Submarine fresh groundwater discharge into Laizhou Bay comparable to the Yellow River flux

Wang, Xuejing; Li, Hailong; Jiao, Jiu Jimmy; Barry, David Andrew; Li, Ling; Luo, Xin; Wang, Xuejing; Wan, Li; Wang, Xusheng; Jiang, Xiao‐Wei; Ma, Qianqian; Qu, Wentao

doi:10.1038/srep08814

Cited by 70 publications

(31 citation statements)

References 47 publications

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“…The result is largely due to the low permeability of the aquifers at the eastern end of the basin, the fact that the sea water depth is relatively shallow in the Bohai Bay (average water depth of $12.5 m), and the much smaller slope of the sea floor (e.g., relative to the slope in the Piedmont/central plain transition). This simulation result is in contrast with the significant amounts of SGD inferred by radium isotope mass-balance calculations (Wang et al, 2015). This may be explained by under-estimation of the terrestrial sediment runoff entering the bay, which may serve as a significant additional secondary source of radon in the marine water of the bay.…”

Section: Submarine Groundwater Dischargecontrasting

confidence: 54%

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Cao

Han

Currell

et al. 2016

Journal of Asian Earth Sciences

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a b s t r a c tGroundwater flow in deep sedimentary basins results from complex evolution processes on geological timescales. Groundwater flow systems conceptualized according to topography and/or groundwater table configuration generally assume a near-equilibrium state with the modern landscape. However, the time to reach such a steady state, and more generally the timescales of groundwater flow system evolution are key considerations for large sedimentary basins. This is true in the North China Basin (NCB), which has been studied for many years due to its importance as a groundwater supply. Despite many years of study, there remain contradictions between the generally accepted conceptual model of regional flow, and environmental tracer data. We seek to reconcile these contractions by conducting simulations of groundwater flow, age and heat transport in a three dimensional model, using an alternative conceptual model, based on geological, thermal, isotope and historical data. We infer flow patterns under modern hydraulic conditions using this new model and present the theoretical maximum groundwater ages under such a flow regime. The model results show that in contrast to previously accepted conceptualizations, most groundwater is discharged in the vicinity of the break-in-slope of topography at the boundary between the piedmont and central plain. Groundwater discharge to the ocean is in contrast small, and in general there are low rates of active flow in the eastern parts of the basin below the central and coastal plain. This conceptualization is more compatible with geochemical and geothermal data than the previous model. Simulated maximum groundwater ages of $1 Myrs below the central and coastal plain indicate that residual groundwater may be retained in the deep parts of the basin since being recharged during the last glacial period or earlier. The groundwater flow system has therefore probably not reached a new equilibrium state with modern-day hydraulic conditions. The previous hypothesis that regional groundwater flow from the piedmont groundwater recharge zone predominantly discharges at the coastline may therefore be false. A more reliable alternative might be to conceptualize deep groundwater below the coastal plains a hydrodynamically stagnant zone, responding gradually to landscape and hydrological change on geologic timescales. This study brings a new and original understanding of the groundwater flow system in an important regional basin, in the context of its geometry and evolution over geological timescales. There are important implications for the sustainability of the ongoing high rates of groundwater extraction in the NCB.

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Section: Submarine Groundwater Dischargecontrasting

confidence: 54%

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Cao

Han

Currell

et al. 2016

Journal of Asian Earth Sciences

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“…Xu et al () indicated that even the minimum estimated SGD value was approximately three times higher than the Yellow River discharge, and the SGD input of dissolved nutrients, being at least 5 times higher than the river input, was shown to be very important to the estuarine nutrient budget. In addition, the SGD flux into the Laizhou Bay reached values approximately eight times higher than the annual Yellow River discharge in August 2012, but the ratio of SFGD to total SGD ratio was low (Wang et al, ). All these results show that SGD plays an important role in the water and nutrient budgets of the Bohai Sea regions.…”

Section: Introductionmentioning

confidence: 99%

Ra Tracer‐Based Study of Submarine Groundwater Discharge and Associated Nutrient Fluxes into the Bohai Sea, China: A Highly Human‐Affected Marginal Sea

