黄河下游地下水中镭氡同位素的分布及影响因素研究

为研究黄河下游地下水中镭氡同位素的含量、分布及其影响因素，于2015年5月至2016年2月，按季度对黄河下游利津水文站至黄河口区间100 km河道内的地下水进行了5次调查，得到结论如下:①黄河下游地下水中3种镭同位素（223Ra、224Ra和226Ra）活度变化范围为0.4~5.9 dpm/100L、23.5~358.1 dpm/100L和11.2~49.4 dpm/100L；222Rn活度变化范围为8.2~700.5 dpm/L，除个别站位（如DP-#）地下水中222Rn浓度较高以外（608.8±105.0 dpm/L），其他站点222Rn浓度水平基本上保持在8~200 dpm/L之间。②远离河口的采样站位（LJ-#、YL-#和YW-#）地下水中镭同位素浓度的季节性特征不明显，而靠近河口的采样点（DP-#和KY-#）的镭同位素浓度季节性差别显著。随着向河口方向的延伸，地下水中镭同位素浓度呈现出逐渐增加的趋势，盐度是影响镭同位素活度的关键因素。③各采样点水体中222Rn浓度变化均呈现出夏季略低于冬季的分布特征，水体停留时间和黄河径流量变化是影响222Rn活度变化的主要原因。

Distribution characteristics and influence factors of radium and radon isotopes in the lower reaches of the Yellow River

In order to study the concentrations, distributions and influence factors of radium and radon isotopes in underground water in the lower reaches of the Yellow River, we carried out five surveys along the lower reaches of the river channel from Lijin station to the Yellow River estuary in different seasons from May, 2015 to February, 2016. The results indicate that:① Concentrations of the three radium isotopes (223Ra, 224Ra and 226Ra) were 0.4~5.9 dpm/100L, 23.5~358.1 dpm/100L and 11.2~49.4 dpm/100L in underground water in lower reaches of Yellow River; The 222Rn contributions was 8.2~700.5 dpm/L, in addition to individual site (such as DP-# site), the 222Rn concentration was higher (608.8±105.0 dpm/L), the 222Rn concentrations ranged from 8 to 200 dpm/L in other sites. ② Far away from the Yellow River Estuary, radium isotopes did not have significant variation among seasons (LJ-#, YL-# and YW-#). In area close to the Yellow River Estuary (DP-# and KY-#), radium isotopes changed a lot among seasons. Along the direction to the Yellow River mouth, radium isotopes concentrations increased, and salinity was found to be the main controlling factor. ③ 222Rn concentration was higher in winter than summer, the groundwater residence time and river discharge amount were the main influence factors.