Open Sea Areas Research Articles

Comparative Analysis of the Methods for Assessing the Thermal State of Civil Construction Facilities on the Example of Marine Stationary Platforms

Offshore oil, gas and other minerals are being actively developed in the world. Various hydraulic structures are used for the development of offshore fields, among which offshore fixed platforms should be singled out separately. These platforms are located in open sea areas and are exposed to heat from the sun. Solving the problem of assessing thermal effects on open metal structures of an offshore platform is important because even insignificant thermal stresses increase significantly in zones of crack-like defects, thus forming zones of local overvoltage. In addition, the determination of the temperatures of the walls of the tanks located on the platform is extremely important in determining the possibility of an outbreak of flammable liquids and other highly flammable substances. Previously, the author developed a technique that allows calculating the temperature of any cylindrical metal structures under the influence of solar radiation. In the work, the author provides a comparative analysis of his own methodology for assessing thermal effects and a method for determining the thermal state based on solving the heat balance equation. Based on the studies carried out, a conclusion is made about local overvoltages and the possibility of an outbreak of stored flammable products is assessed.

Hazardous Substances Assessment in Black Sea Biota

"The assessment of contaminants in biota is important, not only for biomonitoring of the marine pollution, but also in case of biota used for human consumption there are further implications with respect to public health reasons. Since data on this topic are rather limited in the Black Sea region, activities carried out in the framework of CBC Project “Assessing the vulnerability of the Black Sea marine ecosystem to human pressures” (ANEMONE) contributed at filling knowledge gaps identified for the region. Thus, new data on chemical contamination (heavy metals, polycyclic aromatic hydrocarbons, organochlorinated pesticides, polychlorinated biphenyls) of marine organisms (mussels, veined rapa whelk, pelagic and demersal fish), collected in 2019 during specific pilot studies in the selected study areas (open sea, and coastal – in front of river mouths, hot-spots) from Ukraine, Romania, Bulgaria and Turkey were obtained. The HELCOM integrated hazardous substances assessment tool (CHASE) developed by NIVA Denmark was tested in the Black Sea with contaminants in biota data set and the overall scores evinced sub-regional differences in the status results, with worse status predominating in the north-western part of the Black Sea (rivers influenced coastal areas and hotspots) and better status in the open sea area and in the southern part of the Black Sea. Across the investigated biota samples, the CHASE test assessment showed a range of status results from bad to high, almost half (46%) of biota samples being „unaffected by hazardous substances” state (good and high status), whereas the remaining 54 % of biota samples are „affected by hazardous substances” state (bad, poor and moderate). Key-Words: Black Sea, biota, heavy metals, organic pollutants, CHASE. "

Snow-Pit Record from a Coastal Antarctic Site and Its Preservation of Meteorological Features

AbstractPolar snow pits or ice cores preserve valuable information derived from the atmosphere on past climate and environment changes. A 1.57-m snow-pit record from the coastal site (Styx Glacier) in eastern Antarctica covering the period from January 2011 to January 2015 was discussed and compared with meteorological variables. The dominant contribution of the deposition of sea-salt aerosols due to the proximity of the site to the ocean and processes of sea ice formation was revealed in the ionic concentrations. Consistent seasonal peaks in δ18O, δD, MSA, , and indicate the strong enhancement of their source during warm periods, whereas the sea-salt ions (Na+, K+, Mg2+, Ca2+, Cl−, and ) exhibit a distinct distribution. Monthly mean δ18O positively correlates with the air temperature record from an automatic weather station (AWS) located in the main wind direction. Despite the shortness of the record, we suspect that the slight depletion of the isotopic composition and lowering of the snow accumulation could be related to the cooler air temperature with the decrease of open sea area. Consistency with previous studies and the positive correlation of sea-salt ions in the snow pit indicate the relatively good preservation of snow layers with noticeable climate and environmental signals [e.g., changes in sea ice extent (SIE) or sea surface temperature]. We report a new snow-pit record, which would be comparative and supportive to understand similar signals preserved in deeper ice cores in this location.

Is interactive air sea coupling relevant for simulating the future climate of Europe?

