Variability of the distribution of the transparency and suspended matter: Concentration in the surface layer of the northwestern part of the Black Sea in the summer period

Particular features of the distribution of the transparency and particulate matter content, their variability, and their interdependence in the surface water layer (0–5 m) over the northwestern shelf and in the adjacent abyssal part of the Black Sea in the summer were considered on the basis of long-term simultaneous optical, biological, and hydrological observations (1979–1993). In the shelf regions with different river discharges and in the waters of the open part of the sea, the distributions of the transparency, the total particulate matter, and its organic components (organic carbon, nitrogen, and chlorophyll a), as well as the relative content of particulate organic carbon in the total amount of the particulate matter and the content of chlorophyll a in the particulate organic carbon, were considered. The distributions of the transparency and particulate matter and their dependence on the water dynamics are in good agreement. It was demonstrated that extreme anthropogenic eutrophication influences the western and northern coastal shelf areas. The water transparency and particulate organic matter distributions in the central shelf area subjected to the influence of transformed river water and the water properties of the southern part of the shelf, which is influenced by the waters of the open sea, were determined according to the particular structure of the phytoplankton, its abundance, and the processes of its production and destruction.     

2013年夏秋季黄、渤海悬浮颗粒物及粒径分布特征研究

悬浮颗粒物及粒径是水质重要参数,其分布特征研究有助于加深对海洋生态环境的了解。利用2013年6月和2013年11月LISST-100观测数据,研究了黄、渤海区域悬浮物粒径和浓度的分布情况,浓度分布整体上呈现近岸高远岸低的状况,粒径分布呈现近岸细远岸粗的特征,季节分布特征明显;通过典型断面分析,悬浮物粒径和浓度随着水深变化明显,连续站数据分析结果表明大风对底层颗粒物的再悬浮作用显著,潮流对悬浮物的时空分布有着重要影响;水体衰减系数随着体积浓度变化明显;此外,还研究了悬浮颗粒物粒径Junge分布在黄、渤海区域的适用性。     

Phytoplankton growth rate and zooplankton grazing in the western part of the Black Sea in the autumn period

The results of the studies within the framework of the international expedition onboard R/V Vladimir Parshin in September–October 2005 are presented. Intensive development of Bacillariophyceae and Dynophyceae was recorded in the coastal waters of Bulgaria, Turkey, and in the Danube River Delta during the period of the investigations. The increase in the algae population was accompanied by rising of the Chlorophyll a concentration up to 2.0–5.5 mg m^?3. In the deep water region, it did not exceed 0.54 mg m^?3. The phytoplankton growth rate in the surface water layer varied from 0.1 to 1.0 day^?1. The phytoplankton growth rate and NO₂+NO₃ concentration, as well as the silicon concentration, were correlative, as was described by the Michaelis-Menten equation. The phytoplankton growth was affected by the integral impact of basic nutrients. The zooplankton grazing varied from 0.10 to 0.69 day^?1, and the average values in different regions may vary by 1.5 times. The microalgae size range is one of the major factors of the grazing regulation. The rate of the phytoplankton consumption was decreasing according the increasing of the largest diatom Pseudosolenia calcaravis impact on the total biomass of the nano- and microphytoplankton.     

Variability of suspended organic matter in the northwestern Black Sea

The peculiarities in the distribution pattern of the concentration of suspended organic matter (SOM) components were studied for the long-term period of 1979–1995. We have analyzed their seasonal, annual, and interannual variability in the surface water layer and in the photosynthetic water layer in the northwestern Black Sea. Four areas pertaining to different concentrations of SOM components were defined according to the effect of riverine discharge and of open sea water masses, i.e. western, northern, central, and eastern areas. We have found an increase in the concentrations of SOM components in the summer-autumn period in the late 1980s and early 1990s, with the highest values observed in 1992. The concentration of suspended organic carbon was estimated for the concentration of Chlorophyll a in the surface water layer. These calculations are based on the regression relationship between simultaneous measurements of these two parameters in situ. It was found that the seasonal interannual variability in the concentrations of SOM components was affected by the volume of riverine discharge, its run to the sea, and climatic shifts.     

