Oceanic Origin Research Articles

Decoding Bennu: Understanding the solar system and life’s origins

The OSIRIS-REx mission to an asteroid named Bennu collected a sample of its regolith—loose material on the surface of an asteroid—and returned to Earth in September 2023. The successful return and initial research on the sample revealed much data about the elemental composition of Bennu’s regolith. The findings offer new insights into the fundamental building blocks of life, potentially revolutionizing our understanding of life and our solar system. The sample contained organic compounds, key to the origin of life, and also elements like iron and magnesium in abundance. Mineral analysis showed the presence of water-rich minerals, a key factor in understanding the origins of our oceans. Analysis of the data helps further the understanding of the origin of our oceans. By understanding the composition of asteroids like Bennu that trace their origins to the early solar system, we can understand the conditions prevalent in those times. And most importantly, understanding the composition of Bennu also gives us key insights into the origin of life because of the discovery of organic compounds in the regolith. Gathering asteroid samples holds much importance in expanding our knowledge in multiple fields and in shedding on many unanswered questions regarding the origin of life, origin of oceans and understanding of the early solar system.

Severe and long-lasting meteorological drought events develop from precipitation deficits of mixed continental and oceanic origin

Drought is one of the most damaging hydroclimatic hazards, impacting environmental systems and socioeconomic sectors. Therefore, understanding the physical mechanisms that cause drought events is of critical importance. Here we investigate the influence of oceanic and continental moisture deficits on global meteorological drought events in recent decades, utilizing a Lagrangian dispersion model to track the origin of precipitation deficits leading to droughts. Additionally, meteorological drought events between 1980 and 2018 were segmented based on a three-dimension algorithm considering spatial extent, duration, and magnitude of drought events. Severe meteorological drought events exhibit mixed contribution of precipitation deficits from both continental and oceanic sources. This highlights the importance of considering both types of deficits in understanding severe meteorological droughts. Comparative analysis across time periods shows a consistent pattern in the dominant mixed contribution of precipitation deficits. There is no relevant decadal change in the mixed contributions of these deficits, which implies stability in the prevalence of oceanic and continental sources driving extreme drought events. These findings offer valuable insights into the factors shaping meteorological drought evolution.

Decoding organic compounds in lava tube sulfates to understand potential biomarkers in the Martian subsurface

Exploring molecular biomarkers in lava tube speleothems offers insights into environmental dynamics, biogeochemical processes, and subsurface life, with implications for astrobiology, particularly in Martian analog environments. Despite extensive biomarker research in marine and terrestrial settings, lava tube studies are limited. This study employed molecular, isotope and mineralogical characterization to analyze sulfate speleothems from six lava tubes of Lanzarote (Canary Islands), considered analog for the Moon and Mars. The combination of mass spectrometry, thermogravimetry, and mineralogical techniques, revealed geological processes, biomarkers and their biological sources. The identified minerals were primarily calcium and sodium sulfates. Sulfur isotope analyses indicated volcanic and oceanic origins, while carbon isotope composition and pyrolysis analyses suggested influences from vegetation and microbial activity. Lipidic profiles highlighted branched and n-alkanes, as well as palmitic and stearic acid methyl esters, suggesting microbial origins. These findings contribute to understanding geological and environmental dynamics in lava tubes and recognizing potential biosignatures on Earth and other planets.

A new family of freshwater snails with Cretaceous origin from Yunnan, China

Abstract China is a hotspot for species’ discovery nowadays and harbours some of the most threatened environments in the world due to human activities. Here we describe a new remarkable gastropod species from an ancient freshwater lake in Yunnan, south-west China, Squamapex taiji gen. et sp. nov. within a new monospecific family of Truncatelloidea, Squamapicidae fam. nov.. The highly ornamented protoconch of Squamapicidae, with a microstructure distinct from that of the teleoconch, has rarely been found in true freshwater gastropods, being previously mostly known from marine or migratory gastropods with veliger larvae. The most complete family-level and first-dated phylogeny of Truncatelloidea, the largest and most diverse superfamily within Mollusca, based on two mitochondrial and three nuclear markers, shows that Squamapicidae belong to a distinct ancient lineage with Cretaceous origin. Its sister-group, unique protoconch, and distribution suggest a Tethys Ocean origin of this new family.

