Matter In Seawater Research Articles

Sea spray emissions from the Baltic Sea: comparison of aerosol eddy covariance fluxes and chamber-simulated sea spray emissions

Abstract. To compare in situ and laboratory estimates of sea spray aerosol (SSA) production fluxes, we conducted two research campaigns in the vicinity of an eddy covariance (EC) flux tower on the island of Östergarnsholm in the Baltic Sea during May and August 2021. To accomplish this, we performed EC flux measurements for particles with diameters between 0.25 and 2.5 µm simultaneously with laboratory measurements using a plunging jet sea spray simulation chamber containing local seawater sampled close to the footprint of the flux tower. We observed a log-linear relationship between wind speed and EC-derived SSA emission fluxes, a power-law relationship between significant wave height and EC-derived SSA emission fluxes, and a linear relationship between wave Reynolds number and EC-derived SSA emission fluxes, all of which are consistent with earlier studies. Although we observed a weak negative relationship between particle production in the sea spray simulation chamber and seawater chlorophyll-α concentration and a weak positive relationship with the concentration of fluorescent dissolved organic matter in seawater, we did not observe any significant impact of dissolved oxygen on particle production in the chamber. To obtain an estimate of the size-resolved emission spectrum for particles with dry diameters between 0.015 and 10 µm, we combined the estimates of SSA particle production fluxes obtained using the EC measurements and the chamber measurements in three different ways: (1) using the traditional continuous whitecap method, (2) using air entrainment measurements, and (3) simply scaling the chamber data to the EC fluxes. In doing so, we observed that the magnitude of the EC-derived emission fluxes compared relatively well to the magnitude of the fluxes obtained using the chamber air entrainment method as well as the previous flux measurements of Nilsson et al. (2021) and the parameterizations of Mårtensson et al. (2003) and Salter et al. (2015). As a result of these measurements, we have derived a wind-speed-dependent and wave-state-dependent SSA parameterization for particles with dry diameters between 0.015 and 10 µm for low-salinity waters such as the Baltic Sea, thus providing a more accurate estimation of SSA production fluxes.

Registration of Phytoplankton Fluorescence Using an Experimental Sounding Probe

The main optical characteristics of phytoplankton and colored dissolved organic matter are described. The necessity of simultaneous registration of fluorescence of phytoplankton pigments and colored dissolved organic matter in seawater in situ is substantiated. Commercial recording devices, realizing registration of signals of phytoplankton fluorescence intensity in situ, are considered. This paper presents the developed experimental probing autonomous multichannel multichannel meter of fluorescence and light scattering in seawater (FR1). The paper presents the functional scheme of the developed meter, describes its main assemblies and principles of its operation. The developed meter allows quasi-simultaneous registration of a large set of parameters: excitation spectra of phytoplankton fluorescence, fluorescence intensity of phytoplankton pigments (chlorophyll-a, phycoerythrin, phycocyanin, β-carotene), as well as fluorescence intensity of colored dissolved organic matter and spectra of light scattering index at an angle of 90°. Registration of all these parameters is carried out from one measuring volume, where the same composition of suspended matter is located in the process of probing at each specific moment of time. The paper presents the results of approbation of the developed meter and suggests the direction of further research using it.

Contribution of dissolved organic matter to seawater salinity measured by optic refractometer: a case study of DOM extracted from Aoshan Bay

Dissolved organic matter (DOM) in seawater, consisted of a complex mixture of compounds and accounted for about 90% of marine organic carbon, is an important part of the global carbon cycle and also a part of absolute salinity of seawater. As the components of DOM are non-ionized in seawater, electric conductivity measurement cannot observe its contribution to salinity, which could lead to measurement error in salinity. Salinity measurement based on optic refractive index could reveal contribution of all dissolved matters in seawater including both non-ionized and ionized components. In this paper, a comparative study of DOM contribution to the salinity measurement by optic refractive index method and electric conductivity method was carried out for the first time. Adding DOM, extracted from Aoshan Bay, Qingdao, China, into Chinese Standard Seawater, our experimental results showed an increase of optic refractive index at 1.19×10-4 ± 4×10-6 per 1g/kg of DOM, which corresponds to a practical salinity increase of 0.697 ± 0.036 PSU per 1 g/kg of DOM. While, the conductivity of seawater measured by a conductivity-temperature sensor showed a decrease of 0.00065 ± 0.00008 mS/cm per 1 g/kg of DOM, which corresponded to a decrease of salinity at 0.00052 ± 0.00007 PSU per 1 g/kg of DOM. By comparing the optic and electric measurement results, the contribution of non-conductive components in the dissolved organic matters to salinity could be distinguished, which has great significance for the measurement of absolute salinity, global carbon cycle etc.

