Lead concentrations and isotopes in corals and water near Bermuda, 1780–2000

摘要: Abstract The history of the oceanic anthropogenic lead (Pb) transient in North Atlantic Ocean for past 220 yr is documented here from measurements Pb concentration and isotope ratios annually-banded corals that grew coastal seawaters near Bermuda seawater samples collected during last 20 yr 20th century. Anthropogenic emissions this area have been dominated by industrialization America beginning 1840s, introduction leaded gasoline 1920s its phase-out began mid-1970s. was largely completed late 1990s. Coral concentrations occur at a constant low level about 5 nmol Pb/mol Ca (~ 15 pmol/kg seawater) 1700s to ~ 1850. From ~ 1850 ~ 1900 there small increase rising plateau ~ 25 nmol (~ 80 pmol/kg 1930s until 1940s, which point rapidly ~ 60 nmol (~ 200 pmol/kg seawater). In mid 1970s, decline Pb/Ca (40 pmol/kg end century, comparable levels occurring early (Pb I.R.) show maximum 206Pb/207Pb = 1.21 208Pb/207Pb = 2.49 middle 19th We conclude signal reflection dominance Upper Mississippi Valley ore United States, as previously seen estuarine sediments Rhode Island. After 1900, I.R. decrease only slightly 1960s when significant local 1970s 206Pb/207Pb = 1.19 208Pb/207Pb = 2.45 low-Pb sources were phased out States. Then, US utilization decreased more than European gas (which has lower I.R.), western 206Pb/207Pb = 1.17 208Pb/207Pb = 2.44, their lowest values two centuries.