Propagation of uncertainty through geochemical code calculations

Increasing shallow groundwater CO2 and limestone weathering, Konza Prairie, USA

“…We recognize that there is uncertainty in geochemical modeling (Criscenti et al, 1996). To test the validity of using a repetitive annual cycle of calcite saturation state to represent 15 years of aquifer chemistry, we collected samples for headspace CO 2 and field pH determination in 2005.…”

Propagation of Uncertainty in Aqueous Equilibrium Calculations: Non-Gaussian Output Distributions

“…Several authors have used Monte Carlo methods to calculate standard deviations of output concentrations for Al speciation in natural waters, [22][23][24] metal complexation, 25 pH in natural waters, 26 and carbonate equilibria. 27 Even given the assumption of mutually independent Gaussian uncertainties in the input constraints, a non-Gaussian distribution of output concentrations may result. If the linear approximation fails and output distributions are non-Gaussian, then many common statistical tests will be inappropriate, and the uncertainty in the calculated results cannot adequately be described by a standard deviation.…”

Implications of Ground Water Chemistry and Flow Patterns for Earthquake Studies

“…The quartz geothermometer was intermediate between the chalcedony and Na‐K‐Ca geothermometers and was considered applicable for the hot ground water in five of the six wells. The water samples, except Songshan, were only slightly oversaturated with quartz, approaching equilibrium within the error of the methodology (Nordstrom and Ball 1989; Tsang 1991; Plummer 1994; Criscenti et al 1996; Wang et al 2000). Nevertheless, because the tritium data indicated hot ground water at Songshan, Hao3, and Hao4 probably had mixed with younger cold water, a mixing model also was considered for these sites (Fournier and Truesdell 1974).…”