Hydrogeology. Kevin M. Hiscock

[–] activity mol kg⁻¹ (–) concentration (see Box 4.1) mol L⁻¹ or mg L⁻¹ A area m² A radionuclide activity AE actual evapotranspiration mm ASR artificial storage and recovery (aq) aqueous species atm atmosphere (pressure) B barometric efficiency BOD biological oxygen demand mg L⁻¹ Bq becquerel (unit of radioactivity; 1 Bq = 1 disintegration per second) b aquifer thickness m 2b fracture aperture m C Sediment loading efficiency C shape factor for determining k_i C specific moisture capacity of a soil (m of water)⁻¹ C, c concentration °C degrees Celsius (temperature) CEC cation exchange capacity meq (100 g)⁻¹ CFC chlorofluorocarbon Ci curie (older unit of radioactivity; 1 Ci = 3.7 × 10¹⁰ disintegrations per second) COD chemical oxygen demand mg L⁻¹ D hydraulic diffusivity m² s⁻¹ D hydrodynamic dispersion coefficient m² s⁻¹ D* molecular diffusion coefficient m² s⁻¹ DIC dissolved inorganic carbon mg L⁻¹ DNAPL dense, non‐aqueous phase liquid DOC dissolved organic carbon mg L⁻¹ d mean pore diameter m hydraulic gradient E ^o standard electrode potential V EC electrical conductivity S cm⁻¹ Eh redox potential V e void ratio e‐ electron eq chemical equivalent (see Box 4.1) eq L⁻¹ F Faraday constant (9.65 × 10⁴ C mol⁻¹) F Darcy–Weisbach friction factor f _c infiltration capacity cm h⁻¹ f _t infiltration rate cm h⁻¹ f _oc weight fraction organic carbon content G Gibbs free energy kJ mol⁻¹ g gravitational acceleration m s⁻² g gram (mass) (g) gas H depth (head) of water measured at a flow gauging structure m H enthalpy kJ mol⁻¹ h hydraulic head m I ionic strength mol L⁻¹ i hydraulic gradient IAEA International Atomic Energy Agency