Water Resources Research Act Program

Details for Project ID 2018MT326B

Student Research: Understanding root-microbe interactions in the rhizosphere

Institute: Montana
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $2,000 Total Non-Federal Funds: $880

Principal Investigators: Emma Raeside

Abstract: Treatment wetlands (TW) are an accepted method to remove a variety of contaminants from water polluted from a specific source. They are a low-energy low-cost alternative that harness natural biogeochemical processes uniquely inherent to wetland systems. In the USA, TW are used primarily for stormwater and metal-laden mining remediation settings (Stein et al. 2007, Beutel et al., 2009) yet in both the developing and developed world they are often the preferred alternative for municipal, domestic wastewater treatment systems. For example, there are now over 3000 TW systems treating municipal wastewater in France (Paing et al., 2015; Dotro et al. 2017). A continued impediment to broader application is a lack of fundamental understanding of how plant roots interact with the biofilm community in the surrounding rhizosphere, where the bulk of the pertinent biogeochemical transformations take place. In recent years, there has been a push to understand the processes within the rhizosphere more completely, rather than utilizing a black box approach to simply assess overall treatment efficiency (Faulwetter et al., 2009). Paradoxically, plant roots are the primary providers of the oxygen required for many desirable processes in the wetland subsurface (such as the removal of bio-degradable organics and nitrification) (Stein and Hook, 2007; Allen et al., 2013, 2017), but are also known to exude organic carbon required for other beneficial processes such as sulfate reduction and subsequent metal sequestration or denitrification (Zhai et al., 2013). The Wetland Research Group at MSU is developing methodologies to evaluate the net influence of oxygen and organic carbon inputs from roots on these degradation processes. The research described herein seeks to evaluate the influence of root oxygen release on the aerobic microbial degradation capacity of TW by creating a mechanism by which to measure in-situ dissolved oxygen gradients at and near the root surface using micro-scale electrodes. If successful, the methodologies developed can be used to evaluate gradients of other chemicals near the root surface.