The majority of regional climate change assessments for the Euro-CORDEX region is based on high resolution atmosphere models. These models use prescribed lower boundary conditions, such as sea surface temperatures (SST) from global ocean General Circulation Models (GCMs), that do not respond to changes simulated by the regional atmosphere model, thus lacking an important feedback to the atmosphere. However, research during the past decade indicated that the use of coupled atmosphere–ocean models can lead to significantly altered model solutions compared to standalone atmosphere models for the present day climate imposing some uncertainty on the widely used uncoupled future scenarios. We here present the first multi-model and multi scenario (RCP2.6, RCP4.5, RCP8.5) ensemble of future climate change scenarios downscaled with a coupled atmosphere—ocean model in which sea surface temperature and sea ice fields are explicitly simulated by a coupled state-of-the-art high resolution ocean model and communicated to the atmosphere at 3-hourly time steps. Our ensemble generally confirms results of previous uncoupled ensembles over land areas implying that the coupling effect is restricted mainly to the coupled area and the adjacent coastal zone. By contrast, over the North Sea and Baltic Sea small scale processes point to important coupling effects that mediate the response to climate change and that can not be simulated by uncoupled models. Our results therefore impose general uncertainty on the usage of regional climate change data from uncoupled ensembles over marine areas such as for purposes of offshore wind or mussel farming, the planing of marine protected areas, and marine recreation along the coastal zone. It further sets in question the usage of uncoupled scenario data (such as Euro-CORDEX) to force high resolution ocean models. Comparing coupled and uncoupled hindcast simulations reveals that the coupling effect over land is most pronounced during the warm season when prescribed and modelled sea surface temperatures (SST) differ strongest. In addition, a generally weaker wind regime in summer damps the heat dispersion in the atmosphere so that air temperature anomalies can extent further over land compared to winter. Future projections are discussed under consideration of land-sea warming characteristics for selected climate indices as well as mean seasonal climate change. At the end of the century a clear land-sea pattern is seen in all scenarios with stronger warming over land than over open sea areas. On average land areas warm at a rate 1.5 times faster than areas over the open ocean. Over the coupled area, i.e. the North Sea and Baltic Sea tropical nights are impacted strongest and the Baltic Sea turns out to be a hot spot in future climate. This has been unrecognized in previous studies using high resolution atmosphere models with prescribed SSTs from global models which do not represent small scale ocean processes in the Baltic Sea adequately.

Variations of diatom opal Ge/Si in Prydz Bay, East Antarctica

Diatom frustules record the variations of seawater Ge/Si, a ratio related to continental weathering, early diagenesis, and biological productivity. To investigate the geochemistry of germanium and the possibility of using opal Ge/Si as a proxy of changes in Ge and Si budgets in high latitude Antarctic marginal sea, nine surface sediment samples and one sediment core were collected from Prydz Bay during Chinese Antarctic Expeditions from 2005 to 2009. Diatom opal was separated and purified from sediment samples, and opal Ge/Si was determined. The results showed that (Ge/Si)opal ranged from 0.48 to 0.78 μmol mol−1 (0.60 ± 0.09 μmol mol−1) in Prydz Bay. (Ge/Si)opal from sites in the open sea and at the edge of the Amery Ice Shelf are comparable to modern oceanic seawater, while it is relatively low on the continental shelf. The variations in (Ge/Si)opal were not significantly influenced by biological fractionation during diatom uptake, but were related to changes in external input or authigenic loss of Ge. An authigenic sink of Ge was detected at all sites and accounted for 20% ~ 52% of Ge in bulk sediments. Authigenic precipitation of Ge is generally controlled by precipitation of Fe-rich minerals, but is also influenced by biogenic opal delivery in the centre of the bay where siliceous productivity is extremely high. The higher (Ge/Si)opal relative to those on the continental shelf is suggested to be caused by Ge supplementation from oceanic water in the open sea area and by high input of glacial debris from ice-melting at the edge of the Amery Ice Shelf.

