中国七大古都的地球化学环境特征

以全国水系沉积物地球化学调查成果为基础,讨论中国七大古都安阳、西安、洛阳、开封、南京、杭州、北京的环境地球化学背景特征,结果表明,与中国水系沉积物元素含量均值相比,七大古都所在地相对富集镁、钙、硼、锫、银、钴、钡、钠、锶和磷,以人体必需营养元素为主;同时相对贫化镉、钼、锑、铅、钨、铋、砷、锰、铌和汞等,以人体有害元素为主.根据土壤地球化学特征,欧洲的主要国都可分为波罗的海型和地中海型,具有不同的元素分布模式.在中国古都延续时间与元素偶比值之间可建立回归方程Y=0.206X+376,X=(CaO×Fe2O3×V×Co×106)/(SiO2×Pb×Hg×Cd);在欧洲国都与元素偶比值之间也可建立类似的回归方程.充分说明首都的选址还受到地球化学环境的制约.

Geochemical environmental characteristics of China's seven ancient capitals

According to data from geochemical stream sediment survey, this paper deals with the environmental geochemical background characteristics of China's seven ancient capitals, which include Anyang, Xi'an, Luoyang, Kaifeng, Nanjing, Hangzhou and Beijing. The results show that, compared with element contents of stream sediments in China, the body-oriented essential nutrients cal cium, boron, zirconium, silver, cobalt, barium, sodium, strontium and phosphorus are relatively high in areas of the seven ancient capitals. At the same time, these ancient capital areas are relatively depleted in cadmium, molybdenum, antimony, lead, tungsten, bismuth, arsenic, manganese, niobium and mercury, which are mainly harmful elements. In accordance with the soil geochemical characteristics, capitals of major European countries can be divided into the Baltic type and the Mediterranean type, which have different element distribution patterns. According to the relationship between the duration of the ancient capital and the ratio of elements, regression equations can be respectively established: Y_1 = 0.206X +376, X_1=(CaO×Fe_2O_3×V×Co×10~6)/(SiO_2×Pb×Hg×Cd) for China, and Y_2=395.61gX_2-115.5, X_2= (CaO×MgO×Fe_2O_3×Mn×Co×Cd)/(SiO_2×Sr) for Europe, suggesting that the site selection of a capital was restricted by the geochemical environment.