Subscriber access provided by Service des bibliothèques | Université de Sherbrooke
Article
Osmium and Platinum Decoupling in the Environment: Evidences in Intertidal Sediments (Tagus Estuary, SW Europe) Clara Almécija, Mukul Sharma, Antonio Cobelo-Garcia, Juan Santos-Echeandia, and Miguel Caetano Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b00591 • Publication Date (Web): 29 Apr 2015 Downloaded from http://pubs.acs.org on May 3, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 30
Environmental Science & Technology
1
Osmium and Platinum Decoupling in the Environment: Evidences in
2
Intertidal Sediments (Tagus Estuary, SW Europe)
3
Clara Almécija*,†,‡, Mukul Sharma‡, Antonio Cobelo-García†, Juan Santos-Echeandía†
4
and Miguel Caetano§,
5
†
6
Spain
7
‡
8
Dartmouth College, Hanover, New Hampshire 03755, United States
9
§
Bioxeoquímica Mariña, Instituto de Investigacións Mariñas IIM-CSIC, 36208 Vigo,
Radiogenic Isotope Geochemistry Laboratory, Department of Earth Sciences,
IPMA-Portuguese Institute of Sea and Atmosphere, Av. Brasilia, 1449-006, Lisbon,
10
Portugal
11
12
Porto, Portugal
CIIMAR, Marine and Environmental Research Center, Rua dos Bragas, 289, 4050-123
13 14 15 16 17 18 19 20
*corresponding author:
address: Instituto de Investigacións Mariñas IIM-CSIC Eduardo Cabello 6, 36208-Vigo, Spain phone: +34 986231930 fax: +34 986292762 e-mail:
[email protected] 1 ACS Paragon Plus Environment
Environmental Science & Technology
Page 2 of 30
21
ABSTRACT:
22
Catalytic converters in automobiles have significantly increased the input of platinum
23
group elements (PGEs) to the environment and their coupled geochemical behavior has
24
been proposed. To check this hypothesis, Pt and Os concentrations and
25
ratios were determined in sediment cores and interstitial waters from the Tagus Estuary
26
(SW Europe) affected by different traffic pressure.
27
Platinum concentration in surface sediments nearby the high traffic zone (up to 40 ng·g-
28
1
29
observed in surface sediments, with lower
30
Dissolved Pt and Os in interstitial waters, 0.1-0.7 pg g-1 and 0.03-0.10 pg g-1
31
respectively, were higher than in typical uncontaminated waters. Results indicate two
32
sources of Pt and Os into the Tagus Estuary salt marshes: a regional input associated
33
with industrial activities, fossil fuel combustions and regional traffic; and a local source
34
linked to nearby traffic density emissions. Estimations of Os and Pt released by catalytic
35
converters support this two-source model. Differences in geochemical reactivity and
36
range of dispersion from their sources lead to a decoupled behavior of Os and Pt,
37
questioning the use of Os isotopes as proxies of PGE sources to the environment.
187
Os/188Os
) indicated severe contamination. Although lower than Pt, Os enrichment was also 187
Os/188Os ratios than in deeper layers.
38
2 ACS Paragon Plus Environment
Page 3 of 30
Environmental Science & Technology
39
1. INTRODUCTION
40
Platinum group elements (PGE: ruthenium, rhodium, palladium, osmium, iridium and
41
platinum) are amongst the least abundant elements in the upper continental crust, where
42
their typical concentrations range from 20 pg g-1 (Ir) to 500 pg g-1 (Pt, Pd)1. These
43
elements are relatively enriched in the Earth’s mantle, and mantle-derived rocks host
44
some of the largest PGE deposits in the World (e.g. Bushveld Complex2 and Noril’sk3).
45
The use of PGE in several human activities is increasing their environmental
46
concentrations4,5; accordingly, it has been estimated that 86-98% of PGE total flux at
47
Earth’s surface derives from anthropogenic activities6. One of the main application of
48
PGE (especially Pt, Pd and Rh) is their use in automobile catalytic converters in order to
49
reduce the emissions of CO, NOx and SO27. This industrial application has been greatly
50
responsible for an exponential increase of the PGE demand over the past 40 years8. A
51
catalytic converter emits during its lifetime microparticles (1-63 µm9) covered by tiny
52
fragments (?
