Spatial Distribution of Phytoplankton in the Subarctic Estuary (Kem’ River,the White Sea)

Oceanology - The species composition and biomass of phytoplankton, as well as hydrological characteristics, were estimated during four spatial surveys in the Subarctic tidal Kem’ River...     

Biogeochemical transformations of dissolved organic matter at the sediment–water interface: results from in situ incubations within benthic chambers

Biogeochemical transformations of dissolved organic matter at the sediment–water interface were investigated by the use of benthic chambers in the western Gulf of Lions. The experimental approach used for this study consisted of in situ incubations of radiolabeled glutamic acid (¹⁴C-Glu), followed by a sequential extraction allowing the quantification of the radioactivity associated to different chemical fractions, representative of different biogeochemical processes. This technique was devised to simulate the fate of simple dissolved compounds resulting from the degradation of particulate organic matter near the seafloor. In our experiment the substrate underwent both biotic (mineralization, bacterial incorporation) and abiotic (geopolymerization) transformations. Significant spatial variations were put in relation with sediment characteristics (e.g. fine-grained fraction, Eh, CaCO₃ contents) and biological activities, such as bacterial respiration and infaunal burrowing. Biologically mediated processes decreased from onshore to deep sites, with mineralization always accounting for the bulk of transformations of the injected ¹⁴C-Glu. Geopolymerization did not display a clear spatial trend and appeared to be a quantitatively important process on the Gulf of Lions margin.     

Sources and implications of particulate organic matter from a small tropical river—Zuari River,India

Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and its implications to small tropical rivers.Thus,changes in temporal and regional settings are more likely to affect the natural biogeochemical cycles of small tropical rivers.     

Fouling in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea

Abstract-In order to understand the type and extent of marine fouling in offshore areas southeast ofthe Zhujiang (Pearl) River delta, within the period form May 1986 to June 1987, two biologicalbuoys were deployed at water depths of 95 m and 113 m located in 114 km and 160 km off the coast ofHong Kong, respectively. Moreover, the fouling community of a Marex hydrological buoy located in115 m depth water 172 km off Hong Kong was also surveyed. The results show that a total of 78species were collected and identified. The panels exposed for 3 months were mainly dominated bystalked barnacles Conchoderma hunteri and Lepas anatifera and hydroids Orthopyxis sp. As for thebuoys, including the subsurface buoy, and their mooring systems exposed for 6 and 12 months, respec-tively, some hard foulers such as common oysters, pearl oysters, acorn barnacles and bryozoans werealso found. The compositions of fouling communities also varied greatly with depth.     

Dynamics of REE accumulation and fractionation in the subcolloidal fraction of bottom sediments in the Razdol’naya River–Amur Bay section,Sea of Japan

The REE contents (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) are determined by atomic emission spectroscopy in the subcolloidal fraction of bottom sediments in the Razdol’naya River–Amur Bay section. The mean contents of lanthanides in soils and river bottom sediments (before the mixing zone) are calculated. The increase in REE content and the fractioning in the series from light to middle and heavy REE in sediments of different estuary zones (river, water mixing, and marine), with the latter related to flocculation, sorption on iron and manganese hydroxides, clay minerals (hydromica, smectites), and lifetime accumulation of marine plankton, are dtermined. Via extraction of 0.5 N sodium hydroxide solution, the content of lanthanides associated with humic substances of subcolloidal fraction from the Amur Bay sediments are determined: 1.3 to 8.2% of La; 1.1 to 11% of Ce; and 0.3 to 1.5 of Gd.     

