scholarly journals Human-Driven Atmospheric Deposition of N and P Controls on the East Mediterranean Marine Ecosystem

2016 ◽  
Vol 73 (4) ◽  
pp. 1611-1619 ◽  
Author(s):  
S. Christodoulaki ◽  
G. Petihakis ◽  
N. Mihalopoulos ◽  
K. Tsiaras ◽  
G. Triantafyllou ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Inorganic Nitrogen ◽  
Marine Ecosystem ◽  
N:P Ratio ◽  
Biogeochemical Model ◽  
East Mediterranean ◽  
Set Up ◽  
Representative Area ◽  
The Impact

Abstract The historical and future impacts of atmospheric deposition of inorganic nitrogen (N) and phosphorus (P) on the marine ecosystem in the east Mediterranean Sea are investigated by using a 1D coupled physical– biogeochemical model, set up for the Cretan Sea as a representative area of the basin. For the present-day simulation (2010), the model is forced by observations of atmospheric deposition fluxes at Crete, while for the hindcast (1860) and forecast (2030) simulations, the changes in atmospheric deposition calculated by global chemistry–transport models are applied to the present-day observed fluxes. The impact of the atmospheric deposition on the fluxes of carbon in the food chain is calculated together with the contribution of human activities to these impacts. The results show that total phytoplanktonic biomass increased by 16% over the past 1.5 centuries. Small fractional changes in carbon fluxes and planktonic biomasses are predicted for the near future. Simulations show that atmospheric deposition of N and P may be the main mechanism responsible for the anomalous N:P ratio observed in the Mediterranean Sea.

scholarly journals Introduction to the project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem

2013 ◽  
Vol 10 (7) ◽  
pp. 12491-12527 ◽  
Author(s):  
C. Guieu ◽  
F. Dulac ◽  
C. Ridame ◽  
P. Pondaven
Keyword(s):  
Trace Elements ◽  
Atmospheric Deposition ◽  
Mediterranean Sea ◽  
Surface Waters ◽  
Carbon Pump ◽  
Mesocosm Experiments ◽  
The Mediterranean ◽  
Atmospheric Inputs ◽  
Oligotrophic Ecosystem ◽  
The Impact

Abstract. The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea – etymologically, sea surrounded by land – is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".

scholarly journals Influences of Nutrient Sources on the Alternation of Nutrient Limitations and Phytoplankton Community in Jiaozhou Bay, Southern Yellow Sea of China

2020 ◽  
Vol 12 (6) ◽  
pp. 2224
Author(s):  
Jie Shi ◽  
Qian Leng ◽  
Junying Zhu ◽  
Huiwang Gao ◽  
Xinyu Guo ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Phytoplankton Community ◽  
Inorganic Nitrogen ◽  
Marine Ecosystem ◽  
Jiaozhou Bay ◽  
Nutrient Concentrations ◽  
River Input ◽  
Aquaculture Wastewater ◽  
The 1960S ◽  
Yellow Sea Of China

A marine ecosystem box model was developed to reproduce the seasonal variations nutrient concentrations and phytoplankton biomasses in Jiaozhou Bay (JZB) of China. Then, by removing each of the external sources of nutrients (river input, aquaculture, wastewater discharge, and atmospheric deposition) in the model calculation, we quantitatively estimated its influences on nutrient structure and the phytoplankton community. Removing the river input of nutrients enhanced silicate (SIL) limitation to diatoms (DIA) and decreased the ratio of DIA to flagellates (FLA); removing the aquaculture input of nutrients decreased FLA biomass because it provided less dissolved inorganic nitrogen (DIN) but more dissolved inorganic phosphate (DIP) as compared to the Redfield ratio; removing the wastewater input of nutrients changed the DIN concentration dramatically, but had a relatively weaker impact on the phytoplankton community than removing the aquaculture input; removing atmospheric deposition had a negligible influence on the model results. Based on these results, we suppose that the change in the external nutrients sources in the past several decades can explain the long-term variations in nutrient structure and phytoplankton community. Actually, the simulations for the 1960s, 1980s, and 2000s in JZB demonstrated the shift of limiting nutrients from DIP to SIL. A reasonable scenario for this is the decrease in riverine SIL and increase in DIP from aquaculture that has reduced DIA biomass, promoted the growth of FLA, and led to the miniaturization of the phytoplankton.

