Th-234 applied to particle removal rates from the surface ocean: a mathematical treatment revisited

It has been recognized since the 1950 's that radioisotopic disequilibrium between naturally occurring parent daughter isotope pairs in seawater can p rovide information on the rate of processes segregating them. In the surfac e ocean, the U-238: Th-234 parent-daughter pair tends to display measurable disequilibrium that is attributable to the effects of scavenging on partic le reactive thorium. A range of approaches has been applied to deriving qua ntitative information on particle scavenging and sinking rates from U-238:T h-234 measurements. Here, rye review the mathematical underpinnings of a ve ry basic conceptual model of the removal process in order to correct a misu nderstanding that has arisen in recent literature.