2009 Student Science - Abstracts

Permafrost | Wetlands | Lakes | Streams | Invertebrates | Rivers | Satellites | Interviews

Permafrost: Joanne Heslop, Nicholai Torgovkin, advised by Valentin Spektor
	We hope to obtain a picture of how organic carbon is distributed within the soil, how those distributions change over space and time, and how groundwater moving through the active layer gathers nutrients. We seek to compare the composition of Holocene optimum active layer and Pleistocene yedoma (ice-rich permafrost) with that of the modern active layer, to determine how different landscapes vary in active layer qualities, and to profile the active layer’s potential for leeching nutrients into groundwater. We plan to form soil profiles at various locations around the Kolyma River. At each profile, we plan to measure the active layer depth, examine the soil characteristics, and collect one centimeter thick soil samples once every five centimeters. Soil samples will be analyzed for moisture and organic matter content using a drying oven and muffle furnace. Leeching potential will be tested by adding soil to distilled water, incubating it, and testing it for carbon, nitrogen, and phosphorous content. We hypothesize organic matter and moisture content will be higher at shallow depths due to deposition, decomposition, and precipitation. Organic carbon content at lower depths will be low due to little deposition and constant nutrient leeching. Active layer composition from the modern day and the Holocene optimum era will be similar due to similar histories of warming, but yedoma deposits, laid down during the last ice age, will be more nutrient-rich. All active layer soil will have high nutrient leeching levels, but yedoma soil, with its fine particulate size and high nutrient content, will have higher nutrient leeching levels.
Wetlands: Moira Hough advised by Andy Bunn and Karen Frey
	As climate change causes permafrost thaw and active layer deepening in arctic ecosystems, new pools of highly labile organic material are exposed and begin to leach carbon into groundwater. While most soils in northeastern Siberia are composed of carbon-poor loess, there are also many peatlands, which are maintained by cold, wet, and nutrient poor conditions. These peatlands are often found in the basins of drained thermokarst lakes called alases. Because these peat dominated alases contain particularly large pools of poorly decomposed carbon, they are potentially important sources of dissolved organic carbon (DOC). This highlights the importance of understanding how the content and lability of carbon in alases vary with ecosystem type and between the active layer and the permafrost. I will address this question by sampling alases in boreal forest (Duvannyi Yar), at the transition from boreal forest to tundra (Cherskiy), and in the tundra. At each alas I will measure the depth of the active layer, sample soils in both frozen and unfrozen peat in a transect across the alas, and sample pore water. I will use these samples to measure carbon and nutrient content as well as lability of both soil and pore water and will compare this data to that collected by colleagues studying loess soils. I expect that soil carbon content and lability will be higher in soils with slow rates of decomposition which should be those that are peat dominated, have high moisture levels, are in tundra ecosystems, and that are frozen.
Lakes: Kirill Tretyakov, advised by Sudeep Chandra
	Arctic lakes have a great influence on climate through discharge of methane and CO2 to the atmosphere. It is unclear if the position of the lake in the landscape influences carbon dynamics in these lakes. Upland thermokarst lakes are different in nutrients and dissolved organic carbon concentrations compared to lowland floodplain lakes, because of factors like disturbance history and underlying soil characteristics. Additionally, microbes that process dissolved organic carbon in these lakes may be limited by different nutrients concentrating in the lakes due to their location. Therefore microbial organisms may lack basic nutrients, such as nitrogen and phosphorus, which therefore may influence the amount of CO2 and methane released to the atmosphere. Learning the chemical content and physical properties of these lakes would help determine the role of thermokarst upland and floodplain lakes in global climate change. Therefore, I propose to answer the following question: How do thermokarst upland and floodplain lakes differ in concentrations of dissolved organic carbon and nutrients, particularly nitrogen and phosphorus? I expect to find significant differences between lakes at different landscape positions for reasons described above. To approach answering the question, I am collecting water samples from several upland and floodplain lakes and analyzing them for concentrations of nitrogen, phosphorus and dissolved organic carbon from different depths.
