Observations, experiments and data science: pattern and processes of weathering derived solutes 

Examples of recent work

Li Li, Stewart, B., Zhi, W., Sadayappan, K., Kerins, D. Ramesh, S., Sterle, G., Harpold, A., Perdrial, J.N., (2022). The Predominant Control of Climate on River Chemistry. Earth’s Future. https://doi.org/10.1029/2021EF002603
​In this work led by Li Li (Penn State), we used CAMELS-Chem data and found important connections between climate and river chemistry across the continental United states, where arid climates tend to have higher concentrations of solutes, possibly outweighing local factors like geology and topography. Using a watershed reactor model to look “under the hood” of the watersheds, two main processes affecting solute concentrations came up: production through subsurface reactions and weathering, and export or removal through river discharge.
Hicks, N.M., Li, L., Stewart, B., Underwood, K.L., Ul Haq, I., Kincaid, D.W., Lowman, L., Shanley, J.B., Seybold, E.C., Cable, B., Perdrial, J.N., Impact of changes in water availability on water quality: a data-driven investigation of Critical Zone subsurface and vegetation interactions. Poster. AGU Fall meeting. San Francisco, CA 11-15 December 2023.
Niara Hick’s MS thesis is building on this work and investigates how bedrock and vegetation characteristics might modulate the strong climate control on river water quality at the same scale. She is using CAMELS-Chem as well in a combination of deductive, hypotheses driven approaches and iterates with inductive, data driven work.
Kincaid, D.W, Underwood, K.L., Hamshaw, S.D., Li, L., Seybold, E.C., Stewart, B., Rizzo, D.M., Ul Haq, I., Perdrial, J.N. (accepted). Solute Export Patterns Across the Contiguous United States. Hydrological processes.
​In work led by Dustin Kincaid (USGS) we use a dominantly inductive approach to generate hypotheses on solute behavior across the CONUS. Applying Bayesian segmented regression on concentration and discharge for 11 solutes from CAMELS-Chem we identified thresholds and distinct patterns in solute behavior, shedding light on the complexity of solute transport in streams and rivers. 
Cable, B., Bloom, E., Perdrial, N., Treto, V., Underwood, K., Shanley, J.B., Hicks, N.M., Li. L., Kincaid, D.W., Richardson, J.B., Seybold, E.C., Stewart, B., Vierbicher, A., Rice, A., Perdrial, J.N., Disturbances, Resilience, and the Role of Calcium-Bearing Minerals Weathering in Northeastern Forests. Poster, AGU Fall meeting. San Francisco, CA 11-15 December 2023.
​Bren Cable uses a deductive approach for her MS thesis, where hypotheses drive her work on the role of historical acid deposition, logging, weathering of calcium bearing minerals. To test her hypotheses, she uses a combination of soil core experiments, geochemical modeling and field weathering experiments with mesh bags at several sites in collaboration with Justin Richardson and Nico Perdrial. These results can then support interpretation of large-scale patterns observed in other studies. 
Armfield, J., Perdrial, J.N., Gagnon, A., Ehrenkranz, J., Perdrial, N., Cincotta, M., Ross, D., Shanley, J., Underwood, K., Ryan, P. (2019). Does stream water composition at Sleepers River in Vermont reflect dynamic changes in soils during recovery from acidification? Frontiers in Earth Science: Biogeosciences.https://doi.org/10.3389/feart.2018.00246. 
​Speaking about calcium, this study by MS student Jesse Armfield looked at a variety of long-term data (1991–2015) from soils, ground water and streams from the Sleepers River Research Watershed in northeastern Vermont. He found a strong connection between soil base cation decline, particularly calcium (Ca), over time, while DOC and Ca in the stream increased, likely due to lateral transfer and leaching of legacy Ca from riparian zones, and emphasizes that separating organic and inorganic solutes (as I have done for this webpage) does not quite make sense.