Transport of silica encapsulated DNA microparticles in controlled instantaneous injection open channel experiments

Yuchen Tang,Jan Willem Foppen,Thom A Bogaard

doi:10.1016/j.jconhyd.2021.103880

Abstract

Surface water tracing is a widely used technique to investigate in-stream mass transport including contaminant migration. Recently, a microparticle tracer was developed with unique synthetic DNA encapsulated in an environmentally-friendly silica coating (Si-DNA microparticle). Previous tracing applications of such tracers reported detection and quantification, but a massive loss of tracer mass. However, the transport behavior of these DNA-tagged microparticle tracers has not been rigorously quantified and compared with that of solute tracers. Therefore, we compared the transport behavior of Si-DNA microparticles to the behavior of solute NaCl in 6 different, environmentally representative water types using breakthrough curves (BTCs), obtained from laboratory open channel injection experiments, whereby no Si-DNA microparticle tracer mass was lost. Hereafter, we modelled the BTCs using a 1-D advection-dispersion model with one transient storage zone (OTIS) by calibrating the hydrodynamic dispersion coefficient D and a storage zone exchange rate coefficient. We concluded that the transport behavior of Si-DNA microparticles resembled that of NaCl in surface-water relevant conditions, evidenced by BTCs with a similar range of D; however, the Si-DNA microparticle had a more erratic BTC than its solute counterpart, whereby the scatter increased as a function of water quality complexity. The overall larger confidence interval of DSi-DNA was attributed to the discrete nature of colloidal particles with a certain particle size distribution and possibly minor shear-induced aggregations. This research established a solid methodological foundation for field application of Si-DNA microparticles in surface water tracing, providing insight in transport behavior of equivalent sized and mass particles in rivers.

Highlights

Environmental pollution poses an unprecedented burden over sur face water quality and aquatic ecosystems
The zeta potential of the Si-DNA microparticles was between − 17 ± 7.1 mV and − 49.8 ± 5.9 mV, and the mean RhDLS was between ~237 ± 81 nm and ~ 299 ± 129 nm
In the quiescent condition and as a function of time, the mean RhDLS and PDI of Si-DNA microparticles remained constant for each water type (Fig. 2 a)

Summary

Introduction

Environmental pollution poses an unprecedented burden over sur face water quality and aquatic ecosystems. Particle tracers were used only in a few studies, e.g., micron-sized fluorescent microspheres, bac teriophages/bacteria, and natural clay/sediment particles (Goppert and Goldscheider, 2008; Jamieson et al, 2005; Schiperski et al, 2016; Spencer et al, 2011; Wyer et al, 2010) In these studies and as far as we know, particles smaller than ≤1 μm were only used once due to practical limitations (Goeppert and Goldscheider, 2019). Wang et al, 2015), and, when smaller than ~30 nm, their -limited- sizes may cause enhanced biological and chemical re activities (Auffan et al, 2009; Azimzada et al, 2021) These aquatic colloids include naturally occurring biocolloids (e.g., viruses, bacteria, extracellular polymeric substances, etc.), geocolloids (e.g., clay, metal oxides and hydroxides), anthropogenic engineered nanomaterials (e.g., titanium dioxide nanoparticles and carbon nanotubes) and microplastics Traditional tracer tests have several disadvantages: 1) a limited number of distinguishable artificial tracers is available, 2) tracer detections often have background noise with dilution limitations, and 3) practical constraints limit the application of a proper tracer (e.g., strict regulations for uranine or rhodamine or being very expensive like flu orobenzoic acid) (Bencala et al, 2011; Choi et al, 2000; Stern et al, 2001; Whitmer et al, 2000; Wilderer, 2011)

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