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1.
Ki‐mook Kang Duk‐jin Kim Yunjee Kim Eunhee Lee Bong‐Gwan Kim Seung Hee Kim Kyoochul Ha Dong‐Chan Koh Yang‐Ki Cho Guebuem Kim 《水文研究》2019,33(7):1089-1100
Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys. 相似文献
2.
Radium tracing of submarine groundwater discharge (SGD) and associated nutrient fluxes in a highly-permeable bed coastal zone, Korea 总被引：2，自引：0，他引：2
In order to estimate submarine groundwater discharge (SGD) and SGD-driven nutrient fluxes, we measured the concentrations of nutrients, 224Ra, and 226Ra in seawater, river water, and coastal groundwater of Yeongil Bay (in the southeastern coast of Korea) in August 2004 and February 2005. The bottom sediments over the shallow areas of this bay are composed mainly of coarse sands. Large excess concentrations of 224Ra, 226Ra, and Si supplied from SGD were observed in August 2004, while these excess concentrations were not apparent in February 2005. Based on the mass balance for 224Ra, 226Ra, and Si, which showed conservative mixing behavior in seawater, SGD was estimated to be approximately 6 × 106 m3 day− 1 (seepage rate = 0.2 m day− 1) in shallow areas (< 9 m water depth) in August 2004, which is much higher than the SGD level typically found in other coastal regions worldwide. During the summer period, SGD-driven nutrients in this bay contributed approximately 98%, 12%, and 76% of the total inputs for dissolved inorganic nitrogen (DIN), phosphorus (DIP), and silicate (DSi), respectively. Our study implies that the ecosystem in this highly permeable bed coastal zone is influenced strongly by SGD during summer, while such influences are negligible in winter. 相似文献
3.
We examined the contribution of submarine groundwater discharge (SGD) to nutrient budgets in Hwasun Bay, Jeju Island, Korea in August 2009, October 2014, and May 2015. The concentrations of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) in fresh groundwater were in the range of 285?716 μM and 2.3?3.2 μM, respectively, which were each 1?2 orders of magnitude higher than those in the bay seawater. The outer-bay seawater flowing into the bay was oligotrophic (2.9 ± 1.9 μM for DIN and 0.2 ± 0.3 μM for DIP). Nutrient budget calculations were performed for each season by accounting for submarine fresh groundwater discharge (SFGD) and water residence times. In August 2009 (DIN = 1.8 μM and DIN:DIP ratio = 4.6 for the outerbay water), DIN inputs from SFGD accounted for approximately 40% of the DIN inventory in the bay seawater. In October 2014 (DIN = 1.1 μM and DIP < 0.05 μM for the outer-bay water), DIP from SFGD accounted for approximately 100% of the DIP inventory in the bay seawater. In May 2015, mean concentrations of DIN and DIP in the bay seawater were 8.6 ± 12 μM and 0.11 ± 0.04 μM, respectively, with conservative behaviors in the bay seawater in association with excessive groundwater inputs. These results imply that SGD plays a critical but different role in nutrient budgets and stoichiometry in coastal waters off a volcanic island depending on open-ocean nutrient conditions. 相似文献
4.
In order to determine the temporal and spatial variations of nutrient profiles in the shallow pore water columns (upper 30
cm depth) of intertidal sandflats, we measured the salinity and nutrient concentrations in pore water and seawater at various
coastal environments along the southern coast of Korea. In the intertidal zone, salinity and nutrient concentrations in pore
water showed marked vertical changes with depth, owing to the active exchange between the pore water and overlying seawater,
while they are temporally more stable and vertically constant in the sublittoral zone. In some cases, the advective flow of
fresh groundwater caused strong vertical gradients of salinity and nutrients in the upper 10 cm depth of surface sediments,
indicating the active mixing of the fresher groundwater with overlying seawater. Such upper pore water column profiles clearly
signified the temporal fluctuation of lower-salinity and higher-Si seawater intrusion into pore water in an intertidal sandflat
near the mouth of an estuary. We also observed a semimonthly fluctuation of pore water nutrients due to spring-neap tide associated
recirculation of seawater through the upper sediments. Our study shows that the exchange of water and nutrients between shallow
pore water and overlying seawater is most active in the upper 20 cm layer of intertidal sandflats, due to physical forces
such as tides, wave set-up, and density-thermal gradient. 相似文献
5.
The release of dissolved actinium to the ocean: A global comparison of different end-members 总被引：1，自引：1，他引：0
Walter Geibert Matt Charette Guebuem Kim Willard S. Moore Joseph Street Megan Young Adina Paytan 《Marine Chemistry》2008,109(3-4):409
The measurement of short-lived 223Ra often involves a second measurement for supported activities, which represents 227Ac in the sample. Here we exploit this fact, presenting a set of 284 values on the oceanic distribution of 227Ac, which was collected when analyzing water samples for short-lived radium isotopes by the radium delayed coincidence counting system. The present work compiles 227Ac data from coastal regions all over the northern hemisphere, including values from ground water, from estuaries and lagoons, and from marine end-members. Deep-sea samples from a continental slope off Puerto Rico and from an active vent site near Hawaii complete the overview of 227Ac near its potential sources.The average 227Ac activities of nearshore marine end-members range from 0.4 dpm m− 3 at the Gulf of Mexico to 3.0 dpm m− 3 in the coastal waters of the Korean Strait. In analogy to 228Ra, we find the extension of adjacent shelf regions to play a substantial role for 227Ac activities, although less pronounced than for radium, due to its weaker shelf source. Based on previously published values, we calculate an open ocean 227Ac inventory of 1.35 * 1018 dpm 227Acex in the ocean, which corresponds to 37 moles, or 8.4 kg. This implies a flux of 127 dpm m−2 y− 1 from the deep-sea floor. For the shelf regions, we obtain a global inventory of 227Ac of 4.5 * 1015 dpm, which cannot be converted directly into a flux value, as the regional loss term of 227Ac to the open ocean would have to be included.Ac has so far been considered to behave similarly to Ra in the marine environment, with the exception of a strong Ac source in the deep-sea due to 231Paex. Here, we present evidence of geochemical differences between Ac, which is retained in a warm vent system, and Ra, which is readily released [Moore, W.S., Ussler, W. and Paull, C.K., 2008-this issue. Short-lived radium isotopes in the Hawaiian margin: Evidence for large fluid fluxes through the Puna Ridge. Marine Chemistry]. Another potential mechanism of producing deviations in 227Ac/228Ra and daughter isotope ratios from the expected production value of lithogenic material is observed at reducing environments, where enrichment in uranium may occur. The presented data here may serve as a reference for including 227Ac in circulation models, and the overview provides values for some end-members that contribute to the global Ac distribution. 相似文献
6.
