Dataset Information

Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

ABSTRACT: Rare earth element (REE) concentrations and neodymium isotopic composition (?Nd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 ?m), colloidal and particulate REE and ?Nd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ?Nd values are shifted from the dissolved Nd river endmember (-8.9) to values typical of river suspended matter (-10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments.

SUBMITTER: Rousseau TC

PROVIDER: S-EPMC4510642 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

Rousseau Tristan C C TC Sonke Jeroen E JE Chmeleff Jérôme J van Beek Pieter P Souhaut Marc M Boaventura Geraldo G Seyler Patrick P Jeandel Catherine C

Nature communications 20150709

Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in ...[more]

PMID: 26158849

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Project description:Microeukaryotes play key roles in the structure and functioning of marine ecosystems. Little is known about the relative importance of the processes that drive planktonic and benthic microeukaryotic biogeography in subtropical offshore areas. This study compares the microeukaryotic community compositions (MCCs) from offshore waters (n = 12) and intertidal sediments (n = 12) around Xiamen Island, southern China, using high-throughput sequencing of 18S rDNA. This work further quantifies the relative contributions of spatial and environmental variables on the distribution of marine MCCs (including total, dominant, rare and conditionally rare taxa). Our results showed that planktonic and benthic MCCs were significantly different, and the benthic richness (6627 OTUs) was much higher than that for plankton (4044 OTUs) with the same sequencing effort. Further, we found that benthic MCCs exhibited a significant distance-decay relationship, whereas the planktonic communities did not. After removing two unique sites (N2 and N3), however, 72% variation in planktonic community was explained well by stochastic processes. More importantly, both the environmental and spatial factors played significant roles in influencing the biogeography of total and dominant planktonic and benthic microeukaryotic communities, although their relative effects on these community variations were different. However, a high proportion of unexplained variation in the rare taxa (78.1-97.4%) and conditionally rare taxa (49.0-81.0%) indicated that more complex mechanisms may influence the assembly of the rare subcommunity. These results demonstrate that patterns and processes in marine microeukaryotic community assembly differ among the different habitats (coastal water vs. intertidal sediment) and different communities (total, dominant, rare and conditionally rare microeukaryotes), and provide novel insight on the microeukaryotic biogeography and ecological mechanisms in coastal waters and intertidal sediments at local scale.

Dataset Information

Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

Publications

Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

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