Response of protist community dynamics and co-occurrence patterns to the construction of artificial reefs: A case study in Daya Bay, China

Artificial reefs (ARs) are widely used for biodiversity conservation and coastal habitat restoration. Although protists play an important ecological role in marine ecosystems, the response of the protist community to ARs is still poorly understood. In the current study, an Illumina sequencing analysis of 18S rDNA was performed, and the diversity, community structure, and co-occurrence networks of protists in the ARs and open sea area (OW) in Daya Bay were described. The results indicated that significant seasonal differences occur in the seawater protists between the surface and bottom of the ARs and OW. However, the protists in the ARs and OW had different seasonal variations. The ARs always affected the alpha diversity of marine protists in different seasons, while the surface and bottom OW sites had different seasonal effects. The ARs sites had different effects on the community composition of the surface and bottom seawater in different seasons relative to the OW sites. The linear discriminant analysis (LDA) effect size (LEfSe) method showed that 85 biomarkers mainly belonging to 11 taxa, including Bacillariophyta, Chlorophyta, and Dinophyceae, were affected by the ARs (P < 0.05, LDA > 2.0). The ARs played an important role in the seasonal changes in the protist community composition and had different effects on the dominant species of protists in the surface and bottom seawater. A redundancy analysis (RDA) significance test showed that the structure of the protist community in Daya Bay was mainly affected by environmental factors, such as seawater temperature, salinity and dissolved oxygen. Compared with the OW group, the surface and bottom layers of the ARs had more complex protist interactions or more niches. The ARs increased the degree of spatial heterogeneity, which may lead to significant niche differentiation, indicating that ARs as habitat factors affect the complexity and stability of the symbiotic network of protists. The results could provide basic data on the response of the protist community to the ARs in Daya Bay and a reference for assessments of the impact of ARs on the ecological environment.

Estimation of sea clutter inherent Doppler spectrum from shipborne S-band radar sea echo**Project supported by the National Natural Science Foundation of China (Grant No. 61801446).

Measurement of shipborne radar sea echo is instrumental in collecting the sea clutter data in open sea areas. However, the ship movement would introduce an extra Doppler component into the spectrum of the sea clutter, so the sea clutter inherent spectrum must be estimated prior to investigating the sea clutter Doppler characteristics from the shipborne radar sea echo. In this paper we show some results about a shipborne sea clutter measurement experiment that was conducted in the South China Sea in a period between 2017 and 2018; abundant clutter data have been collected by using a shipborne S-band clutter measurement radar. To obtain the sea clutter inherent Doppler spectrum from these data, an estimation method, based on the mapping relationship between the shipborne clutter spectrum and the inherent clutter spectrum, is proposed. This method is validated by shipborne clutter data sets under the same measuring conditions except for the ship speed. Using this method, the characteristics of the Doppler spectrum lineshapes in the South China Sea are calculated and analyzed according to different sea states, wave directions, and radar resolutions, which can be instrumental in designing the radar target detection algorithms.

Spatiotemporal distribution, source identification and inventory of microplastics in surface sediments from Sanggou Bay, China

Microplastic pollution has become a major global environmental issue. Yet the source identification and inventory of microplastics in mariculture areas remain unclear. Here we investigated the spatiotemporal distribution, source and inventory of microplastics in surface sediments from Sanggou Bay, China. The results showed that average abundance of microplastics in the surface sediments was 1674 ± 526 items/kg dry weight, which represented a heavy level when compared with other sea areas, including coastal waters, estuaries, the open sea and other mariculture areas. Microplastics with a size of <0.5 mm were dominant throughout four seasons. The dominant shape of microplastics was granule in summer, autumn and winter, and film in spring, respectively. The most common color of microplastics was transparent. Polyethylene was the dominant polymer in summer, autumn, and winter, while polystyrene accounted for the largest proportion in spring. Approximately 57.72% of the microplastics in surface sediments originated from the plastic mariculture facilities, suggesting that mariculture makes a significant contribution to microplastic pollution in Sanggou Bay. Estimated inventory of microplastics in surface sediments of Sanggou Bay was 183.73 tons. Our results improve the understanding of risks caused by mariculture-derived microplastics to marine ecosystem and human health.

