VERTEX: manganese transport through oxygen minima

摘要: Abstract Manganese transport through a well-developed oxygen minimum was studied off central Mexico (18°N, 108°W) in October–November 1981 as part of the VERTEX (Vertical Transport and Exchange) research program. Refractory, leachable dissolved Mn fractions associated with particulates caught traps set at eight depths (120–1950 m) were analyzed. Particles entering had relatively large loads; however, sank further into minimum, total fluxes steadily decreased from 190 nmol m −2 day −1 120 to 36 400 m. then increased remaining 800–1950 m, reaching rates up 230 1950 concentrations also measured water column. Dissolved levels consistently observed within 150–600 depth interval. In contrast, suspended particulate amounts especially low those depths, never exceeded 0.04 kg . The combined column particle trap data clearly indicate that is released particles they sink minimum. Rate-of-change estimates based on flux yield regeneration 0.44 yr upper (120–200 m). However, only 30% appears be sinking regeneration; other 70% probably results continental-slope-release-horizontal-transport processes. scavenges back onto begin increase depth. Scavenging ranging −0.03 −0.09 700 These scavenging result residence times 16–19 years, rate constants order 0.057 removal via below balanced by along continental boundaries transported horizontally advective-diffusive very weakly particulates. Nevertheless, involved biogenic are large, resulting same magnitude necessary explain excess accumulating sea floor. overall behavior this, other, studies strongly suggests some type equilibrium occurring between phases. This shift direct or indirect response levels.