Variability of suspended organic matter in the surface layer of the Black Sea (deep-sea areas)

The peculiarities of the distribution of the components of the suspended organic matter (SOM) and their interannual and seasonal variability have been analysed in the surface water layer and photic water layer of the Black Sea (the deep-sea areas) for the period of 1978–1995. The statistical assessment of the seasonal and monthly dynamics of the SOM components and their ratios was performed. The seasonal dynamics of the concentration of particulate organic carbon have been calculated based on the data on the Chlorophyll “a” (Chl “a”) concentration in the surface water layer based on the regression relationship between these two parameters measured in situ simultaneously. Taking these relationships into account, the interannual dynamics of the Chl “a” concentration have been analysed for the period of 1978–2010. It was found that the concentrations of the SOM components increased significantly in the 1980’s and early 1990’s with the maximum reached in the summer of 1992. It was also found that the seasonal interannual dynamics of the components of the SOM were mainly preconditioned by the interannual dynamics of the phytoplankton biomass, which, in turn, depended on the climatic conditions.     

Bacterioplankton in the northeastern part of the Black Sea during the summer and autumn of 2005

On the basis of luminescent microscopy using a DAPI dye, the abundance, morphometric characteristics, and biomass of bacteria in the coastal waters off the northeastern part of the Black Sea in 2005 were considered. The material was collected in June, September, and October along the cross section from Golubaya Bay towards the open part of the sea. An analysis of the microorganism development level showed that the bacteria achieved their maximal abundance in September, amounting, in the closest near-shore area, to 2435 × 10³ cells/ml, or 276 mg/m³ of wet weight; the lowest values were characteristic of October. During all the survey periods, coccal forms were prevailing among the microorganisms; regardless of the season, their fraction was maximal at the coastal stations. The greatest prevalence of coccal forms was characteristic of October (83%). The average sizes of the bacterial cells in 2005 varied within 0.073–0.257 μm³. The highest values of the bacterial abundance and biomass, almost in all the cases, were found at coastal stations; with the distance from the coast, a decrease in the bacterioplankton abundance was observed. A comparison of methodically similar data on the concentration of bacteria (dying with acridine orange and DAPI) from 1985 till now shows a trend of the annual growth in the bacterial abundance.     

Characteristics of water mass under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn

Two different cold waters were found under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn 2004. One is cold saline water with a low concentration of dissolved oxygen, and the other is cold less saline water with a high concentration of dissolved oxygen. The older saline water originates from the bottom of the East China Sea, strongly influenced by the Kuroshio water with high salinity. The bottom density in the eastern channel of the Tsushima Straits is coincident with that of the East China Sea in autumn, corresponding to the season when the cold saline water was frequently found in the Tsushima Straits. The newer less saline water originates from the front of Tsushima Warm Current between the Tsushima Warm Current water and the surface cold water in the Japan Sea. This water is formed by subduction above the isopycnal surface from the front of the Tsushima Warm Current.     

Sulfur and iron speciation in surface sediments along the northwestern margin of the Black Sea

The speciation of sedimentary sulfur (pyrite, acid volatile sulfides (AVS), S⁰, H₂S, and sulfate) was analyzed in surface sediments recovered at different water depths from the northwestern margin of the Black Sea. Additionally, dissolved and dithionite-extractable iron were quantified, and the sulfur isotope ratios in pyrite were measured. Sulfur and iron cycling in surface sediments of the northwestern part of the Black Sea is largely influenced by (1) organic matter supply to the sediment, (2) availability of reactive iron compounds and (3) oxygen concentrations in the bottom waters. Biologically active, accumulating sediments just in front of the river deltas were characterized by high AVS contents and a fast depletion of sulfate concentration with depth, most likely due to high sulfate reduction rates (SRR). The δ³⁴S values of pyrite in these sediments were relatively heavy (−8‰ to −21‰ vs. V-CDT). On the central shelf, where benthic mineralization rates are lower, re-oxidation processes may become more important and result in pyrite extremely depleted in δ³⁴S (−39‰ to −46‰ vs. V-CDT). A high variability in δ³⁴S values of pyrite in sediments from the shelf-edge (−6‰ to −46‰ vs. V-CDT) reflects characteristic fluctuations in the oxygen concentrations of bottom waters or varying sediment accumulation rates. During periods of oxic conditions or low sediment accumulation rates, re-oxidation processes became important resulting in low AVS concentrations and light δ³⁴S values. Anoxic conditions in the bottom waters overlying shelf-edge sediments or periods of high accumulation rates are reflected in enhanced AVS contents and heavier sulfur isotope values. The sulfur and iron contents and the light and uniform pyrite isotopic composition (−37‰ to −39‰ vs. V-CDT) of sediments in the permanently anoxic deep sea (1494 m water depth) reflect the formation of pyrite in the upper part of the sulfidic water column and the anoxic surface sediment. The present study demonstrates that pyrite, which is extremely depleted in ³⁴S, can be found in the Black Sea surface sediments that are positioned both above and below the chemocline, despite differences in biogeochemical and microbial controlling factors.     

