College of Science and Health Doctor of Nursing Practice (DNP) Project Theses and Dissertations

Date of Award

Winter 3-20-2022

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Mark Potosnak, PhD

Abstract

Road salt accumulation in the environment influences plants, soils, and surrounding ecosystem. From the use of chloride-based deicers, [Na+] and [Cl-] can be found in leaf tissue and have been shown to affect plant function negatively through reduced photosynthetic activity. Photosynthetic activity is an important plant function that drives plant health and is also linked to isoprene emissions. Certain plant genera emit isoprene, a biogenic volatile organic compound (BVOC) which produces tropospheric ozone and reduces regional air quality. Isoprene is emitted into the atmosphere by photosynthetic activity from leaves. Isoprene emissions from these plants are an indicator of plant health and function despite reducing regional air quality. Past research has shown that isoprene emissions are connected to photosynthetic activity. Salt stress reduces photosynthetic activity in leaves; however, it is not fully understood what effect road salts have on leaf-level isoprene emission. The purpose of this research is to determine if road salts suppress leaf-level isoprene emissions. We hypothesize [Na+] from road salt will suppress leaf-level isoprene emissions since salt stress can act like drought stress, and drought stress can suppress isoprene emissions. This project consisted of field measurements and two growth chamber experiments. For the field measurements, ten suitable field sites from Cook and Lake County Forest Preserves were determined. Five sites had relatively lower salinity index [Na+] (non-road) and the other five sites had relatively higher salinity index and were more exposed to road salt (near-road). Leaf-level isoprene emission and photosynthesis rates from the ten selected field sites were measured in situ to test for a difference between the non-road and near-road sites. There was no significant between the sites for photosynthetic rates and isoprene. In the laboratory, velvet bean plants (Mucuna pruriens) grown from seed were salt-stressed in growth chambers. Leaf-level isoprene emissions and photosynthetic rates were used to test for a difference between treated and control pot. There was no significant difference between the treated and control pots for photosynthetic rates and isoprene. Unfortunately, COVID-19 limited some of the tests in the field and lab measurements leaf and soil [Na+] and [Cl-], not allowing us to test the hypothesis fully. With the results we completed, we failed to reject the null hypothesis and observed no impact of road salt application on photosynthetic or isoprene emission rates.

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