Biosolids as a marsh restoration amendment

As concerns about sea-level rise mount, municipalities in coastal areas are looking to nature-based protection and adaptation. Oftentimes such projects are marsh creations or restorations, where areas of open water are filled with dredged material to an elevation where emergent vegetation can grow. We are investigating ways biosolids can be used as an amendment to dredged material to enhance project outcomes. Marsh mesocosms were constructed in San Francisco Bay and planted with native cordgrass, Spartina foliosa. Some mesocosms contained a subsurface layer of biosolids. Vegetation grown with biosolids had significantly increased number of new shoots, aboveground biomass, and belowground biomass. Vegetation with only dredged material had greater rooting depths but this result was not significant. By combining natural processes with human infrastructure, the application of biosolids for marsh creation is a sustainable practice.