Long-term dynamics of larval and early juvenile spot (Leiostomus xanthurus) off the U.S. East Coast: relating ocean origins, estuarine ingress, and changing environmental conditions

Long-term dynamics of larval and early juvenile spot (Leiostomus xanthurus) off the U.S. East Coast: relating ocean origins, estuarine ingress, and changing environmental conditions

The bioaccessibility and tolerability of marine-derived sources of magnesium and calcium

It is generally accepted that mineral deficiencies, including magnesium and calcium, are widespread globally. Dietary supplementation may be an effective approach to combat such deficiencies. However, challenges associated with limited mineral solubility in the digestive system can impede effective dissolution and hinder absorption, leading to deficiency, and undesirable gastrointestinal disturbances including diarrhoea. Seawater is considered to be a rich source of bioactive magnesium, calcium, and 72 other trace minerals. In this study, we examine two different marine-derived multimineral products as potential dietary supplements. Aquamin-Mg, sourced from seawater is rich in magnesium (12%), and Aquamin F, a seaweed-derived multimineral is rich in calcium (32%). Both products also contain a diverse array of over 72 minerals, characteristic of their oceanic origin. Our study comprises two experiments. The first experiment evaluates and compares the solubility of Aquamin-Mg, commercially available magnesium bisglycinate, and Pure Magnesium Bisglycinate (PrizMAG) during in vitro digestion using the INFOGEST method. Results demonstrate that Aquamin-Mg exhibits superior solubility than the other magnesium sources during the gastric and intestinal phases, particularly when administered alongside food materials. The second experiment is a randomized, double-blind, placebo-controlled study in a small cohort of healthy older aged adults to assess the tolerability of a combined Aquamin-Mg/Aquamin-F supplement over a 12-week period. The findings indicate that this combination supplement is well-tolerated, with no significant adverse events reported, emphasizing its potential as a means of addressing mineral deficiencies.

Deep Structure of Siletzia in the Puget Lowland: Imaging an Obducted Plateau and Accretionary Thrust Belt With Potential Fields

AbstractDetailed understanding of crustal components and tectonic history of forearcs is important due to their geological complexity and high seismic hazard. The principal component of the Cascadia forearc is Siletzia, a composite basaltic terrane of oceanic origin. Much is known about the lithology and age of the province. However, glacial sediments blanketing the Puget Lowland obscure its lateral extent and internal structure, hindering our ability to fully understand its tectonic history and its influence on modern deformation. In this study, we apply map‐view interpretation and two‐dimensional modeling of aeromagnetic and gravity data to the magnetically stratified Siletzia terrane revealing its internal structure and characterizing its eastern boundary. These analyses suggest the contact between Siletzia (Crescent Formation) and the Eocene accretionary prism trends northward under Lake Washington. North of Seattle, this boundary dips east where it crosses the Kingston arch, whereas south of Seattle the contact dips west where it crosses the Seattle uplift (SU). This westward dip is opposite the dip of the Eocene subduction interface, implying obduction of Siletzia upper crust at this southern location. Elongate pairs of high and low magnetic anomalies over the SU suggest imbrication of steeply‐dipping, deeply rooted slices of Crescent Formation within Siletzia. We hypothesize these features result from duplication of Crescent Formation in an accretionary fold‐thrust belt during the Eocene. The active Seattle fault divides this Eocene fold‐thrust belt into two zones with different structural trends and opposite frontal ramp dips, suggesting the Seattle fault may have originated as a tear fault during accretion.

On the drivers of regime shifts in the Antarctic marginal seas, exemplified by the Weddell Sea

Abstract. Recent studies have found evidence for a potential future tipping point, when the density of Antarctic continental shelf waters, specifically in the southern Weddell Sea, will allow for the onshore flow of warm waters of open ocean origin. A cold-to-warm regime shift in the adjacent ice shelf cavities entails a strong enhancement of ice shelf basal melt rates and could trigger instabilities in the ice sheet. From a suite of numerical experiments, aimed to force such a regime shift on the continental shelf, we identified the density balance between the shelf waters formed by sea ice production and the warmer water at the shelf break as the defining element of a tipping into a warm state. In our experiments, this process is reversible but there is evidence for hysteresis behaviour. Using HadCM3 20th-century output as atmospheric forcing, the resulting state of the Filchner–Ronne cavity depends on the initial state. In contrast, ERA Interim forcing pushes even a warm-initialized cavity into a cold state, i.e. it pushes the system back across the reversal threshold to the cold side. However, it turns out that for forcing data perturbations of a realistic magnitude, a unique and universal recipe for triggering a regime shift in Antarctic marginal seas was not found; instead, various ocean states can lead to an intrusion of off-shelf waters onto the continental shelf and into the cavities. Whether or not any given forcing or perturbation yields a density imbalance and thus allows for the inflow of warm water depends on the complex interplay between bottom topography, mean ocean state, sea ice processes, and atmospheric conditions.

