NICKEL AND CHROMIUM GEOCHEMICAL ANALYSIS OF METAVOLCANIC, ULTRAMAFIC FORMATIONS, AND FLOWING WATER IN PARADISE, CA

Heavy metals, such as nickel and chromium, are elements with a high atomic weight and are naturally occurring in the environment. Nickel is shown to be toxic to plants with the World Health Organization having a recommended safe limit of 0.05 parts per million (ppm) for agricultural soil and intervention concentrations at 210 ppm, and adverse effects shown from consuming 250 ppm. The Paradise and Magalia areas are underlain by both ultramafic and metavolcanic rock formations which erode and contribute heavy metals to the surrounding soil. Analysis of two ultramafic rocks, two metavolcanic rocks, their derived soils, and water collected from streams flowing through the area was conducted using an inductively coupled plasma mass spectrometer (ICP-MS) and a portable XRF spectrometer to determine the concentrations of nickel and chromium, as well as major element oxides. Nickel and chromium levels for the ultramafic rocks and soil are between 3,000 to 5,000 ppm of chromium, and 3,000 to 4,000 ppm for nickel, well above levels that have been shown to cause stunted growth and necrosis in crops. Similarly, the nickel and chromium concentrations from the metavolcanic rock and soil samples were also recorded in the toxic concentration range, around 400 ppm for chromium and around 100 ppm for nickel. Water collected from creeks flowing through the area contained less than .02 ppm of chromium and nickel. Most soils contain chromium as the chromium (III) state but can be oxidized to the mobile and toxic valance state (VI) due to brush fires, where in 2018 Paradise, CA had the most destructive and deadly fire in California’s history. This study has potential implications for the communities in the Paradise area due to the concentration of nickel and chromium at levels well above toxicity in the soil, inhibiting residents’ crops from growing and becoming airborne when disturbed.