38 research outputs found
Summer CO2 evasion from streams and rivers in the Kolyma River basin, north-east Siberia
No full textInland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding.We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes.
We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha-Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86% of the total summer CO2 emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2 emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget
Groundwater inflows control patterns and sources of greenhouse gas emissions from streams
No full textHeadwater streams can be important sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. However, the influence of groundwater–stream connectivity on the patterns and sources of carbon (C) gas evasion is still poorly understood. We explored these connections in the boreal landscape through a detailed study of a 1.4 km lake outlet stream that is hydrologically fed by multiple topographically driven groundwater input zones. We measured stream and groundwater dissolved organic C (DOC), CO2, and CH4 concentrations every 50 m biweekly during the ice-free period and estimated in-stream C gas production through a mass balance model and independent estimates of aquatic metabolism. The spatial pattern of C gas concentrations was consistent over time, with peaks of both CH4 and CO2 concentrations occurring after each groundwater input zone. Moreover, lateral C gas inputs from riparian soils were the major source of CO2 and CH4 to the stream. DOC mineralization and CH4 oxidation within the stream accounted for 17–51% of stream CO2 emissions, and this contribution was the greatest during relatively higher flows. Overall, our results illustrate how the nature and arrangement of groundwater flowpaths can organize patterns of stream C concentrations, transformations, and emissions by acting as a direct source of gases and by supplying organic substrates that fuel aquatic metabolism. Hence, refined assessments of how catchment structure influences the timing and magnitude of groundwater–stream connections are crucial for mechanistically understanding and scaling C evasion rates from headwaters.inancial supported was provided by the Swedish Research Foundation (VR) through SITES, Future Forests, Kempe Foundation, FOMA (SLU), Formas, and SKB. Anna Lupon and Blaize Denfeld were supported by a Kempe Foundation stipend.Peer reviewe
Data for Warmer Winters and Ice-Based Cultural Ecosystem Services: Empirical Evidence from USA, Canada, Japan, Germany, Austria, Switzerland, and Sweden
No full textThe years with no ice cover on Lake Suwa, Japan from 1443 - 2017. The years with ice cover on Lake Constance, Germany/Switzerland/Austria from 875 - 2018. The years with a normal Vikingarännet ice skating race, a modified route, or no race on Lake Mälaren, Sweden from 1999 - 2017 as well as associated average winter air temperature. The years with canceled ice fishing tournaments in central and northern Minnesota, USA as well as associated average winter air temperature from 2005 - 2017. Road date openings of the James Bay winter ice road in northern Ontario, Canada and associated freezing degree days from 2005 - 2018.Lakes and rivers covered by seasonal ice are extensively used by humans. Although ice cover duration has been declining over the past 150 years for Northern Hemisphere lakes and rivers, we still know relatively little about how inland ice loss directly affects humans. Here we provide empirical examples that give quantitative evidence for a winter warming effect on a wide range of cultural ecosystem services. We show that in recent decades, warmer temperatures delayed the opening date of the James Bay winter ice road in northern Ontario, Canada and led to cancellations of religious celebrations (Lake Suwa, Japan and Lake Constance, Germany/Switzerland/Austria), an ice skating race on Lake Mälaren, Sweden, and winter ice fishing tournaments in Central and Northern Minnesota.Funding support for BAD was provided by Kempestiftelserna.Knoll, Lesley, B.; Sharma, Sapna; Denfeld, Blaize A; Flaim, Giovanna; Hori, Yukari; Magnuson, John J; Straile, Dietmar; Weyhenmeyer, Gesa A. (2019). Data for Warmer Winters and Ice-Based Cultural Ecosystem Services: Empirical Evidence from USA, Canada, Japan, Germany, Austria, Switzerland, and Sweden. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/3j5g-kc72
