Impact of biochar on plant growth and uptake of ciprofloxacin, triclocarban and triclosan from biosolids

Abstract

Application of municipal biosolids in agriculture present a concern with potential uptake and bioaccumulation of pharmaceutical compounds from biosolids into agronomic plants. We evaluated the efficacy of biochar as a soil amendment to minimize uptake of antimicrobial agents (ciprofloxacin, triclocarban, and triclosan) in lettuce (Lactuca sativa) and carrot (Daucus carota) plants. Biochar reduced the concentration of ciprofloxacin and triclocarban in lettuce leaves and resulted in a 67% reduction of triclosan in carrot roots. There was no substantial difference in pharmaceutical concentrations in carrot and lettuce plant matter at low (2.0 g kg⁻¹ soil) and high (20.4 g kg⁻¹ soil) rates of applied biochar. The co-amendment of biochar and biosolids increased soil pH and nutrient content which were positively correlated with an increase in lettuce shoot biomass. Our results demonstrate the potential efficacy of using walnut shell biochar as a sorbent for pharmaceutical contaminants in soil without negatively affecting plant growth.

Keywords:

• Contaminant
• antimicrobial
• plant accumulation
• translocation
• soil amendment

Acknowledgements

We acknowledge support from the Lockeford Plant Materials Center for the collection of the soil used in the study. We would like to thank Adam C. Lynch for reviewing the manuscript and providing helpful suggestions. We also thank Sarah Hafner and Fungai Mukome for technical support and assistance. Project funding was provided by the National Institute of Environmental Health Sciences (NIEHS), grant number 5 P42 ES004699. NIH and the contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH. Additional funding was provided by the United States Department of Agriculture (USDA) National Institute of Food and Agriculture, Hatch Projects CA-2122-H and CA-2076-H and multistate regional projects W-2082 and W-3045. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the National Institute of Food and Agriculture (NIFA) or the USDA. In addition, funding was provided by the UC Davis Superfund Research Program (Superfund Research Grant and Graduate Student Researcher Traineeship), the UC Davis Soils and Biogeochemistry Block Grant and Henry A. Jastro Graduate Research Award.