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Identifying geochemical hot moments and their controls on a contaminated river floodplain system using wavelet and entropy approaches

Author:
Arora, Bhavna, Dwivedi, Dipankar, Hubbard, Susan S., Steefel, Carl I., Williams, Kenneth H.
Source:
Environmental modelling & software 2016 v.85 pp. 27-41
ISSN:
1364-8152
Subject:
aquifers, computer software, entropy, environmental models, floodplains, groundwater contamination, hydrologic cycle, rivers, temporal variation, wavelet, weather
Abstract:
Geochemical hot moments are defined here as short periods of time that are associated with disproportionally high levels of concentrations (biogeochemically-driven or transport-related) relative to longer intervening time periods. We used entropy and wavelet techniques to identify temporal variability in geochemical constituents and their controls along three transects within a contaminated floodplain system near Rifle CO. Results indicated that transport-dominated hot moments drove overall geochemical processing in the contaminated groundwater and seep zones. These hot moments were associated with seasonal hydrologic variability (∼4 months) in the contaminated aquifer and with annual hydrologic cycle and residence times in the seep zone. Hot moments associated with a naturally reduced zone within the aquifer were found to be biogeochemically-driven, with a different dominant frequency (∼3 months) and no correlation to hydrologic or weather variations, in contrast to what is observed in other regions of the floodplain.
Agid:
5575137