河北平原第四系地下水氦同位素特征

通过对河北平原第四系地下水He同位素进行比较分析,根据过剩He(4Heexc)、3He/4He比值、δ3He值分析认为,河北平原第四系地下水He同位素有5个特征:(1)地下水中过剩He浓度沿着地下水的流向而增高;(2)地下水中的过剩He浓度随着地下水埋深加大而增高;(3)满城—沧州剖面上过剩He浓度大于石家庄—衡水剖面上的过剩He浓度;(4)河北平原第四系地下水主要是由大气降水补给的;(5)衡水热水过剩He浓度很高(>674 83×10-8cm3STPg-1),这表明以放射成因He为主,地幔成因的He极少。另外地下水的3He/4He比值、R/Ra、δ3He值是判断氦源的一个灵敏的指示剂。

Characteristics of helium isotopes of groundwater in the Quaternary System in the Hebei Plain, North China

In this paper, the helium isotopes of groundwater in the Quaternary System in the Hebei Plain are analyzed. According to the“excess helium” ((~(4)He_(exc))), (~(3 )He/(~4He) ) ratios and (δ~3He) value, the helium isotope systematics of Quaternary groundwater in the Hebei Plain shows the following five characteristics: 1concentrations of ~(4)He_(exc) in groundwater increase along the flow direction of groundwater; 2concentrations of ~( 4)Heexc in groundwater increase with the depth of groundwater; 3concentrations of( ~( 4)He_(exc)) of the hydrogeological profile in Mancheng-Cangzhou are higher than those in Shijiazhuang-Hengshui; (4) the Quaternary groundwater in the Hebei Plain is of meteoric origin; (5)the thermal groundwater in Hengshui has a higher concentration of (~(4)He_(exc)) (>674.83×10~(-8) cm~3STPg~(-1)). Radiogenic helium predominates in the groundwater (~3He/~4He) ratios, R/R_a and δ~3He value are sensitive indicators in judgment of the helium source.