Determination of Lead, Arsenic, and Mercury Levels for Pristine and Urban Areas of the Galápagos Islands using a Handheld X-Ray Fluorescence Analyzer on Fresh and Weathered Rocks, Soil and Sand, Biological Materials, Paint, Trash Dumps, and Harbor Areas

The Galápagos Islands are a repository of unique biodiversity that is being lost due to a combination of natural and anthropogenic factors. Weathering processes mobilize pollutants from contaminated areas into the environment. Heavy metals affect reproductive, endocrine, and immune homeostasis, and produce neurotoxic carcinogenic effects. In this study we measured lead, arsenic, and mercury levels that have bioaccumulative effects, most noticeable at higher levels of the food chain, including humans. We used a Thermo Scientific Niton XL5 Plus handheld x-ray fluorescence (XRF) analyzer to measure forty major and trace elements in fresh and weathered rocks, soil and sand, dead biological specimens, and polluted areas. Biological samples included seal carcasses, iguana remains and eggs, fish organs, octopus, crab legs, and shells. Polluted areas such as harbor piers and ramps, trash dumps, road asphalt, and painted items were compared with pristine areas. More than a thousand measurements were taken over five weeks of fieldwork divided between polluted sites, background areas, and calibration standards. Urban areas, as well as protected marine and terrestrial sites of Galapagos National Park, were measured on the four inhabited islands, as well as on eleven uninhabited islands. We discovered especially high levels of heavy metals in marine paints used on water taxis and other vessels in the Galapagos Marine Reserve (Fig. 1): Pb at frequently 1-4%, As at 40-80 ppm and occasionally as high as 4000 ppm, and Hg at up to 30-50 ppm. The second highest levels of these heavy metals were found in anti-fouling products used on wood. We also found Pb up to 80 ppm in passenger docks on all four populated islands. Pb was close to or less than the limits of detection (LOD < 3 ppm) in natural substrates such as basalt, sand, and soil in the intertidal zones surrounding the visitor sites. We also did not find any naturally detectable As or Hg on unpopulated islands (LOD < 3-5 ppm).