The meteoric and hydrothermal waters dispersed across the small-volcanically-active island of Dominica may be used to forecast magmatic activity in the area. Approximately 85 water samples were taken during fieldwork on the volcanic island in order to look at the alkalinity, dissolved inorganic carbon (DIC), δ 18 O, deuterium, and ion concentration values. General water parameters were measured in the field; water temperatures ranged from 24˚-97˚C (meteoric and hydrothermal), dissolve oxygen percent values from 24-105%, total dissolved solids values from 113 up to 32,000(mg/L), and measured pH values ranged from 1.38 to 8.18.
Data has been gathered from the same locations for the past three years which has yielded chemical and isotopic trends for different locations on the island. Deviations from the meteoric water line with respect to δ18 O and deuterium indicate whether evaporation has affected the water. DIC isotopes are used to measure the amount of magmatic degassing that has affected the water, and can be used to approximate the distance from the magmatic source. By analyzing the isotopic and chemical trends in hydrothermal and meteoric waters, we hope establish a baseline that could be used in future monitoring efforts. Δ deuterium values vs SMOW ranged from -6.7 to -1.6 ‰ in meteoric streams and from -6 to 20.5 ‰ in hydrothermal locations, wheras δ 18O values ranged from -2.6 to 1.34 ‰ in meteoric streams and from -2.96 to 7.2 ‰ in hydrothermal locations. Compared to 2015 values, oxygen and deuterium isotope values in meteoric waters were heavier (moving to more positive values), which is attributed to increases in precipitation and evaporation. Variation in δ13C ranged from -20 to -8 ‰ in water of meteoric origin and from -6 to 4 ‰ in hydrothermal waters. Compared to 2015, DIC values were relatively similar in most hydrothermal and meteoric locations, suggesting no changes in magmatic degassing over the last year.