Testament of the efficiency of environmental policies

Human activities, such as the combustion of leaded petrol, emissions from non-ferrous metal smelting, coal combustion and waste incineration constitute major environmental lead (Pb) sources during the past century. This resulted in a considerable increase of anthropogenic Pb in the surface and deep waters of the North Atlantic, large enough to mask the natural lead signal.

Increased usage and then phasing-out of leaded-petrol since the mid-70's yielded a decrease of this contamination. By measuring lead concentrations and isotopes (excellent tracers of the different sources of lead) along the GEOTRACES sections GA02 and GA06, Bridgestock and his co-workers (2016, see reference below) 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.

16 BridgestocklFigure: Locations of the surface seawater samples analyzed in this study (left). The brown shaded box shows the area found to contain the highest amounts of naturally sourced lead (Pb) resulting from the deposition of North African mineral dust. Significant inputs of natural Pb can be identified by higher Pb isotope ratio values (206Pb/207Pb and 208Pb/207Pb; right).


Bridgestock, L., van de Flierdt, T., Rehkämper, M., Paul, M., Middag, R., Milne, A., Lohan, M.C., Baker, A.R., Chance, R.,, Khondoker, R., Strekopytov, S., Humphreys-Williams, E., Achterberg, E.P., Rijkenberg, M.J.A., Gerringa, L. J.A., de Baar, H. J. W. (2016). Return of naturally sourced Pb to Atlantic surface waters. Nature Communications, 7, 12921. doi:10.1038/ncomms12921

Isotopes Atlantic Ocean Iron Global scale Pacific Ocean Neodymium Neodymium isotopes Particles Multiple TEIs Southern Ocean Zinc Thorium Land-ocean inputs Hydrothermal Arctic Ocean Analysis Modelling Circulation Cadmium Land-ocean input Thorium isotopes Data compilation Indian Ocean Cycles Mercury Radium Speciation Barium Silicon Aerosol input Iron isotopes Copper Manganese Hypoxia Radium isotopes Phosphate Cobalt Rare Earth Element Lead Lead isotopes Aluminium Protocol Mediterranean Sea Aerosols Boundary Exchange Protactinium Thorium-Protactinium Paleoceanography Environmental change Organic matter Nepheloids Aerosol Cadmium isotopes Zinc isotopes International Polar Year Uranium Microbial Rare Earth Elements Benthic Limitation Phytoplankton Oxygen Silicon isotopes Chromium Chronium isotopes BioGEOSCAPES Particulate Organic Carbon Export fluxes Residence times Methylmercury Surface waters Helium Paleocirculation Proxy Nickel Remineralization Nitrogen Sediments Climate change Lanthanum Yttrium Scandium Intercalibration Lithogenic Macronutriments Micronutriments Hafnium Hafnium isotopes Ice Sea ice Helium isotopes Particle fluxes Barium isotopes Biological pump Iodine Uranium isotopes Artificial Intelligence Cadmium sulfide Antarctic geology Beryllium Mammals Phosporus Time Series Productivity Red Sea Distribution coefficient Mesoscale transport Fertilisation Processes Estuaries Mesopelagic Anoxia Black Sea ICPMS Ecosystem CO2 degassing Transmissiometer Eddy Kinetic Energy Fate Scavenging Fractionation Distribution Iron sulfide Precipitation Shelf Inputs River Pitzer equations Gadolinium Intercomparison Coastal area Gallium Submarine Ground Water Discharge Cooper isotopes Total Hg Fertilization Experiments Behavior Budget Atmospheric Dynamic SAFE samples Boundary Scavenging Procedure Osmium Arsenic Aerosols input Nitrate Nutrients Deep water Copper isotopes Dissolved concentations

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