Assessment of seasonal forecasting errors of the ECMWF system in the eastern Indian Ocean

The interannual variability of the Equatorial Eastern Indian Ocean (EEIO) is highly relevant for the climate anomalies on adjacent continents and affects global teleconnection patterns. Yet, this is an area where seasonal forecasting systems exhibit large errors. Here we investigate the reasons for these errors in the ECMWF seasonal forecasting system SEAS5 using tailored diagnostics and a series of numerical experiments.Results indicate that there are two fundamental and independent sources of forecast errors in the EEIO. The first one is of atmospheric nature and is largely related with too strong and stable easterly atmospheric circulation present in the equatorial Indian Ocean. This induces an easterly bias which leaves the coupled model predominantly in a state with a shallow thermocline and cold SSTs in the EEIO. The second error is of oceanic origin, associated with a too shallow thermocline, which enhances the SST errors arising from errors in the wind. Ocean initial conditions, which depend on both the quality of the assimilation and the ocean model, play an important role in this context. Nevertheless, it is found that the version of the ocean model used for the forecast can also play a non-negligible role at the seasonal time scales, by amplifying or damping the subsurface errors in the initial conditions.Errors in the EEIO are regime-dependent, having different causes in the warm (deep thermocline) regime with strong atmospheric convection and in the cold (shallow thermocline) regime. Errors also exhibit decadal variations, which challenges the calibration methods used in seasonal forecasts.

Slow evolution of Europa's interior: metamorphic ocean origin, delayed metallic core formation, and limited seafloor volcanism.

Europa's ocean lies atop an interior made of metal and silicates. On the basis of gravity data from the Galileo mission, many argued that Europa's interior, like Earth, is differentiated into a metallic core and a mantle composed of anhydrous silicates. Some studies further assumed that Europa differentiated while (or soon after) it accreted, also like Earth. However, Europa probably formed at much colder temperatures, meaning that Europa plausibly ended accretion as a mixture containing water-ice and/or hydrated silicates. Here, we use numerical models to describe the thermal evolution of Europa's interior assuming low initial temperatures (~200 to 300 kelvin). We find that silicate dehydration can produce Europa's current ocean and icy shell. Rocks below the seafloor may remain cool and hydrated today. Europa's metallic core, if it exists, may have formed billions of years after accretion. Ultimately, we expect the chemistry of Europa's ocean to reflect protracted heating of the interior.

Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, Part II: The pteriomorphs

Systematic documentation of pteriomorph bivalves of the late Eocene–early Oligocene Keasey Formation in western Oregon follows previous monographic treatments of the anomalodesmatans and heteroconchs. It includes material from coeval Cascadia Margin strata in southwestern Washington in the context of major molluscan faunal turnover during the dramatic doubthouse climate transition from an ice-free tropical marine environment to the establishment of permanent polar ice caps and a cold temperate marine climate. The families represented are Crenellidae, Parallelodontidae, Glycymerididae, Limopsidae, Isognomonidae, Pectinidae, Propeamussiidae, and Limidae. New taxa include the genus Bathyisognomon and five new species: Limopsis squiresi, Bathyisognomon smithwickensis, Delectopecten kieli, Delectopecten keaseyorum, and Propeamussium (Parvamussium) mistensis. Small to minute mud pectens and glass scallops are among the most abundant and frequent taxa in the Keasey fauna, although they are poorly preserved and have been overlooked heretofore. Pteriomorphs are prominent elements of recurring associations of species in mudstone and fine-grained siltstone facies adjacent to three Keasey cold methane seeps. Previously described Keasey anomalodesmatans and heteroconchs in these seep-adjacent strata have living relatives adapted to dysoxia and toxic geochemistry. Because the unique macrofaunal associations in these settings are neither seep fauna nor part of the background fauna, this paper introduces and defines the concept of a transitional peri-seep biotope. Relationships, monophyly, systematic resolution within major pteriomorph groups, and global biogeographic distributions are reviewed in each systematic treatment. Recurring patterns include occurrences in active margin settings, inferred oscillatory deepening of the calcium carbonate compensation depth, late Eocene origin of two-layered oceans following establishment of the Antarctic Circumpolar Current, and biogeographic gateway changes that disrupted earlier Paleogene larval dispersal patterns.

