Coastal Acidification Induced by Tidal-Driven Submarine Groundwater Discharge in a Coastal Coral Reef System

Wang, Guizhi; Jing, Wenping; Wang, Shuling; Xu, Y. Jun; Wang, Zhangyong; Zhang, Zhouling; Li, Quanlong; Dai, Minhan

doi:10.1021/es5026867

Cited by 84 publications

(121 citation statements)

References 28 publications

(74 reference statements)

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“…No surface runoff was present during these periods in this area. Surface salinity in Sanya Bay in our sampling period ranged from 33.60 to 33.89 (Wang et al, 2014). Irregular diurnal tides prevail in Sanya Bay, with a mean tidal range of 0.90 m and the largest value of 2.14 m (Zhang, 2001).…”

Section: Site Descriptionmentioning

confidence: 87%

“…During our sampling period the Sanya River plume was confined in the northeast of the bay and the coastal reef station CT was outside the influence of the Sanya River plume ( Fig. 1) (Wang et al, 2014). Investigations of nutrients, Chl a, and phytoplankton in the bay have been conducted seasonally for several years (Dong et al, 2010;Wu et al, 2011Wu et al, , 2012b and demonstrate that the inner bay is influenced by the discharge of the Sanya River with its relatively high nutrient levels, and the central and outer bay are dominated by oceanic exchange with the South China Sea (Wu et al, 2012a).…”

Section: Site Descriptionmentioning

confidence: 99%

“…The setup of the sampling platform at the time-series station CT is provided in detail in Wang et al (2014). Briefly, water was collected using a submersible pump, and depth and salinity were measured with a conductivity-temperature-depth system (Citadel, RDI Co., USA) attached on a buoy.…”

Section: Sampling and Measurementsmentioning

confidence: 99%

“…Briefly, water was collected using a submersible pump, and depth and salinity were measured with a conductivity-temperature-depth system (Citadel, RDI Co., USA) attached on a buoy. Discrete nutrient and radium samples were taken every 3 h during 6-13 February 2012, except on 7-8 February when the maximum tidal range of 1.4 m occurred (Wang et al, 2014), and the samples were collected every 2 h. A mapping cruise was conducted in Sanya Bay during 2-3 February 2012 ( Fig. 1) to evaluate the influence of the Sanya River and to constrain the endmember of the offshore water.…”

Section: Sampling and Measurementsmentioning

confidence: 99%

“…Our previous study showed that tidally driven groundwater discharge affected the carbonate system in the Luhuitou fringing reef (Wang et al, 2014). In this reef system, groundwater discharge played a predominant role during the spring tide, and biological activities (including photosynthesis/respiration and calcification/dissolution) dominated during the neap tide in regulating diurnal variation of the carbonate parameters.…”

Section: Introductionmentioning

confidence: 98%

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Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Wang

et al. 2018

Biogeosciences

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Abstract. To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a timeseries observation of these nutrients and 228 Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228 Ra, 45.3 dpm 100 L −1 , appeared at low tide and the minimum, 14.0 dpm 100 L −1 , appeared during a flood tide in the spring tide. The activity of 228 Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R 2 ≥ 0.9 and P < 0.05) at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitritedepleted, nitrate-and phosphate-rich less saline groundwater and nitrite-rich, nitrate-and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NO x ) and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NO x and phosphate were significantly correlated with regression slopes of 4.60 (R 2 = 0.16) in the spring tide and 13.4 (R 2 = 0.75) in the neap tide, similar to the composition of these nutrients in the water column, 5.43 (R 2 = 0.27) and 14.2 (R 2 = 0.76), respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R 2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

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Section: Site Descriptionmentioning

confidence: 87%

Section: Site Descriptionmentioning

confidence: 99%

Section: Sampling and Measurementsmentioning

confidence: 99%

Section: Sampling and Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Wang

et al. 2018

Biogeosciences

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Submarine Groundwater‐Borne Nutrients in a Tropical Bay (Maowei Sea, China) and Their Impacts on the Oyster Aquaculture

Chen

Lao

Wang

et al. 2018

Geochem Geophys Geosyst

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Submarine groundwater discharge (SGD) has been recognized as an important pathway for nutrients into estuaries, coasts, and the adjacent seas. In this study, 222Rn was used to estimate the SGD‐associated nutrient fluxes into an aquaculture area in a typical tropical bay (Maowei Sea, China). The SGD into the Maowei Sea during June 2016 was estimated to be 0.36 ± 0.33 m d−1 and was associated with SGD‐derived dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicon (DSi) fluxes (mol d−1) of (4.5 ± 5.5) × 106, (5.3 ± 9.1) × 104, and (9.4 ± 9.3) × 106, respectively. The SGD‐derived nutrients (i.e., DIN, DIP, and DSi) were more than 1.9, 0.9, and 3.6 times the amounts in the local river input and served as dominant sources in the nutrient budgets in the Maowei Sea. Moreover, the N/P ratios in the SGD around the Maowei Sea were high (mean: 64), and these ratios likely exceeded the environmental self‐purification capacity, thereby enhancing the biomass and changing the phytoplankton community structure. Therefore, SGD processes with derived nutrients may affect the biogeochemical cycles and marine ecological environment in the Maowei Sea. Furthermore, the N/P ratios (∼67) in oysters are very close to those in the SGD in the Maowei Sea; this coincidence suggests that the high N/P ratios in the SGD are likely to be one of the most important sources that support oyster aquaculture, which might weaken the burden of water eutrophication in the Maowei Sea.

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Acidification mediated by a river plume and coastal upwelling on a fringing reef at the east coast of Hainan Island, Northern South China Sea

et al. 2017

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We investigated the dynamics of carbonate system which was greatly modulated by a river plume and coastal upwelling in July 2014 and July 2015 at the east coast of Hainan Island where a fringing reef distributes inshore. By using a three end‐member mixing model, we semiquantitatively estimated the removal of dissolved inorganic carbon (DIC) mediated by biological production in the river plume and upwelled water to be 13 ± 17 and 15 ± 16 μmol kg−1, respectively. The enhanced organic production was mainly responsible for these DIC consumptions in both two regimes, however, nearly a half of DIC removal was attributed to biocalcification in the plume system while it was negligible in the upwelling system. Furthermore, the modeled results over reefs revealed that river plume and coastal upwelling were two major threats of acidification to coral communities at the east coast of Hainan Island during cruises. In comparison, the biological contribution to acidification was limited for balancing between organic production and biocalcification during July 2014 cruise, whereas the acidification was greatly intensified by organic degradation during July 2015 cruise. It was verified that naturally local acidification (physical and biological processes) played a major role in great pH decreases on a short‐term scale, leading to coastal waters more vulnerable to anthropogenic “ocean acidification” (uptake of atmospheric CO2) by reducing buffering capacity of waters. Finally, effects of acidification associated with other local threats on a fringing reef were further depicted with a conceptual model.

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Coastal Acidification Induced by Tidal-Driven Submarine Groundwater Discharge in a Coastal Coral Reef System

Cited by 84 publications

References 28 publications

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

Submarine Groundwater‐Borne Nutrients in a Tropical Bay (Maowei Sea, China) and Their Impacts on the Oyster Aquaculture

Acidification mediated by a river plume and coastal upwelling on a fringing reef at the east coast of Hainan Island, Northern South China Sea

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