Simulation of transport mechanism of radium isotopes in aquifer on the southern coast of Laizhou Bay
-
Abstract: Naturally occurring radium (223Ra, 224Ra, 226Ra, and 228Ra) isotopes have been widely applied as geochemical tracers in marine environments, especially when estimating the submarine groundwater discharge (SGD). In this sense, the influencing factors and transport mechanism of radium isotope activity in aquifers can be key information for SGD estimation. This work evaluates the adsorption/desorption behavior of 224Ra and 226Ra in the solid-liquid phase through a leaching experiment and analysis of field data. The results suggested that radium isotope activity was positively correlated with salinity and grain size, in the case of abundant sediments. Through ion analysis, we found that the ions (Na+, Ca2+, Mg2+, and Ba2+) exchanged with radium isotopes in the process of transport. A 1-D reactive transport model was established to simulate the transport process of radium isotope in aquifers. The model successfully simulated the variation of radium isotope desorption activity with salinity and was subsequently verified in the field. This study contributes to the understanding of the geochemical behavior of radium isotopes in aquifers and provides guidance for selecting a suitable groundwater endmember in SGD estimation.
-
Table 1. The 224Ra and 226Ra activities (Bq/m3) leaching experiment results
Salinity Layer 1 Layer 2 Layer 3 Layer 4 Layer 5 Mean value 224Ra 226Ra 224Ra 226Ra 224Ra 226Ra 224Ra 226Ra 224Ra 226Ra 224Ra 226Ra 0.1 3.62 2.35 1.37 1.77 26.66 2.61 2.32 2.32 3.66 2.13 7.53 2.23 1 13.16 5.13 7.24 3.22 6.38 3.49 24.06 4.26 8.30 4.10 11.83 4.04 3 47.32 16.81 26.13 9.65 30.60 10.27 32.32 12.78 27.96 6.20 32.86 11.14 10 115.70 43.14 102.94 35.23 100.79 33.97 109.30 38.61 99.41 17.33 105.63 33.65 20 134.86 35.52 148.89 49.47 187.97 44.14 209.91 54.63 203.91 35.39 177.11 43.83 30 179.74 42.81 173.68 55.10 224.72 49.32 270.24 74.99 245.86 40.06 218.85 52.46 Table 2. The 224Ra and 226Ra results of field data
Sample
codeLatitude Longitude Salinity Group
type224Ra/
(Bq·m−3)226Ra/
(Bq·m−3)YW1-1 36.926°N 119.156°E 10.6 4 60.10 1.15 YW1-2 36.907°N 119.154°E 9.9 4 54.28 8.93 YW1-3 36.895°N 119.156°E 4.3 3 11.11 5.72 YW1-4 36.872°N 119.156°E 0.4 1 8.26 6.68 YW1-5 36.859°N 119.157°E 0.5 1 11.17 5.67 YW1-6 36.830°N 119.158°E 0.4 1 12.43 1.30 YW1-7 36.815°N 119.158°E 0.4 1 9.77 1.51 YW1-8 36.808°N 119.164°E 1.2 2 12.54 1.34 YW2-1 37.045°N 119.477°E 26.1 5 403.60 36.40 YW2-2 36.983°N 119.469°E 14.9 4 578.51 13.92 YW2-3 36.948°N 119.470°E 4.9 3 31.08 6.32 YW2-4 36.930°N 119.470°E 13.0 4 228.03 3.01 YW2-5 36.910°N 119.469°E 1.1 2 43.67 6.64 YW2-6 36.885°N 119.469°E 0.2 1 8.59 2.06 YW2-7 36.874°N 119.458°E 0.3 1 14.85 2.87 YW2-8 36.802°N 119.470°E 0.2 1 13.71 3.78 Table 3. Desorption experiments with different grain sizes
Salinity Grain sizes/μm Conclusions References 35 <63 710 Small grain size has strong adsorption capacity and desorption is difficult. Beck and Cochran (2013) 28 >2000, 2000−1000,
1000−500, 500−250,