Adaptive Extraction and Refinement of Marine Lanes from Crowdsourced Trajectory Data

Crowdsourced trajectory data of ships provide the opportunity for extracting marine lane information. However, extracting useful knowledge from massive amounts of trajectory data is a challenging problem. Trajectory data collected from crowdsourcing can be extremely diverse in different areas and its quality might be very low. Moreover, the density distribution of the crowdsourced trajectory points is quite uneven in different areas. Furthermore, it is necessary to extract marine lanes with high extraction precision in offshore and nearshore water areas, but extraction precision can be lower in the open sea. We propose an adaptive approach for marine lane extraction and refinement based on grid merging and filtering to meet the challenges. In this paper, after pre-processing and clustering the trajectory data based on the density value of grids with a parallel GeoHash encoding algorithm, we propose a parallel grid merging and filtering algorithm based on a QuadTree data structure. The algorithm performs grid merging on the simplified grid data according to the density value of grid, then filters the merged grid data based on a local sliding window mechanism to get the marine lane grid data. Applying the Delaunay Triangulation on the marine lane grid data, the marine lane boundary information can be extracted with adaptive extraction precision. Experimental results show that the proposed approach can extract marine lanes with high extraction precision in offshore and nearshore water area and low extraction precision in open sea area.

Deep Learning Toward Autonomous Ship Navigation and Possible COLREGs Failures

Abstract A structured technology framework to address navigation considerations, including collision avoidance, of autonomous ships is the focus of this study. That consists of adequate maritime technologies to achieve the required level of navigation integrity in ocean autonomy. Since decision-making facilities in future autonomous vessels can play an important role under ocean autonomy, these technologies should consist of adequate system intelligence. Such system intelligence should consider localized decision-making modules to facilitate a distributed intelligence type strategy that supports distinct navigation situations in future vessels as agent-based systems. The main core of this agent consists of deep learning type technology that has presented promising results in other transportation systems, i.e., self-driving cars. Deep learning can capture helmsman behavior; therefore, such system intelligence can be used to navigate future autonomous vessels. Furthermore, an additional decision support layer should also be developed to facilitate deep learning-type technologies, where adequate solutions to distinct navigation situations can be facilitated. Collision avoidance under situation awareness, as one of such distinct navigation situations (i.e., a module of the decision support layer), is extensively discussed. Ship collision avoidance is regulated by the Convention on the International Regulations for Preventing Collisions at Sea (COLREGs) under open sea areas. Hence, a general overview of the COLREGs and its implementation challenges, i.e., possible regulatory failures, under situation awareness of autonomous ships is also presented with the possible solutions. Additional considerations, i.e., performance standards with the applicable limits of liability, terms, expectations, and conditions, toward evaluating ship behavior as an agent-based system in collision avoidance situations are also illustrated.

Quantitative evaluation of in-situ bioremediation of compound pollution of oil and heavy metal in sediments from the Bohai Sea, China

Owing to the semi-enclosed environment of the Bohai Sea, the ecological effects caused by an oil spill would be significant. A typical in- situ bioremediation engineering project for of oil-spilled marine sediments was performed in the Bohai Sea and a quantitative assessment of the ecological restoration was performed. The bioremediation efficiencies of n-alkane and PAHs in the sediment are 32.84 ± 21.66% and 50.42 ± 17.49% after 70 days of bioremediation, and 60.99 ± 10.14% and 68.01 ± 18.60% after 210 days, respectively. After 210 days of bioremediation, the degradation rates of two- to three ring PAHs and four-ring PAHs are 84.44 ± 23.03% and 26.62 ± 43.76%, respectively. In addition, the concentrations of the heavy metals first increased by 6.00% due to oil spill degradation and release, and then decreased by 72.60% with the degradation of oil caused by bioremediation or vertical migration. According to the continuous tracking monitoring, the composition of the microbial community in the restored area was similar to that in the control area and the clean area in Bohai Sea after 210 days of bioremediation. These results may provide some theoretical and scientific data to understand the degradation mechanism and assessing the ecological remediation efficiency for oil spills in open sea areas.

