Simulation of experimental synthetic DNA tracer transport through the vadose zone

Chaozi Wang; Geng Liu; Coy P McNew; Till Hannes Moritz Volkmann; Luke Pangle; Peter A Troch; Steven W Lyon; Minseok Kim; Zailin Huo; Helen E Dahlke

doi:10.1016/j.watres.2022.119009

Simulation of experimental synthetic DNA tracer transport through the vadose zone

Water Res. 2022 Sep 1:223:119009. doi: 10.1016/j.watres.2022.119009. Epub 2022 Aug 19.

Authors

Affiliations

¹ College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China; Department of Land, Air, and Water Resources, UC Davis, Davis, CA 95616, USA. Electronic address: chaoziwang@cau.edu.cn.
² College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China.
³ Department of Land, Air, and Water Resources, UC Davis, Davis, CA 95616, USA.
⁴ Biosphere2, University of Arizona, Oracle, AZ 85739, USA.
⁵ Department of Geosciences, Georgia State University, Atlanta, GA 30303, USA.
⁶ Biosphere2, University of Arizona, Oracle, AZ 85739, USA; Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA.
⁷ The Nature Conservancy Southern New Jersey Office, Delmont, NJ 08314, USA; Department of Physical Geography, Stockholm University, Stockholm, Sweden; School of Environment and Natural Resources, The Ohio State University, Columbus, OH, USA.
⁸ Biosphere2, University of Arizona, Oracle, AZ 85739, USA; Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
⁹ Department of Land, Air, and Water Resources, UC Davis, Davis, CA 95616, USA. Electronic address: hdahlke@ucdavis.edu.

PMID: 36037713
DOI: 10.1016/j.watres.2022.119009

Abstract

Although multiple experimental studies have proven the use of free synthetic DNA as tracers in hydrological systems, their quantitative fate and transport, especially through the vadose zone, is still not well understood. Here we simulate the water flow and breakthrough of deuterium (D) and one free synthetic DNA tracer from a 10-day experiment conducted in a transient variably saturated 1m³ 10° sloped lysimeter using the HYDRUS-2D software package. Recovery and breakthrough flux of D (97.78%) and the DNA tracer (1.05%) were captured well with the advection-dispersion equation (R² = 0.949, NSE = 0.937) and the Schijven and Šimůnek two-site kinetic sorption model recommended for virus transport modeling (R² = 0.824, NSE = 0.823), respectively. The degradation of the DNA tracer was very slow (estimated to be 10% in 10 days), because the "loamy sand" porous media in our lysimeter was freshly crushed basaltic tephra (i.e., crushed rocks) and the microbes and DNase that could potentially degrade DNA in regular soils were rare in our "loamy sand". The timing of the concentration peaks and the HYDRUS-2D simulated temporal and spatial distribution of DNA in the lysimeter both revealed the role of the solid-water-air contact lines in mobilizing and carrying DNA tracer under the experimental variably saturated transient flow condition. The free DNA was nearly non-selectively transported through the porous media, and showed a slightly early breakthrough, possibly due to a slight effect of anion exclusion or size exclusion. Our results indicate that free DNA have the potential to trace vadose zone water flow and solute/contaminant transport, and to serve as surrogates to trace viral pathogen pollution in soil-water systems. To our knowledge, this study is the first to simulate transport mechanisms of free synthetic DNA tracers through real soil textured porous media under variably saturated transient flow condition.

Keywords: HYDRUS-2D; Soil-water systems; Synthetic DNA tracer; Vadose zone; Variably saturated; Viral pathogen pollution.

MeSH terms

Deoxyribonucleases
Deuterium
Groundwater*
Models, Theoretical
Sand
Soil
Water
Water Movements*

Substances

Sand
Soil
Water
Deuterium
Deoxyribonucleases