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1.
Advantages of direct determination of surface active substances without sample pretreatment, using the electrochemical method (a.c. polarography) based on the measurement of adsorption effects on the mercury electrode, are illustrated for a number of freshwater and marine samples and phytoplankton culture media. The effects of dilution, filtration and centrifugation of samples were investigated. A high loss of organic material through filtration was observed for selected sea surface microlayer samples and phytoplankton culture media. The samples were compared with different model surfactants and were found to possess similar adsorption characteristics to hydrophobic, fatty surfactants. The freshwater samples were found to be more stable during pretreatment than the marine samples. Humic substances are the predominant surface-active compounds in freshwater systems. The use of a calibration curve for humic material is proposed for the rapid and direct determination of surfactant activity values for freshwater samples. 相似文献
2.
《Marine Chemistry》2001,73(3-4):319-332
The accumulation of dissolved organic matter (DOM) at the air–sea interface is controlled by dynamic physical processes at the boundary between ocean and atmosphere. Much of the DOM concentrated in the surface microlayer is thought to be protein or glycoprotein. Enzymatic hydrolysis of these and other biopolymers is an important step in the microbial uptake of dissolved and particulate organic matter in many aquatic environments. We employed a sensitive fluorescence technique to investigate differences between extracellular enzymatic peptide hydrolysis in the sea surface microlayer and corresponding subsurface water from Stony Brook Harbor, NY. We separated the microlayer from its underlying water and thus measured hydrolysis potential rather than an in-situ process. Peptide turnover was always faster in the microlayer than in subsurface waters. This was confirmed by allowing a new surface film to form on subsurface water; hydrolysis was still faster in the new surface film. In a year-long study, we found the relative difference between turnover times in the surface film and subsurface waters to vary greatly with season. While rate constants of peptide hydrolysis were generally higher in both microlayer and bulk water samples in spring/summer than in fall/winter, the difference in activity between the two environments was greatest in winter. Enhanced hydrolysis in the sea surface microlayer is likely due to the greater concentrations of DOM in the microlayer. Seasonal changes in distribution of hydrolytic activity between surface film and subsurface water probably reflect seasonal variation in the mechanisms of DOM enrichment, which depend on water temperature, substance and energy fluxes across the water–air boundary, activity of aquatic organisms and other seasonal variables. 相似文献
3.
The DYFAMED sediment trap station in the Ligurian Sea (NW Mediterranean) has been active since 1986 and today comprises the longest time‐series of downward particle flux in the Mediterranean Sea. As such, it provides valuable information on the interannual variability of the particle flux, and also documents possible recent changes in the NW Mediterranean pelagic ecosystems. We report an unprecedented episode of downward flux of mucilaginous material at the DYFAMED station during summer 2002 in association with singular hydrometeorological conditions. The rain of mucilaginous aggregates clogged a PPS5 sediment trap at 260 m depth and was also clearly detected at 1080 m depth. The possible factors governing the development and sinking of the mucilaginous material are discussed. A very sharp increase of sea surface temperature during June and the presence of freshened waters in the surface the following month resulted in a stronger than usual stratification of the upper water column throughout the summer season. We suggest that the steepness of the vertical density gradient was responsible for the unusual accumulation of mucous aggregates. Additionally, a diatom bloom took place during the nutrient‐depleted conditions typical of summer, a factor which may have contributed to feed the pycnocline with transparent exopolymer substances. A storm occurring in the beginning of August relaxed the stratification and promoted the deposition of the mucilaginous aggregates accumulated in the upper water column during the preceding months. Important similarities of ambient conditions preceding the apparition of mucilaginous material in our open‐sea site and those reported in the Adriatic Sea during major mucilage events, suggest that general climatic conditions, rather than local factors, drive the occurrence of major accumulations of mucilaginous material in the water column at both sub‐basins of the Mediterranean Sea. In this regard, the strength of the air temperature increase during the onset of the stratified season is proposed as a major controlling factor. 相似文献
4.
5.
