Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environm... more Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environmental sciences and, in the food and health industries. Despite successful ATP detection in a variety of ecosystems, very little data are available on ATP levels in the glacial system. In this study, protocols for ATP detection on glacial ice and sediment samples are investigated, in order to aid in the development of a single-use device for in-field life detection, and also to increase the available data on biomass estimates in the cryosphere. ATP detection in two glacial samples reveals concentrations indistinguishable from internal blanks. Therefore, the samples were centrifuged and their particulate loads were subjected to four different extraction processes. Applying these extraction methods resulted in higher ATP concentration than samples with no extraction process; the different techniques increase the ATP detected between 5 and 15 times (also relative to an internal standard). Concurrent with the laboratory based development of extraction protocols is the development of a single-use device for the detection of ATP at the sampling site, in icy environments. The device is microfluidic-based, using commercially available reagents for the detection of ATP by bioluminescence. In order to produce a robust measure of biomass, both laboratory and field based analyses need to be carried out. This work shows the potential of ATP detection in glacial samples and the early development of a device for in situ life detection. The quantification of ATP in microfluidic format is being developed as the preliminary target for an integrated life detection and characterisation device.
... The McMurdo Dry Valleys form the largest ice-free area on the Antarctic continent and are the... more ... The McMurdo Dry Valleys form the largest ice-free area on the Antarctic continent and are the ... was filtered onto 0.2 mm, 47 mm polycarbonate filters, rinsed three times with ice-cold 5 ... the majority of microbes in glaciers can divide and thus do have an impact on biogeochemical ...
The contribution of ice sheets to the global biogeochemical cycle of phosphorus is largely unknow... more The 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 À2 yr À1. 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 À2 yr À1). 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 À1) and dominates total phosphorus input (408 Gg yr À1), which is more than 3 times that estimated from Arctic rivers (126 Gg yr À1). We predict that these fluxes will rise with increasing ice sheet freshwater discharge in the future.
ABSTRACT linear relationships between the mass of sediment present in a cryoconite hole and the h... more ABSTRACT linear relationships between the mass of sediment present in a cryoconite hole and the hole area are described for a range of glacier and ice-sheet surfaces. The strong relationships found indicate that some mechanism regulates the thickness of the layer of sediment occupying the 'floor' of the hole. We find that this regulation process responds immediately to the addition of new debris to a hole and infer that it is caused by lateral thermal conduction from the debris to the hole wall. This causes hole widening by melt, and a redistribution of the debris within then takes place, usually resulting in 0.04-0.20 g cm(-2) of debris in a layer of single cryoconite grains. The thinning of the debris layer during hole widening also reduces self-shading and thus maximizes the exposure of cryoconite to solar radiation. We explore the implications of the hole widening for biological production. Net photosynthesis (CO(2) fixation) is shown to be favoured by thin debris layers, whilst net heterotrophy (CO(2) respiration) occurs when debris layers are in excess of 2-4 mm. We conclude that the carbon balance of cryoconite holes is sensitive to the thickness of the debris and that the thermodynamic equilibration of the debris thickness helps the ecosystem to maximize primary production during the summer.
Recent studies show that subglacial environments previously thought to be devoid of life contain ... more Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity of labile organic compounds essential for sustaining microbial metabolism in subglacial environments. Three subglacial ecosystems that considerably differ in range and amount of available organic compounds were selected for this study 1-Engabreen, northern Norway, overlying high-grade metamorphic rocks with low organic carbon content; 2-Finsterwalderbreen, Svalbard, overriding ancient black shales with a relatively high carbon content yet recalcitrant to microbiological consumption; and 3-Russell Glacier in western Greenland with recently overridden quaternary organic rich paleosols. Basal and pressure ridge ice samples were collected and subsequently analysed for low molecular weight organic compounds, with the emphasis on volatile fatty acids, carbohydrates and amino acids. The highest concentration of labile organic compounds in Greenland basal ice suggest that recently overridden paleosols have the greatest potential for sustaining microbial populations present within and underneath basal ice. The high concentration of "ancient" organic carbon in basal ice from Finsterwalderbreen, Svalbard, doesn't correlate with the presence of labile organic compounds. This indicates the inability of microbes to digest recalcitrant kerogen carbon in cold temperatures. In all three investigated environments, concentrations of labile organic compounds are elevated in basal ice with a high debris content. Until recently, most models of the global carbon cycle tend to neglect the pool of subglacial organic carbon as little is known about the range and concentrations of organic compounds as well as the composition of microbial communities and their ability to degrade and metabolize organic carbon at low temperatures. Recently overridden paleosols in western Greenland may serve as a biogeochemical model for vast pool of organic carbon from areas of boreal forest and tundra overridden during the Quaternary glacial cycles.
