Technology-critical elements: a need for evaluating the anthropogenic impact on their marine biogeochemical cycles
-
1
Instituto de Investigaciones Marinas (IIM) - Consejo Superior de Investigaciones Cientificas (CSIC), Spain
Around 99.7% of the upper continental crust is composed by a relatively small number of elements (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P) as their oxide forms, mainly SiO2 (66.6%), Al2O3 (15.4%), and FexOy (5.0%), whereas the vast majority of the naturally-occurring chemical elements – the so-called ‘minor’ or ‘trace’ elements –account only for the remaining 0.3% [Rudnick and Gao 2003].
Despite their low concentrations, the discovery and use of several trace elements by humans can be traced back several thousands of years – which is the case of gold (6000 BC), copper (4200 BC), silver (4000 BC) or lead (3500 BC), among others. The massive requirements of these trace elements for a variety of technological applications, especially after the industrial revolution in the late 18th century, led to their extensive extraction from the lithosphere and, as a consequence, caused the remobilisation of these elements in the biosphere. The development of new analytical technologies during the past decades made it possible the determination of their concentrations in the environmental compartments and the study of their environmental cycling and fate [e.g. Salbu and Steinnes 1995]. The deleterious effects of some of these elements to living organisms have been well documented [Fairbrother et al. 2007], and has eventually led to environmental guidelines, policies and laws [e.g. EU Water Framework Directive; WHO Drinking Water Guidelines] being put into place to control the adverse effects of these elements (e.g. As, Cd, Cr, Cu, Hg, Pb) in their various chemical forms.
However, there are a number of trace elements that, until now, were considered just as laboratory curiosities but now have become key components for the development of new technologies [Karn 2011]. This group of elements, which includes Ga, Ge, In, Te, Nb, Ta, Tl, the platinum group elements (PGE: Pt, Pd, Rh, Os, Ir, Ru) and most of the rare earth elements (REE: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu), are now critical for a variety of applications like information and telecommunications technology, semiconductor, display, optic/photonic or energy technologies [Karn 2011].
The current use of these elements in new technological products is resulting in significant changes in their cycle at the Earth’s surface due to their increased mining from the lithosphere, use in a variety of products, increased exposure of the biosphere, unknown biogeochemical or anthropogenic cycling and unknown potential toxicological endpoints and harmful effects. The current significant gaps in the knowledge on technology critical elements, from their environmental levels and fate to their potential (eco)toxicological impact, are mainly explained by two factors: (i) their typical ultra-trace concentrations, making their analytical determination extremely difficult and/or time-consuming, and (ii) the absence of any significant industrial role (apart some biomedical applications) prior to their massive use in the increasing demand of new technological applications, therefore discouraging scientists to assess the (eco)toxicological aspects of the these elements.
As an example, the disturbance of the natural environmental distributions of several rare earth elements (REE) has been recently reported in waters of the Rhine river, Germany [e.g. Kulaksiz and Bau 2013], and San Francisco Bay, USA [Hatje et al. 2014], indicating that human activities are already impacting the geochemical cycles of these elements. However, currently the database is insufficient to support even the calculation of mass balances, sources and/or sinks for these elements. Of further concern is that, despite their widespread use, current knowledge does not support the application of robust risk assessment processes and, as a consequence they are not included in regulations (in contrast to other metals with a longer record of use).
In this presentation we will focus on the recent advances on the marine biogeochemistry of Pt. For this element, the anthropogenic emissions due to its use in catalytic converters in cars are well documented; however, the controls and impact on its ocean biogeochemical behaviour, estuarine mixing and export to the ocean, and its bioaccumulation on marine organisms are not fully understood:
(i) Oceanic behaviour of Pt. Values of dissolved Pt have been reported for the Pacific (Goldberg et al., 1986), Indian (Jacinto and van den Berg, 1989) and Atlantic (Colodner et al., 1993) oceans, with concentrations ranging from 0.2 to 1.6 pM. In these studies, concentrations invariant with depth in the North Atlantic (Colodner et al., 1993) were reported; a scavenged-type profile in the Indian Ocean (Jacinto and van den Berg, 1989) was observed, whereas for the Pacific the two available studies show discrepant behavior: recycled-type (Goldberg et al., 1986) and conservative (Colodner, 1991). As noted by other authors (e.g. Donat and Bruland, 1995), the behavior of platinum derived from these studies is not oceanographically consistent with respect to their basin-to-basin variation, suggesting the possibility of error in some of the data. Here we will present new data on the oceanic distribution of Pt in the Atlantic Ocean in depth profiles collected at three different locations of the Atlantic Ocean during the Dutch GEOTRACES West Atlantic cruise in 2011. Whereas the average concentration of Pt found in this study (0.26 ± 0.06 pM) are identical to those previously reported by Colodner (1991) for the Atlantic Ocean (0.26 ± 0.08 pM), the new depth profiles suggest that this element is more reactive than previously thought.
(ii) Pt behaviour during estuarine mixing. The factors controlling the behaviour of Pt during estuarine mixing and its particle–water interactions will be discussed from the data obtained in the Lérez Estuary (NW Iberian Peninsula) and the Gironde Estuary (SW France), with the implication for its transport and fate in the coastal ocean.
Acknowledgements
Thanks to Micha Rijkenberg (NIOZ) and the Dutch GEOTRACES programm, as well as Jörg Schafer (University of Bordeaux, France) for access to samples.
References
Donat, J.R., Bruland, K.W., 1995. Trace elements in the oceans. In: Salbu, B., Steinnes, E. (Eds.), Trace Elements in Natural Waters. CRC Press, Boca Raton, Florida.
Colodner, D., 1991. PhD Thesis, Massachusetts Institute of Technology.
Colodner, D., et al., 1993. Analytical Chemistry 65, 1419-1425.
Fairbrother, A., et al., 2007. Ecotoxicology and Environmental Safety 68, 145-227.
Goldberg, E.D., et al., 1986. Applied Geochemistry 1, 227-232.
Hatje, V., Bruland, K.W., Flegal, R., 2014. Marine Chemistry 160, 34-41.
Jacinto, G,S., van den Berg, C.M.G., 1989. Nature 338, 332-334.
Karn, B., 2011. Journal of Environmental Monitoring 13, 1184-1189.
Kulaksiz, S and, Bau, M., 2013. Earth and Planetary Science Letters 362, 43-50.
Rudnick, R.L., Gao, S., 2003. Composition of the Continental Crust. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry, Vol. 3. Elsevier, pp. 1-64.
Salbu, B., Steinnes, E., 1995. Trace Elements in Natural Waters. CRC Press, Boca Raton, Florida.
Keywords:
technology-critical elements,
Platinum,
biogeochemistry,
trace element cycling,
estuarine behaviour,
oceanic distribution
Conference:
IMMR | International Meeting on Marine Research 2014, Peniche, Portugal, 10 Jul - 11 Jul, 2014.
Presentation Type:
Oral Presentation
Topic:
OCEANOGRAPHY AND MARITIME TECHNOLOGY
Citation:
Cobelo-Garcia
A
(2014). Technology-critical elements: a need for evaluating the anthropogenic impact on their marine biogeochemical cycles.
Front. Mar. Sci.
Conference Abstract:
IMMR | International Meeting on Marine Research 2014.
doi: 10.3389/conf.fmars.2014.02.00164
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
25 Apr 2014;
Published Online:
18 Jul 2014.
*
Correspondence:
Dr. Antonio Cobelo-Garcia, Instituto de Investigaciones Marinas (IIM) - Consejo Superior de Investigaciones Cientificas (CSIC), Vigo, 36208, Spain, acobelo@iim.csic.es