Response of Nitrate Processing to Bio-labile Dissolved Organic Matter Supply Under Variable Oxygen Conditions in a Sandy Beach Seepage Face

Supply of bio-labile dissolved organic matter (DOM) has been assumed to be a key factor for the intensity of nitrate (NO3–) removal in permeable coastal sediments. In the present study, a series of flow through reactor experiments were conducted using glucose as a N-free bio-labile DOM source to permeable sediments from a sandy beach seepage face to identify its effect on benthic NO3– removal. The results revealed a shift from the dominance of NO3– production to removal processes when NO3– input concentration increased from 10 to 80 μM under oxic conditions. Sediment microbiota information suggests that nitrification (e.g., Nitrosomonas and Nitrososphaera) and denitrification (e.g., Marinobacter and Bacillus) were dominant pathways for benthic NO3– production and removal in the studied sediment. Compared with the active response of sediment microbiota to NO3– additions, the supply of glucose (approximately 300 μM final concentration added) did not significantly change the NO3– removal efficiency under aerobic conditions (dissolved oxygen saturation approximately 100%). Similarly, an insignificant increase of NO3– removal rate after glucose amendment of the circulating water was obtained when dissolved oxygen (DO) saturation decreased to approximately 70% in the input solution. When DO at the input solution was decreased to 30% saturation (sub-oxic conditions), the removal rate of NO3– in the group amended with glucose increased, suggesting that glucose stimulated denitrifiers. These results revealed that NO3– removal relied mainly on the anaerobic environment at particle surfaces, with a dependence on the sedimentary organic matter as an electron supplier under bulk aerobic conditions, while the bio-labile DOM was consumed mainly by aerobic respiration instead of stimulating NO3– reduction. However, the respiration triggered by the over-supply of bio-labile DOM reduced the DO in the porewater, likely depressing the activity of aerobic reactions in the permeable sediment. At this point, the benthic microbiota, especially potential denitrifiers, shifted to anaerobic reactions as the key to support nitrogen metabolism. The glucose amendment benefited NO3– reduction at this point, under sub-oxic conditions

Fresh and saline submarine groundwater discharge in a large coastal inlet affected by seasonal upwelling

Original research paperSubmarine groundwater discharge is recognized as a major source of chemicals to the global ocean, exerting large control over coastal water composition. Radon and 226Ra are used to evaluate, for the first time, the occur rence and magnitude of submarine groundwater discharge in the Ría de Vigo, a large, highly productive embay ment affected by seasonal, wind-driven upwelling. The system is naturally enriched in 222Rn due to the regional granitic basement geology: high 222Rn activities (up to 106 Bq m−3 ) are detected in wells and boreholes in the drainage basin of the embayment. High 222Rn activities (>400 Bq m−3 ) are also measured in certain areas of the embayment. Comparatively lower 226Ra activities (<4 103 Bq m−3 ) were measured in the freshwater sources to the bay. Mass balances obtained with a box model are used to perform a volumetric estimate of fresh and saline submarine groundwater discharge in the Ría de Vigo under contrasting circulation patterns. Fresh groundwater is shown to be a relevant hydrological component of the Ria de Vigo water balance, equivalent to 9% 4% and 23% 9% of the volume discharged by tributary rivers during winter and summer, respectively. On the other hand, recirculation of seawater through permeable sediments is capable of filtering the entire upper volume of the Ria de Vigo through its seafloor in <100 days and might thus be a previously overlooked major source of regenerated solutes to the system.Irish Research Council and European Union Commission Horizon 2020 research and innovation programmeVersión del editor3,38

Modeling nitrate-contaminated groundwater discharge to the Ria Formosa Coastal Lagoon (Algarve, Portugal)

A numerical flow and transport model is developed to assess groundwater discharge and nutrient transport to the Ria Formosa coastal lagoon in southern Portugal. A total N load of 350 ton/year is estimated for the considered area, of which agriculture accounts for 73% of total N load, and domestic effluent and atmospheric deposition for the remaining 9% and 18% respectively. Model results suggest that nutrient recycling has led to the high concentrations observed in the Campina de Faro (M12) aquifer, but is still insufficient to account for observed values at the coastline. Furthermore results suggest that even for the best case mitigation scenario, good quality status will not be achieved by 2027, as mandated by the EU Water Framework Directive.info:eu-repo/semantics/publishedVersio

