ALBERT

Description: The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 22 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017.

Description: Highlights • Active hydrothermal vent ecosystems are extremely rare. • Vent ecosystems are recognized as vulnerable by international organizations. • Mineral resources at active vents would not contribute significantly to the global metal supply. • Effective networks that protect representative active vents cannot be ensured. • A prohibition on mining active vents is consistent with obligations for conservation. Abstract There is increasing interest in mining minerals on the seabed, including seafloor massive sulfide deposits that form at hydrothermal vents. The International Seabed Authority is currently drafting a Mining Code, including environmental regulations, for polymetallic sulfides and other mineral exploitation on the seabed in the area beyond national jurisdictions. This paper summarizes 1) the ecological vulnerability of active vent ecosystems and aspects of this vulnerability that remain subject to conjecture, 2) evidence for limited mineral resource opportunity at active vents, 3) non-extractive values of active vent ecosystems, 4) precedents and international obligations for protection of hydrothermal vents, and 5) obligations of the International Seabed Authority under the UN Convention on the Law of the Sea for protection of the marine environment from the impacts of mining. Heterogeneity of active vent ecosystems makes it extremely challenging to identify “representative” systems for any regional, area-based management approach to conservation. Protection of active vent ecosystems from mining impacts (direct and indirect) would set aside only a small fraction of the international seabed and its mineral resources, would contribute to international obligations for marine conservation, would have non-extractive benefits, and would be a precautionary approach.

Description: Highlights: • We present the first hyperspectral image data from the deep seafloor. • The data were acquired with a new UHI in 4200 m water depth. • Supervised classification is able to detect manganese nodules and fauna. • The UHI is a promising tool for high-resolution seafloor exploration and monitoring. Abstract: Hyperspectral seafloor surveys using airborne or spaceborne sensors are generally limited to shallow coastal areas, due to the requirement for target illumination by sunlight. Deeper marine environments devoid of sunlight cannot be imaged by conventional hyperspectral imagers. Instead, a close-range, sunlight-independent hyperspectral survey approach is required. In this study, we present the first hyperspectral image data from the deep seafloor. The data were acquired in approximately 4200 m water depth using a new Underwater Hyperspectral Imager (UHI) mounted on a remotely operated vehicle (ROV). UHI data were recorded for 112 spectral bands between 378 nm and 805 nm, with a high spectral (4 nm) and spatial resolution (1 mm per image pixel). The study area was located in a manganese nodule field in the Peru Basin (SE Pacific), close to the DISCOL (DISturbance and reCOLonization) experimental area. To test whether underwater hyperspectral imaging can be used for detection and mapping of mineral deposits in potential deep-sea mining areas, we compared two supervised classification methods, the Support Vector Machine (SVM) and the Spectral Angle Mapper (SAM). The results show that SVM is superior to SAM and is able to accurately detect nodule surfaces. The UHI therefore represents a promising tool for high-resolution seafloor exploration and characterisation prior to resource exploitation.

Description: An extensive survey was carried out in the Sidoarjo district (East Java, Indonesia) to investigate the gas leaking properties along fractured zones coinciding with a strike-slip system, the Watukosek Fault System (WFS) in NE Java. This structure has been the focus of attention since the beginning of the spectacular Lusi mud eruption on the 29th May 2006. The sinistral strike-slip WFS originates from the Arjuno-Welirang volcanic complex, intersects the active Lusi eruption site displaying a system of antithetic faults, and extends towards the NE of Java where mud volcanic structures reside. In the Lusi region we completed a geochemical survey along three profiles combining measurements of a) 220Rn and 222Rn activity, b) CO2 and CH4 soil gas content, c) CO2 and CH4 fluxes, and d) gas analyses. The profiles are up to ∼1.2 km long and intersect perpendicularly areas with intense fracturing and surface deformation along the WFS. The purpose was to investigate the presence and origin of soil degassing activity in potentially active fault zones. Results show that the peripheral sectors of the profiles have high 220Rn activity and reduced CO2 and CH4 fluxes and concentrations. This suggests low fluids migration that could be affected by shallow circulation. In contrast, the segments of profiles intersecting the fractured zones have the highest 222Rn activity, CO2 and CH4 flux and gas concentration values. The relationship existing among the measured parameters suggests that the WFS acts as a preferential pathway for active rise of deep fluids. The presence of such advective processes is suggested by the relatively high rate of migration needed to obtain anomalies of short-lived 222Rn in the soil pores. Gas molecular and isotopic composition reveals that all sampled localities have a mixed hydrocarbon origin implying the presence of shallow microbial and deeper thermogenic hydrocarbons. CO2 isotopic values (δ13C-CO2 ranges between −9.48‰ and 4.12‰ V-PDB) indicate the presence of mantle derived CO2 and thermo-metamorphic CO2 suggesting that elevated temperatures have a key role in this active system. The samples collected from fractured and faulted zones reveal to have gas composition similar to that obtained from Lusi crater, indicating deep origin fluids.