scholarly journals Production, partitioning and stoichiometry of organic matter under variable nutrient supply during mesocosm experiments in the tropical Pacific and Atlantic Ocean

2012 ◽  
Vol 9 (11) ◽  
pp. 4629-4643 ◽  
Author(s):  
J. M. S. Franz ◽  
H. Hauss ◽  
U. Sommer ◽  
T. Dittmar ◽  
U. Riebesell
Keyword(s):  
Organic Matter ◽  
Coastal Upwelling ◽  
Global Climate ◽  
Inorganic Nitrogen ◽  
Euphotic Zone ◽  
N:P Ratio ◽  
Nutrient Supply ◽  
N Availability ◽  
Intermediate Water ◽  
The Impact

Abstract. Oxygen-deficient waters in the ocean, generally referred to as oxygen minimum zones (OMZ), are expected to expand as a consequence of global climate change. Poor oxygenation is promoting microbial loss of inorganic nitrogen (N) and increasing release of sediment-bound phosphate (P) into the water column. These intermediate water masses, nutrient-loaded but with an N deficit relative to the canonical N:P Redfield ratio of 16:1, are transported via coastal upwelling into the euphotic zone. To test the impact of nutrient supply and nutrient stoichiometry on production, partitioning and elemental composition of dissolved (DOC, DON, DOP) and particulate (POC, PON, POP) organic matter, three nutrient enrichment experiments were conducted with natural microbial communities in shipboard mesocosms, during research cruises in the tropical waters of the southeast Pacific and the northeast Atlantic. Maximum accumulation of POC and PON was observed under high N supply conditions, indicating that primary production was controlled by N availability. The stoichiometry of microbial biomass was unaffected by nutrient N:P supply during exponential growth under nutrient saturation, while it was highly variable under conditions of nutrient limitation and closely correlated to the N:P supply ratio, although PON:POP of accumulated biomass generally exceeded the supply ratio. Microbial N:P composition was constrained by a general lower limit of 5:1. Channelling of assimilated P into DOP appears to be the mechanism responsible for the consistent offset of cellular stoichiometry relative to inorganic nutrient supply and nutrient drawdown, as DOP build-up was observed to intensify under decreasing N:P supply. Low nutrient N:P conditions in coastal upwelling areas overlying O2-deficient waters seem to represent a net source for DOP, which may stimulate growth of diazotrophic phytoplankton. These results demonstrate that microbial nutrient assimilation and partitioning of organic matter between the particulate and the dissolved phase are controlled by the N:P ratio of upwelled nutrients, implying substantial consequences for nutrient cycling and organic matter pools in the course of decreasing nutrient N:P stoichiometry.

scholarly journals Quantifying the contribution of shipping NO<sub><i>x</i></sub> emissions to the marine nitrogen inventory – a case study for the western Baltic Sea

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 115-134
Author(s):  
Daniel Neumann ◽  
Matthias Karl ◽  
Hagen Radtke ◽  
Volker Matthias ◽  
René Friedland ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Baltic Sea ◽  
Total Nitrogen ◽  
Ocean Model ◽  
Biogeochemical Model ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nitrogen Concentrations ◽  
The Baltic ◽  
The Impact

Abstract. The western Baltic Sea is impacted by various anthropogenic activities and stressed by high riverine and atmospheric nutrient loads. Atmospheric deposition accounts for up to a third of the nitrogen input into the Baltic Sea and contributes to eutrophication. Amongst other emission sources, the shipping sector is a relevant contributor to the atmospheric concentrations of nitrogen oxides (NOX) in marine regions. Thus, it also contributes to atmospheric deposition of bioavailable oxidized nitrogen into the Baltic Sea. In this study, the contribution of shipping emissions to the nitrogen budget in the western Baltic Sea is evaluated with the coupled three-dimensional physical biogeochemical model MOM–ERGOM (Modular Ocean Model–Ecological ReGional Ocean Model) in order to assess the relevance of shipping emissions for eutrophication. The atmospheric input of bioavailable nitrogen impacts eutrophication differently depending on the time and place of input. The shipping sector contributes up to 5 % to the total nitrogen concentrations in the water. The impact of shipping-related nitrogen is highest in the offshore regions distant from the coast in early summer, but its contribution is considerably reduced during blooms of cyanobacteria in late summer because the cyanobacteria fix molecular nitrogen. Although absolute shipping-related total nitrogen concentrations are high in some coastal regions, the relative contribution of the shipping sector is low in the vicinity of the coast because of high riverine nutrient loads.