Interannual variability of the zooplankton on the shelf of the northeastern Black Sea in the autumn period

The variability of the mesozooplankton stock in the shelf pelagic communities was studied in the late summer and autumn of 2006–2008. The plankton community’s structure and distribution were described for the shoreward transect (Gelendzhik city vicinity). The indirect and direct effect of the ctenophores Mnemiopsis leidyi and Beroe ovata on the mesozooplankton community was studied. The long-term changes in the meso- and macroplankton communities of the Black Sea were analyzed for the period of 2001–2008. The effects of the climatic factors, the water mass circulation, and the factors’ interplay on the mesozooplankton dynamics were assessed. Despite the wide range of the environmental conditions, the stock biomass of Mnemiopsis leidyi appeared to be quite stable within the studied period.     

Dissolved microelements (heavy metals) in the near-Danube part of the Black Sea in the autumn of 1997

We analyse the distribution of the dissolved forms of cadmium, lead, cobalt, copper, and manganese in the near-Danube part of the Black Sea and in a section made at 45° 10′N in the autumn of 1997. It is shown that the discharge of rivers results in the appearance of significant amounts of cadmium, lead, cobalt, copper, and manganese in the near-Danube region. Copper is the most labile element in this collection of metals. Its behaviour is correlated with the vital activity of diatomic algae. The distribution of dissolved manganese in the near-bottom region is correlated with the distribution of O₂. Indeed, the elevated concentrations of manganese are observed in the regions with low concentrations of oxygen. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

The organic carbon in the water,the particulate matter,and the upper layer of the bottom sediments of the west Kara Sea

In three sections in the Kara Sea, the contents of the dissolved and particulate organic carbon (the DOC and POC, respectively), as well as of the organic carbon of the bottom sediments (C_org) were determined. The contents of varied from 6.3 to 2400 μg/l for the DOC and from 0.84 to 12.2 mg of C/l for the POC. The average concentrations for all the samples tested amounted to 200 μg/l for the DOC (n = 78, σ = 368) and 2.7 mg/l for the POC (n = 92, σ = 2.7). The concentrations of Corg in the samples of the upper layer of the bottom sediments of the area treated varied from 0.13 to 2.10% of the dry substance at an average value of 0.9% (n = 21, σ= 0.49%). It is shown that the distribution of the different forms of organic matter (OM) is an indicator of the supply and spreading of the particulate matter in the Kara Sea and that the DOC and POC of the Kara Sea are formed under the impact of the runoff of the Ob and Yenisei river waters. It is found that the distribution of the OM of the bottom sediments in the surveyed area of the Kara Sea is closely related to their grain-size composition and to the structure of the currents in the area studied. The variations in the Corg content in the bottom sediment cores from the zone of riverine and marine water mixing represent the variability of the OM burial.     