High efficiency lipid production, biochar yield and chlorophyll a content of Chlorella sp. microalgae exposed on sea water and TiO2 nanoparticles

This study explores the challenges facing microalgae biofuel production, specifically low lipid content and difficulties with algal cell harvesting. The purpose of the research is to investigate the effect of seawater content and nanoparticle concentration on freshwater microalgae growth and biofuel production. The principal results of the study show that increasing the proportion of seawater and nanoparticles enhances the lipid content and cell diameter of microalgae, while excessive concentrations of nanoparticles and low seawater content lead to reduced microalgae growth. Furthermore, an optimal cell diameter was identified at a nanoparticle concentration of 150 mg/L. The study also reveals that increasing seawater content can decrease zeta potential and increase chlorophyll a content due to the concentration of dissolved organic matter. Increasing the seawater content from 0% to 25% decreased zeta potential by 1% owing to the instability and aggregation of the cells. Chlorophyll a for the 0% seawater was 0.55 which is increased to 1.32 only due to the increase in the seawater content. This significant increase is due to the concentration of dissolved organic matter in seawater. Additionally, the presence of seawater positively affects microalgae metabolic activity and biochar yield. The findings of this study offer valuable insights into the potential for optimizing microalgae biofuel production. The use of seawater and nanoparticles has shown promise in enhancing microalgae growth and biofuel yield, and the results of this study underscore the scientific value of exploring the role of seawater and nanoparticles in microalgae biofuel production. Further research in this area has the potential to significantly contribute to the development of sustainable energy solutions.

Trace element enrichment mechanisms in black shales during the early cambrian (ca. 521–514 Ma), South China

It is widely accepted that significant perturbations in ocean redox states are closely related to biological evolution during the early Cambrian. However, the host and geochemical cycle of redox-sensitive elements (V and Zn) of the Niutitang Formation shale in South China have not been well-constrained. This study reports lithofacies, mineralogy and geochemical data of high-resolution samples from slope and basin settings (Xa1 and Xb1 wells, Hunan Province), to evaluate the significance of redox condition and hydrothermal contribution to trace element accumulation during the early Cambrian. Our results reveal the Zn-rich host is primarily sphalerite, while the V-rich host includes organic matter, illite, and anatase minerals in the Niutitang shale. Illite and anatase minerals have significant V concentration (14.8% and 18.3%), whereas organic matter contains relatively lower V concentration (1.4%). Trace elements can be scavenged by dissolved organic matter in seawater, and then taken up by clay minerals or form sulfide during deposition/diagenesis of organic-rich shales. Although seawater restriction of the lower member (LM) shale was stronger than in the upper member (UM) shale, euxinic conditions were more conducive to V and Zn enrichment than ferruginous conditions. Specifically, dwindling concentrations of V and Zn in seawater existed in South China during deposition of the early LM shale. However, the ocean experienced episodic hydrothermal activity, which may have supplied abundant trace elements to supplement seawater content. Overall, we propose that the V and Zn geochemical cycles in the early Cambrian paleo-ocean were controlled by redox condition, organic matter, and the trace element inventory of seawater.

A safer preprocessing system for analyzing dissolved organic radiocarbon in seawater

Measurement of dissolved organic radiocarbon (DO14C) in seawater can provide information about the timescale of the dynamics of dissolved organic matter and its sources in the ocean. Despite the development of accelerator mass spectrometry, the DO14C analysis requires complicated processing techniques such as the use of UV irradiation, which emits high heat. In this study, we developed a safer and easier method for analyzing DO14C in seawater than that used conventionally. A particularly significant change introduced by us was the adoption of a low-pressure mercury lamp in the decomposition system, which enabled direct decomposition of organic matter at lower temperatures. This method of decomposing dissolved organic matter in seawater may be applied not only for the analysis of 14C isotope ratio, but also for analyzing various other dissolved organic elements/isotopes.