The presence of liquid water beneath ice sheets, together with the anoxia caused by the microbial... more The presence of liquid water beneath ice sheets, together with the anoxia caused by the microbial oxidation of organic carbon and sulphide minerals, create favourable conditions for methanogenic archaea in subglacial environments, and hence the process of methanogenesis. This is of significance for the role of ice sheets in global biogeochemical cycles, and is consistent with hypotheses that organic carbon
The Greenland Ice Sheet (GrIS) is the largest mass of ice in the northern hemisphere, and contrib... more The Greenland Ice Sheet (GrIS) is the largest mass of ice in the northern hemisphere, and contributes ~370 km3 in runoff annually to the Arctic Ocean. While recent work has highlighted runoff increases of up to 100% from the GrIS over the next century, very little is known about the associated impacts upon rates of sediment-bound and dissolved organic carbon export from the ice sheet to the coastal ocean. This is relevant given recent work that has suggested that the high proportion of labile dissolved organic carbon (DOC) present in glacial runoff may be important in sustaining the productivity of ecosystems downstream. Here we report the phylogenetic and functional diversity of micro-organisms inhabiting the surface and basal regions of the Greenland Ice Sheet (at Leverett Glacier, SW Greenland), and whose activity influences the biogeochemical composition of runoff. Real time PCR data on runoff, together with 16S-rRNA bacterial clone libraries on sediments, demonstrate a subglaci...
Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir... more Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir of metabolically active microbial cells and organic carbon. Its potential to support the degradation of organic carbon to methane, however, has not yet been evaluated. Large marine sedimentary basins beneath the ice sheet (estimated to cover up to 50% by area and contain sedimentary sequences up to 3 km thick) remain thawed during glaciation. These basins are estimated to contain ~7000 Pg of organic carbon, assuming that sedimentary basins account for 1 and 2 M km2 of the West and East Antarctic Ice Sheets respectively, the organic carbon content of overridden marine sediments is 0.5 % and the mean sediment depth is 1 km. We predict that this carbon is microbially cycled to methane under anoxic conditions beneath the ice sheet. Laboratory experimental data are consistent with this and show that organic carbon overridden by glaciers and ice sheets produces methane under anoxic conditions...
Photosynthesis by microbes on the surfaces of glaciers and ice sheets has the potential to fix ca... more Photosynthesis by microbes on the surfaces of glaciers and ice sheets has the potential to fix carbon, alter the albedo of ice surfaces via the production of organic matter and so enhance ice melt. It could also be important for supplying labile organic matter and nutrients to in situ and downstream ecosystems. This study compares in situ 24 hour incubation methods for measuring rates of gross photosynthesis, respiration and net community production (NCP) in cryoconite holes on three Svalbard valley glaciers. Rates of gross photosynthesis and respiration measured by the Delta CO(2) method were closely balanced, resulting in rates of NCP close to the detection limit (mean of -1.3 mu g C g(-1) d(-1)) consistent with previous measurements in Arctic cryoconite holes. This suggests that organic matter within cryoconite holes may be derived largely from allochthonous sources. The molar ratio of Delta O(2) to Delta CO(2) in incubations gave mean respiratory and photosynthetic quotients of ...
Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environm... more Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environmental sciences and, in the food and health industries. Despite successful ATP detection in a variety of ecosystems, very little data are available on ATP levels in the glacial system. In this study, protocols for ATP detection on glacial ice and sediment samples are investigated, in
Recent studies show that subglacial environments previously thought to be devoid of life contain ... more Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity
Glaciers and ice sheets represent ~10% of the contemporary global surface coverage, yet remain on... more Glaciers and ice sheets represent ~10% of the contemporary global surface coverage, yet remain one of the least explored sectors of the Earth's biosphere. The basal regions of these ice masses, known as subglacial environments, are capable of harbouring a diverse range of microorganisms that are often metabolically active despite the lack of sunlight, the cold temperatures and nutrient scarcity.
Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environm... more Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environmental sciences and, in the food and health industries. Despite successful ATP detection in a variety of ecosystems, very little data are available on ATP levels in the glacial system. In this study, protocols for ATP detection on glacial ice and sediment samples are investigated, in order to aid in the development of a single-use device for in-field life detection, and also to increase the available data on biomass estimates in the cryosphere. ATP detection in two glacial samples reveals concentrations indistinguishable from internal blanks. Therefore, the samples were centrifuged and their particulate loads were subjected to four different extraction processes. Applying these extraction methods resulted in higher ATP concentration than samples with no extraction process; the different techniques increase the ATP detected between 5 and 15 times (also relative to an internal standard). Concurrent with the laboratory based development of extraction protocols is the development of a single-use device for the detection of ATP at the sampling site, in icy environments. The device is microfluidic-based, using commercially available reagents for the detection of ATP by bioluminescence. In order to produce a robust measure of biomass, both laboratory and field based analyses need to be carried out. This work shows the potential of ATP detection in glacial samples and the early development of a device for in situ life detection. The quantification of ATP in microfluidic format is being developed as the preliminary target for an integrated life detection and characterisation device.
... The McMurdo Dry Valleys form the largest ice-free area on the Antarctic continent and are the... more ... The McMurdo Dry Valleys form the largest ice-free area on the Antarctic continent and are the ... was filtered onto 0.2 mm, 47 mm polycarbonate filters, rinsed three times with ice-cold 5 ... the majority of microbes in glaciers can divide and thus do have an impact on biogeochemical ...
The contribution of ice sheets to the global biogeochemical cycle of phosphorus is largely unknow... more The 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 À2 yr À1. 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 À2 yr À1). 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 À1) and dominates total phosphorus input (408 Gg yr À1), which is more than 3 times that estimated from Arctic rivers (126 Gg yr À1). We predict that these fluxes will rise with increasing ice sheet freshwater discharge in the future.
ABSTRACT linear relationships between the mass of sediment present in a cryoconite hole and the h... more ABSTRACT linear relationships between the mass of sediment present in a cryoconite hole and the hole area are described for a range of glacier and ice-sheet surfaces. The strong relationships found indicate that some mechanism regulates the thickness of the layer of sediment occupying the 'floor' of the hole. We find that this regulation process responds immediately to the addition of new debris to a hole and infer that it is caused by lateral thermal conduction from the debris to the hole wall. This causes hole widening by melt, and a redistribution of the debris within then takes place, usually resulting in 0.04-0.20 g cm(-2) of debris in a layer of single cryoconite grains. The thinning of the debris layer during hole widening also reduces self-shading and thus maximizes the exposure of cryoconite to solar radiation. We explore the implications of the hole widening for biological production. Net photosynthesis (CO(2) fixation) is shown to be favoured by thin debris layers, whilst net heterotrophy (CO(2) respiration) occurs when debris layers are in excess of 2-4 mm. We conclude that the carbon balance of cryoconite holes is sensitive to the thickness of the debris and that the thermodynamic equilibration of the debris thickness helps the ecosystem to maximize primary production during the summer.
Recent studies show that subglacial environments previously thought to be devoid of life contain ... more Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity of labile organic compounds essential for sustaining microbial metabolism in subglacial environments. Three subglacial ecosystems that considerably differ in range and amount of available organic compounds were selected for this study 1-Engabreen, northern Norway, overlying high-grade metamorphic rocks with low organic carbon content; 2-Finsterwalderbreen, Svalbard, overriding ancient black shales with a relatively high carbon content yet recalcitrant to microbiological consumption; and 3-Russell Glacier in western Greenland with recently overridden quaternary organic rich paleosols. Basal and pressure ridge ice samples were collected and subsequently analysed for low molecular weight organic compounds, with the emphasis on volatile fatty acids, carbohydrates and amino acids. The highest concentration of labile organic compounds in Greenland basal ice suggest that recently overridden paleosols have the greatest potential for sustaining microbial populations present within and underneath basal ice. The high concentration of "ancient" organic carbon in basal ice from Finsterwalderbreen, Svalbard, doesn't correlate with the presence of labile organic compounds. This indicates the inability of microbes to digest recalcitrant kerogen carbon in cold temperatures. In all three investigated environments, concentrations of labile organic compounds are elevated in basal ice with a high debris content. Until recently, most models of the global carbon cycle tend to neglect the pool of subglacial organic carbon as little is known about the range and concentrations of organic compounds as well as the composition of microbial communities and their ability to degrade and metabolize organic carbon at low temperatures. Recently overridden paleosols in western Greenland may serve as a biogeochemical model for vast pool of organic carbon from areas of boreal forest and tundra overridden during the Quaternary glacial cycles.
