Our mission is to deepen the understanding of the physical, chemical

and biological processes that regulate transport and fate of substances in soils.

Anomalous transport in porous media

Early or delayed arrival of solutes, which leads to poor mixing and long residence times, is a phenomenon known as ”anomalous transport”. Typical upscaling transport models attribute anomalous transport behavior to structures such as fractures. Nevertheless, anomalous transport has been observed even in highly homogeneous porous media, thus highlighting the multiscale complexity of transport mechanisms and our insufficient understanding of it. This work aims to establish formal relationships between structural features of the pore-space and the observed intensity of anomalous transport. 

Publications: Bolster et al., 2019Carrel et al., 2018Carrel et al., 2018; Carrel et al., 2017; Morales et al., 2017Holzner et al., 2015

Soil architecture effects on silver nano-litter filtration

Landfill and agricultural soils are expected to receive large loads of nano-silver (nAg) through land application of wastewater sludge. This puts beneficial soil-microbes at risk because nAg is an indiscriminate antimicrobial agent. The aims of this study are i) to assess the efficiency of interfaces within pores in immobilizing nAg for various typical moisture contents and chemistry conditions, and ii) determine how flow-induced aggregation contributes to immobilization of particles along the pore network.

Publications: Patiño et al., (In preparation); Perez et al., 2020.

Enhanced transport of colloids by dissolved organic matter

Transport of colloid contaminants is enhanced in soils amended with manure, but the mechanisms are not well understood. Results of this work indicate that organic matter from manure creates a hairy structure on the colloid surface, the so-called "corona". The hair length, density and electrostatic charge of this structure greatly alters the short-range forces that provide particles with stability. When the hairy layer is dense and uniform, the colloids are typically highly mobile. When the hairy layer is sparse the colloids become entangled and deposited. 

 

Publications: Hoang et al. (In preparation); Patiño et al., (Under review); Sang et al., 2014Wang et al., 2012Morales et al., 2011aMorales et al.,2011b

Drying drop dynamics

Evaporation deposition is a common phenomenon observed daily in coffee-stains, yet it is central to the microfabrication industry. This work provides a framework for controlling the shape and attachment strength of deposition stains with solutes. Specifically, we show that the addition of nonionic surfactant can be tuned to control (i) the surface tension of the drop, (ii) dynamics of the contact line during evaporation, (iii) colloid-substrate friction, (iv) morphology of deposited stains, and (v) attachment strength of stains.

 

Publications: Morales et al., 2013

Reverse engineering of Biochar

Biochar is a growingly popular biomass carbonization tool with wide-ranging agronomic and environmental gains. However, the benefits of adding biochar to a soil greatly depend on how it is produced, and the links between biochar properties and its production parameters are not well understood. To address this issue, this study built a meta-data library from which links between biochar properties and production parameters were statistically ascertained. Based on these relationships, the Biochar Engineering web-tool was constructed to help producers determine the optimal parameters needed to generate biochar that is tailored to mitigate specific soil deficiencies.

 

Publications: Morales et al., 2015; Zhang et al., 2010

 

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