A 700year record of combustion-derived pollution in northern Spain: Tools to identify the Holocene/Anthropocene transition in coastal environments

When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal

“…the global spread of artificial radionuclides from surface A-bomb explosions (Fairchild and Frisia, 2014;Hancock et al, 2014;Wolff, 2014); doubling of the surface reactive nitrogen reservoir (a result of fertilizer manufacture via the HabereBosch process), reflected in nitrogen isotope changes in far-field lacustrine deposits (Holtgrieve et al, 2011;Wolfe et al, 2013); the creation and wide (global) dispersal of new human-made materials (Ford et al, 2014;Zalasiewicz et al, 2014c) and artefacts that may be regarded as technofossils in the environment e almost all the discarded plastic and aluminium waste in surface sediments date from the midtwentieth century, for instance; rapid expansion in the distribution of artificial deposits on land, associated with urbanization (Ford et al, 2014), and of reworked sediment on continental shelves and slopes, associated with deep-sea trawling (see references in Zalasiewicz et al, 2014a); global dispersal of pollutants associated with expansion of industrial activities, including novel organic contaminants that include persistent organic pollutants (POPs) (Muir and Rose, 2007) and increased concentrations of heavy metals that are relatively rare in nature (Leorri et al, 2014;Gałuszka et al, 2014); a significant 'step' in the rate of increase of anthropogenic biotic change (Wolfe et al, 2013;Wilkinson et al, 2014), including accelerated species invasions on land and in the sea that alter species compositions in a wide spectrum of terrestrial and marine communities, in ways that will leave a clear palaeontological signal as we go into the future; a significant signal in polar ice marked by such indicators as lead from gasoline (Wolff, 2014) of different isotopic characteristics than Roman lead from smelting that forms an earlier signal; acceleration in the burning of hydrocarbons that has produced much of the~120 ppm increase in atmospheric carbon dioxide levels since the mid-twentieth century, and hence much of the associated carbon isotope signal (Al-Rousan et al, 2004); the majority of human-created trace fossils derived from sediment and rock drilling. The drilling for petroleum is often particularly deep.…”

Relative sea-level changes in the Basque coast (northern Spain, Bay of Biscay) during the Holocene and Anthropocene: The Urdaibai estuary case

“…Chronology is further supported by total Pb and Zn profiles that suggest two concentration peaks in 1975 (at 12 cm depth) and 1965 (at 16 cm depth), respectively (Leorri et al, 2008b(Leorri et al, , 2014Leorri and Cearreta, 2009b). The total Pb concentration profile shows a clear deviation from pre-industrial (background) values at 20 cm depth that has been associated with the 1900s (Leorri et al, 2014).…”

“…The total Pb concentration profile shows a clear deviation from pre-industrial (background) values at 20 cm depth that has been associated with the 1900s (Leorri et al, 2014). Error ranges in Fig.…”

Exploring the possibility to detect recent temporal changes in highly disturbed sedimentary records through sampling repetitions and core comparisons of porosity and sand content

“…Scientists interested in studying these issues usually rely upon sediment records that, under specific circumstances of continuous and undisturbed deposition, can provide high-resolution information, from seasonal to multi-decadal time scales (e.g., Frank et al 2002;Bellucci et al 2012;Paquette and Gajewski 2013;Leorri et al 2014). When dealing with researches aimed at studying environmental changes and industrial contamination, the attention is focused on a time window of 100-150 years and suitable chronological proxies must be measured in order to define the age of sediment layers.…”