Spatial and Temporal Controls on Denitrification in an Urban Riparian Zone
Open Access
- Author:
- Altamirano, Katherine
- Graduate Program:
- Ecology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- August 11, 2023
- Committee Members:
- Jason Kaye, Program Head/Chair
Jonathan M Duncan, Thesis Advisor/Co-Advisor
Lauren Mc Phillips, Committee Member
Erica A H Smithwick, Committee Member - Keywords:
- Denitrification
hot spot
hot moment
control point
urban riparian zone - Abstract:
- Humans have drastically altered the nitrogen cycle at global and regional scales through anthropogenic activities and influences on land use. As urbanization increases globally, anthropogenic inputs of nitrogen from burning fossil fuels, lawn care practices, and sanitary wastewater are heightened in cities and their surrounding areas. Despite this, urban watersheds in the Baltimore area remain highly retentive of nitrogen likely due to the presence of control points for denitrification. Nearby forested and agricultural watersheds are consistently more retentive of nitrogen across wet and dry years; with denitrification largely relying on landscape features in riparian soils. Stream incision and erosion of urban streams, however, has degraded these landscape features in urban watersheds and therefore removed many control points for denitrification from the watershed. Here, we examine the spatial and temporal controls on denitrification in contrasting riparian locations to estimate high-frequency denitrification rates. Soil oxygen and soil moisture data were collected from four riparian soil pits in the Dead Run watershed in Baltimore, MD that span gradients of upslope accumulated area, total upslope impervious surface area, and downslope riparian incision. Soil cores were collected seasonally and analyzed to determine rates of denitrification at each riparian location. The objectives of this research are to (1) identify control points for denitrification across a heterogeneous urban riparian zone and (2) determine the characteristics of an urban riparian zone that are limiting denitrification.