A multi-decade record of high quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT_V3_GRID

The tropical Atlantic observing system

The tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southern and northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world’s largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time and out of necessity in order to address the most important outstanding scientific questions and to improve predictions of tropical Atlantic severe weather and global climate variability and change. The tropical Atlantic observing system is motivated by goals to understand and better predict phenomena such as tropical Atlantic interannual to decadal variability and climate change; multidecadal variability and its links to the meridional overturning circulation; air-sea fluxes of CO2 and their implications for the fate of anthropogenic CO2; the Amazon River plume and its interactions with biogeochemistry, vertical mixing, and hurricanes; the highly productive eastern boundary and equatorial upwelling systems; and oceanic oxygen minimum zones, their impacts on biogeochemical cycles and marine ecosystems, and their feedbacks to climate. Past success of the tropical Atlantic observing system is the result of an international commitment to sustained observations and scientific cooperation, a willingness to evolve with changing research and monitoring needs, and a desire to share data openly with the scientific community and operational centers. The observing system must continue to evolve in order to meet an expanding set of research priorities and operational challenges. This paper discusses the tropical Atlantic observing system, including emerging scientific questions that demand sustained ocean observations, the potential for further integration of the observing system, and the requirements for sustaining and enhancing the tropical Atlantic observing system

Importance and controls of anaerobic ammonium oxidation influenced by riverbed geology

Rivers are an important global sink for excess bioavailable nitrogen: they convert approximately 40% of terrestrial N runoff per year (∼47 Tg) to biologically unavailable N 2 gas and return it to the atmosphere. At present, riverine N 2 production is conceptualized and modelled as denitrification. Anaerobic ammonium oxidation, known as anammox, is an alternative pathway of N 2 production important in marine environments, but its contribution to riverine N 2 production is not well understood. Here we use in situ and laboratory measurements of anammox activity using 15 N tracers and molecular analyses of microbial communities to evaluate anammox in clay-, sand-and chalk-dominated river beds in the Hampshire Avon catchment, UK during summer 2013. Abundance of the hzo gene, which encodes an enzyme central to anammox metabolism, varied across the contrasting geologies. Anammox rates were similar across geologies but contributed different proportions of N 2 production because of variation in denitrification rates. In spite of requiring anoxic conditions, anammox, most likely coupled to partial nitrification, contributed up to 58% of in situ N 2 production in oxic, permeable riverbeds. In contrast, denitrification dominated in low-permeability clay-bed rivers, where anammox contributes roughly 7% to the production of N 2 gas. We conclude that anammox can represent an important nitrogen loss pathway in permeable river sediments

modelação diagenética e análise temporal

Dissertação de Mestrado, Estudos Marinhos e Costeiros, Faculdade de Ciências do Mar e Ambiente, Universidade do Algarve, 2007Foi estudada a dinâmica biogeoquímica de sedimentos permeáveis intermareais afectados pelo escoamento costeiro de águas subterrâneas com elevado conteúdo em nitratos na Ria Formosa. Com este objectivo, seguiu-se um meticuloso plano de amostragens, com duração de 14 meses (Novembro de 2005 até Janeiro de 2007), utilizando novas técnicas de amostragem de água intersticial in-situ. Após a identificação e caracterização do escoamento costeiro de águas subterrâneas nos sedimentos da face interna das ilhas barreira da Ria Formosa, procedeu-se ao desenvolvimento de um novo modelo analítico dos processos de diagénese recente que descrevesse a distribuição de nitrato na água intersticial do local, a sua variação espacial e as condicionantes à alteração sazonal dos gradientes observados. Demostramos a pertinência do modelo e a sua coerência física, e estudamos a aplicabilidade da solução analítica com fronteira livre obtida à análise do comportamento biogeoquímico dos sedimentos no local. A análise de sensibilidade demostrou que o sistema é controlado pela velocidade advectiva e pela reactividade biogeoquímica. Utilizou-se então o ajuste efectuado pelo modelo aos dados recolhidos no campo, para explorar a sazonalidade biogeoquímica do local. Demostramos a elevada reactividade do sistema, com taxas reaccionais geralmente da mesma ordem de grandeza que os fluxos resultantes do sedimento para a lagoa. Desta maneira, o bêntos modula de forma significativa os fluxos de nitrato derivados do escoamento. Mostra-se também que a temperatura da água e a disponibilidade de matéria orgânica parecem ter importante influência sobre as trocas de nitrato através da interface sedimento-água. Identificamos um comportamento diferenciado da comunidade bêntica em função da posição no perfil de praia, no que a zona baixa do perfil resultou em potenciadora líquida dos fluxos de nitratos para a lagoa, enquanto o limite superior da zona de escoamento de águas subterrâneas resultou mitigadora. Identificaram-se também indícios de coexistencia de diferentes caminhos reactivos na redução de nitratos no local. O papel mitigador da zona costeira é assim incerto, mas a sua compreensão poderia ser um aspecto crucial no manejo da zona costeira estudada dentro da directiva nitrato da União Europeia.The biogeochemical dynamics of intertidal sandy sediments affected by nitraterich coastal groundwater discharge was studied at the Ria Formosa. A complete sampling plan, with 14 months duration (from November 2005 to January 2007), was executed using novel in-situ sampling techniques. After the identification and characterization of the groundwater seepage phenomenon on sandy sediments located on the inner part of the Ria Formosa barrier system, an analytical early diagenesis model describing processes affecting nitrate gradients in sandy intertidal sediments locus of nitrate-rich groundwater discharge was developed. We demonstrate the pertinence of the model and its physical coherence and explore its range of applicability. Sensitivity analysis demonstrated that the system is controlled by the seepage velocity and by biogeochemical reactivity. The developed model was used to fit field data in order to explore the local biogeochemical reactivity. Reverse modeling demonstrated the system’s highly reactivity, with reaction rates usually of the same order of magnitude than the resulting nitrate fluxes to the lagoon. Thus, the benthic system modulates the nitrate fluxes at the studied site in a significant way. The reactive system, according to our analysis, is controlled mainly by the advective velocity of the porewater, its temperature and organic carbon availability. Indications of the existence, of differential and competing nitrate reduction pathways also resulted from the seasonal and modeling analysis of porewater biogeochemistry at the sampled site. The mitigation potential of the coastal zone where sandy sediments intercept land source nitrate pollution is thus uncertain, but its comprehension would be a major issue in Costal Zone management according to the EU guidelines

MicroSub: Diversidade microbiana e bioxeoquímica agochadas nas augas subterráneas costeiras dos parques nacionais mariños

Poster.-- Close Encounters IIM (3rd Kind), Vigo, 23 June 2022Dous achados recentes revelaron o papel ecolóxico dos acuíferos como reservorios de diversidade e como mediadores de transformacións bioxeoquímicas que poden impactar nos ecosistemas mariños circundantes: - As augas subterráneas albergan unha gran diversidade de microorganismos en moitos casos descoñecidos para a ciencia - A descarga de auga subterránea ao mar achega grandes cantidades de nutrientes que poden afectar á calidade e a función ecolóxica dos ecosistemas mariños. MicroSub reúne un equipo altamente interdisciplinar, con especialistas en hidroxeoloxía costeira, na detección e medida de fluxos de auga subterránea ao mar, na caracterización das transformacións bioxeoquímicas e no estudo da ecoloxía microbiana acuática O obxectivo do proxecto é analizar a diversidade microbiana e xeoquímica de acuíferos costeiros prístinos e o seu impacto no mar circundante. Estes datos servirán de liña de base e como indicadores dos cambios que os ecosistemas dos parques poidan sufrir nos próximos anos por mor do cambio climático actual que poderían causar grandes cambios hidrolóxicos, biolóxicos e xeoquímicos nos acuíferos e nos medios mariños afectados por elesO proxecto MicroSub recibiu financiación do Organismo Autónomo Parques Nacionales e do Ministerio para la Transición Ecológica y el Reto Demográfico a través das subvencións para a realización de proxectos de investigación na rede de parques nacionais 2020 (Ref 2595 2020)N

Seasonal enhancement of submarine groundwater discharge (SGD)-derived nitrate loading into the Ria Formosa coastal lagoon assessed by 1-D modeling of benthic NO₃ profiles

The role of benthic sandy ecosystems in mitigating View the MathML sourceNO3- loads carried by Submarine Groundwater Discharge (SGD) to coastal marine ecosystems is uncertain. Benthic biogeochemical mediation of View the MathML sourceNO3--rich submarine groundwater discharge was studied at the seepage face of a barrier island site in the Ria Formosa coastal lagoon (Southern Portugal). Preliminary analysis of View the MathML sourceNO3- porewater distributions at the seepage face during discharge indicated that benthic biogeochemical processes could significantly affect the fluxes of groundwater-borne View the MathML sourceNO3- into the lagoon. In order to discriminate between the relative contribution of transport and reaction processes to shape and concentration range evidenced by in-situ porewater View the MathML sourceNO3- gradients, an advection-dispersion-reaction (ADR) model of View the MathML sourceNO3- diagenesis was applied to describe View the MathML sourceNO3- porewater profiles obtained in March, June, September and December 2006. Good agreement between modeled and measured profiles was obtained. Model-derived apparent benthic nitrification and View the MathML sourceNO3- reduction rates ranged from 0.01 to 5.2 mmol m-2 h-1, sufficient to explain gross observed changes in View the MathML sourceNO3- fluxes arriving at the seepage face (up to 70% within the surficial 20 cm depth layer). Results of the analysis indicated that the upper limit of the seepage face promoted mitigation of View the MathML sourceNO3- fluxes to the lagoon throughout the year. In contrast, the lower limit of the seepage area promoted net amplification of the View the MathML sourceNO3- fluxes into the lagoon in June and September. These results will help constrain further work aiming to clarify the role of permeable sediments in mitigating nitrogen loading of coastal ecosystems

Die Betrügereien in der territorialen Frage zwischen Japan und der Sowjetunion : Die Gründe für den Streit um das Territorium

Zwischen Japan und der Sowjetunion gibt es auch heute noch eine ungelöste territoriale Frage. Diese wurde aufgrund der Besetzung der Kurilen durch die Sowjetunion, in der Zeit der Regierung Stalins, verursacht. Deswegen gibt es immer noch keinen Friendensvertrag zwischen den beiden Staaten. Die sowjetische Regierung behauptet, daß Habomai und Shikotan zu den Kurilen gehörten. Die japanische Regierung meint dagegen, daß nicht nur Habomai und Shikotan, sondern auch Kunashiri und Etorofu nicht zu dieser Inselkette gehörten. Beide Regierungen verdrehen hier jedoch die Wahrheit, um ihren Anspruch auf diese Inseln zu begründen. Habomai und Shikotan gehören in der Tat zur Insel Hokkaido, Kunashiri und Etorofu sind jedoch ein Teil der Kurilen. Beide Regierungen müßten zuerst diese Tatsache akzeptieren, bevor sie diese schwierige territoriale Frage Iösen können. Die Sowjetunion müßte sofort die Inseln von Habomai und Shikotan an Japan zurückgeben. Danach sollte die Angelegenheit der Kurilen unter Zuhilfenahme der \u22Geheimakten von Brakesley\u22 gelöst werden. Darin wurde die Frage der Kurilen ausführlich durch das amerikanische Außenministerium untersucht. Diese Geheimakten schlugen vor, die Sudkurilen bei Japan zu belassen, die Nord- und Mittelkurilen zum Mandatsgebiet der UNO zu erklären und diese Mandat der Sowjetunion zu übertragen. Dieser Vorschlag stimmt mit der territorialen Forderung der heutigen japanischen Regierung fast überein. Wenn die Staatsgrenze zwischen Japan und der Sowjetunion unter Zuhilfenahme dieser Akten gelöst worden wäre, gäbe es heute diese territoriale Frage nicht. Sollte die Sowjetunion diese Lösung nicht akzeptiren, möchten wir vorschlagen, die Gesamtkurilen als gemeinsames Territorium von Japan und der Sowjetunion zu betrachten. Die Verwaltung der Südkurilen sollte von Japan, die der Nord- und Mittelkurilen dagegen von der Sowjetunion übernommen werden. Für Bevölkerung beider Staaten sollten auf den Gesamtkurilen Freizügigkeit und Niederlassungsrecht herrschen. Dabei muß auch die Situation der Ainu und anderer nationaler Minderheiten berücksichtigt werden. Diese sind durch Staatsgrenzen getrennt. Könnten wir nicht auf Grenzen verzichten und wie auf der Antarktika ohne diese auskommen? Die heutige Weltsituation unterliegt ständigen Veränderungen und alte fixe Ideen lösen sich heutzutage sehr schnell in nichts auf. Die territoriale Frage zwischen Japan und der Sowjetunion muß mit neuen Ideen gelöst werden