Onja Davidson Raoelison
Postdoctoral Scholar, Economics
Bio
Onja Davidson Raoelison is a Postdoctoral Fellow at the King Center on Global Development. Prior to joining Stanford, she earned her PhD in Environmental Engineering from the University of California, Los Angeles. She holds a joint MSc in Civil and Environmental Engineering from UCLA and in Civil Engineering from ESTP Paris, France.
Her overarching research focuses on the connection between wildfires, water quality, and human health, aiming to develop sustainable engineering solutions to mitigate the negative impacts of wildfires on water quality. Specifically, her research agenda at the Stanford Department of Medicine aims to understand how wildfires can increase the risk of waterborne infectious diseases due to their impact on microbial water quality.
Honors & Awards
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Outstanding Ph.D. Student in Civil and Environmental Engineering Award, UCLA (2024)
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Engineering Achievement Award for Student Welfare, UCLA (2024)
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ASCE Los Angeles Younger Member Forum Dr. Bill Goodin Outstanding Mentor Scholarship, American Society of Civil Engineers (2024)
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UCLA Dissertation Year Fellowship, UCLA (2023)
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UCLA Distinguished Teaching Award for Teaching Assistants, UCLA (2023)
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AWWA Woodard and Curran Scholarship, American Water Works Association (2023)
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CWEA Kirt Brooks Memorial Water Environment Scholarship, California Water Environment Association (2023)
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ESCSI John Ries Scholarship, Expanded Shale, Clay, and Slate Institute (2023)
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AEESP Travel Grant Award, Association of Environmental Engineering and Science Professors (2023)
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UCLA Civil and Environmental Engineering Martin Rubin Scholarship, UCLA (2022)
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SWE-LA Inaugural Graduate Academia Research Symposium, 2nd Place Winner, Society of Women Engineers (2022)
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SWE-LA Graduate Scholarship, Society of Women Engineers (2022)
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NSBE 49th National Convention, Elevator Pitch Competition, 1st place, National Society of Black Engineers (2022)
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NSBE Academic Improvement Scholarship, National Society of Black Engineers (2022)
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ASCE Los Angeles Section Outstanding Graduate Student Award, American Society of Civil Engineers (2022)
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ASCE Los Angeles Younger Member Forum Outstanding Graduate Student Award, American Society of Civil Engineers (2022)
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ASCE Le Val Lund Memorial Graduate Scholarship Award, American Society of Civil Engineers (2022)
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Society for the Advancement of Biology Education Research West CIRTL@UCLA Travel Award, UCLA (2022)
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NSBE Region VI Fall Regional Conference Technical Research Competition, 1st place, National Society of Black Engineers (2022)
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Affiliates Private Endowment Scholarship, UCLA (2022)
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ASCE International Women in Engineering Day Supporter Scholarship, American Society of Civil Engineers (2022)
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California Stormwater Quality Association Fellowship, California Stormwater Quality Association (2022)
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Malcolm R. Stacey Scholarship, UCLA (2022)
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AWWA Arcadis Scholarship, American Water Works Association (2022)
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UCLA GradSWE Empowerment Scholarship, Society of Women Engineers (2021)
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Cross-Campus Innovation Challenge in Sustainability, 2nd place, UCLA Anderson School of Management (2021)
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Los Angeles Urban Center Science Fellowship, Los Angeles Center for Urban Natural Resources Sustainability (2021)
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Summer Mentored Research Fellowship, UCLA (2020)
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ESTP Paris Fellowship, France (2016)
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Federation Nationale des Travaux Publics Fellowship, France (2016)
Boards, Advisory Committees, Professional Organizations
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Global Health Postdoctoral Affiliate, Center for Innovation in Global Health, Stanford University School of Medicine (2024 - Present)
Professional Education
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Ph.D., University of California, Los Angeles, Environmental Engineering (2024)
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M.S., University of California, Los Angeles, Civil & Environmental Engineering (2019)
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M.S., Ecole Speciale des Travaux Publics Paris, Civil Engineering (2019)
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B.S., Ecole Speciale des Travaux Publics Paris, Civil Engineering (2017)
Stanford Advisors
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Jason Andrews, Postdoctoral Research Mentor
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Katherine Casey, Postdoctoral Faculty Sponsor
https://orcid.org/0000-0001-6831-5090All Publications
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Resilience of stormwater biofilters following the deposition of wildfire residues: Implication on downstream water quality management in wildfire-prone regions.
Journal of hazardous materials
2024; 465: 132989
Abstract
Stormwater treatment systems such as biofilters could intercept and remove pollutants from contaminated runoff in wildfire-affected areas, ensuring the protection of water quality downstream. However, the deposition of wildfire residues such as ash and black carbon onto biofilters could potentially impair their stormwater treatment functions. Yet, whether and how wildfire residue deposition could affect biofilter functions is unknown. This study examines the impact of wildfire residue deposition on biofilter infiltration and pollutant removal capacities. Exposure to wildfire residues decreased the infiltration capacity based on the amount of wildfire deposited. Wildfire residues accumulated at the top layer of the biofilter, forming a cake layer, but scraping this layer restored the infiltration capacity. While the deposition of wildfire residues slightly changed the pore water geochemistry, it did not significantly alter the removal of metals and E. coli. Although wildfire residues leached some metals into pore water within the simulated root zone, the leached metals were effectively removed by the compost present in the filter media. Collectively, these results indicate that biofilters downstream of wildfire-prone areas could remain resilient or functional and protect downstream water quality if deposited ash is periodically scraped to restore any loss of infiltration capacity following wildfire residue deposition.
