Three students, two undergraduate and one graduate, from the lab presented poster at the 2018 American Geophysical Union (AGU) meeting in Washington, DC. Ginny Jeppi and Patrick McMahon presented preliminary data on the effectiveness of the legacy sediment approach to stream restoration in reducing nutrient and sediment fluxes (funded by the Chesapeake Bay Trust). Melinda Marsh presented on concentration-discharge relationships in local urban streams (funded by NSF).
Additionally, Cassie Cosans (Ph.D. student at Johns Hopkins University [JHU] with Ciaran Harman) gave an oral presentation on which I was a co-author along with Ciaran and Maya Gomes (JHU).
Two undergraduate and one graduate student from the lab – Ginny Jeppi, Melinda Marsh, and Patrick McMahon – presented at the 2018 Annual meeting of the Maryland Water Monitoring Council. Ginny gave an oral presentation while Melinda and Patrick gave poster presentations. Ginny and Patrick presented data about a research project funded by the Chesapeake Bay Trust to assess the effectiveness of stream restoration in reducing nutrient and sediment fluxes. Melinda presented work funded by a NSF grant on concentration-discharge relationships in local urban streams.
I presented on some of my sabbatical research about using high-frequency specific conductance data from the USGS to quantify exceedences of EPA aquatic life criteria for chloride. Rosemary Fanelli from the USGS was my co-author.
Darcy Bird (’17 M.S.) published work on increasing major ion concentrations in urban streams in Environmental Science & Technology. The paper, entitled “Steady-state land cover but non-steady-state major ion chemistry in urban streams“, is based on her M.S. thesis work using samples and data from the Baltimore Ecosystem Study to investigate decadal-scale trends in major ion concentrations in urban streams.
Co-authors are Peter Groffman, Chris Salice, and me.
A major focus of my sabbatical research will be to use high-frequency conductivity data collected by the USGS and other agencies to better characterize how frequently and for how long the EPA ambient life criteria for chloride are exceeded in streams.
While nutrients, trace metals, and persistent organic molecules (e.g., PCBs and PAHs) have been studied extensively in urban streams, the processes that control the major ion chemistry (Ca, K, Mg, Na, dissolved inorganic carbon (DIC)/alkalinity, Cl, SO4, and dissolved silica) of urban streams are poorly understood. One major reason is that urban watersheds have many possible sources for major ions, and a second is that previous studies of major ion chemistry were in watersheds with mixed bedrock lithology, which meant contributions from weathering of carbonates could not be distinguished from urban sources. To date, total chemical fluxes for major ions have not yet been reported in the literature although fluxes have been calculated for subsets of these ions.
To determine the geochemistry of the urban built environment, we collected water samples from 5 small watersheds in the Maryland Piedmont that are arrayed along a forested to urban gradient with similar silicate bedrock chemistry and no significant point source discharges. The most urban watershed (~25% impervious surface area) had major ion concentrations that are 5 to 70 times higher than the forested reference watershed. Concentrations of all major ions increased along the gradient as impervious surface area increased, which has implications for bioavailability of metals and osmotic stresses on aquatic organisms. For example, the 50-fold increase in Ca concentrations resulted in much higher allowable levels of dissolved trace metals in urban streams when using the EPA hardness method to calculate the aquatic life criteria concentration.
The increase in major ion concentrations resulted in high weathering fluxes from the urban watersheds. The area-normalized weathering flux from the forested watershed was 80% lower than the global average, which is expected given the low-relief, tectonically quiescent landscape. The weathering flux for the most urban watershed was 13 times higher than the forested watershed and exceeded fluxes for mountainous watersheds in active orogenies. These results suggest that urban watersheds may be hotspots for chemical weathering.
Data about what motivates geoscience majors at Towson, particularly transfer students.
Broadening and improving transfer pathways for geoscience majors at a large comprehensive university
Joel Moore, Ron Hermann, Rommel Miranda, Kevin Wiechelt, and Kyle Hurley
The mismatch between the high demand for geoscience-trained employees and projections for geoscience graduates over the next decade is well documented. The focus of the NSF GP-EXTRA grant TU GEO Careers (Towson University Geoscience Educational Opportunities for Careers) is to meet this demand for geoscience while conducting research on the effectiveness of recruiting and retention methods.
The Geosciences program at TU is a small program (6 full-time faculty) in a large comprehensive university that offers 2 degrees: Geology and Earth-Space Science (for secondary education) and strongly supports the Geology track of Environmental Science. Two-thirds of current majors and of recent Geology graduates transferred to TU, mostly from community colleges in Maryland. One major emphasis of TU GEO Careers is to broaden and improve transfer pathways through development of articulation agreements and building strong connections with 2YC faculty. Results of these efforts will be reported along with survey data about student motivations and stumbling blocks for degree completion. Where possible, similarities and differences between ‘native’ students and transfer students will be explored. Initial results indicate that personal interest, cost of attendance, and media/books were the most important motivating factors for becoming a geosciences major. Continuing majors identified course content, interaction with other students, and faculty support and advising as important to continuing their degree progress while the most commonly identified stumbling block was course availability.
Graduate student Darcy Bird will be presenting at the 2016 GSA on her analysis of trends in anion concentration and measurement of cation concentrations on archived water samples from the Baltimore Ecosystem Project, Long-Term Ecological Research site. She’s using the USGS Weighted Regressions on Time, Discharge, and Season approach to make sense of the data and getting some really cool results!
Increasing major ion concentrations and changing ion ratios in urban streams over a 15-year period in Baltimore, MD
Darcy Bird, Peter Groffman, Joel Moore
A growing number of studies have shown that urban streams have relatively high major ion concentrations due to contributions from anthropogenic sources (e.g. road salts, fertilizer, concrete). While previous work has documented the differences in major ion chemistry between natural and urban streams, investigation of ion concentration changes in urban streams on the decadal scale is sparse. We used anion data from 1999–2012 from 4 watersheds in the Baltimore Ecosystem Study (BES) and the new USGS water chemistry analysis tool Weighted Regressions on Time, Discharge, and Season (WRTDS) to analyze multi-year trends in ion chemistry. The 4 watersheds lie along a forested to urban gradient, are underlain by felsic bedrock, and have experienced little change in land use and land cover over the study period. The forested watershed had constant Cl– (~2.5 mg/L) concentrations while median annual concentrations increased in the two urban watersheds from 29 to 84 and 73 to 110 mg/L. SO42- concentrations decreased somewhat in all watersheds. Ca2+, Mg2+, and Na+ are also elevated and increasing over time in urban watersheds. Na+/Cl- ratios at the reference site were close to 1, while developed watersheds had lower Na+/Cl- ratios, an indicator of cation exchange processes retarding Na+ movement through the watersheds. The observed changes suggest that urban land use including concrete weathering and application of road salt increased anion (Cl–) and cation (Ca2+, Mg2+, Na+) concentrations, and the use of road salts (NaCl) altered exchange processes in streams leading to different Na+/Cl– ratios in forested and urban streams.