Title: Chemical gradients shape the transport of colloids and bacteria in complex flows

Author (Talk): Amir Pahlavan, Yale University

Abstract:

Chemical gradients are ubiquitous across diverse environmental flows, from oceanic waters to soils and subsurface aquifers. In marine environments, organic particles known as marine snow generate chemical plumes that attract chemotactic bacteria, enabling them to colonize these nutrient-rich aggregates and subsequently influence their settling and degradation dynamics. Similarly, in soil and groundwater systems, gradients arising from natural biochemical reactions or anthropogenic contaminants, such as pesticides, significantly alter the transport behaviors of pathogens and microplastics, with implications for soil health and ecosystem stability. Despite their prevalence, our fundamental understanding of how chemical gradients modulate the transport dynamics of colloids and bacteria remains limited. In this talk, I will share our recent progress from laboratory experiments, computational simulations, and theoretical analyses that reveal key mechanisms underlying these transport phenomena.