Arsenic and Fluoride Contamination Analysis of Agricultural Topsoil in Guanajuato, Mexico

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Fischer, Katie
LaFayette, Gabrielle

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Abstract

Groundwater from Guanajuato, Mexico's Independence Basin has recently been documented to contain elevated levels of arsenic (As) and fluoride (F) from past volcanic activity within the region. Guanajuato's groundwater poses a potential health risk to residents that utilize the groundwater as drinking water, resulting in chronic exposure to toxic levels of As and F. Although contaminated groundwater is extensively used for irrigation, it remains unclear as to whether contaminants are accumulating in agricultural soils and threatening the quality of crops. Therefore, the primary objective of this work was to understand the scale of contamiinant accumulation within inductively coupled plasma mass spectrometry (ICP-MS) for initial levels ofarsenic in topsoil, then analyzed sixteen soil core samples from three farms using a fluoride ion selective electrode to form depth profiles for F accumulation within topsoil. We found that As in agricultural topsoil is currently below the EPA standard of 0.39 parts per million (ppm) for arsenic contamination in soils, ranging from 0.018 ppm to 0.059 ppm. Ongoing work is seeking to define the loading limits of As and F, which influences how much As and F the soil can retain. Ultimately, understanding how As and F accumulate within the region's agricultural topsoil contributes towards creating a management plan in regards to how much and for how long local farmers can irrigate with contaminated groundwater before As and F levels in topsoil become potentially hazardous.

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Single page poster

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Mexico, Guanajuato, Mexico, Soil analysis, Soil contamination, Arsenic, Fluoride

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