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本研究采用莱州湾沿岸含水层中的沉积物,通过渗滤实验模拟镭的解吸过程。结果表明,在典型的地下水流速范围内(0.02~0.30 cm/min),镭同位素(~(223)Ra、~(224)Ra、~(226)Ra)的解吸没有显著变化。在海水与淡水的混合过程中,解吸的镭比活度与水的盐度呈显著的线性正相关关系。当盐度超过海水盐度时(如S=80的卤水中),解吸的镭比活度则趋于最值平台。对比模拟估算的地下水中镭的比活度与莱州湾沿岸实测间隙水中镭的比活度,~(223)Ra和~(224)Ra的结果基本一致,而~(226)Ra的实测结果较模拟估算结果偏小。可能由于含水层中~(226)Ra经反复解吸后得不到母体核素及时补充所致。本研究将为更好地理解镭同位素在含水层中的地球化学行为提供科学依据,为合理地选择量化海底地下水排放(submarine groundwater discharge,SGD)模型的镭端元值提供新的参考视角。
In this study, the sediments in the aquifers along the coast of Laizhou Bay were used to simulate the desorption of radium by percolation experiments. The results show that there is no significant change in the desorption of Ra isotopes (~ (223) Ra, ~ (224) Ra, ~ (226) Ra) at typical groundwater velocities ranging from 0.02 to 0.30 cm / min. During the mixing process of seawater and freshwater, there was a significant linear positive correlation between radium specific activity of desorption and salinity of water. When the salinity exceeds the sea salinity (such as S = 80 in brine), desorbed radium specific activity tends to the most value platform. The specific activity of radium in groundwater simulated by comparison with that of ~ (223) Ra and ~ (224) Ra in the measured interstitial water of Laizhou Bay coast is basically the same, while the measured results of ~ (226) Ra are Simulation results are small. It may be due to the aqueous layer in the (226) Ra after repeated desorption of the parent nuclide can not be replenished. This study will provide a scientific basis for better understanding the geochemical behavior of radium isotopes in aquifers and provide a new reference perspective for the rational selection of the value of radian end-element for quantifying submarine groundwater discharge (SGD) model.