Evidence for a carbon-rich Mercury from the distribution of low-reflectance material (LRM) associated with large impact basins

Low-reflectance material (LRM) on the surface of Mercury is thought to be darkened by 2-7 wt.% carbon, making Mercury's surface the most carbon-rich among the terrestrial planets, but the origin of this carbon is debated. We observe exposures of LRM within large impact basins, which naturally sample Mercury's outer layers, to produce the first observationally constrained estimate of the absolute quantity of carbon present in Mercury's shallow interior. We observe LRM and other spectrally distinct material associated with craters within large basins and use scaling laws to relate these observations to the stratigraphy and composition of the subsurface. We find that many large basins across Mercury's surface have thick layers of LRM in their subsurface. Based on inferences regarding the thickness of these layers, we estimate the absolute quantity of carbon present in Mercury's crust and upper mantle to be at least 1.8×1019−2.3×1020 kg, which permits evaluation of hypotheses as to its origin. This quantity rules out the hypothesis that carbon near Mercury's surface was delivered during late accretion of carbon-rich material, with implications for the delivery of carbon and volatiles to the terrestrial planets. It is also only marginally compatible with a magma ocean origin. Therefore, if Mercury's core and mantle equilibrated with respect to carbon, we infer that Mercury was probably carbon-saturated early in its evolution and that carbon is an abundant light element in its core, with important implications for Mercury's thermal and geological evolution.

Space-Time Causality Analysis of Regional Impacts of ENSO on Terrestrial and Oceanic Precipitation

Future changes are expected in precipitation under climate change, therefore, changes are projected in the oceanic and terrestrial components. However, it remains poorly elucidated how the El Niño–Southern Oscillation (ENSO) can influence these changes. Therefore, we aimed to perform a space-time causality analysis of regional ENSO impacts on terrestrial and oceanic precipitation by using the Granger causality method as a function of eight temporal lags (lags 1–8). The monthly values of total precipitation obtained using the Lagrangian approach and their respective terrestrial (PLT) and oceanic (PLO) components were used. The analysis was performed for the two regions of western North America (WNA) and eastern South America (ESA) with strong ENSO signals. For the WNA region in winter, the maximum Granger causality was observed in the component of oceanic origin for temporal lags 1 and 2 (3 and 6 months), with a predominance of both positive and negative ENSO conditions. For the ESA region, it was verified that the causality of the ENSO index was maximum for PLT. Temporal lags 2–5 (6–15 months) stood out in winter when there was a marked region of the Granger causality over the La Plata Basin. In autumn, for lags 1–4 (3–12 months), the Granger causality values were predominant in the southern and western areas of ESA and showed a tendency to move northward with an increased temporal lag. Finally, it was shown that high correlation values did not imply the causality of the relationship between the ENSO index and precipitation in the two regions.

Pyrolysis GC-MS Characterization of Plastic Debris from the Northern Gulf of Alaska Shorelines

Plastics and their breakdown components are accumulating at alarming rates in global ecosystems, including the Gulf of Alaska. Obtaining knowledge of the chemical composition of plastics is important because different types of plastics are manufactured using different types of polymers and copolymers for specialized applications. We employed pyrolysis GC-MS for the chemical characterization of 115 plastic debris samples of different physical and optical properties nonrandomly collected from shorelines in the northern Gulf of Alaska. A two-tier approach of peak fingerprinting and mass spectral data of marker peaks provided higher confidence in the data. The analyses did not appear to be compromised by the physical properties, optical properties, or weathering conditions of the debris. Polyethylene and polypropylene, the low-density floating plastics possibly of oceanic origins, were some of the most frequently detected polymers in the Katmai National Park and Preserve and Kenai Fjords National Park. Interestingly, a more diverse composition of polyethylene, polypropylene, polystyrene, poly(ethylene terephthalate), and poly(vinyl chloride) was detected in Western Prince William Sound shorelines, possibly of oceanic as well as terrestrial origins. Additional benefits of the pyrolysis GC-MS method included the detection of copolymers and plastic additives in the same analytical runs.

