Perchlorate in Portraits: Quantifying the Disappearance of Perchlorate in Washed Martian Regolith Using Spectroscopic Instrumentation
Education Level
Undergraduate
Faculty Advisor(s)
Professor Stephen O'Shea
Academic Department(s)
Chemistry
Symposium Date
2024
Abstract
On Earth, perchlorate ions are found naturally in isolated deposits. However, on Mars, they are much more widely distributed (1-2 wt%). If plants were to be grown in Martian regolith containing >1 wt% perchlorate, growth would be stunted or halted entirely (Oze et al. 2021). Those plants that do grow would rapidly absorb the perchlorate, making them hazardous to human health upon ingestion. Three Regolith simulants from Exolith Labs® reflecting the elemental composition of Martian regolith were used to compare the efficacy of deionized water, HCl, Acetic Acid, and EDTA at removing 1 wt% perchlorate, sulfates, and nutrient metals. MGS-1 and MGS-1S regolith simulants are Mars Global Simulants that represent the average sediment composition across the Martian planet. MGS-1S is supplemented with additional sulfates. JEZ-1 regolith simulant is representative of the Equatorial Jezero Delta Crater, which is thought to be an ancient sea bed.
Since the concentration of perchlorate in washed samples is below the limit of detection of the Methylene Blue Chemical Spot Test, spectroscopic instrumentation is required to identify and quantify the loss of perchlorate and sulfates in the regolith simulant. ICP-OES permitted the successful quantification of nutrient metals, however chlorine and sulfur could not be quantified at the tested wavelengths. Using XRF, chlorine and sulfur were quantified from dried samples of regolith that had been fully washed. In addition, sulfates could be quantified with HACH® protocols as a proxy for perchlorate due to the similar solubilities of the two compounds. ATR-FTIR and HPLC-IC could both detect highly resolved perchlorate peaks in sediment washes, and HPLC-IC could also detect sulfate peaks. FTIR-DRIFTS and RAMAN spectra obtained from dried regolith exhibited too much background fluorescence for any reliable quantification of either perchlorate or sulfate.
Recommended Citation
Fabrizi, Gabriella; Wells, Jamie; Wade, Gabriella; Foley, Brennan; and O'Shea, Stephen, "Perchlorate in Portraits: Quantifying the Disappearance of Perchlorate in Washed Martian Regolith Using Spectroscopic Instrumentation" (2024). Student Research Symposium. 5.
https://docs.rwu.edu/studentresearchsymposium/5
Comments
This research was presented at the 2024 Rhode Island Summer Undergraduate Research Symposium, held on Friday, July 26, at the University of Rhode Island and supported by Department of Chemistry.