scholarly journals Submarine Groundwater and River Discharges Affect Carbon Cycle in a Highly Urbanized and River-Dominated Coastal Area

2021 ◽  
Vol 8 ◽  
Author(s):  
Xuejing Wang ◽  
Yan Zhang ◽  
Chunmiao Zheng ◽  
Manhua Luo ◽  
Shengchao Yu ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Coastal Area ◽  
Dissolved Inorganic Carbon ◽  
Winter Season ◽  
Pump Efficiency ◽  
Biological Pump ◽  
Carbonate System ◽  
Bay Area ◽  
Submarine Groundwater ◽  
Riverine Carbon Flux

Riverine carbon flux to the ocean has been considered in estimating coastal carbon budgets, but submarine groundwater discharge (SGD) has long been ignored. In this paper, the effects of both SGD and river discharges on the carbon cycle were investigated in the Guangdong-HongKong-Macao Greater Bay Area (GBA), a highly urbanized and river-dominated coastal area in China. SGD-derived nitrate (NO3–), dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) fluxes were estimated using a radium model to be (0.73–16.4) × 108 g/d, (0.60–9.94) × 109 g/d, and (0.77–3.29) × 1010 g/d, respectively. SGD-derived DOC and DIC fluxes are ∼2 times as great as riverine inputs, but SGD-derived NO3– flux is one-fourth of the riverine input. The additional nitrate and carbon inputs can stimulate new primary production, enhance biological pump efficiency, and affect the balance of the carbonate system in marine water. We found that SGD in the studied system is a potential net source of atmospheric CO2 with a flux of 1.46 × 109 g C/d, and river, however, is a potential net sink of atmospheric CO2 with a flux of 3.75 × 109 g C/d during the dry winter season. Two conceptual models were proposed illustrating the major potential processes of the carbon cycle induced by SGD and river discharges. These findings from this study suggested that SGD, as important as rivers, plays a significant role in the carbon cycle and should be considered in carbon budget estimations at regional and global scales future.

scholarly journals How significant is submarine groundwater discharge and its associated dissolved inorganic carbon in a river-dominated shelf system?

2012 ◽  
Vol 9 (5) ◽  
pp. 1777-1795 ◽  
Author(s):  
Q. Liu ◽  
M. Dai ◽  
W. Chen ◽  
C.-A. Huh ◽  
G. Wang ◽  
...  
Keyword(s):  
Submarine Groundwater Discharge ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
River Plume ◽  
Subsurface Water ◽  
Pearl River ◽  
New Production ◽  
Carbonate System ◽  
Submarine Groundwater ◽  
The Pearl River

Abstract. In order to assess the role of submarine groundwater discharge (SGD) and its impact on the carbonate system on the northern South China Sea (NSCS) shelf, we measured seawater concentrations of four radium isotopes 223,224,226,228Ra along with carbonate system parameters in June–July, 2008. Complementary groundwater sampling was conducted in coastal areas in December 2008 and October 2010 to constrain the groundwater end-members. The distribution of Ra isotopes in the NSCS was largely controlled by the Pearl River plume and coastal upwelling. Long-lived Ra isotopes (228Ra and 226Ra) were enriched in the river plume but low in the offshore surface water and subsurface water/upwelling zone. In contrast, short-lived Ra isotopes (224Ra and 223Ra) were elevated in the subsurface water/upwelling zone as well as in the river plume but depleted in the offshore surface water. In order to quantify SGD, we adopted two independent mathematical approaches. Using a three end-member mixing model with total alkalinity (TAlk) and Ra isotopes, we derived a SGD flux into the NSCS shelf of 2.3–3.7 × 108 m3 day−1. Our second approach involved a simple mass balance of 228Ra and 226Ra and resulted in a first order but consistent SGD flux estimate of 2.2–3.7 × 108 m3 day−1. These fluxes were equivalent to 12–21 % of the Pearl River discharge, but the source of the SGD was mostly recirculated seawater. Despite the relatively small SGD volume flow compared to the river, the associated material fluxes were substantial given their elevated concentrations of dissolved inorganic solutes. In this case, dissolved inorganic carbon (DIC) flux through SGD was 153–347 × 109 mol yr−1, or ~23–53 % of the riverine DIC export flux. Our estimates of the groundwater-derived phosphate flux ranged 3–68 × 107 mol yr−1, which may be responsible for new production on the shelf up to 0.3–6.3 mmol C m−2 d−1. This rate of new production would at most consume 11 % of the DIC contribution delivered by SGD. Hence, SGD may play an important role in the carbon balance over the NSCS shelf.

