MERCURY IN HOUSATONIC RIVER AND STILL RIVER SEDIMENTS: A LEGACY OF DANBURY (CT) HATMAKING

Mercury (Hg) concentrations were determined with a Direct Mercury Analyzer based on Atomic Absorption Spectroscopy in surface sediments from the Still River and Housatonic River as well as in cores from wetlands along these rivers. All surface samples have Hg concentrations that are well above the natural background of 50-100 parts per billion (ppb) and also above peak levels of Hg contamination found elsewhere in Connecticut (200-500 ppb). The Still River sediment samples have Hg concentrations that range from 1000 to 60,000 ppb Hg. The highest Hg concentrations are found in fine-grained, organic-rich sediments past the town of Brookfield, which was a secondary hat-making center after Danbury. A core from the northern sector of the Still River shows a Hg pollution profile with values up to 100,000 ppb Hg and 210Pb dates show an age around 1900 AD for that peak. Four cores from Long Island, Carting Island, Pope Island and Fowler Island in the lower section of the Housatonic River show Hg concentrations that range from ~300 to 5000 ppb Hg. A core from Knells Island in the Housatonic River shows a pollution profile that starts around 1820 AD, with a strong peak (1500 ppb Hg) in the 1970’s. The Housatonic River delta in Long Island Sound also has Hg levels up to 1200 ppb. The time of peak hat-production was around 1900 but this was also a very wet period in Southern New England, with major floods in the river basins. The Hg from Danbury hatmaking is stored in Danbury uplands and sediments of the Still River, and it has made its way downstream over time to the Housatonic River and Long Island Sound, especially during high-discharge periods of the rivers. Some cores in Long Island Sound show a distinct positive Hg anomaly around 1900 AD and 1955 AD, the two major episodes with catastrophic floods in Connecticut. This pattern of transport down river will continue in the future and citizens living on the banks of these rivers need to be aware of this contamination problem that is a legacy from industrial activities that took place 100-200 years ago.