Agricultural Water Efficiency and Salinity Research Unit
USDA-ARS US Salinity Laboratory
450 W Big Springs Rd
Riverside, CA 92507-4617

daniel.ashworth@usda.gov

Phone: (909) 845-2219

Dr. Daniel Ashworth is a research soil scientist at the USDA-ARS US Salinity Laboratory in Riverside, CA. Prior to this position, Dr. Ashworth conducted research at Imperial College London and at the University of California Riverside. He has over 25 years of experience working on the fate and transport of a variety of environmental contaminants such as heavy metals, radionuclides, pesticides, antibiotics, and per/poly-fluoroalkyl substances (PFAS).

Dr. Ashworth’s current research focuses on chemicals of emerging concern in agriculture: (i) understanding the transfers of antibiotics and PFAS from treated wastewater and manure/biosolids to soils and crops, (ii) mitigating these transfers using biochar as a soil amendment, and (iii) removing these compounds from treated wastewater using novel biochar-based filtration approaches. The overall goal of Dr. Ashworth’s research program is to reduce the human health risks of chemicals of emerging concern by understanding and mitigating their transfers into food chains.

Educational Background

Ph.D. – University of Reading, UK – Soil Science

M.S. – University of London, UK – Applied Environmental Science

B.S. – University of Plymouth, UK – Rural Resource Management

Recent Publications

1. Ramos P, Ashworth DJ. (2024) Per- and poly-fluoroalkyl substances in agricultural contexts and mitigation of their impacts using biochar: A review. Science of the Total Environment, 927:172275. https://doi.org/10.1016/j.scitotenv.2024.172275
2. Phan D, Bhattacharjee AS, Hanan D, Park S., Herrera D, Ashworth DJ, Schmidt M, Men Y, Ferreira JFS, Ibekwe AM. (2024) Dissemination of antimicrobial resistance in agricultural ecosystems following irrigation with treated municipal wastewater. Science of the Total Environment, 934:173288. https://doi.org/10.1016/j.scitotenv.2024.173288
3. Schmidt MP, Ashworth DJ, Ibekwe AM. (2024) Cephalexin interaction with biosolids-derived dissolved organic matter: binding mechanism and implications for adsorption by biochar and clay. Environmental Science: Water Research and Technology, 10: 949. https://doi.org/10.1039/D3EW00590A
4. Bhattacharjee AS, Phan D, Zheng C, Ashworth DJ, Schmidt M, Men Y, Ferreira JFS, Muir G, Hasan NA, Ibekwe AM. (2024). Dissemination of antibiotic resistance genes through soil-plant-earthworm continuum in the food production environment. Environment International, 183, 108374. https://doi.org/10.1016/j.envint.2023.108374
5. Ashworth DJ, Schmidt MP, Ibekwe AM. (2023) Performance of acid- and base-modified biochars for the removal of antibiotics from water under dynamic conditions. Journal of Environmental Chemical Engineering, 11, 111616. https://doi.org/10.1016/j.jece.2023.111616
6. Ibekwe AM, Bhattacharjee AS, Phan D, Ashworth DJ, Schmidt MP, Murinda S, Obayiuwana A, Murry MA, Schwartz G, Lundquist T, Ma J, Karathia H, Fanelli B, Hasan NA, Yang CH. (2023) Potential reservoirs of antimicrobial resistance in livestock waste and treated wastewater that can be disseminated to agricultural land. Science of the Total Environment, 872, 162194. https://doi.org/10.1016/j.scitotenv.2023.162194
7. Schmidt MP, Ashworth DJ, Celis N, Ibekwe AM. (2023) Optimizing date palm leaf and pistachio shell biochar properties for antibiotic adsorption by varying pyrolysis temperature. Bioresource Technology Reports, 21, 101325. https://doi.org/10.1016/j.biteb.2022.101325
8. Ashworth DJ, Ibekwe AM, Men Y, Ferreira JFS. (2023) Dissemination of antibiotics through the wastewater-soil-plant-earthworm continuum. Science of the Total Environment, 858,159841. https://doi.org/10.1016/j.scitotenv.2022.159841
9. Ashworth DJ, Ibekwe AM. (2020) System of multi-layered environmental media for the removal of antibiotics from wastewater. Journal of Environmental Chemical Engineering, 8, 104206. https://doi.org/10.1016/j.jece.2020.104206