Landscape variability of riparian buffers and its impact on soil and water chemistry of an urbanized watershed

Authors: JAJA, NGOWARI - Orise Fellow; Codling, Eton; MBILA, MONDAY - Alabama A & M University; Tsegaye, Teferi; ODUTOLA, JAMIU - Alabama A & M University

Submitted to: Ecological Indicators
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2022
Publication Date: 3/19/2022
Citation: Jaja, N., Codling, E.E., Mbila, M., Tsegaye, T.D., Odutola, J. 2022. Landscape variability of riparian buffers and its impact on soil and water chemistry of an urbanized watershed. Ecological Indicators. https://doi.org/10.1016/j.ecolind.2022.108777.
DOI: https://doi.org/10.1016/j.ecolind.2022.108777

Interpretive Summary: The distribution and transport of water and sediment around drainage pathways affects the soil chemistry and water quality within watersheds. This problem is exacerbated with watersheds in an urban region which generates runoff and sediments from agricultural and industrial chemicals ending up in the drainage ways. This study estimated the different landforms and patterns of Aldridge Creek Watershed in Alabama and their impact on the water quality and soil properties of the watershed. Soil and water samples were collected from upstream, midstream, and downstream sites and analyzed for trace metals and distributions based on the differences of the landscape. Trace heavy metal concentrations were greater in the riparian zone locations than in the upper slope soils and the stream. There was also a significant difference in the distribution of trace metals in soils between the upslope and riparian zone locations at the upstream, midstream, and downstream sites, but no significant difference in stream water trace metals concentration between the sites of the watershed.

Technical Abstract: Water and sediment transport, and redistribution around drainage ways are major riparian zone processes that affect soil chemistry and water quality of watersheds. Urbanized watersheds generate large amounts of runoff and sediments containing toxic and polluting substances which end up in the drainage ways. This study was done to evaluate the pedogeomorphic variability of the Aldridge Creek Watershed in Alabama, and to assess its impact on the water quality and soil properties of the watershed. Sampling locations along the creek were subdivided into five stream sites and geo-referenced. Soil samples from the riparian buffers and water samples from the creek were collected from upstream, midstream, and downstream sites of the watershed and analyzed for trace metal concentration and distribution. The trace metal concentration in soils of the riparian buffers varied from 20 to 34 µg g-1 for lead (Pb), 50 -85 µg g-1 for zinc (Zn), 6 -17 µg g-1 for copper (Cu), 11 -18 µg g-1 for nickel (Ni) and 5 -21 µg g-1 for arsenic (As). At all sites, Pb, Zn, Ni, Cu and As concentrations in the riparian zone locations were 7 -67% higher than the upper slopes indicating that the riparian zone is a potential source or sink of trace metals along the flow pathways between the upper slope soils and the stream. While there were significant differences in the distribution of trace metals in soils between the upslope and riparian zone locations at the upstream, midstream, and downstream sites, there was no significant difference in the stream water trace metals concentration between the sites of the watershed.