Issue Date: November 7, 2016
Pristine Stone Age wood and bone artifacts are being dissolved by sulfuric acid in the soil
For millennia, the wet boggy conditions at the Star Carr archeological site in Eastern England kept a cornucopia of 10,000-year-old, Stone Age wood and bone objects, including 22 red deer antler headdresses used in shaman rituals, in pristine condition. But in the early 2000s, the land was drained for agriculture, dropping the water table and drying out the archeological site. Since then, archeologists have been alarmed to find that recently unearthed objects at the site are degrading rapidly. Scientists believe oxygen is now reaching sulfur-rich sediments lying below the artifacts. Consequently, sulfides are being oxidized to sulfuric acid, causing acidification of soil near the artifacts to a pH level of 2. A team led by the University of York’s Kirsty Penkman created a lab model of the site to figure out how this geochemistry is affecting the artifacts (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1609222113). The team found that these changes in soil geochemistry have accelerated the breakdown of hydroxyapatite in bone artifacts and lignin in wood artifacts. “Our research demands a reassessment of the assumption that sites such as Star Carr should be preserved in situ,” the study’s authors note.
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