公元前2500年:中国进入铜石并用时代的汞记录

2500BC:THE BEGINNING OF CHALCOLITHIC PERIOD IN CHINA RECORDED BY Hg

对安徽蒙城尉迟寺遗址剖面5050-4000cal.aB.P.间的汞记录研究表明,剖面中Hg的累积速率主要是由大气沉降影响的。在5050-4550cal.aB.P.间,YC1剖面中的汞的累积速率相对较低,并且主要是受气候控制：气候越寒冷,剖面中汞的累积速率则越高;在4530-4000cal.aB.P.间,YC1剖面中汞的累积速率显著升高,此时影响剖面中汞的累积速率的主要因素是人类活动——中国古代人类社会的原始金属冶炼活动,原始金属冶炼活动的规模直接决定了剖面中汞的累积速率。Hg在距今4500年前后的显著上升,标志着中国已经进入了铜石并用时代。

The sediment of archaeology site gives us a good medium to understand ancient human activities, especially those of Pre-history. In this study,230 samples were collected from a 460cm deep sediment profile named YC1 in the Yuchisi Site in Mengcheng of Anhui at an interval of 2cm. The site contains culture layers of the Dawenkou Culture and the Longshan Culture, aged from 5050cal. aB. P. to 4000cal. aB. P. The concentrations of Hg, Ti, Pb, Cu, Cd,TOC,as well as grain size,were analysed to research the primitive metallurgy during that period. The result shows that the profile could be divided into two parts by Hg concentration in the cultural layers （450 -90cm）. The lower part is bellow 280cm,with Hg concentration quite low,averaged at 56ng/g. In the upper part,above 280cm, Hg concentration increased quickly： from 280cm to 250cm,it varied from 55ng/g to 498ng/g; and above 250cm, it kept in a high level of 267ng/g in average. The available evidence suggests that the Hg concentration variation was mainly affected by atmospheric deposit. The Hg accumulation rate （AR）in the YC1 profile could be divided into three steps. Step 1 is before 4750cal. aB. P. ,with a low AR of 105μg/m^2a in average. Step 2 is from 4700cal. aB. P. to 4550cal. aB. P. ,with an obviously increased AR of 563μg/m^2a in average, which is 5 times faster than in Step 1. Step 3 is from 4530cal. aB. P. to 4000cal. aB. P., with its AR obviously shifting compared to Step 2, of 1172μg/m^2 a in average, which is two times faster than Step 2, 11 times faster than Step 1. Compared with climatic evidence, the Hg accumulation rate was found to be mainly affected by climate during Step 1 and Step 2： the cooler the climate,the higher the Hg accumulation rate in the profile. But in Step 3,the climate was no longer the determining factor,but the ancient human activity was. From 4500cal. aB. P. to 4000cal. aB. P., many copper relics were detected by archaeologists,while before 4500cal. aB. P. only two were detected, indicating a quick development of primitive metallurgy of prehistoric society. The scale of the metallurgy activities had great impact on Hg accumulation rate in the YC1 profile： the bigger the scale was,the higher the AR in the profile. As the turning point of Hg accumulation rate happened at about 4500cal. aB. P.,it might be the coming of the Chalcolithic Period in China.