T.-L. Ku J.D. Macdougall V.M. Burns R. Burns J. Dymond M.W. Lyle D.Z. Piper W.S. Moore 1981 <div id="abstracts" class="Abstracts u-font-serif text-s"><div id="ab1" class="abstract author" lang="en"><div id="aep-abstract-sec-id9"><p>Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (²³⁰Th,²³¹Pa,²³²Th,²³⁸U,²³⁴U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr⁻¹<span>&nbsp;</span>for at least 0.5 Myr and accreting Mn at 200 μg cm⁻²<span>&nbsp;</span>kyr⁻¹. The bottom of the nodule had been growing in its collected orientation at about 12 mm Myr⁻¹<span>&nbsp;</span>for at least 0.3 Myr and accreting Mn at about 700 μg cm⁻²<span>&nbsp;</span>yr⁻¹. Although the top of the nodule was enriched in iron relative to the bottom, the nodule had been accreting Fe 50% faster on the bottom.²³²Th was also accumulating more rapidly in the bottom despite a 20-fold enrichment of²³⁰Th on the top.</p><p>The distribution of alpha-emitting nuclides calculated from detailed radiochemical measurements matched closely the pattern revealed by 109-day exposures of alpha-sensitive film to the nodule. However, the shape and slope of the total alpha profile with depth into the nodule was affected strongly by²²⁶Ra and²²²Rn migrations making the alpha-track technique alone an inadequate method of measuring nodule growth rates.</p><p>Diffusion of radium in the nodule may have been affected by diagenetic reactions which produce barite, phillipsite and todorokite within 1 mm of the nodule surface; however, our sampling interval was too broad to document the effect. We have not been able to resolve the importance of nodule diagenesis on the gross chemistry of the nodule.</p></div></div></div> application/pdf 10.1016/0012-821X(81)90217-X en Elsevier Fluxes of metals to a manganese nodule: Radiochemical, chemical, structural, and mineralogical studies article