Streams: Travis Drake and Erin Seybold, advised by John Schade and Bill Sobczak
	Arctic streams are important conduits in the transportation of dissolved organic carbon (DOC) and other inorganic nutrients from terrestrial ecosystems to the Arctic Ocean. In addition to transport, recent carbon budgets indicate that a significant amount of carbon processing occurs within inland waters. Little is known about the processing potential of small Arctic streams underlain by continuous permafrost with low discharge. Several factors make small streams potential hotspots for carbon processing. First, small streams often have a high ratio of benthic contact with the water column, which provides greater surface area for biogeochemical processing. Second, arctic streams receive large amounts of allochthanous inputs in the form of woody debris and DOC leeched from peat soils. This investigation aims to assess the capacity of these small arctic streams to respire DOC. Transient storage and nutrient uptake were identified as two in-stream processes that could significantly impact DOC consumption. To directly assess this impact, nutrient and conservative tracer additions were conducted in 6 arctic streams. Preliminary results lead us to hypothesize that 1. Streams will be highly nutrient limited and heterotrophic due to both the high ratio of organic matter to inorganic nutrients and the low mineralization rates of nutrient-poor detritus. 2. Transient storage will vary inversely with stream discharge. 3. Streams with high transient storage will likely display high nutrient uptake due to extended residence times. Thus, due to the combination of high transient storage and elevated carbon substrate concentrations, small arctic streams are potential hotspots for DOC processing and significantly affecting downstream flux of carbon.
Invertebrates: Kayla Henson and Max Janicek, advised by Andy Bunn and Sudeep Chandra
	Depending on their functional feeding groups (i.e. methods of eating such as shredding organic matter like leaf litter into smaller fine organic matter), macroinvertebrates change the matter available for food at low trophic levels. They also are indicators of ecosystem health; a diversity of specialized taxa indicates a healthy system, whereas highly adaptive taxa can indicate a disturbed aquatic habitat. Thermokarst lakes undergo constant formation and degradation (draining) resulting from frequent disturbance events to the near shore as permafrost slumps into the water from the actively thawing edge. There is substantial evidence that climate change is contributing to increased disturbance. Thermokarst lakes are a stark contrast from floodplain lakes which do not show these dynamics. Thus, perhaps macroinvertebrates can be utilized as an indicator of disturbance. Unfortunately, there is little published research on freshwater macroinvertebrate communities in the Siberian Arctic, and more specifically in a region that is completely underlain by continuous permafrost like the Kolyma River basin. Given the lack of information for these lakes we are determining macroinvertebrate community structure in the littoral and pelagic zone of these lakes. This snap shot of several different lakes gives insight to how these communities are correlated to specific lake parameters: including water depths, mean dissolved oxygen, mean temperature, light (transparency & photosynthetic active radiation [PAR]), dissolved organic carbon (DOC), nitrogen, ammonium, and phosphorous. It will increase both the broad understanding of Arctic Lakes and the specific biological food webs of these two different types of lakes. Specifically, the questions we want to answer are: How do macroinvertebrate communities differ both between floodplain and upland thermokarst and within lakes in Northeastern Siberia? Do specific environmental parameters (e.g. temperature, dissolved oxygen, nutrients) predict invertebrate community abundance and diversity? Hypotheses we are testing include: There is no difference in abundance and diversity between floodplain and upland thermokarst lakes. Macroinvertebrate abundance and diversity across lakes are not related to measurements of environmental parameters (e.g. temperature, dissolved oxygen, nitrogen, dissolved carbon, phosphorus, clarity). Within a lake, disturbance due to thermokarst erosional processes do not determine macroinvertebrate abundance or diversity.
