Comparative rates of leaching of chloride, nitrate and tritiated water under field conditions

Summary The rate of leaching of 36Cl‐, 15NO‐3 and HTO were measured in two experiments under field conditions following the application of irrigation water (40mm and 80 mm) and under winter rainfall (71 mm and 156 mm excess over evaporation). Nitrate and chloride leached at about the same rate, which was on average 23 per cent faster than that of HTO, but with a smaller difference under winter rainfall. It is concluded that although HTO is not an accurate marker for nitrate leaching, ‘bomb’ tritium gives a rough guide to the dating of nitrate pulses in porous rock.