Discharge of Salt Groundwater in the Estuary of the Razdol’naya River (Amur Bay) in February 2020

Semkin, P. Yu.; Tishchenko, P. Ya.; Charkin, Alexander; Pavlova, G. Yu.; Tishchenko, P. Ya.; Anisimova, E. V.; Barabanshchikov, Yu. A.; Leusov, A. E.; Mikhailic, T. A.; Tibenko, E. Yu.; Chizhova, Tatiana

doi:10.1134/s009780782103012x

Cited by 2 publications

(1 citation statement)

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“…Admixing salt water in this aquifer will bring the long-lived isotope 228 Ra, but long-term processes are essential for the significant accumulation of 228 Ra [12,25,38,47]. The composition of stable isotopes δ 18 O and δD in the SW-GW interaction zone is subject to the seawater/river water ratio [48]. It is considered that the main reason for the increase in all three isotopes 223 Ra, 224 Ra, and 228 Ra is that water recirculated into the upper aquifer during the winter period.…”

Section: Identification and Control Factorsof Sw-gw Interactionmentioning

confidence: 99%

Radium Isotopes and Hydrochemical Signatures of Surface Water-Groundwater Interaction in the Salt-Wedge Razdolnaya River Estuary (Sea of Japan) in the Ice-Covered Period

Semkin

Charkin

Pavlova

et al. 2023

Water

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The interaction of surface water and groundwater is important in the ecology of coastal basins, affecting hydrological conditions, oxygen regime, carbon, and nutrient exchange. This study demonstrates a dynamic connection between the salt-wedge region and its underlying aquifer in the eutrophic estuary. In winter, this estuary is covered with ice, and the river flow is at its lowest; that is why the specific response to groundwater discharge is best marked in this season. Groundwater admixture was detected in the salt-wedge region by highly active radium isotopes: 223Ra—4.80 ± 0.42 dpm 100 L−1, 224Ra—55.37 ± 1.1 dpm 100 L−1, and 228Ra—189.71 ± 4.66 dpm 100 L−1. The temperature of groundwater and river water was about +4 °C and 0 °C, respectively; that of seawater was −1.6 °C, and temperature increased up to +2.3 °C in the surface water–groundwater interaction region. Groundwater admixture is accompanied by a lower level of oxygen concentration of 52 μmol/kg; at that time, the maximum oxygen concentration in the salt-wedge region was 567 μmol/kg. In waters with a high activity of radium isotopes, there was a maximum partial pressure of CO2—4454 μatm at the range 100–150 μatm in the salt-wedge region and also observed extremum of NH4+, NO2−, and dissolved phosphorus. The surface water–groundwater interaction through anoxic sediment can form localized anaerobic areas despite the general oxygen supersaturation of eutrophic estuary waters and also cause local recycling of nutrients from bottom sediments.

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