浮游生物对某些化学物质在海洋微表层中富集所起的作用 总被引：3，自引：0，他引：3
本文综合分析了浮游生物对有机物、痕量金属、氮磷营养盐在海洋微表层中富集所起的作用。浮游植物和部分浮游细菌释放的溶解有机物大部分具有表面活性且能与痕量金属络合,它们能靠Gibbs吸附富集于微表层,并促成与络合的痕量金属的富集。浮游细菌对微表层中富集的含氮和含磷有机物的分解可能是促成氮磷营养盐在微表层中富集的重要原因。 相似文献
6.
Gui-Peng Yang 《Marine Chemistry》1999,66(3-4)
A total of 22 sea surface microlayer samples collected from the Nansha Islands waters of the South China Sea were analyzed for dimethylsulfide (DMS), chlorophyll a and nutrients including nitrate, phosphate and silicate. The DMS concentrations in surface microlayer samples ranged from 82 to 280 ng S/l with a mean of 145 ng S/l. A significant correlation was found between DMS and chlorophyll a data both in the surface microlayer as well as in the subsurface water. However, no correlation was observed between DMS and nutrient concentrations in the surface microlayer. The DMS concentrations were higher in all surface microlayer samples, compared with subsurface samples. The enrichment factor (EF) of DMS in the surface microlayer varied from 1.21 to 3.08 with an average of 1.95. The EF of DMS was significantly correlated with that of chlorophyll a in the microlayer. The enrichment of DMS in the microlayer may be due to two factors, including the in situ production from phytoplankton and the transportation from the underlying seawater. The diel variations in DMS and chlorophyll a concentrations were studied at a fixed station. The highest concentrations of DMS in the surface microlayer and subsurface water were simultaneously observed in the late afternoon (1800 h), while the highest levels of chlorophyll a were simultaneously found at night (0200 h). 相似文献
7.
Microlayer samples from a coastal marine area near Marseilles (France) collected in 1979 and 1980 have been analysed for POC, PON, chlorophyll a, ATP, cell counts, carbon fixation and in some cases for heterotrophic activity. Comparison of microlayer data with those of underlying water showed in most cases enrichment of organic matter and microorganisms in the surface microlayer. Carbon fixation values were comparable to those observed at 0·50 m except in the slicks, where phytoneustonic activity was higher than that of the underlying phytoplankton. Though total heterotrophic activity was higher in the surface film, the turnover time was not significantly different in both microlayer and underlying water. Our data show that enrichment is highly dependent on sea conditions; whenever slicks are present, the surface film seems to function like an eutrophic system, including active living material, although detritus is regularly present in large amounts. 相似文献
8.
The paper presents methodology and results of the development of sea states statistics for the Adriatic Sea. Such statistics is still lacking despite a need of the shipping industry. The presented study is based on the Atlas of Climatology containing statistics of sea states observations in the Adriatic Sea made by merchant ships during the period of 15 years. The results, presented in the Atlas in the form of “wave roses”, are digitalized and empirical frequencies of sea state occurrences are obtained. The 3-parametric Weibull distribution is then fitted through empirical data points enabling the “smoothening” of the histogram. The resulting histogram is compared with other studies for the long-term prediction of the sea states in the Adriatic Sea. The paper concludes with the discussion on the accuracy and applicability of the results. 相似文献
9.
《Marine Chemistry》2001,76(3):137-153
Laboratory experiments, along with in situ investigation in Funka Bay, Japan, were conducted to determine the enrichment factor (EF) of dimethylsulfide (DMS) in the sea surface microlayer, as well as its the production and consumption rates. The EF of DMS in the microlayer was largely affected by various factors including sampling methods, sampling thickness, temperature, salinity, and DMS concentration in bulk water. In all cases but the sealed system, a part of DMS in the microlayer was always unavoidably lost during sampling. High temperature, great wind speed, and slow sampling would increase the extent of loss of DMS due to volatilization. In the field, the screen-collected samples usually exhibited greater microlayer enrichment for DMS than the plate-collected samples, showing that the screen sampler might be more effective for collecting the in situ microlayer DMS. The production and consumption rates of DMS in the surface microlayer were higher than those in the bulk water and these two rates were significantly correlated with the microlayer DMS concentrations. Moreover, the EF of DMS appeared to be related to the microlayer production rate of DMS, providing evidence supporting the observed DMS enrichment in the microlayer. The DMS production and consumption rates were not directly related to its concentrations in the bulk water, suggesting that the processes of production and consumption of DMS were very complex. In the surface microlayer, the biological turnover time of DMS varied from 0.4 to 1.9 days, with an average of 0.9 days, which was about 540-fold greater than the mean DMS sea–air turnover time (2.4 min). Thus, the biological process occurring within the microlayer can be neglected when we consider the sea–air exchange of DMS. Considering the microlayer production rate of DMS (an average of 9.7 nM day−1) to be too small to counteract the sea-to-air removal of DMS, the main source of DMS in the microlayer appears to be through vertical transport by turbulent diffusion from the underlying water. 相似文献
10.