Natural and anthropogenic impacts on long-term meiobenthic communities in two contrasting nearshore habitats

The present study investigated the spatiotemporal distributions of meiofauna and corresponding environmental variables in two different subtidal environments. The two habitats represent unique geographical localities; (1) Jinhae Bay for semi-enclosed industrial bay (under anthropogenic pressure) and (2) Samcheok coast for open sea area (rather in natural condition) in Korea. Biotic and abiotic data were seasonally collected from six monitoring stations in each area for 3 years (2013–16) at two study areas and all the data were comparatively analyzed. First, abiotic data such as sediment properties and water quality parameters showed significant variations in time (season/year) and space (site/area) cross the study areas and within sites in each area. Second, meiofauna assemblages, such as number of taxa, abundance, and composition, greatly varied between seasons and localities, reflecting (in)direct association(s) to local activities and/or environmental gradients. Of note, the Jinhae Bay community was directly influenced by a hypoxia during summer season. In general, the site-specific variations rather prevailed masking seasonal fluctuations, indicating significance of both oceanographic settings and terrestrial land use activities. Among the environmental parameters measured, sediment grain size appeared to be the key factor in determining the meiofaunal assemblages and distributions, particularly under natural condition shown at Samcheok. Altogether, clear separations in meiofaunal community cross sites (inner vs. outer stations) and areas (enclosed industrial bay vs. open sea) implied anthropogenic pressures and certain impacted boundaries. In addition, association of benthic communities to anthropogenic environments seemed to prevail in macrofaunal community, being simultaneously influenced by abiotic seasonal fluctuations. Overall, two contrasting nearshore habitats exhibited typical spatiotemporal distributions of subtidal benthic communities being collectively influenced by anthropogenic stresses and site-specific environmental gradients.

Application of GNSS displacement monitoring system in measurement of open sea structure

With the development of deep water port and marine engineering, more and more marine structures are located in open sea area. The measurement development of open sea area structure is restricted by abominable marine environment, no control point and difficult data transmission. Combined with the deep water offshore bucket-based breakwater, the displacement measurement technology of open sea structure is studied. The global navigation satellite system (GNSS) is built to realize real-time monitoring of bucket structure displacement. Different monitoring schemes are formulated based on the characteristics and precision of the structure in the sea conveyance floating stage, installation stage or operation stage. It is found that displacement in the structure along the axis of the breakwater is less than that perpendicular to the axis by monitoring data, and the displacement laws of horizontal displacement and settlement in each stage of the structure are obtained. It has very important guiding significance for the structure construction and post-construction stability control in open sea area.

Polar low variability and future projections for the Nordic and Barents Seas

Polar lows are intense mesoscale cyclones occurring during winter over open sea areas in certain polar sub‐regions. Due to their small size, they are not explicitly represented in present global climate models or Earth system models. In this study 18 members of the CESM Large Ensemble were dynamically downscaled to ∼12 km horizontal mesh width using the quasi‐hydrostatic ALARO model within the HARMONIE script system in climate mode (HCLIM‐ALARO). The domain covers the Nordic and Barents Seas. One historical and two future time‐periods were selected. For validation, the ERA‐Interim reanalysis was also downscaled. A cyclone‐tracking algorithm was used to identify tracks of individual polar lows. Their frequency of occurrence, lifetime, and maximum relative vorticity were estimated. Relative to ERA‐Interim, the historical frequency of occurrence of polar lows was slightly overestimated in the Nordic Seas and underestimated in the Barents Sea, which is likely due to positive biases in sea‐surface temperature and sea‐ice concentration. For future climate projections, the regions of polar low genesis are diagnosed to move northwards in accordance with the sea‐ice retreat. In the Nordic Seas, the number of polar lows decreases at the beginning of the season, while there is an increase in March. In the Barents Sea, a February–April increase in the occurrence of polar lows is seen.

