@article {KNZ001923, title = {Exploring methods of measuring CO2 degassing in headwater streams}, journal = {Sustainable Water Resources Management}, volume = {5}, year = {2019}, pages = {1765{\textendash}1779}, abstract = {

Carbon dioxide (CO2) degassed from ungauged, headwater streams has a significant role in carbon cycling and climate change, making the precise measurement of the degassing of critical importance. Although methods exist for quantifying degassing rates in large bodies of water (seawater, lakes), these methods are often considered invalid for measuring degassing rates in small, turbulent, groundwater fed headwater streams. This manuscript reviews the physics of gas transfer across the stream-atmosphere interface and provides an in-depth critical review of the available methods of measuring CO2 degassing. Further, it discusses applications for some of these methods in small headwater streams and other low-order streams that are dominated by discharged groundwater. Of the methods reviewed, almost all produce fairly low precision and do not compare well with other methods tested in the same location. We suggest much more work is needed to improve the precision and accuracy of field-measured gas transfer coefficients, both by applying multiple methods in the field and by controlled laboratory experiments.

}, keywords = {LTER-KNZ}, doi = {10.1007/s40899-019-00332-3}, url = {https://link.springer.com/article/10.1007/s40899-019-00332-3}, author = {Rawitch, M. J. and G. L. Macpherson and A.E. Brookfield} } @article {KNZ001821, title = {Developing a conceptual framework of landscape and hydrology on tallgrass prairie: A critical zone approach}, journal = {Vadose Zone Journal}, volume = {17}, year = {2018}, pages = {1 - 11}, abstract = {

Agricultural intensification and urbanization have greatly reduced the extent of tallgrass prairie across North America. To evaluate the impact of these changes, a reference ecosystem of unperturbed prairie is required. The Konza Prairie Biological Station in northeastern Kansas is a long-term research site at which a critical zone approach has been implemented. Integration of climatic, ecologic, and hydropedologic research to facilitate a comprehensive understanding of the complex environment provides the basis for predicting future aquifer and landscape evolution. We present a conceptual framework of the hydrology underpinning the area that integrates the extensive current and past research and provides a synthesis of the literature to date. The key factors in the hydrologic behavior of Konza Prairie are climate, ecology, vadose zone characteristics and management, and groundwater and bedrock. Significant interactions among these factors include bedrock dissolution driven by cool-season precipitation and hence a climatic control on the rate of karstification. Soil moisture dynamics are influenced at various timescales due to the short- and long-term effects of prescribed burning on vegetation and on soil physical characteristics. The frequency of burning regimes strongly influences the expansion of woody species in competition with native tallgrasses, with consequent effects on C and N dynamics within the vadose zone. Knowledge gaps exist pertaining to the future of Konza Prairie (a model for US tallgrass prairie)\—whether continued karstification will lead to increasingly flashy and dynamic hydrology and whether compositional changes in the vegetation will affect long-term changes in water balances.

}, keywords = {LTER-KNZ}, doi = {10.2136/vzj2017.03.0069}, url = {https://dl.sciencesocieties.org/publications/vzj/pdfs/17/1/170069}, author = {Vero, S. E. and G. L. Macpherson and Sullivan, P.L. and A.E. Brookfield and Jesse B. Nippert and Kirk, M. F. and Datta, S. and Kempton, P.} } @article {KNZ001779, title = {Effects of changing meteoric precipitation patterns on groundwater temperature in karst environments}, journal = {Groundwater}, volume = {55}, year = {2017}, pages = {227-236}, abstract = {

Climate predictions indicate that precipitation patterns will change and average air temperatures will increase across much of the planet. These changes will alter surface water and groundwater temperatures which can significantly affect the local and regional environment. Here, we examine the role of precipitation timing in changes to groundwater temperature in carbonate-karst aquifers using measured groundwater level and temperature data from the Konza Prairie Long-Term Ecological Research Site, Kansas. We demonstrate that shifts to increased cool-season precipitation may mitigate the increases in groundwater temperature produced by increases in average annual air temperature. In karst, the solution-enlarged conduits allow faster and focused recharge, and the recharge-event temperature can strongly influence the groundwater temperature in the aquifer. Our field data and analysis show that predictions of future groundwater conditions in karst aquifers need to consider changes in precipitation patterns, in addition to changes to average annual air temperature.

}, keywords = {LTER-KNZ}, doi = {10.1111/gwat.12456}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gwat.12456}, author = {A.E. Brookfield and G. L. Macpherson and Covington, M.} }