1,721,089 research outputs found
Chemical sensors for in situ data collection in the cryosphere
Full text linkGlaciers and ice sheets are recognised as important components of global biogeochemical cycles. Chemical sensors have great potential for in situ monitoring in the cryosphere and are available for many analytes of interest, but they are frequently unsuitable for deployment since meltwaters are cold, turbid, experience freeze-thaw cycles and display low ionic strength and concentrations of target analytes. Here, we review in situ chemical sensors currently available for measurement of biogeochemically important analytes and assess their suitability for deployment. These include standard parameters such as dissolved oxygen and pH, along with macronutrients (nitrate/nitrite and phosphate), micronutrients (iron and manganese) and biogenic gases (methane). Where no commercial alternatives are available, we discuss sensors currently in development, and their applicability to these extreme environments. The information presented has great relevance for future science in polar environments, and for the ultimate goal of obtaining in situ data from extreme, inaccessible subglacial environments
Glacial flours as a potential source of Fe(II) and Fe(III) to polar waters
No full textSupply of Fe to high nitrate low chlorophyll (HNLC) waters, such as the Southern Ocean, is the principle limiting factor for primary production and the associated carbon uptake. Glacial meltwaters have recently been shown to provide a globally substantial input of Fe to both Antarctic and Arctic polar waters. The particulate Fe flux in glacial runoff is several orders of magnitude greater than the dissolved Fe flux and yet little is known, to date, about the potential bioavailability of this particulate Fe. A fraction of particulate Fe may be bioavailable to organisms and thus have a significant impact on biota in HNLC zones. Here, we describe in detail the composition and speciation of Fe released from four different glacial flours. We show that the fraction of labile Fe varies markedly between different flours and is not proportional to total Fe. Furthermore a small fraction of the particulate Fe is available to the Fe(II) selective ligand ferrozine, which indicates active redox cycling on the surface of the flour
Hydrological controls on glacially exported microbial assemblages
Full text linkThe Greenland Ice Sheet (GrIS) exports approximately 400 km3 of freshwater annually to downstream freshwater and marine ecosystems. These meltwaters originate in a wide range of well-defined habitats that can be associated with very different physical environments within the ice sheet, ranging from oxygenated surface environments that are exposed to light and supplied with nutrients from atmospheric/aeolian sources to subglacial environments that are permanently dark, isolated from the atmosphere, and potentially anoxic. Hydrological conditions in the latter likely favor prolonged rock-water contact. The seasonally evolving hydrological system that drains meltwaters from the GrIS connects these distinct microbial habitats and exports the microbes contained within them to downstream ecosystems. The microbial assemblages exported in glacier meltwater may have an impact on downstream ecosystem function and development. We explored how the seasonal development of a glacial drainage system influences the character of microbial assemblages exported from the GrIS by monitoring the seasonal changes in hydrology, water chemistry, and microbial assemblage composition of meltwaters draining from a glacier in southwest Greenland. We found that the microbial assemblages exported in meltwaters varied in response to glacier hydrological flow path characteristics. Whether or not meltwaters passed through the subglacial environment was the first-order control on the composition of the microbial assemblages exported from the glacier, while water source (i.e., supraglacial or extraglacial) and subglacial residence times were second-order controls. Glacier hydrology therefore plays a fundamental role in determining the microbial exports from glaciated watersheds
Implementation of in-field life detection and characterisation techniques in icy environments
Full text linkAn emerging trend towards non-laboratory based biological and microbiological marker
analysis is occurring in multiple sectors of science and industry. In the medical sector, these
trends have demonstrated that conducting sample analyses away from centralised laboratories
not only makes analyses quicker and more convenient (e.g. a home pregnancy test), but can
offer services that are otherwise impractical (e.g. mobile laboratories to diagnose disease in
the developing world). In the environmental sector, similar benefits, plus the ability to
develop and test hypotheses, protocols and sampling strategies within a field campaign, are
possible with in-field analyses. Icy environments in particular would benefit from in situ or
in-field life detection as they are typically remote, and hence impart high logistical costs for
repeated field campaigns and associated sample return with the implication that the
efficiency of scientific return is poor. Unfortunately, most equipment and protocols
developed for microbiological analyses in other sectors of science and industry are unsuitable
for direct application to in-field use in icy environments because of poor compatibility with
icy environment sample matrices and frequently inappropriate microbiological targets.
Hence within this work, two hypotheses were tested: that (i) microbiological detection infield
in icy environments is possible and through this (ii) unique and more efficient scientific
studies can be conducted. Cont/d
Particulate organic carbon (POC) concentration in meltwater runoff of Leverett Glacier, Russell Glacier, and Isunnguata Sermia, southwest Greenland (2009-2018)
No full textThis dataset describes particulate organic carbon (POC) and particulate carbon (PC) concentrations of suspended sediments in the proglacial rivers of 3 land-terminating glaciers in the Kangerlussuaq area, Southwest Greenland: Leverett Glacier (LG), Leverett River; Russell Glacier (RG), Akuliarusiarsuup Kuua; and Isunnguata Sermia (IS), Isortoq River. Both the Leverett River and Akuliarusiarsuup Kuua are tributaries of the Qinnguata Kuussua (also known as Watson River). The data have already been part of 3 different publications (Lawson et al. 2014, Kohler et al. 2017, and Vrbická et al. 2022) but are archived here for the first time.