Gelatinous macroplankton in the Black Sea in the autumn of 2010

In October and November of 2010, the gelatinous macroplankton in the northwestern Black Sea and at the Crimean shelf was represented by the scyphozoan jellyfish Aurelia aurita, three species of ctenophores (Beroe ovata, Mnemiopsis leidyi, and Pleurobrachia pileus), and three species of hydromedusae. A. aurita was more common at the shelf, M. leidyi and P. pileus prevailed at the deeper sea stations, and B. ovata was almost ubiquitous with a biomass from below 1 to 49 g/m² A. aurita, which had an average biomass of 82–224 g/m², was dominant at all the stations. M. leidyi, which had a biomass from below 1 to 115 g/m², was recorded in October at only 14 of the 52 stations and in November at 20 of the 46 stations. The highest biomass of M. leidyi in October (105 to 116 g/m²) was recorded in the deep sea areas; in November, it was also the highest in these areas, but it reached at most 100 g/m². The average daily ration of Aurelia ranged from 19.4 to 27.3 mg/m² in October and from 7.0 to 17.2 mg/m² in November; in both cases, it was insufficient to provide for the minimal physiological requirements. The average daily ration of the Mnemiopsis population (2.8–20.5 mg of zooplankton per m²) was invariably more than sufficient to provide for the minimal physiological requirements. Both predatory species together consumed less than 5% of the daily zooplankton production of the sea.     

南黄海和东海表层水两种粒级颗粒物和颗粒氮含量的分布特征

测定了南黄海和东海表层水0.7~53.0μm和〉53.0μm这2种悬浮颗粒物（SPM）、颗粒氮（PN）的含量.其结果表明,南黄海和东海表层水0.7~53.0μm粒级的SPM、PN平均含量分别为4.68 mg/dm3、18.50μg/dm3;而〉53.0μm粒级的SPM、PN平均含量分别为0.20 mg/dm3、2.65μg/dm3.0.7~53.0μm和〉53.0μm粒级的PN/SPM含量平均比值分别为0.78%、1.41%（m/m）,后者约是前者的2倍.统计分析结果表明,尽管这2种粒级的SPM、PN含量和PN/SPM含量比值的范围较大,但约80%的数据集中在较小范围内,即0.7~53.0μm和〉53.0μm粒级SPM含量分别集中在0.37~3.68、0.02~0.29 mg/dm3的范围内;0.7~53.0μm和〉53.0μm粒级PN含量分别集中在2.54~18.90、0.40~2.69μg/dm3的范围内;0.7~53.0μm和〉53.0μm粒级的PN/SPM含量比值分别集中在0.14%~1.00%和0.15%~1.95%之间.研究结果表明,研究海域0.7~53.0μm粒级SPM、PN含量有2个高值区,分别位于近岸海区和东海东北部海区.〉53.0μm粒级SPM、PN含量的分布分为2个部分：南黄海表层水SPM、PN含量分布呈从近岸向外海降低的趋势;而东海表层水SPM、PN含量分布呈断面中间高,并分别向近岸和外海降低的趋势.     

Spatio-temporal variability of the relative transparency of Black Sea waters

The Black Sea relative transparency database covering the period from 1922 to 1993 is described. Seasonal and interannual variabilities of the Secchi disc depthz _σ are studied, along with the meteorological, hydrophysical and biological parameters affecting it. Translated by Vladimir A. Puchkin.     

南海西北部浅海沉积物重金属污染的综合评价

利用在南海西北部北部湾和海南岛周边海域采集的492个站位的底质沉积物样品,以同一海区内同时采集的柱状样品的底层样品和"清洁区"样品中各重金属元素含量值作为背景值,运用潜在生态危害指数法、沉积物富集系数法和ArcGIS软件,对其Cd、Zn、Pb、Cu和Crs种重金属元素分布特征及其上述2种污染指数的分布图进行了分析和比较...     

Aliphatic hydrocarbons in particulate matter from the Baltic Sea

During May 1980, particulate matter was collected at an anchor station from different depths by two methods. In the separated hydrocarbon fraction the most abundant component was the highly unsaturated hydrocarbon n-heneicosahexaene (HEH). Also present was a series of mono- and di-unsaturated olefinic hydrocarbons with an uneven number of carbon atoms, starting with n-C₁₇. The alkane pattern was characterized by a maximum in the range between n-pentadecane and n-heptadecane, with a strong uneven to even carbon number predominance. The peculiar composition of the aliphatic hydrocarbons was compared with literature data given for aliphatic hydrocarbons, whether produced by different marine organisms or derived from crude oil of other anthropogenic sources. A suggestion is made for using a set of conditions as indicators for pollution by fossil hydrocarbons.     

