Charlotte L. Roehm
My broad research interests are related to terrestrial-aquatic linkages. In particular the bioavailability of allochthonous sources of carbon and nutrients to bacterial communities in adjacent lakes and streams, and the subsequent influence this has on carbon dioxide and methane dynamics at the watershed scale. I am interested in understanding the mechanisms underlying the mobilization, transport and transformation of energy and nutrients within and between ecosystem types. The knowledge of the dynamics of redistribution of energy and matter within a landscape is imperative for better predicting the impacts and consequences of land-use (i.e. forest fires, creation of hydroelectric reservoirs), global and climate change on terrestrial and aquatic ecosystems.
I am currently working on and involved in several projects:
a) Great Lakes:
I am interested at studying the impacts of land-use and climate change on both the physical dynamics of water and energy flow and also the biogeochemical dynamics of carbon and nutrients in the Great Lakes.
b) Arctic and Subarctic Sweden:
i) Defining the role of the 'old' terrestrial C transported from degrading permafrost mires to sub-arctic and alpine clearwater lakes in Arctic Sweden and its subsequent impact on the saturation level and potential efflux of carbon dioxide and methane to the atmosphere. I am looking to determine the potential impact of a changing climate on terrestrial-aquatic energy mobilization, using permafrost and altitudinal gradients as climatic proxies.
ii) Analyzing lake sediments to identify periods of strong terrestrial input and deposition of C in lakes that are based along a permafrost gradient in order to determine if changes in the status of permafrost are related to periods of high terrestrial C input.
iii) Defining the carbon quality end members of soils from different altitudinal gradients and following their changing role in stream water bacterial dynamics along alpine watersheds influenced by both climatic and vegetational gradients.
c) Canadian Arctic:
I have been involved in an ongoing project which aims to identify geomorphological and hydrological features in the Canadian arctic which may be used as analogues for periglacial features identified on Mars. My particular interests within this project are focused on using δ18O and δD signatures of massive ice in order to identify the source of massive ice and also 14C to determine the approximate age of sediments deposited both above and within the massive ice features. I am also looking at the hydrology and geomorphology of gully features which are formed as a function of thermal destabilization of massive ice following inertia from thermokarst formation. These last features being analogues for the current formation of recent gullies and thermokarst basins identified in impact craters on Mars.