Prevention, Intervention, + Redemption: Impactful Strategies to Engage Disenfranchised Youth and Their Families at Any Place Along Their Journey to Greatness
No full textIn this interactive workshop, mother, advocate, and author Ms. Bettye Blaize weaves together her personal experiences with walking alongside her son\u27s own long journey to greatness with practical and right-on-time strategies that any educator, advocate, or youth service provider can take back to their schools and organizations and begin to implement immediately. Participants will leave the session both inspired and empowered to look at their own classrooms, schools, and community organizations with fresh eyes and a renewed passion for serving youth and their families who have been the most disenfranchised from the system
Consequences of lake and river ice loss on cultural ecosystem services
No full textPeople extensively use lakes and rivers covered by seasonal ice. Although ice cover duration has been declining over the past 150 years for Northern Hemisphere freshwaters, we know relatively little about how ice loss directly affects humans. Here, we synthesize the cultural ecosystem services (i.e., services that provide intangible or nonmaterial benefits) and associated benefits supported by inland ice. We also provide, for the first time, empirical examples that give quantitative evidence for a winter warming effect on a wide range of ice-related cultural ecosystem services and benefits. We show that in recent decades, warmer air temperatures delayed the opening date of winter ice roads and led to cancellations of spiritual ceremonies, outdoor ice skating races, and ice fishing tournaments. Additionally, our synthesis effort suggests unexploited data sets that allow for the use of integrative approaches to evaluate the interplay between inland ice loss and society
Greenhouse Gas Dynamics in Ice-covered Lakes Across Spatial and Temporal Scales
No full textLakes play a major role in the global carbon (C) cycle, despite making up a small area of earth’s surface. Lakes receive, transport and process sizable amounts of C, emitting a substantial amount of the greenhouse gases, carbon dioxide (CO2) and methane (CH4), into the atmosphere. Ice-covered lakes are particularly sensitive to climate change, as future reductions to the duration of lake ice cover will have profound effects on the biogeochemical cycling of C in lakes. It is still largely unknown how reduced ice cover duration will affect CO2 and CH4 emissions from ice-covered lakes. Thus, the primary aim of this thesis was to fill this knowledge gap by monitoring the spatial and temporal dynamics of CO2 and CH4 in ice-covered lakes. The results of this thesis demonstrate that below ice CO2 and CH4 were spatially and temporally variable. Nutrients were strongly linked to below ice CO2 and CH4 oxidation variations across lakes. In addition, below ice CO2 was generally highest in small shallow lakes, and in bottom waters. Whilst below ice CH4 was elevated in surface waters near where bubbles from anoxic lake sediment were trapped. During the ice-cover period, CO2 accumulation below ice was not linear, and at ice-melt incomplete mixing of lake waters resulted in a continued CO2 storage in bottom waters. Further, CO2 transported from the catchment and bottom waters contributed to high CO2 emissions. The collective findings of this thesis indicate that CO2 and CH4 emissions from ice-covered lakes will likely increase in the future. The strong relationship between nutrients and C processes below ice, imply that future changes to nutrient fluxes within lakes will influence the biogeochemical cycling of C in lakes. Since catchment and lake sediment C fluxes play a considerable role in below ice CO2 and CH4 dynamics, changes to hydrology and thermal stability of lakes will undoubtedly alter CO2 and CH4 emissions. Nevertheless, ice-covered lakes constitute a significant component of the global C cycle, and as such, should be carefully monitored and accounted for when addressing the impacts of global climate change.
