A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe,South America,South Africa and China: separating fads from facts

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, \( {\text{Hg}}_{\text{gas}}^{0} \) ), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m^?3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m^?3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m^?3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.     

Indirect effects of large herbivores on snakes in an African savanna

Many large mammal species are declining in African savannas, yet we understand relatively little about how these declines influence other species. Previous studies have shown that the removal of large herbivorous mammals from large-scale, replicated experimental plots results in a dramatic increase in the density of small mammals, an increase that has been attributed to the relaxation of competition between rodents and large herbivores for food resources. To assess whether the removal of large herbivores also influenced a predator of small mammals, we measured the abundance of the locally common olive hissing snake, Psammophis mossambicus, over a 19-mo period in plots with and without large herbivores. Psammophis mossambicus was significantly more abundant in plots where large herbivores were removed and rodent numbers were high. Based on results from raptor surveys and measurements of vegetative cover, differences in snake density do not appear to be driven by differences in rates of predation on snakes. Instead, snakes appear to be responding numerically to greater abundances of small-mammal prey in areas from which large herbivores have been excluded. This is the first empirical demonstration of the indirect effects of large herbivores on snake abundance and presents an interesting example of how the influence of dominant and keystone species can move through a food web.     

Prenatal diagnostic testing for familial dysautonomia using linked genetic markers

Familial dysautonomia (FD), a recessively inherited disease, has been mapped to chromosome 9q31. Highly polymorphic dinucleotide repeat markers flanking the genetic locus and at the same genetic location have been identified. We describe the prenatal diagnosis of FD using linkage and linkage disequilibrium analyses with these markers. Twelve families were analysed for informativeness and of these, seven went on to have prenatal testing (a total of eight fetuses tested). All of these fetuses were predicted to be heterozygous unaffected (FD carriers). Seven fetuses have come to term and are normal. In the absence of a recombinant proband, a panel of three proximal and three distal markers is sufficient to provide informative flanking markers and an 87–96 per cent likelihood of a highly predictive test. In an additional family at 1:4 risk for FD, no DNA was available from the propositus. This family was analysed using linkage disequilibrium to the #18 allele of the tightly linked marker D9S58 in conjunction with linkage analysis using data from two unaffected children. Prenatal diagnosis in this family indicated an affected fetus.     

Wide-spread genetic variability and the paradox of effective population size in the gag,Mycteroperca microlepis,along the West Florida Shelf

Wide-ranging marine species are often described as having a low effective population size (N _e) to census size (N) ratio. This genetic phenomenon is typically attributed to large variation among individuals in reproductive success because of the high mortality rates and unpredictable environments associated with larval dispersal. In this study, we examined patterns of genetic variation in gag (Mycteroperca microlepis) on the West Florida Shelf across year classes of post-settlement juveniles and spawning adults. With no significant genetic differentiation among year classes despite varying recruitment dynamics, little evidence for chaotic genetic patchiness, and no truncation of adult genetic diversity in subsequent juvenile cohorts, there was little support for large variation among individual in reproductive success contributing to a low N _e/N ratio. In fact, the consistent lack of significant differences in annual recruitment classes indicated that reproductive success among individuals was resistant to skewing. Among the various evolutionary forces that may be affecting N _e, changes to demography due to fishing pressure are posited as a likely mechanism affecting current levels of genetic variation.     

Hospital solid waste management practices in Limpopo Province, South Africa: a case study of two hospitals

The shortcomings in the management practices of hospital solid waste in Limpopo Province of South Africa were studied by looking at two hospitals as case studies. Apart from field surveys, the generated hospital waste was weighed to compute the generation rates and was followed through various management practices to the final disposal. The findings revealed a major policy implementation gap between the national government and the hospitals. While modern practices such as landfill and incineration are used, their daily operations were not carried according to minimum standards. Incinerator ash is openly dumped and wastes are burned on landfills instead of being covered with soil. The incinerators used are also not environmentally friendly as they use old technology. The findings further revealed that there is no proper separation of wastes according to their classification as demanded by the national government. The mean percentage composition of the waste was found in the following decreasing order: general waste (60.74%)>medical waste (30.32%)>sharps (8.94%). The mean generation rates were found to be 0.60kg per patient per day.     

Political transition and emergent forest‐conservation issues in Myanmar

Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions.     

Carbonation of brine impacted fractionated coal fly ash: implications for CO2 sequestration

Coal combustion by-products such as fly ash (FA), brine and CO(2) from coal fired power plants have the potential to impact negatively on the environment. FA and brine can contaminate the soil, surface and ground water through leaching of toxic elements present in their matrices while CO(2) has been identified as a green house gas that contributes significantly towards the global warming effect. Reaction of CO(2) with FA/brine slurry can potentially provide a viable route for CO(2) sequestration via formation of mineral carbonates. Fractionated FA has varying amounts of CaO which not only increases the brine pH but can also be converted into an environmentally benign calcite. Carbonation efficiency of fractionated and brine impacted FA was investigated in this study. Controlled carbonation reactions were carried out in a reactor set-up to evaluate the effect of fractionation on the carbonation efficiency of FA. Chemical and mineralogical characteristics of fresh and carbonated ash were evaluated using XRF, SEM, and XRD. Brine effluents were characterized using ICP-MS and IC. A factorial experimental approach was employed in testing the variables. The 20-150 μm size fraction was observed to have the highest CO(2) sequestration potential of 71.84 kg of CO(2) per ton of FA while the >150 μm particles had the lowest potential of 36.47 kg of CO(2) per ton of FA. Carbonation using brine resulted in higher degree of calcite formation compared to the ultra-pure water carbonated residues.