Is Land-Applying Biosolids to Agricultural Areas “Sustainable”? Part One: Assessing the Potential Chronic, Sublethal and Lethal Ecotoxicity of Biosolids on Folsomia Candida and Lumbricus Terrestris.

Abstract The ecotoxicity of biosolids has been studied extensively using single-compound toxicity testing and ‘spiking’ studies; however, little knowledge exists on the ecotoxicity of biosolids as they are land-applied in the Canadian context. The purpose of this study is to elucidate the chronic, sublethal (i.e., behavioural), and lethal impacts of land- applying biosolids on the environmentally-relevant Folsomia candida (springtails) and Lumbricus terrestris (earthworms) and concomitantly ascertain whether the use of biosolids for nutrient amendment is a sustainable practice. This study is part of a larger multi-compartment program which includes terrestrial plants and aquatic arthropods. After an extensive review of government protocols and existing research in the literature, the current study attempted to elucidate the true nature of the potential ecotoxicity of land-applying biosolids, within a laboratory context. Protocols were developed or modified (e.g., using Evans’ boxes (Evans 1947) for chronic and sublethal testing on L. terrestris). Subsequently, two biosolids were tested on springtails and earthworms using avoidance and reproductive bioassay endpoints, at application rates that are standard (8 tonnes ha-1) and worst-case scenarios (22 tonnes ha-1). Results indicated no effect of biosolids at the environmentally-relevant concentration; the worst-case scenario exhibited a positive significantly significant relationship (indicating preference for treatment conditions). We suggest that further assessment of the potential ecotoxicological impact of biosolids employ i) environmentally-relevant organisms, ii) appropriate bioassays including the use of whole-organism endpoints, and iii) multi-kingdom testing (e.g., Kingdom Plantae, Animalia) to comprehensively elucidate answers. Lastly, in situ (field assays) are strongly encouraged in future studies.