Controversy over the relationship between major components of sediment-trap materials and the bulk distribution coefficients of 230Th, 231Pa, and 10Be

A four-end-member mixing model is introduced to estimate the distribution coefficients of 230Th, 231Pa, and 10Be for pure end members (lithogenic clays, organic carbon, carbonates, and opal) in sediment-trap materials from three oceanic regions. Four pure end members contribute differently to the fractionation of nuclides in three regions. Contribution of organic matter to the bulk distribution coefficients cannot be ignored.