Improved water quality monitoring indicators may increase carbon storage in the oceans

Indicators related to organic matter are important when assessing aquatic environment quality. The chemical oxygen demand (COD) is widely used as a water quality reference. However, oxidizing agents used to determine the COD can oxidize refractory organic matter that is not pollutant and can persist in the ocean for thousands of years. This means the COD can misrepresent the water quality. The actual water quality can be indicated better by the biochemical oxygen demand (BOD) than the COD, but determining the BOD is time-consuming and gives variable results. In this study, the optical properties of dissolved organic matter in water samples from the Chinese coast that had been incubated for a long time or directly oxidized using COD oxidant were analyzed. The results indicated that the oxidizing agent rapidly oxidized 22.93% ± 4.96% of refractory dissolved organic matter (RDOM) that was resistant to microbial degradation, implying that RDOM made a marked contribution to the COD. Meanwhile, size-fractional fluorescence spectroscopy and COD measurements indicated that the COD of the >0.7 μm fraction and the fluorescence intensity of the protein-like component significantly positively correlated with the BOD of the bulk sample. This indicated that, for monitoring organic pollutants in coastal waters, the COD of the >0.7 μm fraction could be used as a proxy for the standard COD and that the fluorescence intensity of the protein-like component could be used as a convenient proxy for the BOD. The method can help retain recalcitrant organic matter in seawater to act as a carbon sink.

Variability of Microbial Community Structure Distribution in Marine Shallow Surface Sediments in Shenhu Area

Due to the frequent exchange of matter and energy between living and non-living matter in seawater, the surface layer, particularly the distribution of microorganisms in centimeter-scale and element concentrations in surface sediments, demonstrates the important message of the local biogeochemical environment. This work probed the differences in microbial communities between two sampling cores obtained from the same area and the possible environmental factors, e.g., in situ component and concentration in porewater. Here, high-throughput sequencing (16S rRNA, Illumina sequencing) and quantitative PCR analysis were used to investigate the diversity of microorganisms in sediments of two push cores of L1 and S8 from Shenhu Area, South China Sea. Porewater concentration of components and isotopic fractionation were also obtained to explore the possible correlation between the microbial community and the chemical compositions of porewater. Q-PCR revealed bacteria play an important role in the geochemical cycle in the surface sediments, and archaea may be the main community in response to environmental changes and maintain the local marine ecosystem. The total gene copies of microorganisms in the study area were lower than nearby marine sediments. Microbial community compositions showed the dominant microbial phyla were similar on Phylum level in L1 and S8, with only different abundances. Firmicutes and Proteobacter were the main bacterial phyla, while Thaumarchaeota, Lokiarchaeota and Bathyarchaeota dominated the archaeal community. The abundance of the dominant class varied significantly between L1 and S8. Bacilli in Firmicutes and Gammaproteobacteria in Proteobacter were prevalent bacterial class, MGI in Thaumarchaeota was the predominant archaeal class in L1, while Thermoplasmata and Group-C3 dominated in S8. PCoA results showed a clear diversity of bacterial and archaeal communities between these two sites, as well as significant geographic variation in microbial communities. RDA results revealed that a complex combination of environmental factors might correlate to microbial communities in a marine dynamic environment. Here, δ13CDIC, DIC and SO4 2– were strongly correlated to the bacterial communities, whereas δ13CDIC, Fe2+ and SO4 2– concentration linked to archaeal communities. Microbial communities and RDA results suggested carbon may be the main factor related to the microbial community in L1, while Fe2+ correlated with microbial community composition in S8. SO4 2– concentration and the distribution of Gammaproteobacteria indicated that the sulfur cycle is probably active in this area.

The Physiology and Biogeochemistry of SUP05.