Spatial and seasonal variations of sea level in the Red Sea, 1958–2001

The present study investigated the variability of monthly mean sea level data and discussed its relation with climatic events in the Red Sea during 1958–2001. The data were obtained from Simple Ocean Data Assimilation (SODA), for three different locations (north, central and south) in the Red Sea. Spatial and temporal variability as well as trends and periodicity of sea level time series records in the three locations was investigated using One-way ANOVA test, weighted running mean filter and autocorrelation spectral analysis. Results revealed that mean sea level in the northern Red Sea was permanently lower than its central and southern parts. Moreover, the mean sea level during winter and spring in the three locations was significantly higher than summer and autumn seasons. Increasing and decreasing of sea level trends with respect to time were also observed. Inter-decadal variations in sea level including a fairly regular quasi 2.5–2.7 year oscillation in all seasons were detected, although its amplitude varied among different cycles. Studying the cyclicity in the hydroclimatic record can resolve some of the complexities of the hydroclimate system. The sign of Quasi Biennial Oscillation, El Niño Southern Oscillation and sunspots events may have an important influence in sea level variations of the Red Sea.     

Preliminary study on the distribution of nutrients, organic matter, trace metals in sea surface microlayer in Xiamen Bay and Jiulong Estuary

-The enrichment of nutrients (NOa-, NOa-, PO43-), suspended particles, organic matter (POC, PON,DOC) , and trace metals (Cu, Ni, Cd) was determined in the sea surface microlayer of Xiamen Bay and Jiulong Estuary. The mean enrichment factors ([Xi]microlayer/[Xi ]15cm in depth) mostly ranged between 1 . 0 and 2. 0. The dissolved forms were the major forms of the components measured, the enrichment of dissolved organic matter and suspended particles could lead to the changes in the total amount and speciation of nutrients and trace metals. No correlation was observed between sample concentrations, speciation, enrichment factors and sample locations. However, some evidence shows that these parameters are correlated with sea state, indicating the complexity and dynamic nature of the sea surface microlayer.     

Biomineralization of organic matter in cobalt-rich crusts from the Marcus–Wake Seamounts of the western Pacific Ocean

Organic matter in cobalt-rich crust(CRC) from the Marcus–Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, including n-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography(GC) and gas chromatography–mass spectrometry(GC–MS). The content of organic carbon(OC) and its stable isotope(δ13C), and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton(e.g., bacteria and algae, respectively) from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitumen "A": OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms of n-alkane molecules:(1) primitive type(bacteria and algae), which is characterized by moderately mature of n-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton;(2) microbial degradation type, which is characterized by low contents of n-alkanes and rising baseline in the chromatogram, with the "bulge" being the products of organic matter by biodegradation;(3) organic matter migration type, which is characterized by low carbon number of n-alkanes with n C18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydrocarbons with high carbon number; and(4) organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weight n-alkanes, pristane, and phytane, accompanied by higher concentration of n-alkanes with carbon number greater than n C18. This study shows that biomarkers can record controlling factors of mineralization and their variation.     

Origin and fate of particulate organic matter in the southern Beaufort Sea – Amundsen Gulf region,Canadian Arctic

To establish the relative importance of terrigenous and marine organic matter in the southern Beaufort Sea, we measured the concentrations and the stable isotopic compositions of organic carbon and total nitrogen in sediments and in settling particles intercepted by sediment traps. The organic carbon content of surface sediment in the Chukchi and southern Beaufort Seas ranged from 0.6 to 1.6% dry wt., without a clear geographical pattern. The C_ORG:N_TOT ratio ranged from 7.0 to 10.4 and did not vary significantly downcore at any one station. Values of δ¹³C_ORG and δ¹⁵N_TOT in the sediment samples were strongly correlated, with the highest values, indicative of a more marine contribution, in the Amundsen Gulf. In contrast, the organic matter content, elemental (C_ORG:N_TOT ratio) and isotopic (δ¹³C_ORG and δ¹⁵N_TOT) composition of the settling particles was different from and much more variable than in the bottom sediments. The isotopic signature of organic matter in the Beaufort Sea is well constrained by three distinct end-members: a labile marine component produced in situ by planktonic organisms, a refractory marine component, the end product of respiration and diagenesis, and a refractory terrigenous component. A three-component mixing model explains the scatter observed in the stable isotope signatures of the sediment trap samples and accommodates an apparent two-component mixing model of the organic matter in sediments. The suspended matter in the water column contains organic matter varying from essentially labile and marine to mostly refractory and terrigenous. As it settles through the water column, the labile marine organic matter is degraded, and its original stable isotope signature changes towards the signature of the marine refractory component. This process continues in the bottom sediment with the result that the sedimentary organic matter becomes dominated by the refractory terrigenous and marine components.     

