A 700 year record of combustion-derived pollution in northern Spain: Tools to identify the Holocene/Anthropocene transition in coastal environments
Graphical abstract
Introduction
Historical atmospheric pollutant emissions data are very limited for SW Europe and consist of country-specific emission records which are fairly recent (i.e. since the 1970s) (Pacyna et al., 2003, Pacyna et al., 2007). In the Iberian Peninsula, atmospheric pollutant records have been mainly restricted to cores from high altitude lake sediments (Fernandez et al., 2002) and peat bogs (Martinez-Cortizas et al., 1997, Martinez-Cortizas et al., 2002), leaving a very limited understanding of atmospheric emissions at regional scale. The historic patterns of these emissions may also be recorded in coastal salt marsh sediments through integration of the atmospheric and aquatic (watershed) deposition. Coastal wetlands are of great ecological value and rank among the most productive of all natural ecosystems, and coastal areas have been attractive sites for human settlement over several millennia (Perillo et al., 2009). Globally, 1.2 billion people (23% of the world's population) live within 100 km of the coast, and 50% are likely to do so by 2030 Common Era (CE) (Adger et al., 2005), highlighting the critical need to study the historical record of pollutant deposition and storage within coastal sediments. In this context, the study of undisturbed sediment cores offers great potential to reconstruct the history of contamination (Valette-Silver, 1993, Ridgway and Shimmield, 2002). Although interpretation of the obtained data may be challenging due to the complicating effects of sediment re-suspension, early diagenetic reactions or bioturbation (Farmer, 1991, Eggleton and Thomas, 2004), these problems can be overcome by a multi-proxy approach including various indicators such as heavy metals, organic chemicals, radionuclides and Pb isotopic signatures (Kim et al., 2004, Cantwell et al., 2007, Louchouarn et al., 2012).
Pollution sources (e.g., burning of wood, coal, and oil-derivate products) may vary greatly but the atmosphere is the predominant route for combustion derived contaminants, including organic molecules such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals such as Pb (Gallon et al., 2005, Louchouarn et al., 2012). The measurement of PAHs (and their isomer ratios) and Pb stable isotope ratios can yield information about contaminant sources and distribution pathways (Louchouarn et al., 2012). For instance, PAH isomer ratios can be used to differentiate between pyrogenic (combustion) and non-pyrogenic (petrogenic) sources of these compounds (Reddy et al., 2002). Moreover PAH isomer ratios can also be used to indicate the ‘fuels’ combusted (e.g., coal versus oil-derivate products) (Vane et al., 2011). Likewise, different sources of atmospheric Pb, such as wood burning, fossil fuel combustion or metal smelting, can be identified by their distinct Pb isotopic signatures (Gallon et al., 2005, Sturges and Barrie, 1987). Another advantage of the use of Pb as a proxy is that its stable isotope ratios are minimally altered by physical or chemical processes within the sediments (Gallon et al., 2005). Lead is considered immobile in peat sediments, peat bogs and lake sediments (see Shotyk et al., 1998 and references therein). The few studies which have examined ratios of Pb stable isotopes in conjunction with PAHs in sediments have been successful in identifying the types of fuel that contributed combustion-derived contaminants to the sediment (e.g. charcoal, wood, coke, coal, smelting, gasoline) (Gallon et al., 2005, Louchouarn et al., 2012, Vane et al., 2011). Further, the combination of several proxies allows assessment of the mobility and stability of each proxy within sediment cores (Brandenberger et al., 2008, Brandenberger et al., 2011, Kuo et al., 2011, Louchouarn et al., 2012).
This study aims to produce a reliable sedimentary record of atmospheric pollution from coastal sediments in northern Spain using a multi-proxy approach. Concentrations of a wide range of PAHs and heavy metals were determined in a sediment core collected in the Kanala salt marsh. From this, a 700 year record of combustion-derived inputs for this estuarine area of southwestern Europe was reconstructed, providing a high resolution historical record of the transition from the Holocene (last interglacial, ca. last 11,500 years) to the Anthropocene (sensu Crutzen and Stoermer, 2000) in this region.
Section snippets
Study site
The study site was selected based on previous sedimentological studies on the Atlantic Iberian coast which have identified zones of consistent and uniform accretion i.e. Kanala salt marsh, Urdaibai estuary, N. Spain (Leorri et al., 2010). The Urdaibai estuary represents the tidal portion of the Oka River, covers an area of 7.65 km2, and occupies the flat bottom of the 11.6 km long, 1 km wide alluvial valley. The local and regional characteristics have been described elsewhere (Leorri and Cearreta,
Sediment chronology
Sedimentation rate estimates derived from the CRS (Appleby and Oldfield, 1978) method indicate that the uppermost 10 cm was deposited over about 100 years. The downcore profile of 137Cs shows a clear subsurface maximum in activity at 3.5 cm depth. Assuming this subsurface 137Cs maximum to be 1963 CE, i.e., during peak atmospheric bomb testing, it corroborates the 210Pbxs-derived age estimates. Considering the apparent minimal sediment mixing in this core, the ages of each sediment depth were
Conflict of interest
The authors declare that there is no any actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations within three years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work.
