which has been shown to be shed in the saliva, urine, and feces of infected cervids.     

The evolution of large and small-scale structures in Kelvin–Helmholtz instabilities

To better understand the dynamics of Kelvin–Helmholtz instabilities in environmental flows, their evolution is investigated using direct numerical simulations (DNS). Two-dimensional DNS is used to examine the large-scale and small-scale structures of the instability at high Reynolds and Prandtl numbers that represent real environmental flows. The semi-analytical model of Corcos and Sherman (J Fluid Mech 73:241–264, 1976) is used to explain the physics of these simulations prior to saturation of the KH billow, and also provide a computationally efficient prediction of the vortex dynamics of the instability. The DNS results show that the large-scale structure of the billow does not depend on the Reynolds number for sufficiently high Reynolds numbers. The billow structure reveals a less straightforward dependence on the Prandtl number. Predictions of the model of Corcos and Sherman (J Fluid Mech 73:241–264, 1976) improve as Reynolds number and Prandtl number increase. The small-scale structure of the vorticity and density fields vary with both Reynolds and Prandtl numbers. Three-dimensional DNS of KH flows and their transition to turbulence are used to study small length scales. Based on the thickness of the braid, a simple method is introduced to estimate the Batchelor scale, which can be used as a guide for the resolution required for the direct numerical simulation of two and three-dimensional Kelvin–Helmholtz flow fields.     

Bright turquoise as an intraspecific signal in the chameleon grasshopper (Kosciuscola tristis)

Bright colours often communicate important information between conspecifics. In sexually dichromatic species where males exhibit bright colours, two hypotheses are often invoked to explain the function of the colour. First, if a male’s bright colour contains information about his quality, females may prefer brighter males. Equally, male colour may reliably provide other males with information about fighting ability or resource holding potential. In such circumstances, brighter males may win altercations and/or males may use rival colour to assess their likelihood of winning an interaction. In the chameleon grasshopper (Kosciuscola tristis), males but not females turn bright turquoise when their body temperature exceeds 25 °C. In this study, we tested whether the turquoise phase of colour change has a signaling role in inter- and intrasexual contexts. We predicted that females would prefer bright turquoise males over dull males, but found no evidence from several choice experiments to support this hypothesis. We also predicted that brighter males would win more fights than duller males. Whilst we did not find that brighter males won more fights in staged experiments, we found that the brightness of males who chose to enter fights was significantly correlated with their opponents’ brightness. Our results suggest that the brightness of males’ turquoise phase may provide competitors with important information about their rival’s fighting ability.     

Geologic occurrences of erionite in the United States: an emerging national public health concern for respiratory disease

Erionite, a mineral series within the zeolite group, is classified as a Group 1 known respiratory carcinogen. This designation resulted from extremely high incidences of mesothelioma discovered in three small villages from the Cappadocia region of Turkey, where the disease was linked to environmental exposures to fibrous forms of erionite. Natural deposits of erionite, including fibrous forms, have been identified in the past in the western United States. Until recently, these occurrences have generally been overlooked as a potential hazard. In the last several years, concerns have emerged regarding the potential for environmental and occupational exposures to erionite in the United States, such as erionite-bearing gravels in western North Dakota mined and used to surface unpaved roads. As a result, there has been much interest in identifying locations and geologic environments across the United States where erionite occurs naturally. A 1996 U.S. Geological Survey report describing erionite occurrences in the United States has been widely cited as a compilation of all US erionite deposits; however, this compilation only focused on one of several geologic environments in which erionite can form. Also, new occurrences of erionite have been identified in recent years. Using a detailed literature survey, this paper updates and expands the erionite occurrences database, provided in a supplemental file (US_erionite.xls). Epidemiology, public health, and natural hazard studies can incorporate this information on known erionite occurrences and their characteristics. By recognizing that only specific geologic settings and formations are hosts to erionite, this knowledge can be used in developing management plans designed to protect the public.     

Reduced effect of Tasmanian devil facial tumor disease at the disease front

Pathogen-driven declines in animal populations are increasingly regarded as a major conservation issue. The Tasmanian devil (Sarcophilus harrisii) is threatened with extinction by devil facial tumor disease, a unique transmissible cancer. The disease is transmitted through direct transfer of tumor cells, which is possible because the genetic diversity of Tasmanian devils is low, particularly in the major histocompatibility complex genes of the immune system. The far northwest of Tasmania now holds the last remaining disease-free wild devil populations. The recent discovery of unique major histocompatibility complex genotypes in the northwestern region of Tasmania has raised the possibility that some animals may be resilient to the disease. We examined the differences in the epidemiology and population effects of devil facial tumor disease at 3 well-studied affected sites in eastern Tasmania and 1 in western Tasmania (West Pencil Pine). In contrast to the 3 eastern sites, there has been no rapid increase in disease prevalence or evidence of population decline at West Pencil Pine. Moreover, this is the only onsite at which the population age structure has remained unaltered 4 years after the first detection of disease. The most plausible explanations for the substantial differences in population effects and epidemiology of the disease between eastern and western sites are geographic differences in genotypes or phenotypes of devils and functional differences between tumor strains in the 2 regions. We suggest that conservation efforts focus on identifying whether either or both these explanations are correct and then, if resistance alleles exist, to attempt to spread the resistant alleles into affected populations. Such assisted selection has rarely been attempted for the management of wildlife diseases, but it may be widely applicable.     

Transcending scale dependence in identifying habitat with resource selection functions

Multi-scale resource selection modeling is used to identify factors that limit species distributions across scales of space and time. This multi-scale nature of habitat suitability complicates the translation of inferences to single, spatial depictions of habitat required for conservation of species. We estimated resource selection functions (RSFs) across three scales for a threatened ungulate, woodland caribou (Rangifer tarandus caribou), with two objectives: (1) to infer the relative effects of two forms of anthropogenic disturbance (forestry and linear features) on woodland caribou distributions at multiple scales and (2) to estimate scale-integrated resource selection functions (SRSFs) that synthesize results across scales for management-oriented habitat suitability mapping. We found a previously undocumented scale-specific switch in woodland caribou response to two forms of anthropogenic disturbance. Caribou avoided forestry cut-blocks at broad scales according to first- and second-order RSFs and avoided linear features at fine scales according to third-order RSFs, corroborating predictions developed according to predator-mediated effects of each disturbance type. Additionally, a single SRSF validated as well as each of three single-scale RSFs when estimating habitat suitability across three different spatial scales of prediction. We demonstrate that a single SRSF can be applied to predict relative habitat suitability at both local and landscape scales in support of critical habitat identification and species recovery.