The SUP05 clade of gammaproteobacteria (Thioglobaceae) comprises both primary producers and primary consumers of organic carbon in the oceans. Host-associated autotrophs are a principal source of carbon and other nutrients for deep-sea eukaryotes at hydrothermal vents, and their free-living relatives are a primary source of organic matter in seawater at vents and in marine oxygen minimum zones. Similar to other abundant marine heterotrophs, such as SAR11 and Roseobacter, heterotrophic Thioglobaceae use the dilute pool of osmolytes produced by phytoplankton for growth, including methylated amines and sulfonates. Heterotrophic members are common throughout the ocean, and autotrophic members are abundant at hydrothermal vents and in anoxic waters; combined, they can account for more than 50% of the total bacterial community. Studies of both cultured and uncultured representatives from this diverse family are providing novel insights into the shifting biogeochemical roles of autotrophic and heterotrophic bacteria that cross oxic-anoxic boundary layers in the ocean.

Utilization and release of biogenic elements by macroalgae Ulva prolifera: A mesocosm experiment off the coast of Qingdao, China

A mesocosm experiment was conducted on the Qingdao coast to study the effects of nutrient enrichment on the physiological responses of Ulva prolifera and the changes in the entire culture system during decomposition of algal blooms. The decomposition trend of U. prolifera off the Qingdao coast was slightly retarded by nutrient enrichment, and could not be reversed to positive growth. The decomposition of U. prolifera was divided into two stages: the early-stage (0–9 d) and the late-stage (9–19 d). High nutrient levels enhanced the amounts of carbon and nitrogen fixed by U. prolifera and accelerated the subsequent degradation of organic matter. The concentration and composition of amino acids in solution also changed, reducing the bioavailability of dissolved organic matter in seawater. This study evaluated the actual decomposition process of green tides, which will help to assess the impact of green tides on coastal ecosystems and the circulation of biogenic elements.

Energy dispersive X‐ray fluorescence methodology and analysis of suspended particulate matter in seawater for trace element compositions and an intercomparison with high‐resolution inductively coupled plasma‐mass spectrometry

AbstractA modification of energy dispersive X‐ray fluorescence (ED‐XRF) for analysis of trace element concentrations in suspended particulate matter (SPM) in seawater and intercomparison with high‐resolution inductively coupled plasma‐mass spectrometry (HR ICP‐MS) is presented. Approximately 250 SPM samples were collected on polycarbonate track‐etched filters in the Indian Ocean during the U.S. CLIVAR/CO2 Repeat Hydrography meridional section I09N cruise in 2007. Samples were first analyzed by ED‐XRF, a nondestructive technique, for Al, P, Ti, Mn, Fe, Ni, Cu, and Zn and subsequently digested and quantified by HR ICP‐MS, creating two blind, basin‐scale data sets used for a paired statistical comparison. Our results found (1) ED‐XRF analysis using thin‐film principles can quantify the elemental composition of SPM at nanomolar concentrations found in the open ocean; (2) there was excellent agreement between ED‐XRF and HR ICP‐MS analyses for Al, Fe, and Mn and good agreement for P and Ti; (3) analytical differences were the largest for Cu, Ni, and Zn; (4) HR ICP‐MS methods have lower detection limits for most elements when compared to the ED‐XRF; (5) ED‐XRF analysis has a closer agreement to reported values for the NIST SRM 2783 standard and lower relative standard deviations when compared to the HR ICP‐MS. We recommend continued refinement of nondestructive ED‐XRF methods as this would allow for the easy exchange of filtered samples between lab groups for intercalibration and intercomparison of basin‐scale hydrographic cruises and archival for future analysis.

Characterization of marine dissolved organic matter and its effect on ozonation

As the marine industry develops, the importance of seawater treatment process is increasing. To treat seawater, oxidation processes have primarily been used, such as ballast water treatment systems, aquaculture farm operations, aquarium management, and seawater desalination. However, dissolved organic matter in seawater, whose characteristics vary spatially and seasonally, affects the efficiency of oxidation processes. Therefore, in this study, seawater samples were acquired from various locations in the Republic of Korea to understand the spatio-temporal patterns of marine dissolved organic matter. It was reported that the characterization of marine dissolved organic matter using liquid chromatography—organic carbon detector and excitation-emission matrix—parallel factor modeling. Furthermore, the effects of marine dissolved organic matter were evaluated on ozonation, an oxidation process. The results demonstrate that marine dissolved organic matter varies in its aquagenic, pedogenic, and intermediate characteristics based on region and season. These variations affect ozonation by influencing the consumption of oxidants (e.g., bromine). As a result, it was concluded that characterizing marine dissolved organic matter can help improve the effectiveness of oxidation processes, particularly ozonation.