The presence of liquid water beneath ice sheets, together with the anoxia caused by the microbial... more The presence of liquid water beneath ice sheets, together with the anoxia caused by the microbial oxidation of organic carbon and sulphide minerals, create favourable conditions for methanogenic archaea in subglacial environments, and hence the process of methanogenesis. This is of significance for the role of ice sheets in global biogeochemical cycles, and is consistent with hypotheses that organic carbon
The Greenland Ice Sheet (GrIS) is the largest mass of ice in the northern hemisphere, and contrib... more The Greenland Ice Sheet (GrIS) is the largest mass of ice in the northern hemisphere, and contributes ~370 km3 in runoff annually to the Arctic Ocean. While recent work has highlighted runoff increases of up to 100% from the GrIS over the next century, very little is known about the associated impacts upon rates of sediment-bound and dissolved organic carbon export from the ice sheet to the coastal ocean. This is relevant given recent work that has suggested that the high proportion of labile dissolved organic carbon (DOC) present in glacial runoff may be important in sustaining the productivity of ecosystems downstream. Here we report the phylogenetic and functional diversity of micro-organisms inhabiting the surface and basal regions of the Greenland Ice Sheet (at Leverett Glacier, SW Greenland), and whose activity influences the biogeochemical composition of runoff. Real time PCR data on runoff, together with 16S-rRNA bacterial clone libraries on sediments, demonstrate a subglaci...
Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir... more Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir of metabolically active microbial cells and organic carbon. Its potential to support the degradation of organic carbon to methane, however, has not yet been evaluated. Large marine sedimentary basins beneath the ice sheet (estimated to cover up to 50% by area and contain sedimentary sequences up to 3 km thick) remain thawed during glaciation. These basins are estimated to contain ~7000 Pg of organic carbon, assuming that sedimentary basins account for 1 and 2 M km2 of the West and East Antarctic Ice Sheets respectively, the organic carbon content of overridden marine sediments is 0.5 % and the mean sediment depth is 1 km. We predict that this carbon is microbially cycled to methane under anoxic conditions beneath the ice sheet. Laboratory experimental data are consistent with this and show that organic carbon overridden by glaciers and ice sheets produces methane under anoxic conditions...
Photosynthesis by microbes on the surfaces of glaciers and ice sheets has the potential to fix ca... more Photosynthesis by microbes on the surfaces of glaciers and ice sheets has the potential to fix carbon, alter the albedo of ice surfaces via the production of organic matter and so enhance ice melt. It could also be important for supplying labile organic matter and nutrients to in situ and downstream ecosystems. This study compares in situ 24 hour incubation methods for measuring rates of gross photosynthesis, respiration and net community production (NCP) in cryoconite holes on three Svalbard valley glaciers. Rates of gross photosynthesis and respiration measured by the Delta CO(2) method were closely balanced, resulting in rates of NCP close to the detection limit (mean of -1.3 mu g C g(-1) d(-1)) consistent with previous measurements in Arctic cryoconite holes. This suggests that organic matter within cryoconite holes may be derived largely from allochthonous sources. The molar ratio of Delta O(2) to Delta CO(2) in incubations gave mean respiratory and photosynthetic quotients of ...
Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environm... more Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environmental sciences and, in the food and health industries. Despite successful ATP detection in a variety of ecosystems, very little data are available on ATP levels in the glacial system. In this study, protocols for ATP detection on glacial ice and sediment samples are investigated, in
Recent studies show that subglacial environments previously thought to be devoid of life contain ... more Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity
Glaciers and ice sheets represent ~10% of the contemporary global surface coverage, yet remain on... more Glaciers and ice sheets represent ~10% of the contemporary global surface coverage, yet remain one of the least explored sectors of the Earth's biosphere. The basal regions of these ice masses, known as subglacial environments, are capable of harbouring a diverse range of microorganisms that are often metabolically active despite the lack of sunlight, the cold temperatures and nutrient scarcity.
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Papers by Jon Telling