How HY-2A/GM altimeter performs in marine gravity derivation: assessment in the South China Sea

SUMMARY HY-2A is China's first satellite altimeter mission, launched in Aug. 2011. Its geodetic mission (GM) started from 2016 March 30 till present, collecting sea surface heights for about five 168-d cycles. To test how the HY-2A altimeter performs in marine gravity derivation, we use the least-squares collocation method to determine marine gravity anomalies on 1′ × 1′ grids around the South China Sea (covering 0°–30°N, 105°E–125°E) from the HY-2A/GM-measured geoid gradients. We assess the qualities of the HY-2A/GM-derived gravity over different depths and areas using the bias and tilt-adjusted ship-borne gravity anomalies from the U.S. National Centers for Environmental Information (NCEI) and the Second Institute of Oceanography, Ministry of Natural Resources (MNR) of P. R. China. The RMS difference between the HY-2A/GM-derived and the NCEI ship-borne gravity is 5.91 mGal, and is 5.33 mGal when replacing the HY-2A value from the Scripps Institution of Oceanography (SIO) V23.1 value. The RMS difference between the HY-2A/GM-derived and the MNR ship-borne gravity is 2.90 mGal, and is 2.76 mGal when replacing the HY-2A value from the SIO V23.1 value. The RMS difference between the HY-2A and SIO V23.1 value is 3.57 mGal in open sea areas at least 20 km far away from the coast. In general, the difference between the HY-2A/GM-derived gravity and ship-borne gravity decreases with decreasing gravity field roughness and increasing depth. HY-2A results in the lowest gravity accuracy in areas with islands or reefs. Our assessment result suggests that HY-2A can compete with other Ku-band altimeter missions in marine gravity derivation.

Age and growth of European flounder from the Chupa Inlet (Kandalaksha Bay, the White Sea)

We studied age structure, growth and distribution of European flounder Platichthys flesus at the sea in Chupa Inlet (Kandalaksha Bay, the White Sea). Immature and mature fishes fed at shallows of Chupa Inlet and adjacent open sea area in June-August. Size-age and sex composition of fishes in catches are presented in the paper. Individuals of 17–27 cm length and 4–5 year age constituted the majority of catches (45%). On the whole, males numerically predominated over females in the samples. Analysis of sexual differences of growth has shown that females grew faster than males. The most intensive growth took place in July–August, according to the increments on the otoliths. Growth rate of the flounder from Chupa Inlet appeared to be similar to the growth rate of the flounder from other open shore sites of Kandalaksha Bay. We have compared also peculiarities of growth and age structure of flounder populations from Kandalaksha Bay to those from other bays of the White Sea. Significant differences of the growth rate were found between flounders from Kandalaksha, Onega, Dvina and Mezen' Bays. Both males and females from Onega Bay grew faster than other. Growth rate of fish decreased towards the north (Kandalaksha Bay) and the north-east (Mezen' Bay). The most slow-growing flounder inhabited shallows of Mezen' Bay. Statistical analysis has shown that age structure of flounder populations varied in different bays of the White Sea, and observed regional variations were characteristic for both males and females. Flounder population in Onega Bay was characterized by the dominance of the younger individuals compared to populations in other bays. The greatest mean age of flounder was registered in populations from the north-west (Kandalaksha Bay) and the north-east (Mezen' Bay) parts of the White Sea. Males and females in populations from Onega and Dvina Bays differed significantly in the mean age, and as a rule females were older. No age differences between sexes were found in flounder population of Mezen' Bay. We suppose that temperature conditions were among the main factors influencing regional differences in growth rate and age structure of the flounder populations in the White Sea.

Holocene ostracod assemblages from the Co To Islands, northeastern Vietnam

Abstract. In this study, we investigated ostracod assemblages from the Co To Islands in northeastern Vietnam. We identified 77 ostracod species belonging to 46 genera in nine surface sediment samples and recognized three biofacies (I, II, and III) based on Q-mode cluster analysis. The dominant species of biofacies I and II were Aurila hataii, Loxoconcha japonica, and Xestoleberis hanaii, which commonly occur in seaweed beds from southern China to Japan. This is the first report on the ostracod assemblage from the open-sea area in northeastern Vietnam. We clarified that the ostracod assemblages in the Gulf of Tongking, including northern Vietnam, have a strong biogeographical relationship with East Asia seas. A new species, Loxoconcha cotoensis sp. nov., was described herein from the Co To Islands (http://www.zoobank.org/NomenclaturalActs/41d3fb9f-ae17-4215-82c1-0874a8bf1a30, last access: 3 June 2019).