Control of V accumulation in organic-rich shales by clay-organic nanocomposites

Organic-rich shales exhibit a wide range of vanadium (V) concentrations in deep-time successions. Although V accumulation is generally acknowledged to be related to redox state, organic matter and clay mineral content, previous studies have failed to explain the mechanism of variable V enrichment in organic-rich shales. Here, we hypothesize that clay-organic nanocomposites control authigenic V uptake in organic-rich shales. Specifically, V is scavenged by dissolved organic matter in seawater, which is then taken up by smectite during transport or deposition, followed by V incorporation into illite through illitization of smectite and pyrolysis of organic matter during diagenesis. To test this hypothesis, lower Cambrian black shales from South China were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) at a micro- and nanoscale. Results show that only 1M/1Md-type illite, generated through transformation from a smectite precursor, has significant V concentrations (0.7–4.8 wt%), whereas 2M1-type illite and other minerals contain little or no V. All 1M/1Md-type illite was closely associated with organic matter, occurring as clay-organic nanocomposites. Our results are significant in (i) showing clay-organic nanocomposites play a key role in V cycling in the marine system, (ii) providing a mechanism for understanding variations in the V concentrations of deep-time organic-rich shales, and (iii) improving strategies for prospecting and extraction of V ores.

Spectral Characterization of Dissolved Organic Matter in Seawater and Sediment Pore Water from the Arctic Fjords (West Svalbard) in Summer

Fjords in the high Arctic, as aquatic critical zones at the interface of land-ocean continuum, are undergoing rapid changes due to glacier retreat and climate warming. Yet, little is known about the biogeochemical processes in the Arctic fjords. We measured the nutrients and the optical properties of dissolved organic matter (DOM) in both seawater and sediment pore water, along with the remote sensing data of the ocean surface, from three West Svalbard fjords. A cross-fjord comparison of fluorescence fingerprints together with downcore trends of salinity, Cl−, and PO43− revealed higher impact of terrestrial inputs (fluorescence index: ~1.2–1.5 in seawaters) and glaciofluvial runoffs (salinity: ~31.4 ± 2.4 psu in pore waters) to the southern fjord of Hornsund as compared to the northern fjords of Isfjorden and Van Mijenfjorden, tallying with heavier annual runoff to the southern fjord of Hornsund. Extremely high levels of protein-like fluorescence (up to ~4.5 RU) were observed at the partially sea ice-covered fjords in summer, in line with near-ubiquity ice-edge blooms observed in the Arctic. The results reflect an ongoing or post-phytoplankton bloom, which is also supported by the higher levels of chlorophyll a fluorescence at the ocean surface, the very high apparent oxygen utilization through the water column, and the nutrient drawdown at the ocean surface. Meanwhile, a characteristic elongated fluorescence fingerprint was observed in the fjords, presumably produced by ice-edge blooms in the Arctic ecosystems. Furthermore, alkalinity and the humic-like peaks showed a general downcore accumulation trend, which implies the production of humic-like DOM via a biological pathway also in the glaciomarine sediments from the Arctic fjords.

Organic matter composition and heterotrophic bacterial activity at declining summer sea ice in the central Arctic Ocean

