206 research outputs found

    Sentinel-1 detects firn aquifers in the Greenland ice sheet

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    Firn aquifers in Greenland store liquid water within the upper ice sheet and impact the hydrological system. Their location and area have been estimated with airborne radar sounder surveys (Operation IceBridge, OIB). However, the OIB coverage is limited to narrow flight lines, offering an incomplete view. Here, we show the ability of satellite radar measurements from Sentinel-1 to map firn aquifers across all of Greenland at 1 km(2) resolution. The detection of aquifers relies on a delay in the freezing of meltwater within the firn above the water table, causing a distinctive pattern in the radar backscatter. The Sentinel-1 aquifer locations are in very good agreement with those detected along the OIB flight lines (Cohen's kappa = 0.84). The total aquifer area is estimated at 54,800 km(2). With continuity of Sentinel-1 ensured until 2030, our study lays a foundation for monitoring the future response of firn aquifers to climate change

    Technical, economic and environmental evaluation of advanced tertiary treatments for micropollutants removal (oxidation and adsorption)

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    International audienceTwo pilots for tertiary treatment, an advanced oxidation processes (AOP - O3/UV/H2O2) pilot and a granular activated carbon pilot, were tested in three different wastewater treatment plants after a secondary treatment. A total of 64 micropollutants including drugs, pesticides, alkylphenols, PAHs and metals were analysed in the samples at the inlet and the outlet of the pilots. The tertiary treatments studied (ozone, AOP and activated carbon) were efficient for the removal of most of the compounds analysed in this study, except metals. The addition of hydrogen peroxide to ozone increased the number of substances well removed but it did not improve the removal of substances that readily react with ozone (such as betablockers or carbamazepine). The other AOP (ozone/H2O2 and UV/H2O2) did not improve the number of substances well removed in comparison with ozone alone. The granular activated carbon was still efficient (R>70%) after 6 months working 24/7 for most of the drugs and the urea and triazine pesticides. The 5 technologies studied were sized at full scale in order to calculate their cost for two sizes of WWTP. The implementation of a tertiary treatment on a 60 000 to 200 000 PE WWTP would increase the wastewater treatment cost by 1,5 to 17,6 euros cents per cubic meter treated according to the technology and the removal objective. Concerning the environmental impact, for the big WWTP, the activated carbon is more impacting than the other processes for most of the impacts calculated. The order of POA by increasing environmental impact is ozone < ozone/H2O2 < ozone/UV ~ UV/H2O2. For the medium size WWTP however, the activated carbon is comparable to the other solutions regarding environmental impact

    Loving work: drawing attention to pleasure and pain in the body of the cultural worker

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    In this article, we present our current research into the body and mind at work, with a particular focus on experiences and implications of enjoyment and love of work within the culture sector. This research is developed through the project Manual Labours that explores the historical conditioning between the body and mind in the so-called immaterial labour conditions. The project aims to identify positive and negative affective labour and the role that physical relationships to work can have in helping conceptualise current working conditions. The enjoyment of work leads to complex differentiations between work and life. This article explores the implications of exploitative labour conditions as self-employed or salaried passionate workers are internalising and developing a sense of ‘un-alienated’ ownership over their wage labour

    Extensive Liquid Meltwater Storage in Firn Within the Greenland Ice Sheet

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    The accelerating loss of mass from the Greenland ice sheet is a major contribution to current sea level rise. Increased melt water runoff is responsible for half of Greenlands mass loss increase. Surface melt has been increasing in extent and intensity, setting a record for surface area melt and runoff in 2012. The mechanisms and timescales involved in allowing surface melt water to reach the ocean where it can contribute to sea level rise are poorly understood. The potential capacity to store this water in liquid or frozen form in the firn (multi-year snow layer) is significant, and could delay its sea-level contribution. Here we describe direct observation of water within a perennial firn aquifer persisting throughout the winter in the southern ice sheet,where snow accumulation and melt rates are high. This represents a previously unknown storagemode for water within the ice sheet. Ice cores, groundairborne radar and a regional climatemodel are used to estimate aquifer area (70 plue or minus 10 x 10(exp 3) square kilometers ) and water table depth (5-50 m). The perennial firn aquifer represents a new glacier facies to be considered 29 in future ice sheet mass 30 and energy budget calculations

    The fate and behavior of selected endocrine disrupting chemicals in full scale wastewater and sludge treatment unit processes

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    Endocrine disrupting chemicals are discharged into the environment mainly through wastewater treatment processes. There is a need for better understanding of the fate of these compounds in the unit processes of treatment plant to optimize their removal. The fate of oestrone, 17β-estradiol, 17α-ethinyestradiol and nonylphenol in the unit processes of full scale wastewater treatment plants in the UK, including activated sludge plant, oxidation ditch, biofilter and rotating biological contractor were investigated. The overall removal efficiencies of all the compounds ranged from 41 % to 100 %. The removals were predominantly during the secondary biological treatment with the rates of removal related to the nitrification rates and the sludge age. The removal efficiency of the treatment processes were in the order activated sludge > oxidation ditch > biofilter > rotating biological contractors. Activated sludge plant configured for biological nutrient removal showed better removal of the endocrine disrupting chemicals compared to conventional activated sludge plant effluents. Tertiary treatment was also significant in the removal process through solids removal. Overall mechanisms of removal were biodegradation and sorption unto sludge biomass. Phytoremediation was also significant in the removal processes. The endocrine disrupting chemicals persisted in the anaerobic sludge digestion process with percentage removals ranging fro 10-48 %. Sorption of the endocrine disrupting chemicals onto the sludge increased with increasing values for the partitioning coefficients and the organic carbon contents of the sludge

    Evolutionary Genetics of an S-Like Polymorphism in Papaveraceae with Putative Function in Self-Incompatibility

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    Papaver rhoeas possesses a gametophytic self-incompatibility (SI) system not homologous to any other SI mechanism characterized at the molecular level. Four previously published full length stigmatic S-alleles from the genus Papaver exhibited remarkable sequence divergence, but these studies failed to amplify additional S-alleles despite crossing evidence for more than 60 S-alleles in Papaver rhoeas alone.Using RT-PCR we identified 87 unique putative stigmatic S-allele sequences from the Papaveraceae Argemone munita, Papaver mcconnellii, P. nudicuale, Platystemon californicus and Romneya coulteri. Hand pollinations among two full-sib families of both A. munita and P. californicus indicate a strong correlation between the putative S-genotype and observed incompatibility phenotype. However, we also found more than two S-like sequences in some individuals of A. munita and P. californicus, with two products co-segregating in both full-sib families of P. californicus. Pairwise sequence divergence estimates within and among taxa show Papaver stigmatic S-alleles to be the most variable with lower divergence among putative S-alleles from other Papaveraceae. Genealogical analysis indicates little shared ancestral polymorphism among S-like sequences from different genera. Lack of shared ancestral polymorphism could be due to long divergence times among genera studied, reduced levels of balancing selection if some or all S-like sequences do not function in incompatibility, population bottlenecks, or different levels of recombination among taxa. Preliminary estimates of positive selection find many sites under selective constraint with a few undergoing positive selection, suggesting that self-recognition may depend on amino acid substitutions at only a few sites.Because of the strong correlation between genotype and SI phenotype, sequences reported here represent either functional stylar S-alleles, tightly linked paralogs of the S-locus or a combination of both. The considerable complexity revealed in this study shows we have much to learn about the evolutionary dynamics of self-incompatibility systems
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