Repository logo
 

In-reservoir transformation of dissolved organic matter as a function of hydrological flow

Date

2024-01

Authors

Imtiazy, Md Noim
Hunter, Kristine
Hudson, Jeff J

Journal Title

Journal ISSN

Volume Title

Publisher

Journal of Environmental Management

ORCID

Type

Article

Degree Level

Abstract

Reservoirs are vital to meet the ever-increasing demands for freshwater in a warming climate. Dissolved organic matter (DOM) represents an important pool of carbon and can be a major concern in drinking water sources. However, insights into DOM dynamics in temperate, semi-arid reservoirs remain limited. Therefore, we investigated the variations in DOM properties in Lake Diefenbaker, a large reservoir on the Canadian Prairies, by analyzing eight years of DOM concentrations and composition through linear mixed effect modeling. Contrary to expectations, reservoir dissolved organic carbon (DOC) concentration showed no correlation with inflow from the South Saskatchewan River (p = 0.12), while dissolved organic nitrogen (DON) increased with decreasing inflow (p = 0.002). DOM optical indices (SUVA254 and E4:E6 ratio) and DOC:DON ratio revealed a pronounced influence of inflow on reservoir DOM composition (p < 0.001), i.e., allochthonous characteristics increased with increasing flow, and autochthonous characteristics increased with declining flow. Travel time corrected comparison of approximately the same water parcel along the reservoir length revealed that increasing water residence time in downstream regions led to a significant transformation in DOM composition, favoring autochthonous characteristics (mean SUVA254 reduced by 0.52 L mg-C−1 m−1, and the E4:E6 and spectral slope ratio increased by 1.6 and 0.06, respectively). Autochthonous DOC inputs likely offset the allochthonous DOC losses, which resulted in a relatively stable DOC concentration throughout the reservoir (mean 3.7 mg L−1). Additionally, the effect of a large aquaculture operation on reservoir DOM properties was investigated, but no effect was detected. The results have significant implications for managing large river-reservoirs. Autochthonous DOM poses challenges to water processing, necessitating monitoring of DOM composition for reservoir drinking water quality. Insights on climate-induced changes in DOM properties will also assist with understanding changes to habitat conditions and contaminant transport.

Description

Keywords

River-reservoir, Dissolved organic carbon, Dissolved organic nitrogen, Water residence time, Longitudinal zonation concept, Autochthonous input

Citation

Imtiazy, M. N., Hunter, K., & Hudson, J. J. (2024). In-reservoir transformation of dissolved organic matter as a function of hydrological flow. Journal of Environmental Management, 352, https://doi.org/10.1016/j.jenvman.2024.120099

Degree

Department

Program

Advisor

Committee

Part Of

item.page.relation.ispartofseries

DOI

https://doi.org/10.1016/j.jenvman.2024.120099

item.page.identifier.pmid

item.page.identifier.pmcid