scholarly journals Contribution of shipping NO<sub><i>x</i></sub> emissions to the marine nitrogenbudget of the western Baltic Sea – A case study

2019 ◽  
Author(s):  
Daniel Neumann ◽  
Matthias Karl ◽  
Hagen Radtke ◽  
Volker Matthias ◽  
René Friedland ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Baltic Sea ◽  
Total Nitrogen ◽  
Biogeochemical Model ◽  
Nutrient Loads ◽  
Coastal Regions ◽  
The Baltic Sea ◽  
Nitrogen Concentrations ◽  
The Baltic ◽  
The Impact

Abstract. The western Baltic Sea is impacted by various anthropogenic activities and stressed by high riverine and atmospheric nutrient loads. Atmospheric deposition accounts for up to a third of the nitrogen input into the Baltic Sea and contributes to eutrophication. Amongst other emission sources, the shipping sector is a relevant contributor to atmospheric concentrations of nitrogen oxides (NOx) in marine regions. Thus, it also contributes to atmospheric deposition of bioavailable oxidized nitrogen into the Baltic Sea. In this study, the contribution of shipping emissions to the nitrogen budget in the western Baltic Sea is evaluated with the coupled three-dimensional physical biogeochemical model MOM-ERGOM in order to assess the relevance of shipping emissions for eutrophication. The input of bioavailable nitrogen impacts eutrophication differently depending on time and place of input – e.g. nitrogen is processed and denitrified faster in flat coastal regions. The shipping sector contributes up to 5 % to the total nitrogen concentrations in the water. The impact of shipping-related nitrogen is highest in the off-shore regions distant to the coast in early summer but is considerably reduced during blooms of cyanobacteria in later summer. Although absolute shipping-related total nitrogen concentrations are high in some coastal regions, the relative contribution of the shipping sector is low in the vicinity to the coast because of high riverine nutrient loads.

A state-of-the-art parameterization of atmospheric nutrient deposition fluxes in the global ocean

2020 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Matthias Gröger ◽  
Jenny Hieronymus ◽  
Ralf Döscher
Keyword(s):  
Atmospheric Deposition ◽  
State Of The Art ◽  
Marine Ecosystem ◽  
Open Ocean ◽  
Marine Phytoplankton ◽  
Global Ocean ◽  
Model Calculations ◽  
Deposition Fluxes ◽  
Atmospheric Processing ◽  
The Impact

&lt;p&gt;Atmospheric deposition of trace constituents of natural and anthropogenic origin act as a nutrient source into the open ocean, affecting the marine ecosystem functioning and subsequently the exchange of CO&lt;sub&gt;2&lt;/sub&gt; between the atmosphere and the global ocean. Among other species that are deposited into the open ocean, nitrogen (N), iron (Fe), and phosphorus (P) are considered as highly significant nutrients that can limit marine phytoplankton growth and thus directly impact on ocean carbon fluxes in the ocean, particularly where the nutrient availability is the limiting factor for productivity. For this work, we take into account the up-to-date understanding of the effects of air quality on the atmospheric aerosol cycles to investigate the potential ocean biogeochemistry perturbations via the atmospheric input with the European Community Earth System Model EC-Earth (http://www.ec-earth.org/), which is jointly developed by several European institutes. In more detail, state-of-the-art N, Fe, and P atmospheric deposition fields are coupled to the embedded marine biogeochemistry model and the response of oceanic biogeochemistry to natural and anthropogenic atmospheric aerosols deposition changes is demonstrated and quantified. Model calculations show that compared to the present day, the preindustrial atmospheric deposition fluxes are calculated lower (~1.7, ~1.5, and ~1.4 times for N, Fe, and P, respectively) corresponding to a respective lower marine primary production. On the other hand, future changes in air pollutants under the RCP8.5 scenario result in a modest decrease of the bioaccessible nutrients input into the global ocean (~ -15%, ~ -16% and ~ -22% for N, Fe and P, respectively) and overall to a slightly lower projected export production compared to present day. Although the impact of atmospheric processing on atmospheric inputs to the ocean results in a relatively weak response in total global-scale simulated marine productivity estimates, strong regional changes up to 40-60% are calculated in the subtropical gyres. Overall, this study indicates that both the atmospheric processing and the speciation of the atmospheric nutrients deposited in the ocean should be considered in detail in carbon-cycling studies, since they may significantly affect the marine ecosystems and thus the current estimates of the carbon cycle feedbacks to climate.&lt;/p&gt;&lt;p&gt;This work has been financed by the National Observatory of Athens internal grant (number 5065), the &amp;#8220;Atmospheric deposition impacts on the ocean system&amp;#8221;, and the European Commission's Horizon 2020 Framework Programme, under Grant Agreement number 641816, the &quot;Coordinated Research in Earth Systems and Climate: Experiments, kNowledge, Dissemination, and Outreach (CRESCENDO)&quot;.&lt;/p&gt;

