Washington, June 23 : By using ancient sediments taken from a Chinese lake, scientists have been able to trace the 7,000-year-old history of mining and metal use in central China from the Bronze age to the military and industrial periods of the country.
The carbon-dated core sediments were taken from Liangzhi Lake in Hubei province by scientist Xiang-Dong Li and colleagues, who were able to track metal deposit trends at the lake dating back to 5,000 B.C.
The study could help scientists better assess the accumulative environmental effects of human activity in the region since prehistory times.
According to the scientists, Liangzhi Lake, located in an important region in the development of Chinese civilization, is relatively undistributed by local wastewater discharges and is therefore an ideal site to study ecological changes and the effects of past human activity.
The researchers found that beginning in about 3,000 B.C., concentrations of copper, nickel, lead and zinc in the sediments began to rise, indicating the onset of Bronze Age in ancient China.
In the late Bronze Age (475 B.C. to 220 A.D.), an era corresponding with numerous wars, sediment concentrations of copper increased 36 percent and lead by 82 percent.
Copper and lead were used extensively to make bronze tools and weapons.
The sediments suggest mining and metal usage in the region continued to wax and wane into the modern era, reflecting the environmental changes influenced by past human activity.