The Princeton Ocean Model was implemented to investigate the response of northern Adriatic Sea during the Bora event in January 2001 when strong wind and surface cooling was reported. The model has been run with realistic wind stress, surface heat flux and river runoffs forcings continuously from 1 January 1999 to 31 January 2001. The wind stress and surface heat flux was computed by the bulk parameterization, using the European Centre for Medium Range Weather Forecast analysis fields and the Comprehensive Ocean Atmosphere Data Set cloud data. All the freshwater sources along the Adriatic coastlines were represented by point or line source functions. Open boundary conditions in the Ionian Sea along a latitudinal boundary were nested within a large scale model of the Mediterranean Sea. The numerical study found that, before the Bora event of 13–17 January 2001, the water column of the northern Adriatic Sea was stratified by salinity, and the temperature was already cooler at the surface and over the shallower shelf region. The pre-Bora circulation of the northern Adriatic Sea was relatively weak and baroclinic with maximum surface currents occurred near the Italian coast. During the Bora event, the water column was well mixed in the most of coastal region of the northern Adriatic Sea. The atmospheric cooling produced colder water over the northern and western Adriatic Coast. The circulation of the northern Adriatic Sea was barotropic and dominantly wind driven, with maximum current speed of about 1 m s−1. The numerical study also demonstrated that the Bora event decreased the heat content of the water column with an area averaged value of 205 W m−2 over the shallow northern shelf. It was concluded that the heat budget of the northern Adriatic Sea during the Bora event was a balance between the surface heat loss, horizontal net heat inflow and resulting heat content decrease. The horizontal advection played a particularly important role in controlling the water temperature change over the shallower northern shelf. 相似文献
11.
Comparison of sampling devices for the determination of polychlorinated biphenyls in the sea surface microlayer 总被引：1，自引：0，他引：1
García-Flor N Guitart C Bodineau L Dachs J Bayona JM Albaigés J 《Marine environmental research》2005,59(3):255-275
Over 30 sea surface microlayer (SML) samples from two contrasting sites in the North Western Mediterranean -- Barcelona (Spain) and Banyuls-sur-Mer (France) -- were collected using three different sampling devices, namely, glass plate, metal screen (MS) and a surface slick sampler (SS), and compared with the corresponding underlying water (16 samples). The distributions of 41 polychlorinated biphenyl congeners (PCBs) were determined in the different phases: particulate (1.17-10.8 SigmaPCB ng L(-1)), truly dissolved (0.080-16.7 SigmaPCB ng L(-1)) and colloidal matter (1.17-43.0 SigmaPCB ng L(-1)), being the last two estimated from the analysis of the apparently dissolved phase. Concentrations of PCBs in the SML were higher than those in the underlying water (ULW), giving rise to enrichment factors (EF=[C](SML)/[C](ULW)) up to first-order of magnitude. The ANOVA statistical approach was used to assess differences of bulk data (e.g. dissolved organic carbon, DOC; particulate organic carbon, POC; suspended particulate matter, SPM) among sampling devices, whilst p-tailed t paired tests were used in order to compare the enrichments obtained for each sampling date. In this respect, no significantly different enrichment factors were found among sampling devices (p < 0.05), although the surface SS showed lower enrichments, probably due to the dilution of the SML with the ULW during sampling. The MS seemed to be the most suitable device for the determination of PCBs in the SML in terms of sampling efficiency under a variety of meteorological conditions. 相似文献
12.