AbstractThe Arctic Ocean is highly susceptible to climate change as evidenced by rapid warming and the drastic loss of sea ice during summer. The consequences of these environmental changes for the microbial cycling of organic matter are largely unexplored. Here, we investigated the distribution and composition of dissolved organic matter (DOM) along with heterotrophic bacterial activity in seawater and sea ice of the Eurasian Basin at the time of the record ice minimum in 2012. Bacteria in seawater were highly responsive to fresh organic matter and remineralized on average 55% of primary production in the upper mixed layer. Correlation analysis showed that the accumulation of dissolved combined carbohydrates (DCCHO) and dissolved amino acids (DAA), two major components of fresh organic matter, was related to the drawdown of nitrate. Nitrate‐depleted surface waters at stations adjacent to the Laptev Sea showed about 25% higher concentrations of DAA than stations adjacent to the Barents Sea and in the central Arctic basin. Carbohydrate concentration was the best predictor of heterotrophic bacterial activity in sea ice. In contrast, variability in sea‐ice bacterial biomass was largely driven by differences in ice thickness. This decoupling of bacterial biomass and activity may mitigate the negative effects of biomass loss due to ice melting on heterotrophic bacterial functions. Overall, our results reveal that changes in DOM production and inventories induced by sea‐ice loss have a high potential to enhance the bacterial remineralization of organic matter in seawater and sea ice of the Arctic Ocean.

Концентрирование ртути во взвешенном веществе пены и воды Чёрного моря

Способность взвешенного вещества концентрировать ртуть может быть превалирующим фактором в очищении водной толщи Чёрного моря. В результате седиментации взвешенные частицы выносят загрязнения из поверхностного слоя воды и в итоге могут депонировать их в донных осадках, участвуя таким образом в процессах самоочищения морской акватории. Взвешенное вещество как дисперсная фаза водной среды, рассматриваемой в качестве гетерогенной дисперсной системы, может быть более насыщено ртутью, чем сама вода как дисперсионная среда. В данной работе определён вклад растворённой и взвешенной форм ртути в её общее содержание и оценена концентрирующая способность взвешенного вещества в отношении ртути, обуславливающая биогеохимическое самоочищение вод от ртути. Все пробы воды разделяли на фильтрат и взвесь путём их фильтрации через нуклеопоровые фильтры с диаметром пор 0,45 мкм. Измерения содержания ртути проводили на анализаторе «Хиранума-1» методом атомно-абсорбционной спектрофотометрии. Концентрацию растворённой ртути в воде определяли в пересчёте на литр, а во взвешенном веществе — на литр и на грамм сухой массы. Выявлено превалирование растворённой формы ртути независимо от сезона года с варьированием её процентного содержания в диапазоне 66,3–85,8 % от общей (суммарной) концентрации ртути. Средняя концентрация взвешенной формы составила 14,2–33,7 % от её общего содержания. При этом значения концентрации взвешенного вещества (mвзв) варьировали от 0,1 до 15,0 мг·л−1 за весь исследованный период, а коэффициент накопления ртути взвешенным веществом (Кнвзв) изменялся в диапазоне от n·10³ до n·107. Определён значительный вклад взвешенной формы ртути в её общее содержание в морской пене, образованной в штормовую погоду. Так, при концентрации взвешенного вещества в морской воде 9,6 мг·л−1 концентрация растворённой формы ртути имела значение 55 нг·л−1, а взвешенной — 20 нг·л−1. В морской пене концентрация взвешенного осадочного вещества составила 895,2 мг·л−1, а концентрация ртути достигла 200 нг·л−1 в растворённой форме и 260 нг·л−1 — во взвешенной. Содержание общей (суммарной) ртути в морской пене при этом превышало предельно допустимую концентрацию (100 нг·л−1) для морской воды. В данном случае Кнвзв для морской воды был равен 3,8·104, а для пены — 1,5·103. Такое распределение ртути в морской взвеси, пене и воде, а также полученные значения коэффициента накопления свидетельствуют о большой важности взвешенного вещества в самоочищении морской акватории. При низком содержании ртути в воде концентрирующая способность взвешенного вещества, характеризуемая относительно высокими значениями его коэффициента накопления ртути, становится весьма значимым фактором в седиментационном самоочищении вод от ртути, однако при повышении загрязнения вод ртутью влияние этого фактора снижается.