Description: Highlights • A multipurpose drone has been designed and constructed to access and sample extreme environments. • Gas, water, and mud sampling is coupled with temperature measurements, video records, photogrammetry, infra-red, and gas distribution mapping. • Successful missions have been completed at the active Lusi eruption site. • The drone is an excellent tool to study harsh or unreachable sites where conventional operations are too expensive, dangerous or impossible. Abstract Extreme and inaccessible environments are a new frontier that unmanned and remotely operated vehicles can today safely access and monitor. The Lusi mud eruption (NE Java Island, Indonesia) represents one of these harsh environments that are totally unreachable with traditional techniques. Here boiling mud is constantly spewed tens of meters in height and tall gas clouds surround the 100 m wide active crater. The crater is surrounded by a ∼600 m diameter circular zone of hot mud that prevents any approach to investigate and sample the eruption site. In order to access this active crater we designed and assembled a multipurpose drone. The Lusi drone is equipped with numerous airborne devices suitable for use on board of other multicopters. During the missions, three cameras can complete 1) video survey, 2) high resolution photogrammetry of desired and preselected polygons, and 3) thermal photogrammetry surveys with infra-red camera to locate hot fluids seepage areas or faulted zones. Crater sampling and monitoring operations can be pre-planned with a flight software, and the pilot is required only for take-off and landing. A winch allows the deployment of gas, mud and water samplers and contact thermometers to be operated with no risk for the aircraft. During the winch operations (that can be performed automatically), the aircraft hovers at a safety height until the tasks controlled by the winch-embedded processor are completed. The drone is also equipped with GPS-connected CO2 and CH4 sensors. Gridded surveys using these devices allowed obtaining 2D maps of the concentration and distribution of various gasses over the area covered by the flight path. The device is solid, stable even with significant wind, affordable, and easy to transport. The Lusi drone successfully operated during several expeditions at the ongoing active Lusi eruption site and proved to be an excellent tool to study other harsh or unreachable sites, where operations with more conventional methods are too expensive, dangerous or simply impossible.

Description: The Sea of Marmara is traversed by the North Anatolian Fault system and also presents abundant emission sites of methane gas into the water column. In order to assess the spatial relationship between gas emissions and active faults, the distribution of distances between gas emission sites and the nearest fault is calculated and compared with the distribution of distances between a uniform random distribution of points (Poisson process representing the null hypothesis of an absence of relationship between gas emissions and faults) and the nearest fault. Interestingly, the distance distribution for the Poisson process is nearly exponential, indicating that the fault map does not have a characteristic scale other than that representing the intensity of the fault network. The distance distribution for the observed gas emissions is significantly narrower than that arising from the Poisson process, with a Kolmogorov distance of 0.25 ± 0.02. The crossing point between the two distributions defines the characteristic half-width of the swath of gas emission sites around the mapped active faults. For the whole Sea of Marmara data set a characteristic half-width of 900–1000 m is found which matches the half-width of the seafloor deformation zone observed around the main active fault. When the same analysis is applied to zones covering the Western High and the Central High it is found that the swath of gas emissions is wider on the Central High (2 km half-width), and not clearly related to the seafloor deformation zone there. This difference is put in perspective with recent work showing that creep is occurring on the western segment of the Main Marmara Fault (this also causing microseismicity) while the central Istanbul-Silivri segment may have remained locked since the 1766 magnitude 7+ earthquake. This suggests that aseismic slip (and not only earthquake occurrence) effectively maintains high permeability conduits in fault zones in sediments.

Description: The potential of crustose coralline algae as high-resolution archives of past ocean variability in mid- to high-latitudes has only recently been recognized. Few comparisons of coralline algal proxies, such as temperature-dependent algal magnesium to calcium (Mg/Ca) ratios, with in situ-measured surface ocean data exist, even rarer are well replicated records from individual sites. We present Mg/Ca records from nine coralline algal specimens (Clathromorphum compactum) from a single site in the Gulf of Maine, North Atlantic. Sections from algal mounds were analyzed using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) yielding individual Mg/Ca records of up to 30 years in length. We first test intra- and intersample signal replication and show that algal Mg/Ca ratios are reproducible along several transects within individual sample specimens and between different samples from the same study site. In addition, LA-ICP-MS-derived Mg/Ca ratios are compared to electron microprobe (EMP) analyzed data on the longest-lived specimens and were found to be statistically commensurable. Second, we evaluate whether relationships between algal-based SST reconstructions and in situ temperature data can be improved by averaging Mg/Ca records from multiple algal specimens (intersample averages). We found that intersample averages yield stronger relationships to sea surface temperature (SST) data than Mg/Ca records derived from individual samples alone. Thus, Mg/Ca-based paleotemperature reconstructions from coralline algae can benefit from using multiple samples per site, and can expand temperature proxy precision from seasonal to monthly.