Acknowledgments
The research was funded by the following projects: TANYA (MICINN, CGL2009-08840), IT365-10 and IT767-13 (GV, Harea-Coastal Geology Research Group), and UFI11/09 (UPV/EHU, Unidad de Formación e Investigación en Cuaternario). Dr. Manuel R. Monge-Ganuzas (Technical Office of the Urdaibai Biosphere Reserve) helped in the field. This is a contribution to the IGCP Project 588, Northwest Europe working group of the INQUA Commission on Coastal and Marine Processes, and Departamento de Geodesia of the
References (77)
- et al.
A European lead isotope signal recorded from 6000 to 300 years BP in coastal marshes (SW France)
Atmos Environ
(2001) - et al.
Isotopic identification of natural vs. anthropogenic lead sources in marine sediments from the inner Ria de Vigo (NW Spain)
Sci Total Environ
(2012) - et al.
The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sediment
Catena
(1978) Po-210 and Pb-210 as atmospheric tracers and global atmospheric Pb-210 fallout: a review
J Environ Radioact
(2011)- et al.
Pb isotope ratios of lake sediments in West Greenland: inferences on pollution sources
Atmos Environ
(2001) Adsorption of heavy metal ions on soils and soils constituents
J Colloid Interface Sci
(2004)- et al.
Compression behaviour of minerogenic low energy intertidal sediments
Sediment Geol
(2011) - et al.
Analysis of geomorphic systems' response to natural and human drivers in northern Spain: implications for global geomorphic change
Geomorphology
(2013) - et al.
Reconstruction of contaminant trends in a salt wedge estuary with sediment cores dated using a multi-proxy approach
Mar Environ Res
(2007) - et al.
Environmental transformation of the Bilbao estuary, N. Spain: microfaunal and geochemical proxies in the recent sedimentary record
Mar Pollut Bull
(2002)
Recent salt marsh development and natural regeneration of reclaimed areas in the Plentzia estuary, N. Spain
Estuar Coast Shelf Sci
Recent environmental evolution of regenerated salt marshes in the southern Bay of Biscay: anthropogenic evidences in their sedimentary record
J Mar Syst
Lead isotope ratios in Spanish coals of different characteristics and origin
Int J Coal Geol
Atmospheric inputs of selected polycyclic aromatic hydrocarbons and polychlorinated biphenyls to southern Chesapeake Bay
Mar Pollut Bull
A synthesis of lead isotopes in two millennia of European air
Earth Planet Sci Lett
Stable lead isotopic characterisation of the historical record of environmental lead contamination in dated freshwater lake sediment cores from northern and central Scotland
Sci Total Environ
A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events
Environ Int
Sources and chronology of atmospheric lead deposition to a Canadian Shield lake: inferences from Pb isotopes and PAH profiles
Geochim Cosmochim Acta
Anthropogenic impact and lead pollution throughout the Holocene in Southern Iberia
Sci Total Environ
Polycyclic aromatic hydrocarbons in an anoxic sediment core from the Pettaquamscutt River (Rhode Island, USA)
Geochim Cosmochim Acta
Historical signature of Roman mining activities in the Bidasoa estuary (Basque Country, northern Spain): an integrated micropalaeontological, geochemical and archaeological approach
J Archaeol Sci
Accumulation records of radionuclides and trace metals in two contrasting Delaware salt marshes
Mar Chem
Combustion-derived substances in deep basins of the Puget Sound: historical inputs from fossil fuel and biomass combustion
Environ Pollut
Quantitative assessment of the salinity gradient within the estuarine systems in the southern Bay of Biscay using benthic foraminifera
Cont Shelf Res
Development of a foraminifera-based transfer function in the Basque marshes, N. Spain: implications for sea-level studies in the Bay of Biscay
Mar Geol
Atmospheric Pb deposition in Spain during the last 4600 years recorded by two ombrotrophic peat bogs and implications for the use of peat as archive
Sci Total Environ
Reconstructing historical Pb and Hg pollution in NW Spain using multiple cores from the Chao de Lamoso bog (Xistral Mountains)
Geochim Cosmochim Acta
Multiple site study of recent atmospheric metal (Pb, Zn and Cu) deposition in the NW Iberian Peninsula using peat cores
Sci Total Environ
Improving the 210Pb-chronology of Pb deposition in peat cores from Chao de Lamoso (NW Spain)
Sci Total Environ
Current and future emissions of selected heavy metals to the atmosphere from anthropogenic sources in Europe
Atmos Environ
Pre-industrial accumulation of anthropogenic polycyclic aromatic hydrocarbons found in a blanket bog of the Iberian Peninsula
Environ Res
Five thousand years of atmospheric Ni, Zn, As, and Cd deposition recorded in bogs from NW Iberia: prehistoric and historic anthropogenic contributions
J Archaeol Sci
PAH fluxes in the Laja Lake of south central Chile Andes over the last 50 years: evidence from dated sediment core
Sci Total Environ
Stable lead isotopes and lake sediments — a useful combination for the study of atmospheric lead pollution history
Sci Total Environ
Estuareis as repositories of historical contamination and their impact on shelf seas
Estuar Coast Shelf Sci
PAHs in the Fraser River basin: a critical appraisal of PAH ratios as indicators of PAH source and composition
Org Geochem
Social-ecological resilience to coastal disasters
Science
Chronostratigraphic techniques in recent sediments
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