250−125, <125The desorption capacity is higher when the average grain size is >2000 μm, the maximum when the average grain size is <125 μm, and the other four grain sizes are similar. Yuan et al. (2014) 33.9 0.9, 5.5, 13.6, 43.7, 76.5, 136 The desorption capacity decreases with the increase of grain size. But, when the average grain size is 136 μm, the desorption is slightly higher than that of the previous grain size. Luo et al. (2019) 0.1, 1, 3, 10, 20, 30 33.43, 35.07, 40.22, 41.71, 79.88 The sediment is abundant without complete desorption, with large grain size and large desorption capacity. this study -
Beck A J, Cochran M A. 2013. Controls on solid-solution partitioning of radium in saturated marine sands. Marine Chemistry, 156: 38–48. doi: 10.1016/j.marchem.2013.01.008 Beck A J, Rapaglia J P, Cochran J K, et al. 2007. Radium mass-balance in Jamaica Bay, NY: Evidence for a substantial flux of submarine groundwater. Marine Chemistry, 106(3–4): 419–441 Beneš P, Strejc P, Lukavec Z. 1984. Interaction of radium with freshwater sediments and their mineral components. I. Ferric hydroxide and quartz. Journal of Radioanalytical and Nuclear Chemistry, 82(2): 275–285. doi: 10.1007/BF02037050 Burnett W C, Bokuniewicz H, Huettel M, et al. 2003. Groundwater and pore water inputs to the coastal zone. Biogeochemistry, 66(1–2): 3–33 Burnett W C, Taniguchi M, Oberdorfer J. 2001. Measurement and significance of the direct discharge of groundwater into the coastal zone. Journal of Sea Research, 46(2): 109–116. doi: 10.1016/S1385-1101(01)00075-2 Cai Pinghe, Shi Xiangming, Moore W S, et al. 2014. 224Ra: 228Th disequilibrium in coastal sediments: Implications for solute transfer across the sediment–water interface. Geochimica et Cosmochimica Acta, 125: 68–84. doi: 10.1016/j.gca.2013.09.029 Charette M A, Lam P J, Lohan M C, et al. 2016. Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 374(2081): 20160076 Charette M A, Moore W S, Burnett W C. 2008. Uranium-and thorium-series nuclides as tracers of submarine groundwater discharge. Radioactivity in the Environment, 13: 155–191 Chen Guangquan, Xiong Guiyao, Lin Jin, et al. 2021. Elucidating the pollution sources and groundwater evolution in typical seawater intrusion areas using hydrochemical and environmental stable isotope technique: A case study for Shandong Province, China. Lithosphere, 2021: 4227303. doi: 10.2113/2021/4227303 Cho H M, Kim G. 2016. Determining groundwater Ra end-member values for the estimation of the magnitude of submarine groundwater discharge using Ra isotope tracers. Geophysical Research Letters, 43(8): 3865–3871. doi: 10.1002/2016GL068805 Diego-Feliu M, Rodellas V, Saaltink M W, et al. 2021. New perspectives on the use of 224Ra/228Ra and 222Rn/226Ra activity ratios in groundwater studies. Journal of Hydrology, 596: 126043. doi: 10.1016/j.jhydrol.2021.126043 Garcia-Orellana J, Rodellas V, Tamborski J, et al. 2021. Radium isotopes as submarine groundwater discharge (SGD) tracers: Review and recommendations. Earth-Science Reviews, 220: 103681. doi: 10.1016/j.earscirev.2021.103681 Gonneea M E, Morris P J, Dulaiova H, et al. 2008. New perspectives on radium behavior within a subterranean estuary. Marine Chemistry, 109(3–4): 250–267 Gonneea M E, Mulligan A E, Charette M A. 2013. Seasonal cycles in radium and barium within a subterranean estuary: Implications for groundwater derived chemical fluxes to surface waters. Geochimica et Cosmochimica Acta, 119: 164–177. doi: 10.1016/j.gca.2013.05.034 Hao Xin, Yi Lixin, Li Luxuan, et al. 2022. Distribution coefficient of Ra in groundwater and its determination technique. Geoscience (in Chinese), 36(2): 552–562 Ivanovich M, Harmon R S. 1992. Uranium-Series Disequilibrium: Applications to Earth, Marine, and Environmental Sciences. 