Long-term variation in the salinity of the Southern Yellow Sea Cold Water Mass, 1976–2006

This paper discusses the long-term variation in the salinity of the Southern Yellow Sea Cold Water Mass (SYSCWM) and examines factors influencing the SYSCWM based on hydrographic datasets of the China National Standard section and the Korea Oceanographic Data Center. The mean salinity at the center of the SYSCWM showed a decreasing long-term trend. In empirical orthogonal function (EOF) analysis, the second EOF mode showed a similar long-term trend. The mean salinity of the center of the SYSCWM was related to the intrusion of saline water from the Yellow Sea Warm Current (YSWC), the salinity of the source area of the YSWC, the evaporation minus precipitation (E–P) flux, and discharge from the Changjiang River. The decreasing salinity trend to the southwest of Cheju Island produced a freshening trend in the YSWC, resulting in a reduction in the salinity of the SYSCWM. The freshening trends of the water from the northwest Pacific and the South China Sea were seen as the reason for the decreasing salinity trend from the intrusion of water into the Yellow Sea (YS). The freshwater flux influenced the surface salinity and was brought to deep layers by strong mixing in winter. The mean E–P flux signal and Changjiang River discharge signal lagged the first principal component of the SYSCWM by approximately 5 months.     

Absorption of light by phytoplankton,detritus, and dissolved organic substances in the coastal region of the Black Sea (July–August 2002)

We present some results of our investigations of the concentrations of pigments and the biooptical characteristics of suspended and dissolved organic substances in the coastal region of the sea near the coast of the Crimea. Under the conditions of variable meteorological situation, we observe well-pronounced variations of the concentrations of pigments in the surface layer and their different vertical profiles. The inhomogeneity of the distribution of pigments in depth is accompanied by a decrease in the specific coefficients of absorption of light by phytoplankton. In the analyzed case, the contribution of detritus to absorption does not vary with depth and its maximum values are observed under the storm conditions. The dependences of the absorption of light by phytoplankton and suspended substances on the content of pigments and of the absorption of light by dissolved organic substances on the wavelength are established. These dependences are well described by power and exponential functions.Translated from Morskoi Gidrofiziche-skii Zhurnal, No. 4, pp. 39–50, July–August, 2004.     

Tracing water mass mixing in the Baltic–North Sea transition zone using the optical properties of coloured dissolved organic matter

The distribution and characteristics of coloured dissolved organic matter (CDOM) in the Baltic – North Sea transition zone were studied. The aim was to assess the validity of predicting CDOM absorption in the region on the basis of water mass mixing alone and demonstrate the utility of CDOM as an indicator of water mass mixing in coastal seas. A three-end-member mixing model representing the three major allochthonous CDOM sources was sufficient to describe the patterns in CDOM absorption distribution observed. The three-end-member water masses were the: Baltic outflow, German Bight and the central North Sea. Previously, it was thought that water from the German Bight transported northwards in the Jutland coastal current only sporadically influenced mixing between the Baltic and North Sea. The results from this study show that water from the German Bight is detectable at salinities down to 12 in the Kattegat and Belt Sea. On average, 23% of the CDOM in bottom waters of the Kattegat, Great Belt, Belt Sea, Arkona Sea and the Sound originated from the German Bight. Using this conservative mixing model approach, local CDOM inputs were detectable but found to be limited, representing only 0.25% of CDOM in the surface waters of the Kattegat and Belt Sea. The conservative mixing of CDOM makes it possible to predict its distribution and characteristics and offers a powerful tool for tracing water mass mixing in the region. The results also emphasize the need to include the Jutland Coastal current in hydrodynamic models for the region.     