POC data was collected for LG during the 2009 and 2010 melt seasons (Lawson et al. 2014) as well as 2015 (Kohler et al. 2017). For the 2018 melt season, only total carbon concentrations of suspended sediments (PC) is archived as opposed to POC (see Vrbická et al. 2022).Additional funding from:
NERC CASE studentship (NERC DTG/GEOG SN1316.6525)
Czech Science Foundation Junior grant (GACR 15-17346Y)
Charles University grant (GAUK 279715)
Leverhulme Trust Research Grant (RPG-2016-439)
Royal Society Wolfson Merit Award to J.L.W.
Czech Science Foundation grants (GACR; 15-17346Y and 18-12630S)
Charles University Research Centre program no. 20406
High-Resolution in situ measurement of nitrate in runoff from the Greenland Ice Sheet
Full text linkWe report the first in situ high-resolution nitrate time series from two proglacial meltwater rivers draining the Greenland Ice Sheet, using a recently developed submersible analyzer based on lab-on-chip (LOC) technology. The low sample volume (320 μL) required by the LOC analyzer meant that low concentration (few micromolar to submicromolar), highly turbid subglacial meltwater could be filtered and colorimetrically analyzed in situ. Nitrate concentrations in rivers draining Leverett Glacier in southwest Greenland and Kiattuut Sermiat in southern Greenland exhibited a clear diurnal signal and a gradual decline at the commencement of the melt season, displaying trends that would not be discernible using traditional daily manual sampling. Nitrate concentrations varied by 4.4 μM (±0.2 μM) over a 10 day period at Kiattuut Sermiat and 3.0 μM (±0.2 μM) over a 14 day period at Leverett Glacier. Marked changes in nitrate concentrations were observed when discharge began to increase. High-resolution in situ measurements such as these have the potential to significantly advance the understanding of nutrient cycling in remote systems, where the dynamics of nutrient release are complex but are important for downstream biogeochemical cycles.<br/
The Greenland Ice Sheet as a hotspot of phosphorus weathering and export in the Arctic
Full text linkThe contribution of ice sheets to the global biogeochemical cycle of phosphorus is largely unknown, due to the lack of field data. Here we present the first comprehensive study of phosphorus export from two Greenland Ice Sheet glaciers. Our results indicate that the ice sheet is a hot spot of phosphorus export in the Arctic. Soluble reactive phosphorus (SRP) concentrations, up to 0.35?µM, are similar to those observed in Arctic rivers. Yields of SRP are among the highest in the literature, with denudation rates of 17–27?kg?P?km?2?yr?1. Particulate phases, as with nonglaciated catchments, dominate phosphorus export (>97% of total phosphorus flux). The labile particulate fraction differs between the two glaciers studied, with significantly higher yields found at the larger glacier (57.3 versus 8.3?kg?P?km?2?yr?1). Total phosphorus yields are an order of magnitude higher than riverine values reported in the literature. We estimate that the ice sheet contributes ~15% of total bioavailable phosphorus input to the Arctic oceans (~11?Gg?yr?1) and dominates total phosphorus input (408?Gg?yr?1), which is more than 3 times that estimated from Arctic rivers (126?Gg?yr?1). We predict that these fluxes will rise with increasing ice sheet freshwater discharge in the future
Thriving below 0ºC: searching for microbacterial communities in glacial waters
Full text linkClimate change is a major concern regarding human, animal and environmental health. Glaciers, one of the most affected areas, are shrinking, triggering diverse dangers, such as methane gas release into the atmosphere and glacial water contamination with heavy metals and pathogenic agents. As such, methane concentrations were measured in meltwaters from 20 glaciers in Norway. The bacterial communities and potential bacterial pathogens were also analyzed in 10 glaciers (6 from Norway, 2 from Svalbard and 2 from Peru). The results revealed methane oversaturation in one Norwegian site, and highly variable and distinct bacterial communities, across regions. In Shallap glacier (Peru), iron metabolizing bacteria were predominant, whereas in Svalbard glaciers, methanotrophs dominated. In Norway samples, iron and nitrogen related bacteria seemed more evident. In general, there was low evidence for the existence of potential pathogens. Nonetheless, more studies, especially entailing a multidisciplinary approach, are necessary to fully understand the community structure and dynamics, providing a One Health perspective; - Resumo:
As mudanças climáticas são uma preocupação prioritária relativa à saúde humana, animal e ambiental. A diminuição da cobertura de gelo nos glaciares, uma das áreas mais afetadas, potenciam diversos perigos, como a libertação de metano para a atmosfera e a contaminação das águas glaciares com metais e agentes patogénicos. Por isto, realizou-se um estudo avaliando a concentração de metano em 20 glaciares na Noruega. Analisaram-se, também, as comunidades e os potenciais agentes patogénicos, em 10 glaciares (6 na Noruega, 2 em Svalbard e 2 no Peru). Os resultados revelarem saturação de metano num dos glaciares da Noruega, e comunidades bacterianas altamente distintas e variáveis nas diferentes regiões. Em Shallap (Peru) predominavam bactérias metabolizadoras de ferro, enquanto que, nos em Svalbard, a metanotrofia dominava. Na Noruega, evidenciavam-se bactérias associadas à metabolização do ferro e azoto. A existência de potenciais patogénicos foi baixa, em geral. No entanto, mais estudos (preferencialmente com abordagem multidisciplinar) são necessários para compreender a estrutura e a dinâmica destas comunidades, traduzindo uma perspectiva em Uma Saúde
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