Chemical inputs from a karstic submarine groundwater discharge (SGD) into an oligotrophic Mediterranean coastal area

2014 ◽  
Vol 488-489 ◽  
pp. 1-13 ◽  
Author(s):  
Alexandra Pavlidou ◽  
Vassilis P. Papadopoulos ◽  
Ioannis Hatzianestis ◽  
Nomiki Simboura ◽  
Dionisis Patiris ◽  
...  
Keyword(s):  
Coastal Area ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Submarine Groundwater ◽  
Chemical Inputs

scholarly journals FITOPLANKTON DAN SIKLUS KARBON GLOBAL

OSEANA ◽  
2019 ◽  
Vol 44 (2) ◽  
pp. 35-48
Author(s):  
Mochamad Ramdhan Firdaus ◽  
Lady Ayu Sri Wijayanti
Keyword(s):  
Carbon Cycle ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Sedimentary Rocks ◽  
Global Carbon Cycle ◽  
Biological Pump ◽  
Large Role ◽  
The World ◽  
Pump Mechanism ◽  
Global Carbon

PHYTOPLANKTON AND GLOBAL CARBON CYCLE. Scientists around the world believe that phytoplankton, although microscopic, have a large role in the global carbon cycle. Various research results show that the net primary productivity of all phytoplankton in the sea is almost as large as the net primary productivity of all plants on land. Phytoplankton through the process of photosynthesis absorbs 40-50 PgC / year from the atmosphere. Also, phytoplankton is known to be responsible for transporting carbon from the atmosphere to the seafloor through the carbon biological pump mechanism. Phytoplankton from the coccolithophores group is known to play a role in the sequestration of carbon on the seabed through the carbonate pump mechanism. The mechanism is capable of sequestering carbon for thousands of years on the seabed in the form of sedimentary rocks (limestone).

scholarly journals Ocean carbon inventory under warmer climate conditions – the case of the Last Interglacial

2018 ◽  
Vol 14 (12) ◽  
pp. 1961-1976 ◽  
Author(s):  
Augustin Kessler ◽  
Eirik Vinje Galaasen ◽  
Ulysses Silas Ninnemann ◽  
Jerry Tjiputra
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Climatic Conditions ◽  
Interglacial Period ◽  
Quasi Equilibrium ◽  
Biological Pump ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Ocean Carbon ◽  
Carbon Inventory

Abstract. During the Last Interglacial period (LIG), the transition from 125 to 115 ka provides a case study for assessing the response of the carbon system to different levels of high-latitude warmth. Elucidating the mechanisms responsible for interglacial changes in the ocean carbon inventory provides constraints on natural carbon sources and sinks and their climate sensitivity, which are essential for assessing potential future changes. However, the mechanisms leading to modifications of the ocean's carbon budget during this period remain poorly documented and not well understood. Using a state-of-the-art Earth system model, we analyze the changes in oceanic carbon dynamics by comparing two quasi-equilibrium states: the early, warm Eemian (125 ka) versus the cooler, late Eemian (115 ka). We find considerably reduced ocean dissolved inorganic carbon (DIC; −314.1 PgC) storage in the warm climate state at 125 ka as compared to 115 ka, mainly attributed to changes in the biological pump and ocean DIC disequilibrium components. The biological pump is mainly driven by changes in interior ocean ventilation timescales, but the processes controlling the changes in ocean DIC disequilibrium remain difficult to assess and seem more regionally affected. While the Atlantic bottom-water disequilibrium is affected by the organization of sea-ice-induced southern-sourced water (SSW) and northern-sourced water (NSW), the upper-layer changes remain unexplained. Due to its large size, the Pacific accounts for the largest DIC loss, approximately 57 % of the global decrease. This is largely associated with better ventilation of the interior Pacific water mass. However, the largest simulated DIC differences per unit volume are found in the SSWs of the Atlantic. Our study shows that the deep-water geometry and ventilation in the South Atlantic are altered between the two climate states where warmer climatic conditions cause SSWs to retreat southward and NSWs to extent further south. This process is mainly responsible for the simulated DIC reduction by restricting the extent of DIC-rich SSW, thereby reducing the storage of biological remineralized carbon at depth.

scholarly journals Diagnosis of CO2 dynamics and fluxes in global coastal oceans

2019 ◽  
Vol 7 (4) ◽  
pp. 786-797 ◽  
Author(s):  
Zhimian Cao ◽  
Wei Yang ◽  
Yangyang Zhao ◽  
Xianghui Guo ◽  
Zhiqiang Yin ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Analytical Framework ◽  
Coastal System ◽  
Coastal Oceans ◽  
Co2 Dynamics ◽  
Earth System Models

Abstract Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.

Ocean acidification as a multiple driver: how interactions between changing seawater carbonate parameters affect marine life

2020 ◽  
Vol 71 (3) ◽  
pp. 263 ◽  
Author(s):  
Catriona L. Hurd ◽  
John Beardall ◽  
Steeve Comeau ◽  
Christopher E. Cornwall ◽  
Jonathan N Havenhand ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Multiple Stressors ◽  
Rapid Expansion ◽  
Coralline Algae ◽  
Carbonate System ◽  
Saturation State ◽  
Marine Life ◽  
Key Terms

‘Multiple drivers’ (also termed ‘multiple stressors’) is the term used to describe the cumulative effects of multiple environmental factors on organisms or ecosystems. Here, we consider ocean acidification as a multiple driver because many inorganic carbon parameters are changing simultaneously, including total dissolved inorganic carbon, CO2, HCO3–, CO32–, H+ and CaCO3 saturation state. With the rapid expansion of ocean acidification research has come a greater understanding of the complexity and intricacies of how these simultaneous changes to the seawater carbonate system are affecting marine life. We start by clarifying key terms used by chemists and biologists to describe the changing seawater inorganic carbon system. Then, using key groups of non-calcifying (fish, seaweeds, diatoms) and calcifying (coralline algae, coccolithophores, corals, molluscs) organisms, we consider how various physiological processes are affected by different components of the carbonate system.