Dynamics of Aerobic Anoxygenic Phototrophs along the trophic gradient in the central Adriatic Sea

Although Aerobic Anoxygenic Phototrophs (AAPs) are widespread in aquatic environments, relatively little is known about their dynamics in the Adriatic Sea. Therefore, we investigated their distribution along the trophic gradient from coast to the open sea over a year-round period, for the first time, as well as the factors that influenced the spatio-temporal distribution. AAP abundances varied between 0.26 × 104 at the open sea, and 23.45 × 104 cell mL−1 in the estuarine area, while their relative abundances ranged between 1.13% and 23.88% respectively. The biomass of AAPs ranged between 0.07 and 6.24 μg C L−1; thus, we observed a trend of decreasing abundances and biomass of the studied groups from more eutrophic coastal to the oligotrophic open sea area. AAP biomass exhibited the highest values during summer in the estuarine areas and the lowest during winter in the open sea. The main driving factors for the whole picoplankton community variance were transparency (Secchi disc), chlorophyll and salinity, whereas AAPs were grouped with heterotrophic bacteria, picoeukaryotes and heterotrophic nanoflagellates. Our data indicate that phosphorus limitation in the environment could be an important factor for the AAP growth.

The place of Optilite system in a decision making-based laboratory department

These data relate to the research article entitled “Imprint and short-term fate of the Agia Zoni II tanker oil spill on the marine ecosystem of Saronikos Gulf” by Parinos et al., 2019 [1]. The dataset includes the concentrations of 32 individual compounds/groups of polycyclic aromatic hydrocarbons (PAHs) determined in 235 seawater samples and 55 sediment samples analyzed during the monitoring survey conducted by the Hellenic Centre for Marine Research (H.C.M.R.) following the September 2017 Agia Zoni II heavy fuel oil (HFO) spill incident in Saronikos Gulf, Greece. The survey effort included 69 seawater sampling sites, of which 55 coastal and 14 open sea areas, and 22 sediment sampling sites across the inner Saronikos Gulf, aiming to assess the spatial and temporal imprint of the spilled oil during the first six months from the incident. The data were acquired by means of gas chromatography - mass spectrometry, following proper pre-treatment of the collected samples. This dataset is, to the best of our knowledge, the very first PAHs record related to the Agia Zoni II oil spill incident, that should be of interest for future scientific research on this and HFO spills in general.

Geochemical characteristics and potential biogeochemical effect of water-soluble ions in atmospheric aerosols over the western boundary regions of Pacific Ocean

Atmospheric aerosol samples over the western boundary regions of Pacific Ocean were collected during August 2014–October 2014 and November 2015–February 2016 on R/V Ke Xue, and concentrations of major water-soluble ions, NO3−, NO2−, NH4+, PO43−, SO42−, MSA−, Cl−, and Na+, were determined to study their seasonal distributions, sources and biogeochemical effect. The results showed that the average concentrations of NO3−, Cl− and Na+ were higher in winter, while the other ions had higher concentrations in summer. Most water-soluble ions presented obvious high-value centers in nearshore, indicating the significant influence of terrestrial input. Terrestrial input and marine emission were two major factors causing variation in concentrations of water-soluble ions, although their relative contributions were different in summer and winter. The average MSA/nss-SO42− ratios in summer and in winter were 1.60% and 2.10%, respectively, based on which the contributions of anthropogenic sources to the total SO42− were calculated to be 45.7% and 30.1% in summer and winter, respectively. Yet the contribution of biogenic sources to the total SO42−, which was 14.9% in summer and 14.4% in winter, showed no seasonal change. Apart from air masses from Asian continent, air masses from Japan as well as from Indonesia were also important terrestrial sources of aerosol ions according to air mass backward trajectories analysis. Based on the distribution patterns of aerosol ions, the studied area was divided into Southeast China coastal sea area and Western Pacific open sea area, and the dry deposition fluxes of DIN for these two areas were 6166 μg m−2 day−1 and 574 μg m−2 day−1, which could support 5.6–19.4% and ~13.8% of the new production in the East China Sea and the Western Pacific, respectively. Therefore, atmospheric aerosols as an important medium for transporting nutrients to the study area should attract much attention.