Liu

2017

JGR Oceans

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Nutrient concentrations in coastal bays and estuaries are strongly influenced by not only riverine input but also submarine groundwater discharge (SGD). Here we estimate the SGD and the fluxes of the associated dissolved inorganic nitrogen (DIN), phosphorus (DIP), and silicon (DSi) into the Bohai Sea based on a 226Ra and 228Ra mass balance model. This procedure shows that in the Bohai Sea the average radium activities (dpm 100 L−1) are 42.8 ± 6.3 (226Ra) and 212 ± 41.7 (228Ra) for the surface water and 43.0 ± 6.1 (226Ra) and 216 ± 38.4 (228Ra) for the near‐bottom water. According to the 228Ra/226Ra age model, the residence time in the Bohai Sea is calculated to be 1.7 ± 0.8 yrs. The mass balance of 226Ra and 228Ra suggests that the yearly SGD flux into the whole Bohai Sea is (2.0 ± 1.3) × 1011 m3 yr−1, of which the percentage of submarine fresh groundwater discharge (SFGD) to the total SGD is approximately (5.1 ± 4.1)%. However, the DIN and DSi fluxes from SFGD constitute 29% and 10%, respectively, of the total fluxes from the SGD. Moreover, nutrient loads, which exhibit high DIN/DIP from SGD, especially the SFGD, may substantially contribute to the nutrient supplies, resulting in the occurrence of red tide in the Bohai Sea.

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“…In addition, we followed Wang et al (2015) to evaluate a water mass balance in the KRE surface layer under 20 the assumption that the study area of interest was a single box at steady state. The conceptual water mass balance for the KRE surface layer is presented by Figure 10.…”

Section: Sgd Derived From the Tidal Cyclesmentioning

confidence: 99%

<sup>226</sup>Ra and <sup>228</sup>Ra in the stratified estuary of the Krka River (Adriatic Sea, Croatia): implications for submarine groundwater discharge and its derived nutrients

Liu

Gašparović

et al. 2017

Preprint

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Abstract. We conducted a field survey in the Krka River and its estuary (Croatia) in September 2014 to study the significance of submarine groundwater discharge (SGD) and derived nutrients. During the sampling period, the exchange time of the brackish water above the halocline in the Krka River Estuary (KRE) was 15 calculated to be 8.3 ± 3.5 days. Three approaches of three end-member model, mass balance model and time series observation in tidal period based on Ra isotopes were used to evaluate the SGD fluxes in the KRE surface layer. We estimated the SGD flux to be (1.3-7.8) × 10 5 m 3 d -1, which was approximately 2.7-16.1 % of the Krka River discharge into the estuary. By establishing the nutrient budgets in the KRE surface layer, SGD dominated the nutrient sources, followed by Krka River. SGD-derived dissolved inorganic nitrogen 20(DIN) and dissolved orthosilicate (DSi) contributed 26.8-68.6 % and 9.5-38.3 % to the total DIN and DSi fluxes into the surface waters of KRE, respectively. This indicates that SGD was likely a major external source of those nutrients in the KRE. We have identified that SGD-derived nutrients and their high N:P ratios may affect the ecosystem productivity in the KRE and nearby Adriatic.

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Submarine fresh groundwater discharge into Laizhou Bay comparable to the Yellow River flux

Cited by 70 publications

References 47 publications

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Ra Tracer‐Based Study of Submarine Groundwater Discharge and Associated Nutrient Fluxes into the Bohai Sea, China: A Highly Human‐Affected Marginal Sea

<sup>226</sup>Ra and <sup>228</sup>Ra in the stratified estuary of the Krka River (Adriatic Sea, Croatia): implications for submarine groundwater discharge and its derived nutrients

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Submarine fresh groundwater discharge into Laizhou Bay comparable to the Yellow River flux

Cited by 70 publications

References 47 publications

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Revised conceptualization of the North China Basin groundwater flow system: Groundwater age, heat and flow simulations

Ra Tracer‐Based Study of Submarine Groundwater Discharge and Associated Nutrient Fluxes into the Bohai Sea, China: A Highly Human‐Affected Marginal Sea

&lt;sup&gt;226&lt;/sup&gt;Ra and &lt;sup&gt;228&lt;/sup&gt;Ra in the stratified estuary of the Krka River (Adriatic Sea, Croatia): implications for submarine groundwater discharge and its derived nutrients

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<sup>226</sup>Ra and <sup>228</sup>Ra in the stratified estuary of the Krka River (Adriatic Sea, Croatia): implications for submarine groundwater discharge and its derived nutrients