Biological communities can be useful indicators of water quality. Mollusks and crustaceans require adequate alkalinity and mineral content, along with an appropriate pH, to molt, build, and maintain shells and exoskeletons. Calcium is a crucial mineral for these animals. Consequently, they often dominate springs sourced from calcium-rich source rocks. Conversely, insects dominate springs flowing through source rocks with insoluble, Ca-poor minerals. Previous work documenting the link between spring water chemistry and biological communities in the Valley and Ridge Province (V&R) examined end-member springs whose source rock was either sandstone or carbonate. However, this overlooks mixed lithology springs and the variability of water chemistries spatially and temporally. Integrated chemical and biological data are limited and don’t account for source rocks or chemical variability.
Our goal is to fill this knowledge gap by examining the chemistries of different spring types. We compared chemical data from 78 springs in the V&R in West Virginia and Pennsylvania (374 samples total). Data included pH, specific conductance (SC), alkalinity, and major dissolved ions. The study focuses on springs sourced from siliciclastic rocks (e.g., sandstone and shale) and carbonates (limestone and dolomite); springs from deeper thermal flow systems were included for comparison.
The spring water chemistry ranged from very dilute (sandstones) to highly mineralized (thermal-mineral waters). The carbonate-fed springs had circumneutral pH and high concentrations of Ca. Chemistry of siliciclastic springs varies by lithology. Shale-sourced springs had comparable pHs to carbonate springs, higher alkalinity, SC, and Ca concentrations than sandstone springs, likely due to small limestone layers and cements associated with the shale strata. Based on these preliminary data, we predict that shale springs will have a higher number of crustaceans and mollusks than sandstone springs.
Future studies include the collection of integrated chemical and biological data for all spring types to better understand the relationship between chemical conditions and biological communities in V&R springs. We hope that this data can be used in the future to develop biological indices for spring water chemistry. Understanding the connection between time-averaged biological communities and sporadic water samples could also be useful for evaluating roadside spring-related public health issues.