Solution Exercise 3
Based on that study, Leenheer and others (1974) made four principal observations:
- DOC concentrations in groundwater were generally much lower than commonly found in surface waters, with median concentrations ranging between 0.5 and 0.7 mg/L (41.7 to 58.3 µmol/L);
- a shallow aquifer in Florida receiving active recharge from surface-water sources had much higher DOC concentrations (15 mg/L; 1,250 µmol/L) than wells tapping the deeper Floridan aquifer (1.4 to 0.1 mg/L; 117 to 8.3 µmol/L) that was not immediately influenced by surface water;
- there were no statistically significant differences in DOC concentrations between aquifers of differing lithologies; and,
- there were clear statistical correlations between DOC concentrations, specific conductance, and alkalinity.