کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5764685 | 1626305 | 2017 | 75 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Kinetics of thorium and particle cycling along the U.S. GEOTRACES North Atlantic Transect
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We find that the adsorption rate constant (k1) generally decreases with depth across the section: broadly, the time scale 1/k1 averages 1.0 yr in the upper 1000 m and (1.4-1.5) yr below. A positive relationship between k1 and particle concentration (P) is found, i.e., k1âPb, where bâ¥1, consistent with the notion that k1 increases with the number of surface sites available for adsorption. The rate constant ratio, K=k1/(kâ1+βâ1), which measures the collective influence of rate parameters on Th scavenging, averages 0.2 for most stations and most depths. We clarify the conditions under which K/P is equivalent to the distribution coefficient, KD, test that the conditions are met at the stations, and find that K/P decreases with P, in line with a particle concentration effect (dKD/dP<0). In contrast to the influence of colloids as envisioned by the Brownian pumping hypothesis, we provide evidence that the particle concentration effect arises from the joint effect of P on the rate constants for thorium attachment to, and detachment from, particles.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Deep Sea Research Part I: Oceanographic Research Papers - Volume 125, July 2017, Pages 106-128
Journal: Deep Sea Research Part I: Oceanographic Research Papers - Volume 125, July 2017, Pages 106-128
نویسندگان
Paul Lerner, Olivier Marchal, Phoebe J. Lam, Ken Buesseler, Matthew Charette,