Physical and chemical processes driving remote seasonal atmospheric exposure to cyclic volatile methysiloxanes and short-chain chlorinated paraffins

Cyclic volatile methylsiloxanes (cVMS) and short-chain chlorinated paraffins (SCCPs) use has been restricted in recent years due to environmental health concerns. Both of these classes of emerging contaminants possess long range transport potential (LRTP), highlighting the need for continuous monitoring to assess effectiveness of implemented regulations. However, emission source elucidation and understanding processes affecting atmospheric transport remain challenging. Atmospheric levels of cVMSs and SCCPs were simultaneously monitored at a background monitoring site in Norway from January–July 2020. Concentrations obtained from active air samplers ranged from 49.9 to 845 (mean: 208) pg/m3 for ƩSCCPs and from 0.4 to 3.5 (mean: 1.5), 1.1–15 (mean: 5.6) and 0.1–0.9 (mean: 0.4) ng/m3 for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), respectively. As SCCPs pose several challenges to analysts, different quantification methodologies and blank handling procedures were investigated to ensure reliable environmental measurements. Simulations using a Lagrangian atmospheric transport model (FLEXPART) revealed air masses impacting sampling measurements were of Oceanic origin, but periodic emission events from Europe and Russia were also observed. Seasonal pattern in cVMS concentrations was mainly driven by atmospheric degradation via hydroxyl radical reaction, whereas SCCP concentrations were more influenced by periodic anthropogenic inputs from local and continental Europe. No clear correlation could be observed with SCCP atmospheric concentrations and temperature over the entire sampling campaign. However, increased volatilization at elevated temperatures may be important with emissions originating from local sources. Higher chlorinated homologue groups dominated during the winter season and declined towards spring and summer, whereas reverse was found for the lower and more volatile chlorinated homologue groups.

Seasonal variation in morphotype composition of pelagic Sargassum influx events is linked to oceanic origin

The recent proliferation of pelagic Sargassum spp. in the Tropical Atlantic causes major ecological and socioeconomic impacts to the wider Caribbean when it washes ashore, with regional fisheries and tourism industries particularly affected. The Caribbean influxes have been tracked to a new bloom region known as the North Equatorial Recirculation Region (NERR) encompassing the area between the South Equatorial Current and the North Equatorial Counter Current and extending from Africa to South America. The vast biomass of Sargassum presents serious problems when it washes ashore but also represents significant commercial opportunities, especially with biofuel and fertilizer. The floating Sargassum mats are themselves diverse ecosystems that vary both in their biodiversity and biochemical attributes. Two major species (Sargassum fluitans and S. natans) have been identified as well as several distinguishable morphotypes of each. Oceanic mixing tends to blend the morphotypes together making it difficult to determine if there are regions of the NERR that favour bloom and growth of the distinct types. In this study, we quantify the species and morphotype composition of Sargassum strandings in Barbados and test if this is related to separate oceanic origins and routes travelled using a backtracking algorithm based on ocean drifter data. We found significant seasonal variation in the relative abundance of three morphotypes and this could be traced to two distinct easterly sub-origins and/or transport pathways; one area around 15° N that travels directly E–W across the Atlantic, and another area generally south of 10° N that takes a more meandering route coming close the coast of South America. These findings contribute towards our understanding of why the Tropical Atlantic bloom is presently occurring as well as towards addressing valorisation constraints surrounding variation in the supply of the three commonly occurring morphotypes.

The exotic species Pteris ensiformis (Pteridaceae) in South America: an aproach to naturalization process

Abstract Pteris has numerous representatives of Asian and Oceanic origin naturalized in America, some of them recognized as invasive weeds. Pteris ensiformis was introduced in America in the middle of the 19th century and subsequently naturalized in USA and Central America, but the records of its distribution in South America are isolated and the establishment or naturalization of the populations is unclear. As part of a broader study whose objective is to review the diversity of ferns and lycophytes in the Paranaense forest P. ensiformis was found for the first time in Argentina. In addition to describing, illustrating, and distinguishing the species from other species of the genus in the country, we review the distribution of P. ensiformis in South America comparing herbarium collections and iNaturalist observations, a citizen science platform. Additionally, a status for the species is proposed or suggested in each country where it is registered according to its stage of the naturalization process.