Role of the small-size fraction of mesozooplankton in the pelagic community of the northeastern part of the Black Sea in the autumn

The role of the small-size (SF; 0.1–0.5 mm) and large-size (LF; 0.5–20.0 mm) fractions in the biomass and abundance of mesozooplankton (0.1–20.0 mm) was assessed using the database of samples obtained during the cruises of RV Akvanavt in the northeastern Black Sea in November 2000 and October 2006. The mesozooplankton was collected by means of Juday nets (37/50, filtering gauze 160 μm) and Niskin bottles in two areas: (1) the shelf and continental slope (30–1480 m depth) and (2) the deep sea (depths of more than 1500 m). The plankton net was considerably less effective in collecting the SF of the mesozooplankton (by a factor of 30–36) than the Niskin bottles. When comparing the SF and LF, we estimated the abundance and biomass of the SF in the samples obtained with the Niskin bottles. The abundance of the SF in the deep-sea area was 2.5 times lower compared to the shelf and continental slope, and the LF abundance was 5.0 times lower in the same way. The abundance of the SF constituted 88% of the total mesozooplankton on the shelf and continental slope, and 78% in the deep-sea area. The biomass of the SF was higher as well on the shelf and continental slope. Meroplankton played a significant role in the SF zooplankton abundance (0.5 × 10³ + 0.16 ind. m⁻³) in this area. The SF grazing impact was 10% of the total mesozooplankton grazing on the shelf and continental slope, and 17% in the deepsea area. Appendicularia and nauplii of copepods had the greatest contribution to the mesozooplankton grazing among the SF group.     

Mineral composition of the suspended particulate matter in the White Sea

The mineral composition of the suspended particulate matter (SPM) was studied for the White Sea area. The comparative analysis of the composition of the marine SMP and the SPM of the rivers of the White Sea catchment area was performed, including the Severnaya Dvina River, one of the major sources of the terrigenous suspended matter to the sea. The research of such kind is faced with numerous methodological difficulties, which slows down the study process. Data on the mineral composition of the SPM are scarce. Applying the method of X-ray powder diffractometry, we assessed the bulk mineral composition of the SPM with special regard to its clay fraction.     

珠江口表层水体颗粒物中古菌四醚类脂物的分布特征

类异戊二烯甘油二烷基甘油四醚类化合物（isoGDGTs）是古菌微生物的特征脂类标志物,由这组化合物构造出的TEX₈₆温标在海水古温度重建中得到了广泛应用。本文调查了珠江口及近岸海域（水深小于30 m）4个季节水体悬浮颗粒物（SPM）的isoGDGTs分布情况。结果显示:虎门上游河流水体中的isoGDGTs主要来自原地生产的甲烷古菌输入,进入河口水体后,主要来自原地奇古菌和广古菌的输入。陆源古菌的输入在5月份和8月份,对河流水体产生一定的影响,但对河口水体的影响相对较小。珠江口水体isoGDGTs中的GDGT-2与GDGT-3比值（GDGT-[2]/[3]）和GDGT-Cren'的丰度百分比（Cren'%）分别小于4和4%,与南海深水沉积物明显不同,表明珠江口与南海深水沉积物中isoGDGTs的古菌来源存在差异,这也可能是引起珠江口水体TEX₈₆温度（基于全球标定公式）偏离水体实际温度的原因。珠江口表层水体isoGDGTs中的GDGT-2和GDGT-3的丰度百分比与南海表层水体存在差异,这可能与GroupⅠ奇古菌和GroupⅡ广古菌相对比例空间变化有关。珠江口表层水体isoGDGTs的TEX₈₆温度在2月份明显高于原地表层水体温,而其他月份都低于原地表层水体温度,可能与Group Ⅰ奇古菌和Group Ⅱ广古菌相对比例的季节变化有关。几个月份中11月份isoGDGTs绝对含量最高,8月份较低,表明11月份和8月份分别是原地古菌生产量较大和较小时期。统计分析的结果显示,水体铵根离子含量、水体温度,以及溶解氧水平可能是控制珠江口水体isoGDGTs分布的主要环境因素。