2nd ed. Oxford: Clarendon Press; Oxford, New York: Oxford University Press Kim G, Ryu J W, Yang H S, et al. 2005. Submarine groundwater discharge (SGD) into the Yellow Sea revealed by 228Ra and 226Ra isotopes: Implications for global silicate fluxes. Earth and Planetary Science Letters, 237(1–2): 156–166 Kiro Y, Weinstein Y, Starinsky A, et al. 2013. Groundwater ages and reaction rates during seawater circulation in the Dead Sea aquifer. Geochimica et Cosmochimica Acta, 122: 17–35. doi: 10.1016/j.gca.2013.08.005 Knauss K G, Ku T L, Moore W S. 1978. Radium and thorium isotopes in the surface waters of the East Pacific and coastal Southern California. Earth and Planetary Science Letters, 39(2): 235–249. doi: 10.1016/0012-821X(78)90199-1 Krest J M, Harvey J W. 2003. Using natural distributions of short-lived radium isotopes to quantify groundwater discharge and recharge. Limnology and Oceanography, 48(1): 290–298. doi: 10.4319/lo.2003.48.1.0290 Krest J M, Moore W S, Rama. 1999. 226Ra and 228Ra in the mixing zones of the Mississippi and Atchafalaya rivers: indicators of groundwater input. Marine Chemistry, 64(3): 129–152. doi: 10.1016/S0304-4203(98)00070-X Krishnaswami S, Graustein W C, Turekian K K, et al. 1982. Radium, thorium and radioactive lead isotopes in groundwaters: Application to the in situ determination of adsorption-desorption rate constants and retardation factors. Water Resources Research, 18(6): 1663–1675. doi: 10.1029/WR018i006p01663 Li Yuanhui, Mathieu G, Biscaye P, et al. 1977. The flux of 226Ra from estuarine and continental shelf sediments. Earth and Planetary Science Letters, 37(2): 237–241. doi: 10.1016/0012-821X(77)90168-6 Liu Yi, Jiao J J, Mao Rong, et al. 2019. Spatial characteristics reveal the reactive transport of radium isotopes (224Ra, 223Ra, and 228Ra) in an intertidal aquifer. Water Resources Research, 55(12): 10282–10302. doi: 10.1029/2019WR024849 Luo Xin, Jiao J J, Moore W S, et al. 2018. Significant chemical fluxes from natural terrestrial groundwater rival anthropogenic and fluvial input in a large-river deltaic estuary. Water Research, 144: 603–615. doi: 10.1016/j.watres.2018.07.004 Luo Hao, Li Linwei, Wang Jinlong, et al. 2019. The desorption of radium isotopes in river sediments in Qinzhou Bay. Haiyang Xuebao (in Chinese), 41(4): 27–41 Martin P, Akber R A. 1999. Radium isotopes as indicators of adsorption–desorption interactions and barite formation in groundwater. Journal of Environmental Radioactivity, 46(3): 271–286. doi: 10.1016/S0265-931X(98)00147-7 Moore W S. 1996. Large groundwater inputs to coastal waters revealed by 226Ra enrichments. Nature, 380(6575): 612–614. doi: 10.1038/380612a0 Moore W S. 2000. Ages of continental shelf waters determined from 223Ra and 224Ra. Journal of Geophysical Research: Oceans, 105(C9): 22117–22122. doi: 10.1029/1999JC000289 Moore W S. 2008. Fifteen years experience in measuring 224Ra and 223Ra by delayed-coincidence counting. Marine Chemistry, 109(3–4): 188–197 Moore W S, Arnold R. 1996. Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. Journal of Geophysical Research: Oceans, 101(C1): 1321–1329. doi: 10.1029/95JC03139 Moore W S, Astwood H, Lindstrom C. 1995. Radium isotopes in coastal waters on the Amazon shelf. Geochimica et Cosmochimica Acta, 59(20): 4285–4298. doi: 10.1016/0016-7037(95)00242-R Nathwani J S, Phillips C R. 1979. Adsorption of 226Ra by soils in the presence of Ca2+ ions. Specific adsorption (II). Chemosphere, 8(5): 293–299. doi: 10.1016/0045-6535(79)90112-7 Porcelli D. 2008. Investigating groundwater processes using U- and Th-series nuclides. Radioactivity in the Environment, 13: 105–153 Rodellas V, Garcia-Orellana J, Masqué P, et al. 2015. Submarine groundwater discharge as a major source of nutrients to the Mediterranean Sea. Proceedings of the National Academy of Sciences of the United States of America, 112(13): 3926–3930. doi: 10.1073/pnas.1419049112 Santos I R, Chen Xiaogang, Lecher A L, et al. 2021. Submarine groundwater discharge impacts on coastal nutrient biogeochemistry. Nature Reviews Earth & Environment, 2(5): 307–323 Swarzenski P W, Baskaran M, Rosenbauer R J, et al. 2013. A combined radio- and stable-isotopic study of a California coastal aquifer system. Water, 5(2): 480–504. doi: 10.3390/w5020480 Szabo Z, dePaul V T, Fischer J M, et al. 2012. Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States. Applied Geochemistry, 27(3): 729–752. doi: 10.1016/j.apgeochem.2011.11.002 Tomasky-Holmes G, Valiela I, Charette M A. 2013. Determination of water mass ages using radium isotopes as tracers: implications for phytoplankton dynamics in estuaries. Marine Chemistry, 156: 18–26. doi: 10.1016/j.marchem.2013.02.002 Vinson D S, Lundy J R, Dwyer G S, et al. 2018. Radium isotope response to aquifer storage and recovery in a sandstone aquifer. Applied Geochemistry, 91: 54–63. doi: 10.1016/j.apgeochem.2018.01.006 Vinson D S, Tagma T, Bouchaou L, et al. 2013. Occurrence and mobilization of radium in fresh to saline coastal groundwater inferred from geochemical and isotopic tracers (Sr, S, O, H, Ra, Rn). Applied Geochemistry, 38: 161–175. doi: 10.1016/j.apgeochem.2013.09.004 Wang Qidong, Song Jinming, Li Xuegang, et al. 2015. Environmental radionuclides in a coastal wetland of the southern Laizhou Bay, China. Marine Pollution Bulletin, 97(1–2): 506–511 Webster I T, Hancock G J, Murray A S. 1995. Modelling the effect of salinity on radium desorption from sediments. Geochimica et Cosmochimica Acta, 59(12): 2469–2476. doi: 10.1016/0016-7037(95)00141-7 Xia Dong, Mi Tiezhu, Zhen Yu, et al. 2016. Simulating the process of radium desorption from coastal aquifer sediments by seawater. Marine Environmental Science (in Chinese), 35(1): 63–67 Xu Bochao. 2008. Study of the chronology of aquifer strata and the geochemical behavior of uranium of the underground brine along the southern coast of Laizhou Bay (in Chinese) [dissertation]. Qingdao: Ocean University of China Yuan Xiaojie, Guo Zhanrong, Liu Jie, et al. 2014. Characteristics of radium desorption from sediments in the salt water environment. Acta Geoscientica Sinica (in Chinese), 35(5): 582–588 Zhang Yongxiang, Xue Yuqun, Chen Honghan. 1996. Deposit seawater characteristics in the Strata and its formation environment in the south coastal plain of Laizhou Bay since late Pleistocene. Haiyang Xuebao (in Chinese), 18(6): 61–68