СТРУКТУРНАЯ ПОЗИЦИЯ, ПЕТРОГЕОХИМИЧЕСКАЯ И ПЕТРОПАЛЕОМАГНИТНАЯ ХАРАКТЕРИСТИКА ВУЛКАНИТОВ НИЛАНСКОГО ТЕРРЕЙНА (ЗОНА СОЧЛЕНЕНИЯ МОНГОЛО-ОХОТСКОГО И СИХОТЭ-АЛИНЬСКОГО ОРОГЕНОВ) И ГЕОДИНАМИЧЕСКИЕ ВЫВОДЫ

The paper presents the results of structural, geochemical, magnetic and paleomagnetic studies on Mesozoic rocks of the Nilan terrane, which from the north flank on the Paleozoic rocks of the Paukan block (52.0°N, 135.6°E). Jurassic and Triassic (?) multiple disturbance deposits of the terrane were found to be fragments of the Middle-Late Jurassic accretionary complex with accumulations of older oceanic rocks varying in thickness and the oceanic plate with completely destroyed stratigraphy. Basic and intermediate volcanic rocks hosted within Jurassic and Triassic (?) sedimentary rocks of the terrane are of oceanic origin. Based on geochemical and paleomagnetic data, it is assumed that the volcanic rocks formed near the equator in geodynamic settings of mid-ocean ridge and intraplate ocean islands.

Ocean Emission Pathway and Secondary Formation Mechanism of Aminiums Over the Chinese Marginal Sea

AbstractAmines/aminiums are recognized for their importance in new particle formation, organic nitrogen cycle, and aerosol forcings. Among the complex sources, the ocean origins and generation pathways of aminiums are less understood. During a cruise campaign over the Chinese marginal sea (Bohai Sea), five low‐molecular‐weight aminiums were measured. The strong anthropogenic period (terrestrial transport) and the weak anthropogenic period (dust, clean, and sea fog periods) were identified based on the traceable aerosol chemical species, air masses transport patterns, and marine chlorophyll‐a. Inconsistent spatiotemporal variations of various aminiums were observed. Monomethylaminium (MMAH+), dimethylaminium (DMAH+), ethylaminium (EAH+), and diethylaminium (DEAH+) were more enriched during the weak anthropogenic period than the strong anthropogenic period and especially peaked during the sea fog period. The significant correlation between the four aminiums and methanesulfonic acid suggested their secondary formation pathways. Through further exploring the governing factors, the acid–base neutralization via the aqueous phase processing was identified as a critical process for the secondary transformation of aminiums. In contrast, trimethylaminium (TMAH+) showed moderate correlation with Na+ in the total suspended particles only, suggesting its primary marine sources via enrichment in the sea‐spray aerosol through bubble bursting. Based on the step‐wise correlation analysis, the sea surface organic nitrogenous reservoir was found as the dominant contributor to the measured aminiums over the Bohai Sea, while the role of marine phytoplankton emission in the formation of aminiums was limited.

The Bornholm intermediate waters: Origination, pathway, and detection within the cold intermediate layer of the Baltic Sea

The Cold Intermediate Layer (CIL) is a distinctive feature of the Baltic Sea thermohaline structure: it is evident annually from March to December between the upper freshened layer and the deep layer with saline waters of oceanic origin. Water parameters are vertically inhomogeneous within the CIL, reflecting a complicated process of its formation that hasn’t been exhaustively described yet. On the base of field measurements and remote sensing data, a detailed study of the CIL formation in spring 2006 was performed. It showed that the core of the CIL (the coldest water) has a specific T,S-index that indicates the source of these waters in the south-western part of the sea. The data of CTD measurements, satellite-derived sea surface temperature (SST), and meteorological information were used to distinguish and trace the CIL core waters. The abrupt transformation of the SST field was observed in March 2006 when the coldest waters (0.9–2.1 °C) of moderate salinity (7.6–8.1) plunged from the upper mixed layer in the vicinity of Bornholm Island into intermediate layers. These waters were later identified as the sublayer of the CIL in the Baltic Proper in April and May 2006. The drivers of the penetration of winter-cold surface waters into the intermediate layers are suggested to be the negative surface buoyancy flux due to warming of cold surface waters with temperature below that of the density maximum and the intensification of easterly winds. Considering the importance of the CIL formation process for the entire Baltic Sea conveyor belt, these CIL core waters were termed the Bornholm Intermediate Waters (BIW). The T,S-index of the BIW shall vary from year to year, reflecting the severity of the past winter and the conditions of the particular spring. However, the BIW location right above the pycno/halocline, the lowest (specific for the current year) water temperature and its characteristic salinity of 7.6–8.1 are repeatedly confirmed by field observations in the Baltic Proper in spring. Joint application of satellite observations, field measurements, and meteorological data provides a coherent view on the process of the BIW waters origination. The results are particularly important it the context of growing hypoxia of deep Baltic waters, providing evidence of the mechanism of seasonal ventilation of intermediate water layers.