Rivers: Blaize Denfeld, advised by Karen Frey and Bill Sobczak
	Understanding how carbon is processed from terrestrial to marine ecosystem by analyzing a variety of watersheds is critical in determining the implications it has on the overall water quality and productivity of the ocean. The amount of Dissolved Organic Carbon (DOC) being transferred to the ocean and its lability is dependent on different dynamics within the watershed. Important spatial and temporal patterns in the Kolyma watershed include climate, watershed size, water source and hydrology. The following hypotheses investigate these four variations as possible drivers for observed variability in stream and river biogeochemistry: Climate - Waters draining from the south will have higher DOC. During summer thaw the active layer in the south is deeper, which creates more carbon in these watersheds. Watershed Size - Small streams found in the Koylma watershed will have the most amount of labile carbon. As organic matter is transported downstream it is degraded by microbial activity, reducing the lability of the carbon. Watershed Source - The type of soil the water is draining from impacts the organic matter flowing into streams. Waters that are draining from peat lands will have higher DOC concentrations because peat has high carbon content. Hydrology - Rain events will have a temporal impact on DOC concentrations. Small streams will be most affected by rain because discharge of smaller streams will increase, forcing DOC to flush out of the system quickly and reducing decomposition time. In order to study theses hypothesis water samples need to be collected from diverse watersheds. Further a variety of measurements should be made to asses different aspects of DOC concentrations. Particular measurements will be made on DOC, CDOM, nutrients, absorbance, POC, C:N isotope, and lability.
Satellites: Claire Griffin, advised by Karen Frey
	Spaced-based remote sensing can be used to monitor lakes and rivers throughout the Kolyma River basin. A model relating water characteristics, such as colored dissolved organic matter (CDOM) and clarity, to satellite reflectance can enable extrapolation to water bodies that have not been sampled on the ground. It might be possible to track changes in water characteristics through time and determine whether climate variability influences these waters. I hypothesize that CDOM reduces light penetration by absorbing light and thus clarity is negatively correlated with CDOM. Additionally, I hypothesize that CDOM concentrations and clarity are significantly different between river and lakes. Lastly, I hypothesize that ASTER imagery can capture the variability in lake and stream characteristics. Lakes and rivers will be sampled using Secchi disk depths and CDOM at several locations on the lower Kolyma basin. A CDOM probe will be used at different lake depths and stream surface waters. CDOM will also be determined from specific UV absorbance (SUVA) measurements of absorbance at 254nm normalized by DOC concentrations. The turbidity field data will be related to the difference between ASTER band 1 and band 2. CDOM should be correlated with a ratio between band 2 and band 3. The relationship between empirical data and imagery will be determined after leaving the field. Once this is established, differences in water clarity and CDOM can be quantified from imagery. I will model this association by linear regression.
Interviews: Brian Kantor, advised by Sudeep Chandra and Chris Linder
	Tantamount to understanding the biological, chemical, and physical mechanisms of climate change is a greater socio-cultural context. Such a context is invaluable to climate science because it can help shape socially relevant research questions. As well, personal accounts can supplement ecological research of environmental change. For example, interviewing locals in Cherskiy could provide eye-witness accounts of environmental change, be it flooding, fires, or species population change, as well as reflection on how this influences local lifestyles. Thus, with the polaris project, I’ve designed my research project to interview Russians on or near the North East science station to determine how life in Russia influences one’s conception and experience of climate change. My overarching question is how do Russian views of climate change differ from our own? In addition, I know from climate science that the manifestations of climate change are especially evident here in the Arctic. A secondary question, therefore, is how are their attitudes shaped by the evident changes in the Arctic environment? I expect that participants in my research will provide examples of environmental change such as widening rivers or warmer winters. I also expect that damaged infrastructure or changes in subsistence activities may present novel challenges to lifestyle, which will influence responses. At the same time, I understand education, media, and politics may influence how participants may explain these changes, therefore, I expect that anthropogenic explanations for these environmental phenomena may be underemphasized. Though my sample will be limited by both time and participants, I believe my results will be useful to the Polaris Project. Understanding local views of climate change will be useful to the outreach efforts of the Polaris Project. Perhaps explaining climate change to locals here in Chersky will become a priority.