РАСЧЕТ ЗНАЧЕНИЙ ПАРАМЕТРОВ ДЛЯ ХАРАКТЕРИСТИКИ ПОСЛЕДСТВИЙ РАБОТ ПО ДНОУГЛУБЛЕНИЮ И ДАМПИНГУ ДОННЫХ ОСАДКОВ: ОЦЕНКА С ПОМОЩЬЮ ВВ-МОДЕЛИ

The developed SM-model, describing the suspended matter concentrations in water environment, was used to assess the consequences of the works on dredging and dumping ground during the reconstruction and modernization of the water body area in the Pionersky Port (Kaliningrad region). The complex of recreated works includes 11 stages of the dredging works during which the various types of bottom sediments are extracted, some part of these sediments are transported outside the port water area and discharged into the marine underwater dump, while other their part are used for hydraulic engineering works in the port area. At the dredging and dumping the sediments, additional zones of water turbidity are formed (with a suspended matter concentration > 50 mg/L), its deposition causes the formation of a layer of sediments on the bottom. For each work stages, the technological data on the currents in the port water area are used for mathematical modeling and calculations of the amounts of various types of sediments extracted from the bottom, their redistribution over the sea area, the concentration of suspended matter in sea water, and the indicators (areas and volumes) of the emerging turbidity zones water due as a result of the construction works. Calculated data may be used to compile a report “Assessment of influence on the water environment state” (or AIWES) in the frame of these works.

The Long-Term Dynamics and Morphology of the Diatom Thalassiosira nordenskioeldii Cleve, 1873 (Bacillariophyta) from the Coastal Waters of Peter the Great Bay, Sea of Japan

Long-term study of the species composition and numbers of phytoplankton in the coastal waters of Peter the Great Bay, the Sea of Japan, revealed the seasonal and year-to-year dynamics in the abundance of the diatom Thalassiosira nordenskioeldii Cleve, 1873. The species dominated the phytoplankton in the winter and early spring, growing under the sea ice at a surface water temperature of –1.8 to 0°С and a salinity of 33.0–35.0‰. The observations of the long-term population dynamics of T. nordenskioeldii (2005–2015) showed a decline in its significance in the phytoplankton community compared to that in the 1970s, resulting in a complete loss of dominance in winter–spring plankton assemblages. The year-round occurrence of T. nordenskioeldii cells in the studied area, as well as data from the literature, indicate that the species has a tropical–arctic–boreal distribution. Positive correlations were found between the surface water salinity, the content of organic matter in seawater, and the abundance of T. nordenskioeldii. A negative relationship with nitrate concentration reflected a depletion of nitrates caused by the mass growth of T. nordenskioeldii.

PAHs in the atmospheric aerosols and seawater in the North–West Pacific ocean and sea of Japan

PAHs were analyzed in samples of atmospheric aerosols and suspended matter in seawater collected in the Sea of Japan, Sea of Okhotsk and the North-Western Pacific in June–July 2012. The concentrations of Σ(15) PAHs in the suspended matter of seawater ranged between 1984.7 pg/L to 30260.3 pg/L. The concentration of Σ(14) PAHs in marine aerosols ranged from 17.09 pg/m3 on June 19–22, 2012 in the northern part of the Sea of Japan, the La Perouse Strait to 142.47 pg/m3 on June 25–28, 2012 near middle Kuril Islands. The results of diagnostic ratios analysis indicate that the primary sources of PAH are pyrogenic. This paper discusses the main anthropogenic (coal-fired power plants and population) and natural sources (wildfires) of PAHs and their effect on the concentration of these compounds in the marine air and suspended matter of seawater. Long-range atmospheric transport of PAHs from the continent to the ocean is shown using HYSPLIT backward trajectories. Active fire products (MODIS and VIIRS) data were used to build a regression model. The model as a whole explains 58% and 75% of the Σ 5-ring PAHs and BaP variations in seawater in June–July 2012, respectively. The analysis shows that anthropogenic sources were not a significant contribution factor for PAHs in the seawater at the Sea of Japan during this period.

Adsorption kinetics of platinum group elements onto macromolecular organic matter in seawater

Adsorption kinetics of the interaction between Pt, Pd and Rh (defined here as platinum group elements, PGEs) ions and macromolecular organic compounds (MOCs, >10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter (>1 kDa and >3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and >1 kDa cutoff, and between Pd and humic acid. For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient (log10Kd) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter (NDOM), an obvious difference in the change trends of log10Kd and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log10Kd of PGEs in the >1 kDa NDOM fraction were higher and more stable than those in the >3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research.