Organic and inorganic whole system metabolism in two acidified coastal systems in Ireland

2020 ◽  
Author(s):  
Maria Teresa Guerra ◽  
Carlos Rocha
Keyword(s):  
Ocean Acidification ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Carbonate System ◽  
Net Community Production ◽  
Coastal Acidification ◽  
Autumn And Winter ◽  
System Metabolism ◽  
Internal Buffer ◽  
Community Production

<p>Organic and inorganic whole system metabolism for two Irish coastal areas were compared to evaluate carbonate system resilience to acidification. The two systems are characterized by contrasting watershed input types and composition. Kinvara Bay is fed by Submarine Groundwater Discharge (SGD) derived from a karstic catchment while Killary Harbour is fed by river discharge draining a siliciclastic catchment. Freshwater sources to sea have distinct Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC) concentrations, higher and lower than the open ocean, respectively, but both evidence seasonally variable low pH, ranging from 6.20 to 7.50. Retention of TA and DIC was calculated for the two areas using LOICZ methodology. In Kinvara bay, annually averaged retention of DIC was greater than for TA (5 × 10<sup>4</sup> and 1.5 × 10<sup>5</sup> mol d<sup>-1</sup>), suggesting the system is acidifying further. Conversely, Killary Harbour shows negative TA and DIC retention, with DIC:TA <1, suggesting an internal buffer against ocean acidification is operating.</p><p>Net Community Production (NCP) was calculated for both systems using Dissolved Oxygen data. Subsequently, we estimated Net Community Calcification (NCC) from the ratio between TA and DIC. NCP was always positive in Killary Harbour with an average of 318 mmol O<sub>2</sub> m<sup>-2 </sup>d<sup>-1</sup> (equivalent to 89 mol C m<sup>-2</sup> y<sup>-1</sup>). However, Kinvara Bay shows relatively lower positive NCP in spring and summer (average of 46 mmol O<sub>2</sub> m<sup>-2</sup> d<sup>-1</sup>), but negative NCP in autumn and winter. Therefore, Kinvara Bay’s Total Organic Carbon (TOC) production was low, at ~21 g m<sup>-2</sup> y<sup>-1</sup> and not enough to overcome acidification driven by the SGD source composition. These results emphasize the complexity of interactions between the drivers of coastal acidification rate, affecting our ability to accurately assess the resilience of the carbonate system in these areas to ocean acidification pressure in the future.</p>

scholarly journals Carbon isotope excursions during the late Miocene recorded by lipids of marine Thaumarchaeota, Piedmont Basin, Mediterranean Sea

Geology ◽  
2021 ◽  
Author(s):  
Mathia Sabino ◽  
Daniel Birgel ◽  
Marcello Natalicchio ◽  
Francesco Dela Pierre ◽  
Jörn Peckmann
Keyword(s):  
Carbon Cycle ◽  
Mediterranean Sea ◽  
Water Column ◽  
Late Miocene ◽  
Dissolved Inorganic Carbon ◽  
Proximal Part ◽  
Fractionation Factor ◽  
Water Column Stratification ◽  
Group I ◽  
Thermohaline Stratification

Group I mesophilic Thaumarchaeota fix dissolved inorganic carbon (DIC), accompanied by a biosynthetic fractionation factor of ~20‰. Accordingly, the δ13C signature of their diagnostic biomarker crenarchaeol was suggested as a potential δ13CDIC proxy in marine basins if input from nonmarine Thaumarchaeota is negligible. Semi-enclosed basins are sensitive to carbon-cycle perturbations, because they tend to develop thermohaline stratification. Water column stratification typified the semi-enclosed basins of the Mediterranean Sea during the late Miocene (Messinian) salinity crisis (5.97–5.33 Ma). To assess how the advent of the crisis affected the carbon cycle, we studied sediments of the Piedmont Basin (northwestern Italy), the northernmost Mediterranean subbasin. A potential bias of our δ13CDIC reconstructions from the input of soil Thaumarchaeota is discarded, since high and increasing branched and isoprenoid tetraether (BIT) index values do not correspond to low and decreasing δ13C values for thaumarchaeal lipids, which would be expected in case of high input from soil Thaumarchaeota. Before the onset of the crisis, the permanently stratified distal part of the basin hosted a water mass below the chemocline with a δ13CDIC value of approximately –3.5‰, while the well-mixed proximal part had a δ13CDIC value of approximately –0.8‰. The advent of the crisis was marked by 13C enrichment of the DIC pool, with positive δ13CDIC excursions up to +5‰ in the upper water column. Export of 12C to the seafloor after phytoplankton blooms and limited replenishment of remineralized carbon due to the stabilization of thermohaline stratification primarily caused such 13C enrichment of the DIC pool.

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