Characterizing shallow aquifers using tritium and 14C: periodic sampling based on tritium half-life

摘要: Abstract Thirteen water-production wells in glacial sediments and around Waterloo, Ontario, (Canada) were sampled for major ions, 3H, 13C, 14C 18O 1976 again 1988 to gauge the movement of bomb-spike tritium through Waterloo aquifer also assess reliability a hydrogeochemical interpretation dynamic character an based only on single sampling episode. The suite samples collected was not able indicate how fast spike moving or even if each well-screen intercepting front end tail peak corresponding infiltration mid-1960s precipitation. second event portrayed which, qualitatively at least, gave information relating more permeable zones direction water movement. Water from all but one 13 registered drop relative sampling. A well is deemed be its activity (±2 TU analytical uncertainty) greater than half that measured (±8 uncertainty). Only two shallow piezometers met this criterion. Ten had TU1988/TU1976 ratios which could interpreted as either less 0.5, uncertainties both analyses ratio are rigorously applied. Screens intercept because their uncertainty-adjusted range 0.29 0.41. Carbon-14 individual varied by no 6 Per cent Modern Carbon (PMC) between 1988. Bomb-spike so easily detected passage aquifers thermonuclear input into atmosphere much intense (relative pre-bomb, background levels) tritium. Also, incongruent dissolution dolomite, coupled with differing kinetics dolomite calcite, precipitates 14C-bearing calcite saturated zone. Although chemistry can reasonably characterized episode, recharge rate groundwater flow paths best delineated geochemical perspective multiple samplings persistent chemical and/or isotopic tracer sought out repeatedly analyzed. In aquifer, these Cl. sameness waters 12 apart makes poor candidate use scheme.