Lead (Pb) occurs naturally in the environment as a trace element. Lead major natural sources include volcanoes and weathering of rocks. Human activities, including mining, coal combustion, addition to gasoline and waste incineration, have greatly increased the distribution and abundance of lead in the environment. Increased usage and then phasing-out of leaded-petrol since the mid-70s yielded a decrease of this contamination.
Lead can enter the ocean by atmospheric deposition and fluvial freshwaters are common to other trace metals. Therefore, lead provides a proxy of trace metal inputs to the ocean. Isotopic ratios of Pb can be applied to determining the source material (ie. gasoline, coal) or the source location (ie. Asia, North America) of Pb inputs.
By measuring lead concentrations and isotopes GEOTRACES scientists reveal for the first time that natural lead can be detected again in the surface water of the North Atlantic. Indeed, significant proportions of up to 30–50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters off the Sahara. This clearly reflects the success of the global effort to reduce anthropogenic Pb emissions. Indeed, the increased usage and then phasing-out of leaded petrol since the mid-70s yielded a decrease in this pollution.
Atlas
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Atlantic Ocean:
Indian Ocean:
Pacific Ocean:
Arctic Ocean:
Data
Data is available to download after registration here: https://geotraces.webodv.awi.de/login
Discoveries include:
Unveiling the Complexity of Lead Distribution in the Pacific Ocean: Insights from the GEOTRACES GP15 Transect
This recent study by Jiang and colleagues investigate the distribution and sources of lead in the Pacific Ocean.
Iron and zinc isotopes disentangle the anthropogenic, natural and wildfire sources of aerosols over the North and Equatorial Pacific Ocean
Bunnell and co-authors analysed aerosol iron and zinc isotopic compositions along the North Pacific GEOTRACES GP15 section (Alaska-Tahiti).
Warning on Polonium-210/Lead-210 data quality!
Alerted by the fact that the published Polonium-210:Lead-210 profiles showed ubiquitous disequilibrium in the deep ocean, Mark Baskaran and colleague conducted a critical review…
Lead isotopes, reversible scavenging and ventilation processes in the South Atlantic Ocean
Olivelli and co-authors present seawater lead concentrations and lead isotopes for 10 depth profiles collected in the South Atlantic Ocean.
Trace metal fluxes of cadmium, copper, lead and zinc from the Congo River into the South Atlantic Ocean are supplemented by atmospheric inputs
Liu and colleagues show that rainfall augments some fluxes of trace metals from the Congo River.
Aluminium, manganese, iron, cobalt, and lead display contrasting fate along north–south and east–west sections in the North Pacific Ocean
Chan et co-authors provide a comprehensive view of trace metal distribution in the subarctic Pacific Ocean.
Lead isotopes allow tracing the processes injecting of anthropogenic lead in deep waters
This work follows the penetration of anthropogenic lead (traced using its isotopic signatures) into the pristine deep Pacific Ocean.
Pulling back the veil on reversible scavenging of lead
This work further contains the role that reversible scavenging may play in the cycling of lead in the ocean, an ever-evolving global experiment where lead contamination can be tracked in real-time.
Decline of the anthropogenic lead imprint to the ocean confirmed by data from the South West Atlantic Ocean
This study reveals that the mean lead concentrations in the surface waters of the western South Atlantic Ocean decreased by 34 % between the 1990s and 2011.