Masters Theses

Date of Award

8-2017

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering

Major Professor

Andrea L. Ludwig

Committee Members

Daniel C. Yoder, John R. Buchanan, Qiang He

Abstract

The United States Environmental Protection Agency (USEPA) reports that over 40% of waters nationwide are affected by non-point sources pollutant (NPS). Agricultural runoff has been shown to cause harmful algal blooms and ecological degradation in coastal estuaries and water sources. In order to treat and prevent pollution from agricultural runoff, many best management practices (BMPs) have been developed and researched, including constructed wetlands.

This research had multiple objectives. Chapter 1 presents work conducted to gain better understand constructed wetlands as a BMP for agricultural runoff, through: 1) Quantifying the performance of two wetlands in terms of event-scale runoff sediment reduction and nutrient attenuation, and 2) Identifying the relationship between wetland attenuation performance, and inflow runoff characteristics including volume, pollutant loads, 3) Assessing the need for water quality protection best management practices on an East Tennessee dairy farm and neighboring crop farm.

Chapter 2 presents work conducted to gain a better understanding of the transport properties of pollutants generated from agricultural land by: 1) to detect the strength of first flush effects among potential pollutants from basins draining to constructed stormwater treatment wetlands, 2) identifying how environmental parameters of rainfall intensity, flow duration, and dry periods influence pollutant first flush effects, and 3) Identifying the relationship between wetland attenuation performance, and first flush coefficient.

There were several overarching findings from this research: 1) TSS and ammonia were significantly attenuated at the event scale in both wetlands sampled during this study. 2) TSS attenuation showed a positive correlation with inflow pollutant loads, while total phosphorus attenuation was negatively correlated. 3) Particulate pollutants tend to have a stronger first flush effect, compared to non-particulate nutrients. 4) Particulate pollutant first flush effects differed between sites, which could be attributed to differences in catchment land use. 5) TSS showed a negative correlation between the first flush effects and pollutant attenuation.

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