Lop Nur is a playa located in the east of Tarim basin

Xinjiang

China. A plenty of brine is reserved in the upper evaporates of the upper-middle Pleistocene strata in Luobei depression

Lop Nur. The brines have higher salinity and are rich in potassium

with average 1.40% tenor of KCl. And high percentage of tritium in the upper ground water is measured

with average content of 40.6 TU. Laterally the tritium content variation is: higher in periphery and lower in center; while vertically the tritium content becomes lower with the burial depth increasing. With the use of piston model and completely-mixing model

the age of the upper brine is calculated as 36—80 a. Therefore

brine contained large portion of nuclear-bombing tritium

which verified that since 1952

atmospheric water had precipitated and seeped into the playa of this area. The tritium-bearing modern precipitated water is imbibed into sediments through the aeration zone

in which karst is developed intensively

and tritium mixed with shallow brine uniformly. Owing to the slow evaporation of brine

fractional distillation happened

and “lighter water” with less tritium evaporated. So most of tritium has been rich in relic brine. The characteristics of lateral tritium distribution are believed to be the results of groundwater flow pattern in a salt lake basin.