Grant: Discovery Grants Program - Individual

Biosolids are municipal sewage solids that have undergone treatment to reduce or eliminate pathogens and chemical contaminants. Treatment approaches include: composting, anaerobic digestion, and alkaline stabilization. In reality, these treatments have different levels of effectiveness at removing novel or emerging contaminants such as microplastics or pharmaceutical drugs leading to potential environmental impacts when biosolids are land applied. As a result, large uncertainty exists regarding the long-term safety of land applying biosolids and no single chemical or biological indicator is able to determine the state of health of a biosolid amended soil. The long-term objective of my research program is to build science-based evidence on the impacts of using biosolids as soil amendments in food production systems. My research program has largely focused on soil chemistry, including nutrients and emerging contaminants, and impacts on specific soil biological indicators from two long-term research sites receiving biosolids. Current approaches in biosolids science typically aim to identify and quantify the myriad of potential chemical contaminants, such as ESOCs, microplastics, PFAS, but the high analytical cost and difficulty of measurement make this approach unwieldy. Moreover, policy and regulatory frameworks for disposal and management of biosolids in Canada would benefit more from having good indicators of health or contamination in receiving environments than just identifying what contaminants are present. In reality, so many different contaminants enter into wastewater treatment plants making source control almost impossible to achieve. The proposed research program is to develop integrated measures of biological indicators in soil, at micro- and meso-scales, that correlate to soil health or stress associated with long-term biosolids use in soils. Short-term objectives over the 5-year Discovery Grant will focus on evaluating how different types of biosolids, frequencies or rates of application, land use management approaches, and contaminants, such as microplastics, influence soil biological abundance, community structure, and function, i.e. mesofauna, microbiomes, by linking next generation genomic sequencing and mesofauna surveys and ecotoxicity testing. The research will address questions such as: How do soil biological indicators or end-points respond to biosolid applications with respect to their community structure, diversity, taxonomic composition, reproductive success? Are biological metrics, such as soil invertebrate diversity, earthworm assays, genomic tools, viable as indicators of environmental health and cost-effective to apply? Do these indicators respond to specific constituents associated with biosolids? If so, are we able to determine which ones? Do eco-toxicological assays, in microcosms or mesocosms, provide an opportunity to identify the mechanisms for the responses of biological or end-point indicators?