Agricultural activities lead to sediment infilling of wetlandscapes in the Canadian Prairies: Assessment of soil erosion and sedimentation fluxes

Technical Note: Comparison of radiometric techniques for estimating recent organic carbon sequestration rates in freshwater mineral soil wetlands

“…137 natural radioactive decay, with the 137 Cs 30-year half-life reducing the peak size over time, and ( 2) peak attenuation due to physical, chemical, or biological reasons (Drexler et al 2018). The declining 137 Cs activity limits its applicability as a radioisotope dating tool; however, recent studies have reported adequate 137 Cs reference inventories for Canadian landscapes (Sutherland, 1991;Kachanoski and Von Bertoldi, 1996;Li et al, 2008;Mabit et al, 2014;Zarrinabadi et al, 2023). In addition, the use of 137 Cs inventory for dating to complement the peak has addressed the potential inadequacies that could be attributed to declining peak resolution with the passage of time.…”

“…The cutoff cumulative 137 Cs inventory value of 500 Bq m -2 was established by assessing the 137 Cs reference inventory value, the value of 137 Cs present in a non-eroded system with an undisturbed profile. The 137 Cs reference inventory value differs from region to region (Owens and Walling, 1996), and the most proximal regional value was used to select the cutoff 137 Cs inventory value (Sutherland, 1991;Kachanoski and Von Bertoldi, 1996;Zarrinabadi et al, 2023). The 137 Cs reference inventory is a catchment-wide reference value and not specific to the wetland center; thus, the cumulative…”

“…A potential weakness of 137 Cs radioisotope dating arises from the challenges in interpreting the disturbed 1963 peak. The noise in the 1963 peak in wetlands on agricultural landscapes can be due to redistribution of sediments since wetlands are susceptible to receiving a large mass of sediments resulting from various erosional processes due to their positioning within the landscape (Lobb et al, 2011;Zarrinabadi et al, 2023). Soil erosion resulting from wind, water, and/or tillage can lead to higher or lower 137 Cs levels (Li et al, 2010;Foucher et al, 2021;Zarrinabadi et al, 2023) in wetlands in agricultural landscapes.…”

“…The noise in the 1963 peak in wetlands on agricultural landscapes can be due to redistribution of sediments since wetlands are susceptible to receiving a large mass of sediments resulting from various erosional processes due to their positioning within the landscape (Lobb et al, 2011;Zarrinabadi et al, 2023). Soil erosion resulting from wind, water, and/or tillage can lead to higher or lower 137 Cs levels (Li et al, 2010;Foucher et al, 2021;Zarrinabadi et al, 2023) in wetlands in agricultural landscapes. If 137 Cs enriched soil from the surrounding landscape gets deposited on top of the original soil layer in the wetland, then it can lead to an increased 137 Cs inventory value (Walling and Quine, 1991;Li et al, 2010).…”

“…A cutoff cumulative 137 Cs inventory value can be useful in excluding questionable profiles. The range of 137 Cs reference inventory values from previous erosion studies within the study area (e.g., Sutherland, 1991;Kachanoski and Von Bertoldi, 1996;Zarrinabadi et al 2023) can help in establishing and setting the cutoff cumulative 137 Cs inventory value. The mean 137 Cs reference inventory values in the four provinces of Canada where our wetland sites are located are 1,684 Bq m -2…”