A gradient of mercury concentrations in Scottish single malt whiskies

Mercury (Hg) concentrations were measured in 26 Scottish single malt whiskies, and all found to be very low (<10 ng L⁻¹), posing no threat to human health through reasonable levels of consumption. However, a significant south-to-north declining gradient in Hg concentrations was observed reflecting that reported for atmospheric deposition. We speculate that this gradient could be due to a combination of contemporary deposition and the legacy of industrial mercury emissions and deposition over the last 200 years affecting concentrations in local waters used in whisky production. As UK atmospheric emissions of mercury have declined by 90 % since the 1970s, we suggest that whisky being produced today should have even lower Hg concentrations when consumed in 10- to 15-years time. This reduction may be compromised by the remobilisation of contaminants stored in catchment soils being transferred to source waters, but is very unlikely to raise the negligible health risk due to Hg from Scottish single malt whisky consumption.

     

Empirical realised niche models for British coastal plant species

Coastal environments host plant taxa adapted to a wide range of salinity conditions. Salinity, along with other abiotic variables, constrains the distribution of coastal plants in predictable ways, with relatively few taxa adapted to the most saline conditions. However, few attempts have been made to quantify these relationships to create niche models for coastal plants. Quantification of the effects of salinity, and other abiotic variables, on coastal plants is essential to predict the responses of coastal ecosystems to external drivers such as sea level rise. We constructed niche models for 132 coastal plant taxa in Great Britain based on eight abiotic variables. Paired measurements of vegetation composition and abiotic variables are rare in coastal habitats so four of the variables were defined using community mean values for Ellenberg indicators, i.e. scores assigned according to the typical alkalinity, fertility, moisture availability and salinity of sites where a species occurs. The remaining variables were the canopy height, annual precipitation, and maximum and minimum temperatures. Salinity and moisture indicator scores were significant terms in over 80 % of models, suggesting the distributions of most coastal species are at least partly determined by these variables. When the models were used to predict species occurrence against an independent dataset 64 % of models gave moderate to good predictions of species occurrence. This indicates that most models had successfully captured the key determinants of the niche. The models could potentially be applied to predict changes to habitats and species-dependent ecosystem services in response to rising sea levels.     

Rethinking the study of human–wildlife coexistence

Although coexistence with wildlife is a key goal of conservation, little is known about it or how to study it. By coexistence we mean a sustainable though dynamic state in which humans and wildlife coadapt to sharing landscapes, where human interactions with wildlife are effectively governed to ensure wildlife populations persist in socially legitimate ways that ensure tolerable risk levels. Problems that arise from current conflict-oriented framing of human–wildlife interactions include reinforcing a human–nature dichotomy as fundamentally oppositional, suggesting coexistence requires the absence of conflict, and skewing research and management toward direct negative impacts over indirect impacts and positive aspects of living with wildlife. Human behavior toward wildlife is framed as rational calculus of costs and benefits, sidelining emotional and cultural dimensions of these interactions. Coexistence is less studied due to unfamiliarity with relevant methodologies, including qualitative methods, self-reflexivity and ethical rigor, and constraints on funding and time. These challenges are illustrated with examples from fieldwork in India and Africa. We recommend a basic approach to case studies aimed at expanding the scope of inquiries into human–wildlife relations beyond studies of rational behavior and quantification of costs and benefits of wildlife to humans.     

Exposure to DDT and HCH congeners and associated potential health risks through khat (Catha edulis) consumption among adults in South Wollo,Ethiopia

Environmental Geochemistry and Health - Khat (Catha edulis) chewing is widespread in the region of East Africa. Even low levels of organochlorine pesticides (OCPs) in khat could induce public...     

Cytotoxic activity of spark‐decomposed sulfur hexafluoride and analysis of cytotoxic contributions of individual spark decomposition products†

Sulfur hexafluoride decomposed by electrical sparks has been found to by cytotoxic to hamster cells when tested in an in vitro cell survival assay, while SF₆ shows no cytotoxic activity. Chemical analysis of spark‐decomposed SF₆ has identified and quantified the following compounds: SOF₂, SO₂F₂, SF₄, SOF₄, SiF₄, SO₂ and HF. Each of these gases, at concentration ranges expected in spark‐decomposed SF₆, were tested for cytotoxic activity toward hamster cells. Of the gases showing cytotoxic activity, SO₂F₂ and SOF₄ were similar in activity, as were SOF₂ and SF₄, while the behavior of SiF₄ was different from the rest. None of these individual gases, at concentrations expected in spark‐decomposed SF₆, has sufficient cytotoxic activity to account for the cytotoxic effect of spark‐decomposed SF₆ observed in our assay system. A four‐component mixture of some of the gases enumerated above (at concentrations overestimating their abundance in spark‐decomposed SF₆) was much less cytotoxic than the spark‐decomposed SF₆ gas. A mathematical simulation of the cytotoxic activity of a mixture of gases at concentrations found in spark‐decomposed SF₆ was made, assuming independent cytotoxic effects from each component. The simulated cytotoxic effect thus computed was less than that seen in spark‐decomposed SF₆. Since individual components or mixtures of the major decomposition products do not account for the observed biological activity of spark‐decomposed SF₆, this suggests there may be one or more components, present in the spark‐decomposed gas at very low concentrations, which may have a very strong cytotoxic activity.     