scholarly journals Assessing the impact of nutrient loads on eutrophication in the semi-enclosed Izmir Bay combining observations and coupled hydrodynamic-ecosystem modelling

2021 ◽  
Author(s):  
OZGE YELEKCI ◽  
VALERIA IBELLO ◽  
BETTINA A. FACH ◽  
FILIZ KUCUKSEZGIN ◽  
CAGLAR YUMRUKTEPE ◽  
...  
Keyword(s):  
Inorganic Nitrogen ◽  
Marine Ecosystem ◽  
Waste Water Treatment ◽  
Treatment Plant ◽  
Waste Water Treatment Plant ◽  
Spatial And Temporal Variability ◽  
Nutrient Loads ◽  
Algal Production ◽  
Izmir Bay ◽  
The Impact

Intense human activities may strongly affect coastal environments threatening natural, societal and economic resources. In order to propose adequate measures to preserve coastal marine areas, a thorough understanding of their physical and biogeochemical features is required. This study focuses on one such coastal area, Izmir Bay located in the Eastern Mediterranean Sea. Izmir Bay is a highly populated area subject to many human induced stressors such as pollution and eutrophication, that has been suffering high nutrient loads for decades. Despite the construction of the Çiğli waste water treatment plant in 2000-2001 to reduce eutrophication, such pressures continue to occur. To study the current physical and biogeochemical dynamics of Izmir Bay and their spatial and temporal variability, a three-dimensional coupled hydrodynamic-ecosystem model (Delft3D modelling suite’s FLOW and ECO modules) is implemented. Using the model, the effect of excessive inorganic nutrient loading on the marine ecosystem as the main cause of this eutrophication is explored in an effort to advise on mitigation efforts for the Bay focusing on eliminating eutrophication. Results of different model scenarios show that the Inner and Middle Bay are nitrogen-limited while the Outer Bay is phosphorus-limited. Inner regions are more sensitive to variations in inorganic nitrogen input due to the low (<16) N/P ratio of nutrients in seawater. An increase in inorganic nitrogen triggers eutrophication events with primary production as an immediate response. Conversely, the Outer Bay ecosystem with N/P ratios above 16 is more sensitive to phosphate inputs, of which an increase causes a considerable enhancement in algal production. This study shows the vulnerability of Izmir Bay to anthropogenic nutrient input and model simulations indicate that management plans should consider reducing DIN discharges both in the inner-middle zones of Izmir Bay as well as inputs from the Gediz River. Additionally, phosphate inputs should be reduced to avoid an overall increase of algal production in the Outer Bay, the larger part of Izmir Bay.

scholarly journals Modeling the biogeochemical impact of atmospheric phosphate deposition from desert dust and combustion sources to the Mediterranean Sea

2017 ◽  
Author(s):  
Camille Richon ◽  
Jean-Claude Dutay ◽  
François Dulac ◽  
Rong Wang ◽  
Yves Balkanski
Keyword(s):  
Mediterranean Sea ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Primary Source ◽  
Biogeochemical Model ◽  
Chemical Transport Model ◽  
Chl A ◽  
The North ◽  
The Mediterranean ◽  
The Impact

Abstract. We used phosphate deposition from natural dust, anthropogenic combustion and wildfires simulated for the year 2005 by a global atmospheric chemical transport model (LMDz–INCA) as additional sources of external nutrient for a high resolution regional coupled dynamical–biogeochemical model of the Mediterranean Sea. In general, dust is considered as the main atmospheric source of phosphorus, but the LMDz–INCA model suggests that combustion is dominant over natural dust as an atmospheric source of phosphate (the bioavailable form of phosphorus in seawater) for the Mediterranean Sea. According to the atmospheric transport model, anthropogenic phosphate deposition from combustion (Pcomb) brings on average 40.5 10−6 mol PO4 m−2 year−1 over the entire Mediterranean Sea for the year 2005 and is the primary source over the northern part (101 10−6 mol PO4 m−2 year−1 from combustion deposited in 2005 over the North Adriatic against 12.4 10−6 from dust). Lithogenic dust brings 17.2 10−6 mol PO4 m−2 year−1 on average over the Mediterranean Sea in 2005 and is the primary source of atmospheric phosphate to the southern Mediterranean basin in our simulations (31.8 10−6 mol PO4 m−2 year−1 from dust deposited in 2005 on average over the South Ionian basin against 12.4 10−6 from combustion). We examine separately the different soluble phosphorus (PO4) sources and their respective fluxes variability and evaluate their impacts on marine surface biogeochemistry (phosphate concentrations, Chl a, primary production). The impacts of the different phosphate deposition sources on the biogeochemistry of the Mediterranean are found localized, seasonally varying and small, but yet statistically significant. The impact of the different sources of phosphate on the biogeochemical cycles is remarkably different and should be accounted for in modeling studies.

scholarly journals The Mediterranean subsurface phytoplankton dynamics and their impact on Mediterranean bioregions

2018 ◽  
Author(s):  
Julien Palmiéri ◽  
Jean-Claude Dutay ◽  
Fabrizio D'Ortenzio ◽  
Loïc Houpert ◽  
Nicolas Mayot ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Phytoplankton Biomass ◽  
Trophic Levels ◽  
Biogeochemical Model ◽  
Limited Area ◽  
Phytoplankton Dynamics ◽  
Total Phytoplankton Biomass ◽  
Total Phytoplankton ◽  
The Mediterranean ◽  
The Impact

Abstract. Ocean bioregions are generally defined using remotely-sensed sea surface chlorophyll fields, based on the assumption that surface chlorophyll is representative of euphotic layer phytoplankton biomass. Here we investigate the impact of subsurface phytoplankton dynamics on the characterisation of ocean bioregions. The Mediterranean Sea is known for its contrasting bioregimes despite its limited area, and represents an appropriate case for this study. We modelled this area using a high resolution regional dynamical model, NEMO-MED12, coupled to a biogeochemical model, PISCES, and focused our analysis on the bioregions derived from lower trophic levels. Validated by satellite and Biogeochemical-Argo float observations, our model shows that chlorophyll phenology can be significantly different when estimated from surface concentrations or integrated over the first 300 m deep layer. This was found in both low chlorophyll, oligotrophic bioregions as well as in high chlorophyll, bloom bioregions. The underlying reason for this difference is the importance of subsurface phytoplankton dynamics, in particular those associated with the Deep Chlorophyll Maximum (DCM) at the base of the upper mixed layer. Subsurface phytoplankton are found to significantly impact the bloom bioregions, while in oligotrophic regions, surface and subsurface chlorophyll are of similar importance. Consequently, our results show that surface chlorophyll is not representative of total phytoplankton biomass. Analysis of the DCM finds that its dynamics are extremely homogeneous throughout the Mediterranean Sea, and that it follows the annual cycle of solar radiation. In the most oligotrophic bioregion, the total phytoplankton biomass is almost constant along the year, implying that the summertime DCM biomass increase is not due to DCM photoacclimation, nor an increase of DCM production, but instead of the migration – with photoacclimation – of surface phytoplankton into the DCM.

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