Status and trends in Arctic vegetation: Evidence from experimental warming and long-term monitoring

Changes in Arctic vegetation can have important implications for trophic interactions and ecosystem functioning leading to climate feedbacks. Plot-based vegetation surveys provide detailed insight into vegetation changes at sites around the Arctic and improve our ability to predict the impacts of environmental change on tundra ecosystems. Here, we review studies of changes in plant community composition and phenology from both long-term monitoring and warming experiments in Arctic environments. We find that Arctic plant communities and species are generally sensitive to warming, but trends over a period of time are heterogeneous and complex and do not always mirror expectations based on responses to experimental manipulations. Our findings highlight the need for more geographically widespread, integrated, and comprehensive monitoring efforts that can better resolve the interacting effects of warming and other local and regional ecological factors.     

Environmental quality assessment of reservoirs impacted by Hg from chlor-alkali technologies: case study of a recovery

Mercury (Hg) pollution legacy of chlor-alkali plants will be an important issue in the next decades with the planned phase out of Hg-based electrodes by 2025 within the Minamata convention. In such a context, the present study aimed to examine the extent of Hg contamination in the reservoirs surrounding the Oltchim plant and to evaluate the possible improvement of the environmental quality since the closure of its chlor-alkali unit. This plant is the largest chlor-alkali plant in Romania, which partly switched to Hg-free technology in 1999 and definitely stopped the use of Hg electrolysis in May 2012. Total Hg (THg) and methylmercury (CH₃Hg) concentrations were found to decrease in the surface waters and sediments of the reservoirs receiving the effluents of the chlor-alkali platform since the closure of Hg units. Hence, calculated risk quotients (RQ) indicated no adverse effect of Hg for aquatic organisms from the ambient water exposure. RQ of Hg in sediments were mostly all higher than 1, showing important risks for benthic organisms. However, ecotoxicity testing of water and sediments suggest possible impact of other contaminants and their mixtures. Hg hotspots were found in soils around the platform with RQ values much higher than 1. Finally, THg and CH₃Hg concentrations in fish were below the food safety limit set by the WHO, which contrasts with previous measurements made in 2007 revealing that 92 % of the studied fish were of high risk of consumption. Discontinuing the use of Hg electrodes greatly improved the surrounding environment of chlor-alkali plants within the following years and led to the decrease environmental exposure to Hg through fish consumption. However, sediment and soil still remained highly contaminated and problematic for the river reservoir management. The results of this ecological risk assessment study have important implications for the evaluation of the benefits as well as limits of the Minamata Convention implementation.

     

Genetic biomonitoring of an urban population exposed to mutagenic airborne pollutants

Biomonitoring studies have increased as a consequence of risks and effects to human health on exposure to environmental contaminants, mainly air pollutants. Genetic biomarkers are useful tools for the early assessment of exposure to occupational and environmental pollution. The objective of the present study was to investigate genotoxic effects on people residing and/or working downwind from an oil refinery in southern Brazil and the mutagenic activity of airborne particulate matter (PM10). Samples of peripheral blood and buccal mucosa cells were evaluated using the single-cell gel electrophoresis assay (comet assay) and the micronucleus (MN) assay, respectively. PM10 samples were collected in the target site and the organic matter extraced with dichloromethane was assessed for mutagenic activity in the Salmonella/microsome assay. The exposed group (n = 37) was compared to a reference group (n = 37) of subjects living in an urban area with limited traffic and industrial influence, located far from the main industrial areas. All PM10 organic extracts showed mutagenic positive responses and the effect decreased in the presence of S9 mix indicating that the predominant compounds present were direct-acting mutagens. The responses of YGs strains are consistent with aromatic amines and nitroarenes being present in the PM10 extracts. The group in the area under the influence of the oil refinery (exposed group) showed significantly higher DNA damage in lymphocytes than the reference group. The MN frequencies in buccal mucosa were very low for both groups and no difference between groups was observed. No association was found between age and tobacco smoking habit and level of DNA damages measured by the comet assay. The results indicate that the comet assay was a sensitive tool to detect DNA damage in subjects under the influence of an oil refinery, with marked genotoxic activity in the atmospheric environment.     

Relationship between occupational social class and exposure to organochlorine pesticides during pregnancy

Background

Little evidence is available on the influence of socioeconomic factors on exposure to persistent organic pollutants, especially during vulnerable periods such as pregnancy and early life.

