DRIVERS AND CONTROLS OF SALINIZATION IN SMALL FARM PONDS

Small farm ponds are naturally occurring (wetlands) or artificially constructed (dugouts) reservoirs that store water for various agricultural purposes. These ponds trap a suite of substances including sulphate (SO₄^2-). High SO₄^2- suppresses methane production and contributes positively to climate change mitigation, but it is also considered toxic, as it enhances salinization and impacts aquatic ecosystem interactions, with adverse effects on livestock and human well-being. This research explores opportunities to predict SO₄^2- dynamics in ponds by assessing several physical, chemical and biological features to identify key drivers and controls of SO₄^2- in ponds. Forty (40) ponds with SO₄^2- concentrations ranging from 0.3 mg/L to 24637.0 mg/L were studied in Saskatchewan, Canada during the summer months (May to August) of 2021, 2022 and 2023.  Evidence of higher SO₄^2- levels in sediment suggests that spatially, SO₄^2-  is more concentrated at the pond bottom (5675 ± 4083.4 mg/L) relative to water column (838.0 ± 1933.7 mg/L) and upland soils (1120.2 ± 2062.0 mg/L), suggesting that dredging may be useful in controlling SO₄^2- in ageing ponds. Generalized Linear Models indicate that pore SO₄^2- in upland soils is a key driver of pond SO₄^2- and vegetation serves as a potent control to its migration into ponds. While further work is required to unravel the complexities involved in the identified interactions, these findings highlight the opportunities that environmental features, particularly sediment, but also vegetation offer in addressing the classic issue of pond salinization.

Primary Presenter: Michael Mensah, University of Regina (mikemenz253@gmail.com)

Authors:

Michael Mensah, University of Regina  (mikemenz253@gmail.com)

Ryan Rimas, University of Regina  (ryanivanrimas@gmail.com)

Michael Lavender, University of Regina  (lmike92@gmail.com)

Kerri Finlay, University of Regina  (Kerri.Finlay@uregina.ca)