We measured the time-series variations in 222Rn activity at a fixed station in the Yeongsan River Estuary (YRE), Korea, where the upstream water is obstructed by an artificial dam, during November 18–24, 2008, and conducted a horizontal 222Rn survey in the Seomjin River Estuary (SRE), Korea, during December 16–18, 2008. In the YRE, we observed constantly low levels of 222Rn activity over the sampling period, relative to the summer in 2008. The 222Rn variations and 222Rn mass-balance modeling results indicate that the submarine groundwater discharge (SGD) in the YRE was relatively low and constant over the sampling period and that the temporal SGD variations were not related to tides or to the water elevation in the dam upstream. This low and constant SGD appears to be due to the lower water level in the dam relative to the local sea level during the study period, resulting in the SGD mostly from the surrounding land areas rather than from the dam. In the SRE, higher 222Rn activities were observed at upstream stations of the river (salinity: <5) and decreased as the salinity increased, but there were marked increases of 222Rn, together with dissolved inorganic silicate (DSi), at stations close to the river mouth (salinity: ～33). This suggests that the river has major groundwater inputs from the two extreme upstream and downstream areas. Because most chemical flux estimations via river discharge do not account for groundwater inputs from the downstream high-salinity zone, our results suggest that there is an important unaccounted source of river-driven chemical fluxes. Overall, our study shows that the continuous 222Rn monitoring system provides high-resolution information on SGD over different locations and times. 相似文献
7.
Large seasonal changes in the recharge of seawater in a subterranean estuary revealed by a radon tracer 
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下载免费PDF全文 Activities of radon (222Rn) in groundwater were continuously monitored in a saline aquifer from September 2010 to July 2011. The activities of 222Rn ranged from 200 to 4300 Bq m?3, with a large seasonal variation. Because the activity of 222Rn in seawater is low, 222Rn in saline groundwater must be produced in the aquifer from radium (226Ra) in rocks and sediments. The 222Rn activities were higher in the warm‐dry seasons (September–November 2010 and April–May 2011) when the saline aquifer was stable. In contrast, the lowest 222Rn activities were observed in the cold‐dry season (December 2010 and January–March 2011), because of the effective exchange between groundwater and seawater. In addition, sudden decreases of 222Rn activities coincided with episodic drops in groundwater temperatures. These results reveal that lower seawater temperature in winter may result in density‐driven seawater intrusion. During the wet season (June–July 2011), 222Rn activities were more clearly affected by semi‐monthly and diurnal tidal pumping, showing higher 222Rn activities during low and spring tides. Such a tidal effect was not clearly observed during the warm‐dry and cold‐dry seasons. This result implies that the residence time of SGD in coastal zones is significantly affected by seasonal changes in driving forces such as tidal pumping and seawater intrusion. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
8.
The concentrations of trace elements in groundwater and seawater were measured in a coastal embayment (Bangdu Bay) of a volcanic island (Jeju) off the southernmost coast of Korea in August and December of 2009. The concentrations of trace elements (Al, Mn, Fe, Co, Ni, and Cu) in the groundwater in summer were approximately 20-fold higher than those in winter, with good correlation to each other. Overall, the concentrations of most of the trace elements in the groundwater were 3- to 70-fold higher than those in the seawater of this Bay. Simple budget calculations showed that large fluxes of submarine groundwater discharge (SGD)-driven trace elements were responsible for the unusually enhanced concentrations of trace elements (particularly for Al, Fe and Co) in the summer seawater. The results imply that the temporal changes in SGD-driven trace element fluxes are large and may contribute considerably to the budget of trace elements in the coastal ocean, particularly off a highly permeable volcanic island. 相似文献
9.
The Yeongsan River estuary (YRE) is located downstream of a dam housing an artificial lake on the southwestern coast of Korea. Intermittent discharges of lake water through dam gates control the water level of the lake. This study compares fluxes of dissolved nutrients in discharged water with those of submarine groundwater discharge (SGD) occurring in the YRE in July and October 2008. With the exception of dissolved inorganic phosphorus (DIP) which limits primary production, nutrient concentrations in the YRE are controlled mainly by conservative mixing between lake water and open ocean water during periods of lake water discharge. In comparison with lake water discharge, the magnitude of SGD, based on a 222Rn mass balance model, is relatively small (about 1.5×105 m3 day?1 in July and about 30% higher in October) and dependent on the water elevation in the lake. However, SGD contributes considerably to the input of DIP when discharge of lake water is halted. Our study shows that SGD is more important in the delivery of biogeochemical components into estuaries that are obstructed by artificial dams. 相似文献
10.
Ocean Science Journal - Thorium-234 (234Th; t1/2 = 24.1 days) has been widely used as a tracer of particle settling and organic carbon export in the ocean. However, the use of... 相似文献