Objective

To investigate the relationship of maternal social class with placental concentrations of organochlorine pesticides (OCPs) and their combined estrogenic activity measured with a biomarker of exposure.

Methods

Exposure to 16 OCPs (DDTs, endosulfans, and seven other compounds) and the total effective xenoestrogenic burden (TEXB) were analyzed in placentas from a mother-child cohort. OCP concentrations were quantified by gas chromatography and mass spectrometry, and TEXB was assessed with the E-Screen bioassay. Social class was classified according to maternal occupation. Multivariate regression analysis was conducted to examine variations in pesticide exposure and TEXB as a function of maternal social class in 257 subjects.

Results

Placental p,p′-DDT concentrations were higher in social classes III and IV than in classes I-II (the most affluent); concentrations of the sum of DDTs were higher in class IV; and exposure to the sum of endosulfans was greater in class III. HCB concentrations were higher among women in class IV than in classes I-II and among manual (classes III-V) than non-manual workers. However, the trend across social classes was only statistically significant for HCB. Social class significantly explained 10% of the variability in concentrations of the sum of endosulfans.

Conclusion

There is a need to explore whether more disadvantaged populations suffer higher levels of exposure to pesticides or other environmental chemicals and how different social processes contribute to this exposure.     

Assessing potential for community-based management of peccaries through common pool resource theory in the rural area of the Argentine Chaco

Community-based management (CBM) has been recognized as an appropriate approach to conservation, assuming that local communities have higher stakes than the state in their natural resources and have better knowledge of local resources and, therefore, can manage them more efficiently. However, the implementation of CBM has not always been successful. The objective of this research was to assess the potential for the implementation of a governmental proposal for community-based management of peccaries (Tayassuidae) in the Impenetrable northern Argentine, through the examination of the reasons why arrangements to avoid overexploitation have not evolved in this region. I used the theory of common pool resources (CPRs) as a framework for this analysis. CPRs theory explains the conditions under which appropriators of a resource are likely to engage in devising and altering governing arrangements and the conditions under which such arrangements are likely to succeed. Fieldwork was conducted between June 2000 and August 2003 using a mixed methods approach. It was found that most of the condition of the resource and users identified by the CPR theory as associated with an increased likelihood of successful management of natural resources are absent or scarcely developed in the Impenetrable. Thus, the situation in the Impenetrable does not seem appropriate for the implementation of CBM of peccaries. It is first necessary to invest in training and development of local institutions' capacities and social capital. It is also important to increase the flow of relevant information, which will enable institutions to be effective, responsible, and accountable to the community. For the moment, a more appropriate approach will have to include a mixture of protectionism and comanagement of collared peccaries while the propitious conditions for a complete local management of the resource are developed.     

Pesticide adsorption on a calcareous soil modified with sewage sludge and quaternary alkyl-ammonium cationic surfactants

BACKGROUND, AIM AND SCOPE: Pesticides are often found in soil as a result of their application to control pests. They can be transported on soil particles to surface waters or they can lixiviate and reach other environmental compartments. Soil modification with amendments, such as sewage sludge, and with surfactants, h been proposed to reduce pesticide environmental fate. METHODS: The sorption of atrazine, methidathion and diazinon using the batch technique has been studied on non-modified soil and soil modified with sewage sludge and cationic surfactants, as well as the effect of their addition on soil properties such as organic carbon (OC) content and exchange cations. RESULTS AND DISCUSSION: The OC content of the surfactant modified soils was the highest with the surfactant with the longest hydrocarbon chain (hexadecyltrimethyl ammonium bromide, HDTMA). The results of the OC content run in parallel with the increase in pesticide retention. When the sorption was n malized to soil OC content, the retention induced by addition of HDTMA was still the highest, which is an indication that the organic matter derived from the organic cations is a more effective medium to retain dissolved contaminants, than organic matter from native soil. The addition of sewage sludge to the soil did only result in a slight increase of the soil CEC and, hence, moderately affected the ability of the cationic surfactant to retain the pesticides. CONCLUSIONS: The addition of cationic surfactants to soil would possibly reduce the movement to groundwater of atrazine, methidathion and diazinon. In the case of HDTMA, the decrease in sorption at high surfactant loadings was very slow, being that the surfactant was able to retain the pesticides at concentration values which clearly exceeded the monolayer coverage. RECOMMENDATIONS AND PERSPECTIVES: Contamination by pesticides, which are present in the soil due to their direct input in this medium or to spills or illegal tipping, may be hindered from migration to groundwater by application of a cationic surfactant.