## Effect of Sampling Design on Characterizing Surface Soil Fingerprinting Properties

Maria A Luna Miño1, Alexander J Koiter*2 and David A Lobb3

*corresponding author

2Brandon University, Masters in Environmental and Life Sciences
270 18th St, Brandon, MB Canada, R7A 6A9
ORCID: 0009-0004-3739-5103

2Brandon University, Department of Geography & Environment
270 18th St, Brandon, MB Canada, R7A 6A9
email: koitera@brandonu.ca
ORCID: 0000-0002-9355-9561

3University of Manitoba, Department of Soil Science
13 Freedman Crescent, Winnipeg, MB Canada, R3T 2N2
ORCID: 0000-0003-1059-8715

This manuscript has been submitted for peer-reviewed at the Journal of Soils and Sediments. A preview of the manuscript, including notebooks for analysis, can be found at https://alexkoiter.ca/sampling-design-manuscript/

## Abstract

Purpose: The characterization of soil properties is an important part of many different types of agri-environmental research including inventory, comparison, and manipulation studies. Sediment source fingerprinting is a method that is increasingly being used to link sediment sources to downstream sediment. There is currently not a standard approach to characterizing sources and the different approaches to sampling have not been well assessed.

Methods: Grid (n=49), transect (n=14), and likely to erode (n=8) sampling designs were used to characterize the geochemical, colour, grain size distribution, and soil organic matter content at two sites under contrasting land uses (agricultural and forested). The impact of the three sampling designs on characterization of fingerprint properties, the relationship between particle size and organic matter content on fingerprint properties, fingerprint selection, source discrimination, and mixing apportionment results were evaluated using a range of methods including 21 virtual mixtures.

Results: The likely to erode design resulted in a unique fingerprint signature compared to the other two sampling designs. The correlation between particle size and organic matter on fingerprint properties varied between fingerprint, source, and sampling design. While the number and composition of the fingerprints selected varied between sampling designs there was strong (100%) discrimination between sources regardless of the sampling approach. The maximum absolute difference between the virtual mixtures and the modeled proportions was 7.7, 7.8, and 8.9% for the grid, transect, and likely to erode sampling designs, respectively.

Conclusions: The likely to erode sampling design was not representative of the upslope areas as characterized by the grid and transect methods. Despite these differences the final apportionment results using virtual mixtures were qualitatively similar between the three sampling designs. Continued work at the watershed scale is needed to fully evaluate the importance of source sampling design on the sediment source fingerprinting approach.