267-7 Oxbow Lake Sediments and Two Centuries of Environmental Change in the Arkansas River Basin

Session: Advances in Fluvial Processes and Sediment Transport (Posters)

Poster Booth No.: 169

Presenting Author:

Charlotte Commons

Authors:

Commons, Charlotte¹, Chambers, Liv², Constantine, José Antonio³, Dethier, David P.⁴, Racela, Jay⁵, Landis, Joshua⁶, Munoz, Samuel⁷

(1) Geosciences, Williams College, Williamstown, MA, USA, (2) Geosciences, Williams College, Williamstown, MA, USA, (3) Geosciences, Williams College, Williamstown, MA, USA, (4) Geosciences, Williams College, Williamstown, MA, USA, (5) Environmental Studies, Williams College, Williamstown, MA, USA, (6) Earth Science, Dartmouth College, Hanover, NH, USA, (7) Marine and Environmental Sciences, Northeastern University, Boston, MA, USA,

Abstract:

Oxbow lakes provide valuable sedimentary archives of watershed-scale environmental change, particularly in large, engineered river systems. This study analyzes two sediment cores from Atkins Lake, an oxbow lake adjacent to the Arkansas River near Pine Bluff, Arkansas, to reconstruct environmental transformations associated with westward expansion, agricultural development, and river engineering over the past two centuries. Radioisotopic dating of the cores reveal a sharp increase in sedimentation rates from 0.09 cm/yr (908-1878), 1.6 cm/yr (1878–1938) to 5.6 cm/yr (1938–1963), followed by a decline to 0.73 cm/yr (1963–2018), trends consistent with historical deforestation, channel modification, and the sediment-trapping effects of dam construction under the McClellan-Kerr Arkansas River Navigation System. Grain size distributions, total organic content, and concentrations of heavy metals (Cu, Zn, Pb, Fe, Mn) were also measured. Metal concentrations increased by 27–115% relative to pre-settlement background levels, with Cu, Zn, and Fe elevated throughout much of the core; Pb remained below EPA sediment quality thresholds but showed a discernible rise from 1938. Together, these proxies indicate a strong anthropogenic imprint on sedimentation dynamics and contaminant delivery in the Arkansas River Basin. The consistency of patterns across both cores highlights the value of oxbow lakes as long-term integrators of landscape and riverine change, with implications for interpreting environmental responses to industrialization and land use transitions in similarly modified watersheds worldwide.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9457

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