The development and application of DNA-encapsulated nanoparticle tracers in hydrological studies

The field of hydrological tracers has the availability of a limited amount of different unique tracers which are typically fluorescent dyes and salts. This hinders multi-tracer experiments which preferably consist of tracers with identical behaviour. This is particularly true when tracing colloids and nano-particles in the hydrological system. We aim to develop a range of environmental friendly, easily recoverable hydrological nanoparticle tracers with encapsulated DNA. The underlying hypothesis is to use DNA as a fingerprint for the tracers which would enable to synthesize virtually unlimited number of tracers, each carrying a specific DNA sequence. DNA use in low concentrations is non-toxic to flora and fauna, therefore, is environmentally safe. As a result, a more enhanced insight about temporal and spatial variation in water, contaminant and colloid pathways in hydrological systems can be obtained.

We use a set of encapsulated DNA-tagged NP with different cores and surface characteristics in range of 100-300 nm. For easy separation and qPCR analysis of tracers downstream, we use magnetic fields for up-concentration, which requires the synthesis of magnetic tracers. Magnetic nanoparticles (NPs) synthesized using co-precipitation results in water-based polydisperse suspension. On the other hand, thermal decomposition provides precise control over particle size, shape and distribution producing highly magnetic monodisperse NPs.

We developed protocols to use these novel tracers in hydrological studies; from pore-scale laboratory experiments, column experiments using undisturbed natural soils, hillslope experiments and surface water applications. An overview of our results in lab, soil, hillslope and surface water will be presented, discussing the applicability, limitations and further developments. With this overview of our results we aim to bring this novel NP tracer and the developed protocols to the hydrological and geoscience community to apply in their field of interest.

WaterTagging team (Bahareh Kianfar, Yuchen Tang, Swagatam Chakraborty, Felix Nyarko, Zina Al Saffar, Bas Van der Zaan, Joachim Rozemeijer, Pieter Stuyfzand, Arnaut van Loon, Jesse Middelwijk, Jack Schijven)