180-13 Development and Adjustment of a Spectrophotometric Assay to Quantify Ammonia in Shallow Groundwater of Carbuna Village, Moldova

Session: Geoscience Outreach Efforts to Broaden Participation (Posters)

Poster Booth No.: 13

Presenting Author:

Ayanna Stewart

Authors:

Stewart, Ayanna¹, Ghosh, Unmesh², Moon, Samira³, Bassoo, Joel⁴, Martinez, Maria⁵, Abu Yousuf, Ruqaiya⁶, Singh, Ranjit⁷, Dhar, Ratan⁸

Abstract:

Groundwater is a crucial resource supporting both the social and economic well-being of Carbuna Village, located in Laloveni District about six miles from Moldova’s capital, Chisinau. In this rural community, household water is predominantly sourced from aging manually-dug wells, constructed without modern technical guidance. Prior studies across the Republic of Moldova have revealed that nitrate-nitrogen concentrations in many water sources often exceed the national legislative maximum of 50 mg/L, highlighting potential health risks. This investigation aims to evaluate the quality of local water resources by analyzing physico-chemical properties of samples drawn from twenty hand-dug wells, a functioning spring, two artisanal deep well taps, and a village lake. Specifically, a colorimetric method was developed to quantify ammonia levels in previously collected water samples. The method required optimizing spectrophotometric wavelength settings; calibration experiments were conducted in both ammonia-spiked nanopure water and in spiked local well water samples. High linearity was achieved in both test matrices, with linear regression coefficients exceeding 99.6%. Using a Hach DR 5000 spectrophotometer, scans from 900 nm to 200 nm determined that 640 nm was the optimal wavelength for analyzing ammonia in Carbuna's well water. Results indicated that ammonia concentrations in local water were slightly elevated but remained safely below the critical threshold of 1.5 mg/L. This observation is in line with previous reports of significant nitrate levels in Moldovan water sources. The newly developed ammonia test was validated on acidified samples (adjusted to 1% hydrochloric acid), which showed no substantial difference compared to non-acidified samples. To further assess overall water quality, major ions—including fluoride, chloride, nitrate, nitrite, phosphate, sulfate, and iodide—will be measured using DIONEX 2100 Ion Chromatography. These comprehensive analyses will provide essential data to inform water management strategies and safeguard public health in Carbuna village.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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