Spatial–temporal distribution of phytoplankton pigments in relation to nutrient status in Jiaozhou Bay,China

We conducted studies of phytoplankton and hydrological variables in a semi-enclosed bay in northern China to understand the spatial–temporal variability and relationship between these variables. Samples were collected during seven cruises in Jiaozhou Bay from November 2003 to October 2004, and were analyzed for temperature, nutrients and phytoplankton pigments. Pigments from eight possible phytoplankton classes (Diatoms, Dinoflagellates, Chlorophyceae, Prasinophyceae, Chrysophyceae, Haptophyceae, Cryptophyceae and Caynophyceae) were detected in surface water by high performance liquid chromatography (HPLC). Phytoplankton pigment and nutrient concentrations in Jiaozhou Bay were spatially and temporally variable, and most of them were highest in the northern and eastern parts of the sampling regions in spring (May) and summer (August), close to areas of shellfish culturing, river estuaries, dense population and high industrialization, reflecting human activities. Chlorophyll a was recorded in all samples, with an annual mean concentration of 1.892 μg L⁻¹, and fucoxanthin was the most abundant accessory pigment, with a mean concentration of 0.791 μg L⁻¹. The highest concentrations of chlorophyll a (15.299 μg L⁻¹) and fucoxanthin (9.417 μg L⁻¹) were observed in May 2004 at the station close to the Qingdao Xiaogang Ferry, indicating a spring bloom of Diatoms in this area. Although chlorophyll a and other biomarker pigments showed significant correlations, none of them showed strong correlations with temperature and nutrients, suggesting an apparent de-coupling between the pigments and these hydrological variables. The nutrient composition and phytoplankton community composition of Jiaozhou Bay have changed significantly in the past several decades, reflecting the increasing nutrient concentrations and decline of phytoplankton cell abundance. The unchanged total chlorophyll a levels indicated that smaller species have filled the niche vacated by the larger species in Jiaozhou Bay, as revealed by our biomarker pigment analysis.     

Spatial distribution of the crab larvae (Decapoda: Anomura et Brachyura) in Possyet Bay (Peter the Great Bay of the Sea of Japan) in 2000–2001

The analysis of the data obtained during the plankton surveys in Possyet Bay (Peter the Great Bay of the Sea of Japan) in 2000–2001 is presented. The larvae of eight crab species were registered in the plankton: the red king crab Paralithodes camtschaticus (Tilesius, 1815), the snow (opilio) crab Chionoecetes opilio (Fabricius, 1780), the Arctic lyre crab Hyas coarctatus ursinus (Leach, 1815), the kelp crab Pugettia quadridens (de Haan, 1839), the helmet crab Telmessus cheiragonus (Tilesius, 1815), the Japanese swimming crab Charybdis japonica (A. Milne-Edwards, 1861), the pea crab Pinnixa rathbuni (Sakai, 1934), and the porcelain crab Pachycheles stevensii (Stimpson, 1858). These species belonged to six families: Lithodidae, Atelecyclidae, Majidae, Portunidae, Porcellanidae, and Pinnotheridae. The role of the variability of some of the hydrological factors in the meroplankton larvae development was studied. In May, the crab larvae were found mostly in the open part of the bay. In June, they were transported by the current to the northern part of the bay. In July, they spread uniformly in all the bay areas; however, patchiness was observed. The maximal population density of the crab larvae was registered for July and varied from 6.8 to 23.3 ind. m⁻³. The crab larvae appeared in the plankton in 2000 and 2001 earlier than for the average season.     

