Presentation Title

Testing the effect of solution pH and ionic strength on dissolved organic matter leaching from soils

Presenter's Name(s)

Lindsey M. StinsonFollow

Project Collaborators

"Thomas Adler (Graduate Student Mentor)" "Jamie Shanley (Collaborating Mentor)" "Andrea Lini (Collaborating Mentor)" "Julia Perdrial (Principal Investigator)"

Abstract

Dissolved organic carbon (DOC) can increase the transport of trace metals and other pollutants, complicate water treatment, and cause potentially significant imbalances in aquatic ecosystems. Therefore, the mobilization of DOC is an increasingly studied topic. Considering soils are a major contributor of DOC to streams, processes that mobilize DOC from soils warrant further attention. In particular, soil aggregates that are sensitive to changes in soil solution chemistry may be an important source of carbon and areas that have been affected by acidification, like the NE US, may be especially of importance to study. We specifically hypothesize that i) DOC mobilization is in part controlled by soil aggregate stability, ii) soil aggregates destabilize under changing pH and ionic strength (IS) conditions of precipitation and iii) that these effects are dependent on the topography.

Soil samples were collected from Sleepers River Research Watershed (SRRW) in the forested W-9 catchment at various landscape positions. A batch experiment was conducted to test the three treatment solutions, which included a control (low IS, low pH), acidification (low pH, high IS), and recovery (neutral pH, low IS). The solutions were tested for cation, anion, and DOC concentrations, and SEM imaging was taken of aggregates to form a visualization of the effects of treatment.

Preliminary results have shown significant differences in DOC concentrations across treatments and test sites, as revealed through Kruskal-Wallis analyses. Specifically, ionic strength of solutions seems to account for significant differences, as more DOC was released from the recovery solution (2.03ppm±1.05) than the control (1.51ppm±0.72) and acidification (1.08ppm±0.42). This allows for early speculation that cation bridging may have the greatest effect on DOC release and deaggregation.

Primary Faculty Mentor Name

Julia Perdrial

Graduate Student Mentors

Thomas Adler

Status

Undergraduate

Student College

College of Arts and Sciences

Program/Major

Chemistry

Primary Research Category

Engineering & Physical Sciences

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Testing the effect of solution pH and ionic strength on dissolved organic matter leaching from soils

Dissolved organic carbon (DOC) can increase the transport of trace metals and other pollutants, complicate water treatment, and cause potentially significant imbalances in aquatic ecosystems. Therefore, the mobilization of DOC is an increasingly studied topic. Considering soils are a major contributor of DOC to streams, processes that mobilize DOC from soils warrant further attention. In particular, soil aggregates that are sensitive to changes in soil solution chemistry may be an important source of carbon and areas that have been affected by acidification, like the NE US, may be especially of importance to study. We specifically hypothesize that i) DOC mobilization is in part controlled by soil aggregate stability, ii) soil aggregates destabilize under changing pH and ionic strength (IS) conditions of precipitation and iii) that these effects are dependent on the topography.

Soil samples were collected from Sleepers River Research Watershed (SRRW) in the forested W-9 catchment at various landscape positions. A batch experiment was conducted to test the three treatment solutions, which included a control (low IS, low pH), acidification (low pH, high IS), and recovery (neutral pH, low IS). The solutions were tested for cation, anion, and DOC concentrations, and SEM imaging was taken of aggregates to form a visualization of the effects of treatment.

Preliminary results have shown significant differences in DOC concentrations across treatments and test sites, as revealed through Kruskal-Wallis analyses. Specifically, ionic strength of solutions seems to account for significant differences, as more DOC was released from the recovery solution (2.03ppm±1.05) than the control (1.51ppm±0.72) and acidification (1.08ppm±0.42). This allows for early speculation that cation bridging may have the greatest effect on DOC release and deaggregation.