View details for DOI 10.1016/j.jhazmat.2023.132989
View details for PubMedID 38000283
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PFAS release from the subsurface and capillary fringe during managed aquifer recharge.
Environmental pollution (Barking, Essex : 1987)
2024; 343: 123166
Abstract
Managed aquifer recharge (MAR) is a sustainable way of harvesting groundwater in water-stressed urbanized areas, where reclaimed wastewater or stormwater is applied on a large basin to infiltrate water into the groundwater aquifer naturally. This process could rapidly fluctuate the water table and move the capillary fringe boundary, and the change in flow dynamic and associated geochemical changes could trigger the release of sequestered pollutants, including per- and polyfluoroalkyl substances (PFAS), also known as 'forever chemicals', from the subsurface and capillary fringe. Yet, the potential of PFAS release from the subsurface and capillary zone during recharge events when the water table rapidly fluctuates has not been evaluated. This study uses laboratory column experiments to simulate PFAS release from pre-contaminated subsurface and capillary fringe during groundwater table fluctuation. The results reveal that the groundwater level fluctuations during MAR increased the release of perfluorobutanesulfonic acid (PFBS) and perfluorooctanesulfonic acid (PFOS) from the capillary fringe, but the fraction released depended on PFAS type and their association with soil colloids. A higher proportion of PFOS in column effluent was found to be associated with particles, while a greater portion of released PFBS was in a free or dissolved state. The direction of water table fluctuation did not affect the release of PFAS in this study. A lack of change in the concentration of bromide, a conservative tracer, during flow interruption, indicates that diffusion of PFAS through reconnected pores during water table rise had an insignificant effect on PFAS release. Overall, this study provides insights into how PFAS can be released from the subsurface and capillary fringe during managed aquifer recharge when the groundwater level is expected to fluctuate quickly.
View details for DOI 10.1016/j.envpol.2023.123166
View details for PubMedID 38110050
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Do drinking water treatment residuals underperform in the presence of compost in stormwater media filters?
The Science of the total environment
2023; 904: 166635
Abstract
Drinking water treatment residuals (WTR), a waste-derived product, are often recommended to use as an amendment in stormwater biofilters to enhance their capacity to remove phosphate and microbial pollutants. However, their efficacy has been assumed to remain high in the presence of compost, one of the most common amendments used in biofilters. This study tests the validity of that assumption by comparing the removal capacities of WTR-amended biofilters with and without the presence of compost. Our results show that amending sand with WTR increased E. coli removal by at least 1-log, but the addition of compost in the sand-WTR media lowered the removal capacity by 13 %. Similarly, the addition of WTR to sand improved phosphate removal to nearly 1177 %, but the removal decreased slightly by 8 % when adding compost to the media. The results confirmed that dissolved organic carbon (DOC) leached from the compost could compete for adsorption sites for bacteria and phosphate, thereby lowering WTR's adsorption capacity based on the amount of DOC adsorbed on WTR. Collectively, these results indicate that the stormwater treatment industry should avoid mixing compost with WTR to get the maximum benefits of WTR for bacterial removal and improve the performance lifetime of WTR-amended biofilters.
View details for DOI 10.1016/j.scitotenv.2023.166635
View details for PubMedID 37647961
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Use of expanded shale, clay, and slate aggregates and biochar in the clear zone of road infrastructures for sustainable treatment of stormwater
JOURNAL OF CLEANER PRODUCTION
2023; 428
View details for DOI 10.1016/j.jclepro.2023.139443
View details for Web of Science ID 001102751000001
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Wildfire impacts on surface water quality parameters: Cause of data variability and reporting needs.
Environmental pollution (Barking, Essex : 1987)
2023; 317: 120713
Abstract
Surface runoff mobilizes the burned residues and ashes produced during wildfires and deposits them in surface waters, thereby deteriorating water quality. A lack of a consistent reporting protocol precludes a quantitative understanding of how and to what extent wildfire may affect the water quality of surface waters. This study aims to analyze reported pre- and post-fire water quality data to inform the data reporting and highlight research opportunities. A comparison of the pre-and post-fire water quality data from 44 studies reveals that wildfire could increase the concentration of many pollutants by two orders of magnitude. However, the concentration increase is sensitive to when the sample was taken after the wildfire, the wildfire burned area, discharge rate in the surface water bodies where samples were collected, and pollutant type. Increases in burned areas disproportionally increased total suspended solids (TSS) concentration, indicating TSS concentration is dependent on the source area. Increases in surface water flow up to 10 m3 s-1 increased TSS concentration but any further increase in flow rate decreased TSS concentration, potentially due to dilution. Nutrients and suspended solids concentrations increase within a year after the wildfire, whereas peaks for heavy metals occur after 1-2 years of wildfire, indicating a delay in the leaching of heavy metals compared to nutrients from wildfire-affected areas. The concentration of polycyclic aromatic hydrocarbons (PAHs) was greatest within a year post-fire but did not exceed the surface water quality limits. The analysis also revealed inconsistency in the existing sampling protocols and provides a guideline for a modified protocol along with highlighting new research opportunities. Overall, this study underlines the need for consistent reporting of post-fire water quality data along with environmental factors that could affect the data so that the post-fire water quality can be assessed or compared between studies.
View details for DOI 10.1016/j.envpol.2022.120713
View details for PubMedID 36435284