Technical note: Comparison of radiometric techniques for estimating recent organic carbon sequestration rates in inland wetland soils

For wetlands to serve as natural climate solutions, accurate estimates of organic carbon (OC) sequestration rates in wetland sediments are needed. Dating using cesium-137 (137Cs) and lead-210 (210Pb) radioisotopes is commonly used for measuring OC sequestration rates in wetland sediments. 137Cs radi...

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Bibliographic Details
Published in:Biogeosciences 2024-10, Vol.21 (21), p.4699-4715
Main Authors: Mistry, Purbasha, Creed, Irena F, Trick, Charles G, Enanga, Eric, Lobb, David A
Format: Article
Language:English
Subjects:
Caesium
Caesium 137
Carbon sequestration
Cesium
Cesium 137
Cesium isotopes
Cesium radioisotopes
Climate change
Comparative analysis
Cores
Dating
Fallout
Homogenization
Lead isotopes
Methods
Nuclear accidents & safety
Organic carbon
Organic soils
Plating
Radioisotopes
Sample size
Scientific imaging
Sediment
Sedimentation & deposition
Sedimentation rates
Sediments
Sediments (Geology)
Soils
Wetland soils
Wetlands
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Summary:For wetlands to serve as natural climate solutions, accurate estimates of organic carbon (OC) sequestration rates in wetland sediments are needed. Dating using cesium-137 (137Cs) and lead-210 (210Pb) radioisotopes is commonly used for measuring OC sequestration rates in wetland sediments. 137Cs radioisotope dating is relatively simple, with calculations based on a single point representing the onset (1954) or peak (1963) of the 137Cs fallout. 210Pb radioisotope dating is more complex, as the calculations are based on multiple points. Here, we show that reliable dating of sediment cores collected from wetlands can be achieved using either 137Cs or 210Pb dating or their combination. However, 137Cs and 210Pb profiles along the depth of sediment cores need to be screened, analyzed, and interpreted carefully to estimate OC sequestration rates with high precision. To this end, we propose a decision framework for screening 137Cs and 210Pb profiles into high- and low-quality sediment profiles, and we compare dating using the 1954 and 1963 time markers, i.e., the rates of sedimentation and, consequently, OC sequestration over the past ∼ 60 years. Our findings suggest that 137Cs- and 210Pb-based OC sequestration rates are comparable, especially when using the 1963 (vs. 1954) time marker.
ISSN:1726-4189
1726-4170
1726-4189
DOI:10.5194/bg-21-4699-2024