Tritium in a pine forest ecosystem: Relation between fresh pine needles, organic materials on a forest floor and atmosphere

Tritium concentrations were analyzed in organic and water fractions of fres h pine needles, dead and degraded pine needles accumulating on a pine fores t floor to examine tritium cycle in a forest ecosystem. Tritium concentrati on was higher in the organic fraction of dead and degraded pine needles com pared to others, suggesting two tritium sources. Rain is responsible for wa ter fractions in the samples, while atmospheric hydrogen and methane are sp eculated to be responsible for high tritium level in the organic fraction o f dead and degraded pine needles.