Evaluating animal personalities: do observer assessments and experimental tests measure the same thing?

The animal personality literature uses three approaches to assess personality. However, two of these methods, personality ratings and experimentation, have been little compared in captivity and never compared in the wild. We assessed the boldness of wild chacma baboons Papio ursinus using both ratings and experimental methods. Boldness was experimentally assessed when individuals were presented with a novel food item during natural foraging. The boldness of the same individuals was rated on a five-point scale by experienced observers. The ratings and experimental assessments of boldness were found to correlate positively and in a linear fashion. When considered categorically the two approaches showed variable agreement depending on the number of categories assigned and the cut-off criteria adopted. We suggest that the variation between approaches arises because each method captures different aspects of personality; ratings consider personality in absolute terms (using predefined criteria) and multiple contexts, while experimental assessments consider personality in relative terms (using experimental scores relative to the population average) and in limited contexts. We encourage animal personality researchers to consider adopting both methodologies in future studies. We also propose that future studies restrict their analyses to continuous data, since the greatest comparability between methods was found with these data. However, if individuals must be categorised, we suggest that researchers either (a) analyse only those individuals categorised as bold or shy by both ratings and experimental approaches or, if these methods cannot be employed simultaneously, (b) do not use approach-specific criteria but choose a cut-off that can be compared by both approaches.     

Note--On the Timing of Greenhouse Gas Emissions Reductions: A Final Rejoinder to the Symposium on "The Economics of Climate Change: The Stern Review and its Critics"

In this final rejoinder to the symposium on "The Economics ofClimate Change: The Stern Review and Its Critics," we respondto comments published in the last issue of this journal by RobertMendelsohn, Thomas Sterner and U. Martin Persson, and John P.Weyant (Mendelsohn et al. 2008). In particular, we examine thepoint of debate with arguably the greatest practical importancefor ongoing negotiations over an international agreement tosucceed the Kyoto Protocol: namely the appropriate timing ofglobal reductions in greenhouse gas emissions. Too often in the past, this debate has been presented as onebetween the poles of "act now" and "wait-and-see". Weyant (seeWeyant's     

Bio-Based Polymers and End-of-Life Vehicles

As new materials, such as bio-based plastics and composites, are introduced in vehicles for their improved environmental performance, it is necessary to understand how to efficiently recover these biodegradable materials. This paper provides an overview of the end-of-life phase for automobiles, focusing on the dismantling and shredding processes, and the recovery of materials. Targeted unit operations, such as dismantling of components from vehicles and pretreatment prior to shredding, along with design-for-environment principles, should enable the efficient recovery of materials at the end-of-life phase compared with popularly conceived all-in-one-approaches because of the diverse arrangement of material components.     

Alteration of cuticular hydrocarbon composition affects heterospecific nestmate recognition in the carpenter ant Camponotus fellah

Nestmate recognition is a ubiquitous phenomenon in social insects as a means to prevent entry of undesired individuals aiming at exploiting the rich nest resources. The recognition cues in ants were shown in a few cases to be cuticular hydrocarbons, although there are a quite number of correlated associations. In the present study we modified the cuticular profiles of workers Camponotus fellah hydrocarbons with cuticular washes from a closely related, yet undescribed species, Camponotus sp. Although these sympatric species are morphologically indistinguishable, cuticular washes of C. sp. contain 9,13-dimethylpentacosane and 11,15-dimethylheptacosane that are either absent or occur as traces in C. fellah. In addition, C. sp. contains significantly greater amounts of 3-methylpentacosane than C. fellah workers. The cuticle modification was done solventless in a manner that minimized disruption to the cuticular structure of the ant being modified. Judging from the 3 focal compounds, such treatment added between 20 and 30% of the original amounts present in C. sp. to the treated C. fellah workers. This addition changed consistently the cuticular hydrocarbon profile of the treated ant. Dyadic assays between C. fellah and their nestmates treated with C. sp. cuticular rinses revealed a significantly higher level of aggression compared to non-treated nestmates. There was no aggression between nestmates of C. sp. These results demonstrate that in heterospecific interactions between the two Camponotus species there is a correlation between cuticular hydrocarbons and a nestmate recognition response, albeit not as high as the response of C. fellah to of C. sp. workers. This is consistent with the hypothesis that cuticular hydrocarbons may play a role in nestmate recognition.     

Production of food-associated calls in wild male chimpanzees is dependent on the composition of the audience

Chimpanzees produce acoustically distinct calls when encountering food. Previous research on a number of species has indicated that food-associated calls are relatively widespread in animal communication, and the production of these calls can be influenced by both ecological and social factors. Here, we investigate the factors influencing the production of food-associated calls in wild chimpanzees and examine whether male chimpanzees produce food-associated calls selectively in the presence of important social partners. Male chimpanzees form stable long-term social relationships with each other, and these social bonds are vital in enabling a range of cooperative activities, such as group hunting and territory defence. Our data show that males were significantly more likely to produce food-associated calls if an important social partner was nearby, regardless of the size of the audience or the presence of oestrus females. Call production was also mediated by the size of the food patch and by whether or not the food could be monopolised. The presence of important social partners explained most of the variation in male calling behaviour, indicating that food-associated calls are socially directed and serve a bonding function.