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Environmental Legacy of Copper Metallurgy and Mongol Silver Smelting Recorded in Yunnan Lake Sediments
journal contribution
posted on 2015-03-17, 00:00 authored by Aubrey L. Hillman, Mark B. Abbott, JunQing Yu, Daniel J. Bain, TzeHuey Chiou-PengGeochemical
measurements on well-dated sediment cores from Lake
Er (Erhai) are used to determine the timing of changes in metal concentrations
over 4500 years in Yunnan, a borderland region in southwestern China
noted for rich mineral deposits but with inadequately documented metallurgical
history. Our findings add new insight into the impacts and environmental
legacy of human exploitation of metal resources in Yunnan history.
We observe an increase in copper at 1500 BC resulting from atmospheric
emissions associated with metallurgy. These data clarify the chronological
issues related to links between the onset of Yunnan metallurgy and
the advent of bronze technology in adjacent Southeast Asia, subjects
that have been debated for nearly half a century. We also observe
an increase from 1100 to 1300 AD in a number of heavy metals including
lead, silver, zinc, and cadmium from atmospheric emissions associated
with silver smelting. Culminating during the rule of the Mongols,
known as the Yuan Dynasty (1271–1368 AD), these metal concentrations
approach levels three to four times higher than those from industrialized
mining activity occurring within the catchment today. Notably, the
concentrations of lead approach levels at which harmful effects may
be observed in aquatic organisms. The persistence of this lead pollution
over time created an environmental legacy that likely contributes
to known issues in modern day sediment quality. We demonstrate that
historic metallurgical production in Yunnan can cause substantial
impacts on the sediment quality of lake systems, similar to other
paleolimnological findings around the globe.
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1500 BCimpactday sediment qualityYunnan Lake SedimentsGeochemical measurementssediment qualitypaleolimnological findingsYunnan historylegacyYunnan metallurgyborderland regionLake Erissuesilver smeltingapproach levelsmetal concentrations1300 AD4500 yearsmetal resourceslake systemsMongol Silver Smelting Recordedemissionmineral depositsEnvironmental LegacySoutheast Asiabronze technologyCopper Metallurgymetal concentrations approach levelscatchment todaymining activity