Carbon emission from Western Siberian inland waters [Elektronisk resurs]
No full textHigh-latitude regions play a key role in the carbon (C) cycle and climate system. An important question is the degree of mobilization and atmospheric release of vast soil C stocks, partly stored in permafrost, with amplified warming of these regions. A fraction of this C is exported to inland waters and emitted to the atmosphere, yet these losses are poorly constrained and seldom accounted for in assessments of high-latitude C balances. This is particularly relevant for Western Siberia, with its extensive peatland C stocks, which can be strongly sensitive to the ongoing changes in climate. Here we quantify C emission from inland waters, including the Ob' River (Arctic's largest watershed), across all permafrost zones of Western Siberia. We show that the inland water C emission is high (0.08-0.10 Pg C yr(-1)) and of major significance in the regional C cycle, largely exceeding (7-9 times) C export to the Arctic Ocean and reaching nearly half (35-50%) of the region's land C uptake. This important role of C emission from inland waters highlights the need for coupled land-water studies to understand the contemporary C cycle and its response to warming. Rivers and lakes are thought to be a major conduit of loss for the massive amounts of carbon locked away in high-latitude systems, but such losses are poorly constrained. Here the authors quantify carbon emissions from rivers and lakes across Western Siberia, finding that emissions are high and exceed carbon export to the Arctic Ocean
Heterogeneous CO2 and CH4 patterns across space and time in a small boreal lake
No full textSmall boreal lakes emit large amounts of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Yet emissions of these greenhouse gases are variable in space and time, in part due to variable within-lake CO2 and CH4 concentrations. To determine the extent and the underlying drivers of this variation, we measured lake water CO2 and CH4 concentrations and estimated associated emissions using spatially discrete water samples collected every 2 weeks from a small boreal lake. On select dates, we also collected groundwater samples from the surrounding catchment. On average, groundwater draining a connected peat mire complex had significantly higher CO2 and CH4 concentrations compared to waters draining forest on mineral soils. However, within the lake, only CH4 concentrations nearshore from the mire complex were significantly elevated. We observed little spatial variability in surface water CO2; however, bottom water CO2 in the pelagic zone was significantly higher than bottom waters at nearshore locations. Overall, temperature, precipitation, and thermal stratification explained temporal patterns of CO2 concentration, whereas hydrology (discharge and precipitation) best predicted the variation in CH4 concentration. Consistent with these different controls, the highest CO2 emission was related to lake turnover at the end of August while the highest CH4 emission was associated with precipitation events at the end of June. These results suggest that annual carbon emissions from small boreal lakes are influenced by temporal variation in weather conditions that regulate thermal stratification and trigger hydrologic land-water connections that supply gases from catchment soils to the lake
Discrete groundwater inflows influence patterns of nitrogen uptake in a boreal headwater stream
No full textDissolved organic carbon (DOC) influences stream nitrogen (N) dynamics by regulating the nutrient demand of heterotrophic microbes and mediating their interactions with nitrifiers. However, DOC supply to streams is dynamic in space and time, which may create variability in N dynamics as a result of shifts between heterotrophic and chemoautotrophic influences. To test this, we measured spatial and temporal variation in concentrations and net uptake of dissolved organic nitrogen (DON), ammonium (NH4+), and nitrate (NO3−) along a 1.4-km boreal stream fed by 4 discrete groundwater inflow zones. We also performed constant rate additions of NH4+, with and without acetate, to test the influence of labile DOC availability on N cycling. Groundwater N supply did not drive spatial patterns in N concentrations. However, we observed high rates of net NH4+ uptake at the sub-reach with the greatest groundwater DOC inputs, whereas net nitrification occurred where such inputs were negligible. At the reach scale, net DON and NH4+ uptake increased with greater groundwater discharge, DOC∶DIN, and ecosystem respiration, whereas net nitrification increased with greater DOC aromaticity. Finally, constant rate additions showed that, under increased DOC availability, NH4+ uptake increased 2×, whereas the proportion of NH4+ nitrified decreased from 42 to 15%. Together, these observations suggest that nitrification rivals heterotrophic uptake when aromatic DOC promotes heterotrophic carbon limitation. Discrete groundwater inflows and periods of elevated discharge can partially alleviate this limitation by supplying labile DOC from riparian soils. Hence, accounting for these land–water connections, over both time and space, is critical for understanding N dynamics in boreal streams.Peer reviewe
Regional Variability and Drivers of Below Ice CO2 in Boreal and Subarctic Lakes
No full textNorthern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO(2)) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO(2) variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO(2) across the 506 lakes(.) Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO(2). Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO(2). Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes
