Soluble, Colloidal, and Particulate Iron Across the Hydrothermal Vent Mixing Zones in Broken Spur and Rainbow, Mid-Atlantic Ridge

The slow-spreading Mid-Atlantic Ridge (MAR) forms geological heterogeneity throughout the ridge system by deep crustal faults and their resultant tectonic valleys, which results in the existence of different types of hydrothermal vent fields. Therefore, investigating MAR hydrothermal systems opens a gate to understanding the concentration ranges of ecosystem-limiting metals emanating from compositionally distinct fluids for both near-field chemosynthetic ecosystems and far-field transport into the ocean interiors. Here, we present novel data regarding onboard measured, size-fractionated soluble, colloidal, and particulate iron concentrations from the 2018 R/V L'Atalante - ROV Victor research expedition, during which samples were taken from the mixing zone of black smokers using a ROV-assisted plume sampling. Iron size fractionation (200nm) data were obtained from onboard sequential filtering, followed by measurement via ferrozine assay and spectrophotometric detection at 562nm. Our results showed the persistent presence of a nanoparticulate/colloidal phase (retained within 20-200nm filtrates) even in high-temperature samples. A significant fraction of this phase was retrievable only under treatment with HNO3 - a strong acid known to attack and dissolve pyrite nanocrystals. Upon mixing with colder bottom waters and removal of iron in the higher parts of the buoyant plume, the larger size fractions became dominant as the total iron levels decreased, but it was still possible to detect significant (micromolar) levels of nanoparticulate Fe even in samples collected 5m above the orifice in the rising plume. The coolest sample

Thermodynamic Predictions of Hydrogen Generation during the Serpentinization of Harzburgite with Seawater-derived Brines

Salty aqueous solutions (brines) occur on Earth and may be prevalent elsewhere. Serpentinization represents a family of geochemical reactions where the hydration of olivine-rich rocks can release aqueous hydrogen, H2(aq), as a byproduct, and hydrogen is a known basal electron donor for terrestrial biology. While the effects of lithological differences on serpentinization products have been thoroughly investigated, effects focusing on compositional differences of the reacting fluid have received less attention. In this contribution, we investigate how the chemistry of seawater-derived brines affects the generation of biologically available hydrogen resulting from the serpentinization of harzburgite. We numerically investigate the serpentinization of ultramafic rocks at equilibrium with an array of brines at different water activities (a proxy for salt concentration in aqueous fluids and a determinant for habitability) derived from seawater evaporation. Because the existing supersaturation of aqueous calcium carbonate, a contributor to dissolved inorganic carbon (DIC) in natural seawater, cannot be captured in equilibrium calculations, we bookend our calculations by enabling and suppressing carbonate minerals when simulating serpentinization. We find that the extent of DIC supersaturation can provide an important control of hydrogen availability. Increased DIC becomes a major sink for hydrogen by producing formate and associated complexes when the reacting fluids are acidic enough to allow for CO2. Indeed, H2(aq) reduces CO2(aq) to formate, leading to a hydrogen deficit. These conclusions provide additional insights into the habitability of brine systems, given their potential for serpentinization across diverse planetary bodies such as on Mars and ocean worlds

Geochemistry of Deep-Sea Hydrothermal Vent Fluids from Broken Spur, Rainbow and Lost City Hydrothermal Vent Fields, Mid-Atlantic Ridge

Mid- Atlantic Ridge (MAR) is a very special tectonic environment which contains compositioanlly distinct hydrothermal vent fields as a result of its slow spreading character. Considering the increasing efforts on understanding the role of hydrothermal vents in both local and global ocean system, MAR enables to develop a wholistic approach to study formation, evolution and near field transportation of hydrothermal vent products in different vent fields at the same time. Here we present our results obtained from one of each representative vent settings that exists on the MAR (Type 1: Broken Spur, Type 2: Rainbow and Type 3: Lost City) during a research expedition with N/O L’Atalante and ROV Victor 6000 in 2018. ROV-assisted hydrothermal fluid sampling was conducted and samples were taken from the orifice as well as different heights of the hydrothermal plumes of corresponding vents. Upon the sample collection, both on-board and on-shore measurements for major ions, hydrogen sulfide and transition metals were performed by using ion chromatography, colorimetric methods, and ICP-MS. Our results, in support of previous reports for endmember fluid compositions, show that interplay of temperature, pH, Cl and H2S concentrations control the formation and transportation of dissolved species in Rainbow, Broken Spur and Lost City hydrothermal fluids. On the other hand, Rainbow and Lost City fields show high temporal stability over ~20 years’ time span however substantial changes were observed in Broken Spur fluids in ~25 years, which contrasts with previous findings describing high temporal stability of MAR hydrothermal vents. Considering intense cooling (~100 °C) upon the fluid rise to seafloor in Broken Spur hydrothermal field, we are proposing Broken Spur experiences extensive Si (up to 50%) and Fe precipitation in the subseafloor as Fe-silicate and Fe-sulfide minerals. Furthermore, plume geochemistry results indicate metal oxide and silicate phases are important fraction of Rainbow (nano)particle pool while low Fe:H2S dynamics in Broken Spur plume result in formation and domination of metal sulfide phases. Considering high removal trends and high correlations observed in metals, silica and cations, we are proposing reverse weathering reactions might be responsible in formation of metal silicate phases especially in Rainbow and possibly in Broken Spur plumes. Finally, our findings in conjunction with previous studies show that hydrothermal vents are factories for biologically important (nano)particles regardless of the setting. Hence, considering the possible global scale effects of such hydrothermal vent products, we are suggesting hydrothermal (nano)particles might have played much more important roles in major geological events in the Earth’s history than previously thought

ORTA ATLANTİK SIRTINDA BULUNAN BROKEN SPUR, RAINBOW VE LOST CITY DERİN DENİZ HİDROTERMAL BACALARININ AKIŞKANLAR JEOKİMYASI

Mid- Atlantic Ridge (MAR) is a very special tectonic environment which contains compositioanlly distinct hydrothermal vent fields as a result of its slow spreading character. Considering the increasing efforts on understanding the role of hydrothermal vents in both local and global ocean system, MAR enables to develop a wholistic approach to study formation, evolution and near field transportation of hydrothermal vent products in different vent fields at the same time. Here we present our results obtained from one of each representative vent settings that exists on the MAR (Type 1: Broken Spur, Type 2: Rainbow and Type 3: Lost City) during a research expedition with N/O L’Atalante and ROV Victor 6000 in 2018. ROV-assisted hydrothermal fluid sampling was conducted and samples were taken from the orifice as well as different heights of the hydrothermal plumes of corresponding vents. Upon the sample collection, both on-board and on-shore measurements for major ions, hydrogen sulfide and transition metals were performed by using ion chromatography, colorimetric methods, and ICP-MS. Our results, in support of previous reports for endmember fluid compositions, show that interplay of temperature, pH, Cl and H2S concentrations control the formation and transportation of dissolved species in Rainbow, Broken Spur and Lost City hydrothermal fluids. On the other hand, Rainbow and Lost City fields show high temporal stability over ~20 years’ time span however substantial changes were observed in Broken Spur fluids in ~25 years, which contrasts with previous findings describing high temporal stability of MAR hydrothermal vents. Considering intense cooling (~100 °C) upon the fluid rise to seafloor in Broken Spur hydrothermal field, we are proposing Broken Spur experiences extensive Si (up to 50%) and Fe precipitation in the subseafloor as Fe-silicate and Fe-sulfide minerals. Furthermore, plume geochemistry results indicate metal oxide and silicate phases are important fraction of Rainbow (nano)particle pool while low Fe:H2S dynamics in Broken Spur plume result in formation and domination of metal sulfide phases. Considering high removal trends and high correlations observed in metals, silica and cations, we are proposing reverse weathering reactions might be responsible in formation of metal silicate phases especially in Rainbow and possibly in Broken Spur plumes. Finally, our findings in conjunction with previous studies show that hydrothermal vents are factories for biologically important (nano)particles regardless of the setting. Hence, considering the possible global scale effects of such hydrothermal vent products, we are suggesting hydrothermal (nano)particles might have played much more important roles in major geological events in the Earth’s history than previously thought.Orta Atlantik Sırtı (MAR), yavaş açılım karakterinin bir sonucu olarak kompozisyonel açıdan farklı hidrotermal bacalar içeren çok özel bir tektonik ortamdır. Hem yerel hem de küresel okyanus sistemindeki hidrotermal bacaların rolünü anlamaya yönelik artan çabaları göz önünde bulundurarak, Orta Atlantik Sırtı, hidrotermal baca ürünlerinin oluşumunu, gelişimi ve taşınımını aynı anda farklı alanlarda çalışmak için bütünsel bir yaklaşım sunmaktadır. Burada, 2018 yılında N / O L'Atalante ve ROV Victor 6000 ile yapılan bir araştırma gezisi sırasında MAR'da bulunan her temsili hidrotermal baca örneğinin birinden elde ettiğimiz sonuçları sunuyoruz (Tip 1: Broken Spur, Tip 2: Rainbow ve Tip 3: Lost City). ROV destekli hidrotermal sıvı örneklemesi gerçekleştirilerek ilgili bacaların hidrotermal püskürtülerinin farklı yüksekliklerinden örnekler alındı. Örneklemeyi takiben hem gemide hem de karada iyonların, hidrojen sülfürün ve geçiş metallerinin ölçümleri iyon kromatografisi, kolorimetrik yöntemler ve ICP-MS kullanılarak gerçekleştirildi. Hidrotermal sıvı bileşimleri konusunda önceki raporları destekleyen sonuçlarımız, sıcaklık, pH, Cl ve H2S konsantrasyonlarının karşılıklı etkileşiminin Rainbow, Broken Spur ve Lost City hidrotermal sıvılarında çözünmüş türlerin oluşumunu ve taşınmasını kontrol ettiğini göstermektedir. Öte yandan, Rainbow ve Lost City sahaları, ~20 yıllık bir zaman diliminde yüksek zamansal kararlılık sergilerken Broken Spur sıvılarında, MAR hidrotermal bacalarının yüksek zamansal kararlılığını tanımlayan önceki bulgulara aykırı olarak, ~25 yıl içinde önemli değişiklikler gözlenmiştir. Broken Spur alanında hidrotermal sıvıların derinlerden deniz tabanına taşınması sırasında meydana gelen yoğun sıcaklık kaybını (~100 ° C) göz önünde bulundurarak, bu alanda deniz tabanının altında aşırı miktarda silika (50% kadar) ve demirin Fe-silikat ve Fe-sülfit mineralleri olarak çökeldiğini öngörüyoruz. Ayrıca, püskürtü jeokimyası sonuçları, metal oksit ve silikat fazlarının Rainbow (nano)parçacık havuzunun önemli bir parçası olduğunu, Broken Spur sistemindeki düşük Fe:H2S dinamiklerinin ise metal sülfit fazlarının oluşumuna ve hakimiyetine neden olduğunu göstermektedir. Metal, silika ve katyon konsantrasyonlarında gözlemlenen azalım eğilimleri ve yüksek korelasyonlar göz önüne alındığında, özellikle Rainbow ve muhtemelen Broken Spur püskürtülerinde metal silikat fazlarının oluşumunda “reverse weathering” reaksiyonlarının sorumlu olabileceğini öneriyoruz. Son olarak, önceki çalışmalarla bağlantılı olarak bulgularımız, hidrotermal bacaların, ortam ne olursa olsun biyolojik olarak önemli (nano)parçacık fabrikaları olduğunu göstermektedir. Bu nedenle, bu tür hidrotermal baca ürünlerinin olası küresel ölçekli etkilerini göz önünde bulundurarak, hidrotermal (nano)parçacıkların Dünya tarihindeki önemli jeolojik olaylarda daha önce düşünülenden çok daha önemli roller oynamış olabileceğini öne sürüyoruz.M.S. - Master of Scienc

Dissolved, Colloidal and Particulate Iron in Hydrothermal Vent Fluids and Rising Plumes from Broken Spur and Rainbow, Mid-Atlantic Ridge

Mid-Atlantic Ridge (MAR), with its slow spreading character, forms geological heterogeneity throughout the ridge system by deep crustal faults and their resultant tectonic valleys, which result in existence of different types of hydrothermal vent fields. Therefore, examining MAR opens a gate to understand the concentration ranges of ecosystem- limiting metals emanating from compositionally distinct hydrothermal settings for both near-field chemosynthetic ecosystems and far-field transport into the ocean interiors. Here we present on-board measured, size fractionated dissolved iron results from 2018 R/V Atalante – ROV Victor expedition, during which samples were taken from the mixing zone of black smokers with Titanium majors and PEP samplers attached to ROV Victor, using a ROV-assisted plume sampling. Iron size fractionation (<2, 2-200 and >200 nanometer) data were obtained on board sequential filtering, followed by measurement via ferrozine assay and spectrophotometric detection at 562 nm. Our results showed the persistent presence of a nanoparticulate/colloidal phase (retained within 20-200 nm filtrates) even in high- temperature samples and a significant fraction of this phase was retrievable only under a HNO3treatment – a stronger acid known to attack and dissolve pyrite nanocyrstals (HCl cannot dissolve this). Upon mixing and removal of iron in the higher parts of the buoyant plume, the larger size fractions become dominant as the total iron levels decreased but we still detected significant (micromolars) levels of nanoparticulate/colloidal Fe even in Niskin bottles sampled from 5 m in the plume. The lowest-temperature sample (<10 degrees C) still contained more than 1 μM of only nitric-acid leachable nanoparticle/colloidal, about 200 times higher than a typical Fe concentration in the non-buoyant plume. Our results are in support of previous reports of dissolved Fe in MAR vents and we propose that this recalcitrant Fe pool - surviving the immediate precipitation- is the fraction that maintains high hydrothermal iron fluxes to the deep ocean

Iron oxidation and porosity generation in serpentinized abyssal peridotite

Natural Sciences and Engineering Research Council (NSERC

Frequency of Respiratory Syncytial Virus Infection Among Patients Hospitalized for Influenza-like Diseases and its Impact on Mortality: Prospective, Multi-center Real Life Results

Introduction: Respiratory syncytial virus (RSV) is among the major causes of severe mortality and morbidity in both children and adults worldwide. This study aimed at demonstrating the course of RSV in our country. Materials and Methods: Simultaneous RSV surveillance was implemented within the scope of Global Influenza Hospital Surveillance Network in Ankara in the season of 2016-2017. Results: A total of 917 cases were included into the study, and RSV polymerase chain reaction was positive in 145 patients (15.8%). Among the RSV positive cases, 132 were under five years old and 13 were over five. There was no underlying disease in 86.3% of the cases under five years of age, and the most common underlying disease was chronic obstructive pulmonary disease in the five years and older group. While 9.8% of the cases under the age of five was admitted to the intensive care unit, only one case out of 13 patients over the age of five was admitted to the intensive care unit. Although the rate of infection was higher among children under five years of age, there was one mortal case in this group, while one of two patients older than 65 years died in the group over the age of five. Conclusion: In our country, clinical and epidemiological data have great importance for the prevention of mortality and morbidity associated with RSV infections, and extensive surveillance studies are needed