Unraveling the multi-source history of lead contamination in North America’s oldest city St John’s, Newfoundland

• Main Authors: Sylvester, P., Magalios, R., Poujol, Marc
• Other Authors: Terre, Temps, Traçage, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2006
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Canada; British Columbia; Sullivan; Newfoundland
• Online Access: https://insu.hal.science/insu-01083537

International audience Lead isotopes were used to determine sources of high quantities of lead in soilsin urban St. John’s, Newfoundland. Highest lead levels are found near roads(mean=674 ppm) and along the drip line of houses built prior to 1945(mean=2107 ppm) and are an order of magnitude higher than background levelsfrom C-horizon tills (40 ppm). In many cases values exceed national guidelines(CCME, 140 ppm). Sources likely include atmospheric precipitation, coal ashwastes and deposition of lead-based paints along drip lines of buildings. Leadwas likely contributed to the atmosphere from burning of coal for home heatingand from leaded gasoline.Previous measurements of lead isotopes in lake sediments in and aroundthe city suggested that the sources of lead used in the manufacture of dispersedcontaminants changed in about 1960 from ores with low 206Pb/207Pb ratios(~1.064 in the Sullivan mine in Trail, British Columbia or ~1.037 in Broken Hill,Australia) to ores with much higher 206Pb/207Pb ratios (~1.16 in Bathurst, NewBrunswick or 1.28-1.33 from southeastern Missouri, U.S.A.). This studydetermined lead isotopes ratios in 27 soils, 7 C-horizon tills, 2 exterior paints anda piece of archived coal to constrain the sources of lead and their relativecontributions.A linear trend from bedrock-derived lead in tills with high 206Pb/207Pb(~1.18-1.20) and low 208Pb/206Pb (~2.06-2.08) ratios to leads from clapboard driplines and paint from >100 year-old houses with low 206Pb/207Pb (~1.12-1.13) andhigh 208Pb/206Pb (~2.13-2.14) ratios is apparent. Coal and paint from a 50 yearoldhouse fall mid-way along the trend (as do ratios from ores from Bathurst).Soils with moderate lead levels from vacant lots and parks plot toward higher206Pb/207Pb values, whereas lead-rich soils from residential settings plot towardlower 206Pb/207Pb. Contamination of open spaces is dominated by lead fromCape Breton coal and/or gasoline residues and <50-year-old paint derived fromBathurst ores. Contamination of urban residential sites also ...