Three centuries of heavy metal pollution in Paris (France) recorded by urban speleothems

• Published in: The Science of the total environment 2015-06, Vol.518-519, p.86-96
• Main Authors: Pons-Branchu, Edwige, Ayrault, Sophie, Roy-Barman, Matthieu, Bordier, Louise, Borst, Wolfgang, Branchu, Philippe, Douville, Eric, Dumont, Emmanuel
• Format: Article
• Language: English
• Subjects: Aqueduct; Aqueducts; Continental interfaces, environment; Environmental Monitoring - methods; Environmental Pollution - statistics & numerical data; Geologic Sediments - chemistry; Heavy metal pollution; Heavy metals; Lead (metal); Lead stable isotopes; Metals, Heavy - analysis; Mining; Ocean, Atmosphere; Paris; Pollution abatement; Sciences of the Universe; Signatures; Speleothems; Urban groundwater; Urbanization; Water pollution
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.02.071

The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th–18th centuries (206Pb/207Pb=1.180+/−0.003). The mean 206Pb/207Pb ratio, for one of the speleothems is 1.181+/−0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183+/−0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172+/−0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975+/−15years) deposit (206Pb/207Pb=1.148+/−0.003), and the second, a thin subactual layer (206Pb/207Pb=1.181+/−0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore). •Urban speleothems from underground aqueduct in Paris, France were studied.•Speleothems are used to reconstruct the history of sub-surface water pollution.•Two distinct periods of heavy metal pollution occurred during the last 300years.•Lead isotope ratio is used to constrain lead contamination sources.•18th century metal contamination originates from the use of urban wastes as fertilizer.