Description: Olivine-hosted inclusions of silicate and sulfide melts, Cr-spinel and pyroxene were studied to estimate magma composition, temperature, pressure, and fO2 at the onset and during the silicate-sulfide immiscibility in modern arc basalt from Tolbachik volcano, Kamchatka arc. We demonstrate that the olivine phenocrysts hosting sulfide and silicate melt inclusions belong to the same population. The compositions of the silicate melt inclusions in most primitive olivine (88–91 mol% Fo) represent moderately oxidized (~ QFM + 1.1) high-MgO (up to 12–12.6 wt%) and high CaO/Al2O3 (0.8–1.2) melt that has abundances and ratios of the lithophile trace elements typical of island arc magmas. The initial volatile contents in parental Tolbachik magma are estimated from the melt inclusions and mass-balance considerations to be at least 4.9 wt% H2O, 2600 ppm S, 1100 ppm Cl, 550 ppm F, and 1200 ppm CO2. These data are used to calculate the temperature (~ 1220 °C) and minimum pressure (3 kbar) at which the beginning of crystallization and exsolution of sulfide melt took place. The presence of anhydrite, especially ubiquitous in the crystallized silicate melt associated with sulfide globules, suggest that much higher sulfur abundances prior to degassing and sulfate immiscibility and/or crystallization should be expected. We tentatively considered hydrothermal accumulations of sulfur (elemental, sulfate and sulfide) in the volcanic conduit responsible for local contamination and oversaturation of the Tolbachik magma in sulfur and related sulfide immiscibility. Coexisting sulfide and sulfate can be also interpreted in favor of the magmatic sulfide oxidation and related generation of S-rich fluids. Such fluids are expected to accumulate metals released from decomposed sulfide melts and supply significant epithermal mineralization, including native gold.

Description: Highlights • A carbonic anhydrase gene was identified from an hydrothermal vent metagenome. • The gene product LOGACA is a dimeric α-type carbonic anhydrase. • LOGACA is highly thermostable at alkaline pH. • Thermostability correlates with secondary structure, surface charges and ion pairs. Abstract Carbonic anhydrases (CAs) are extremely fast enzymes, which have attracted much interest in the past due to their medical relevance and their biotechnological potential. An α-type CA gene was isolated from DNA derived from an active hydrothermal vent chimney, in an effort to identify novel CAs with suitable properties for CO2 capture. The gene product was recombinantly produced and characterized, revealing remarkable thermostability, also in the presence of high ionic strength alkaline conditions, which are used in some CO2 capture applications. The Tm was above 90 °C under all tested conditions. The enzyme was crystallized and the structure determined by molecular replacement, revealing a typical bacterial α-type CA non-covalent dimer, but not the disulphide mediated tetramer observed for the hyperthermophilic homologue used for molecular replacement, from Thermovibrio ammonificans. Structural comparison suggests that an increased secondary structure content, increased content of charges on the surface and ionic interactions compared to mesophilic enzymes, may be main structural sources of thermostability, as previously suggested for the homologue from Sulfurihydrogenibium yellowstonense.

Description: Highlights: • A High Resolution-LOPC and a FlowCAM were evaluated for ballast water monitoring. • Both instruments underestimated density compared to microscopy. • Size measurements can be affected by organism orientation and complex morphology. • Both tools might be particularly useful when working with a known community. Abstract: Many commercial ships will soon begin to use treatment systems to manage their ballast water and reduce the global transfer of harmful aquatic organisms and pathogens in accordance with upcoming International Maritime Organization regulations. As a result, rapid and accurate automated methods will be needed to monitoring compliance of ships' ballast water. We examined two automated particle counters for monitoring organisms ≥ 50 μm in minimum dimension: a High Resolution Laser Optical Plankton Counter (HR-LOPC), and a Flow Cytometer with digital imaging Microscope (FlowCAM), in comparison to traditional (manual) microscopy considering plankton concentration, size frequency distributions and particle size measurements. The automated tools tended to underestimate particle concentration compared to standard microscopy, but gave similar results in terms of relative abundance of individual taxa. For most taxa, particle size measurements generated by FlowCAM ABD (Area Based Diameter) were more similar to microscope measurements than were those by FlowCAM ESD (Equivalent Spherical Diameter), though there was a mismatch in size estimates for some organisms between the FlowCAM ABD and microscope due to orientation and complex morphology. When a single problematic taxon is very abundant, the resulting size frequency distribution curves can become skewed, as was observed with Asterionella in this study. In particular, special consideration is needed when utilizing automated tools to analyse samples containing colonial species. Re-analysis of the size frequency distributions with the removal of Asterionella from FlowCAM and microscope data resulted in more similar curves across methods with FlowCAM ABD having the best fit compared to the microscope, although microscope concentration estimates were still significantly higher than estimates from the other methods. The results of our study indicate that both automated tools can generate frequency distributions of particles that might be particularly useful if correction factors can be developed for known differences in well-studied aquatic ecosystems.