Rates of bacterial sulfate reduction and their response to experimental temperature changes in coastal sediments of Qi’ao Island, Zhujiang River Estuary in China

Subtropical sediment cores(QA09-1 and QA12-9) from the coastal zone of Qi'ao Island in the Zhujiang River Estuary were used to determine the rates of sulfate reduction and their response to experimental temperature changes. The depth distribution of the sulfate reduction rates was measured from whole-core incubations with radioactive tracer 35SO42-, and peaks of 181.19 nmol/(cm3·d) and 107.49 nmol/(cm3·d) were exhibited at stations QA09-1 and QA12-9, respectively. The profiles of the pore water methane and sulfate concentrations demonstrated that anaerobic oxidation of methane occurred in the study area, which resulted in an increase in the sulfate reduction rate at the base of the sulfate-reducing zone. Meanwhile, the sulfate concentration was not a major limiting factor for controlling the rates of sulfate reduction. In addition, the incubation of the sediment slurries in a block with a temperature gradient showed that the optimum temperature for the sulfate reduction reaction was 36℃. The Arrhenius plot was linear from the lowest temperature to the optimum temperature, and the activation energy was at the lower end of the range of previously reported values. The results suggested that the ambient temperature regime of marine environments probably selected for the microbial population with the best-suited physiology for the respective environment.     

Short-Term Variability of Hydrological and Hydrochemical Characteristics of the Kyanda Estuary in Onega Bay,the White Sea (July 28–August 15, 2016)

The paper presents information on joint research of the short-term (tidal and synoptic) variability of the hydrological and hydrochemical parameters during the summer 2016 low-water period in mesotidal estuary of the Kyanda River, which flows into Onega Bay, the White Sea. It is demonstrated that semidiurnal, diurnal, and synoptic variations of almost all observed parameters are significant and differ notably along the estuary.     

Geological–Geophysical and Oceanographic Research in the Sea of Japan,Tatar Strait,on Cruise 61 of the R/V Akademik Oparin

Oceanology - The paper presents brief results of comprehensive studies of the water area of the Tatar Strait and Sea of Japan obtained on cruise 61 of the R/V “Akademik Oparin” in...     

Structural Elements of the Sea of Japan’s Basin and Adjacent Continental and Island Dry Land,According to Data from Space-Based Geological Investigations

Izvestiya, Atmospheric and Oceanic Physics - A representative system of fault and block dislocations in the Sea of Japan segment of the continent–ocean transition zone, identified using...     

Geochemical evolution of Oligocene–Middle Miocene sediments in the deep-water area of the Pearl River Mouth Basin,northern South China Sea

The deep-water area of the Pearl River Mouth Basin in the South China Sea has received much scientific attention since the Ocean Drilling Program (ODP) Leg 184 in 1999 due to its potential economic prospects and distinct tectono-sedimentary evolutionary processes. In this study, we present the composition of major and trace elements from two newly sampled deep-water boreholes (BY6 and LW3) in the Baiyun Sag of the southern Pearl River Mouth Basin. The geochemical evolution in the Oligocene–Middle Miocene, as well as potential controlling factors, are investigated based on a comparative study with previous data from ODP site 1148 and borehole PY33. The Chemical Index of Alteration (CIA) and A–CN–K plot reveal that the observed weathering trends are not compatible for the four discussed boreholes. Sedimentary sorting is primarily observed in borehole PY33, where data trend away from the A apex to the feldspar join in the A–CN–K plot and show a spread of Al₂O₃/SiO₂ and Nb/Zr ratios. Compared to chemical weathering and hydrodynamic sorting, provenance has a greater impact on sediment composition of the deep-water area. From the north, the Pearl River was the primary sediment supply. However, a positive Eu anomaly and the provenance discrimination diagrams (i.e., La/Th versus Th/Yb and Zr/Co versus Th/Co) reveal the mafic nature of borehole BY6 sediments in the Zhuhai–Lower Zhujiang (32.0–18.5 Ma) and Upper Hanjiang (13.8–10.5 Ma) formations. These compositions are unusual and differ from the well-defined felsic sources in the majority of the Baiyun Sag; these discrepancies are likely related to multistage magmatism. The sediments at site 1148 are characterized by slightly enriched heavy rare earth elements and relatively high Zr/Co ratios, which could possibly be caused by zircon enrichment from local sources.