The Mediterranean endemic Cladocora caespitosa (Linnaeus, 1767) is a colonial scleractinian coral belonging to the family Faviidae and the only zooxanthellate coral from Mediterranean whose colonies may fuse in reef‐like structures (hermatypic). Recent surveys are focused on three locations where banks occur in the Adriatic Sea (Croatia): near Prvi? Island in the northern Adriatic, near Pag Island in the central Adriatic and in Veliko jezero (Mljet National Park) in the southern Adriatic. The C. caespitosa bank in Veliko jezero covers an area more than 650 m2 and is thus the largest bank of C. caespitosa found to date. The strong sea currents, which occur as a result of tidal exchange in the channel, appear to favour the growth of the bank. The goal of the study was to present the influence of major environmental factors upon the build‐up process of the coral bank. Biometrical parameters in the C. caespitosa colonies like diameter of the calyces, polyp ash free dry weight (AFDW), corallite linear growth rate and index of sphericity were investigated and compared from these three locations. The morphology of coral banks from the Adriatic Sea and the disposition of the biometrical values are affected by the sea currents, temperature and sedimentation. 相似文献
13.
R.M. Kocan H. von Westernhagen M.L. Landolt G. Furstenberg 《Marine environmental research》1987,23(4)
This study was designed to determine whether contaminated sea-surface microlayer was toxic to marine fish embryos in its ntaive form and as a hexane extract. Developing embryos of Atlantic cod (Gadus morhua) and Baltic herring (Clupea harengus) were exposed to hexane extracts of sea-surface microlayer collected from five locations in the North Sea and Baltic Sea. Extracts from two of these locations produced significant embryos mortality as well as severe deformities in live hatched larvae. A control sample of bulk water collected from 20 cm under the surface and extracted in the same way produced no significant mortality or deformities. Significaant changes in timing of hatching were also observed in those samples which produced embryo toxic effects. A comparison of these data with those obtained from code embryos exposed to unextracted microlayer showed a similar biological effect with both unextracted samples and hexane extracts.Chemical analyses revealed the greatest biological effect in samples with petroleum hydrocarbon concentrations between 180 and > 200 μg liter−1. The bulk water control had 1 μg liter−1 while the three samples that showed no biological activity had 3 to 8 μg liter−1 petroleum hydrocarbons. Phthalic acid esters were detected in four samples and chlorinated hydrocarbons in one, but could not be positively correlated with any of the toxic responses. No other chemical contaminants were detected in the five samples.The data presented here show that some sites contain sea-surface microlayer which can be toxic to marine fish embryos: that Baltic herring and Atlantic cod embryos respond similarly to the toxic effects of contaminated microlayer: and that unextracted microlayer and hexane extract of microlayer produce essentially the same toxic effect(s) if only organic contaminants are considered. 相似文献
14.
Gui-Peng Yang Maurice Levasseur Sonia Michaud Michael Scarratt 《Marine Chemistry》2005,96(3-4):315-329
Sixteen surface microlayer samples and corresponding subsurface water samples were collected in the western North Atlantic during April–May 2003 to study the distribution and cycling of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) and the factors influencing them. In the surface microlayer, high concentrations of DMS appeared mostly in the samples containing high levels of chlorophyll a, and a significant correlation was found between DMS and chlorophyll a concentrations. In addition, microlayer DMS concentrations were correlated with microlayer DMSPd (dissolved) concentrations. DMSPd was found to be enriched in the microlayer with an average enrichment factor (EF) of 5.19. However, no microlayer enrichment of DMS was found for most samples collected. Interestingly, the DMS production rates in the microlayer were much higher than those in the subsurface water. Enhanced DMS production in the microlayer was likely due to the higher concentrations of DMSPd in the microlayer. A consistent pattern was observed in this study in which the concentrations of DMS, DMSPd, DMSPp (particulate) and chlorophyll a in the microlayer were closely related to their corresponding subsurface water concentrations, suggesting that these constituents in the microlayer were directly dependent on the transport from the bulk liquid below. Enhanced DMS production in the microlayer further reinforces the conclusion that the surface microlayer has greater biological activity relative to the underlying water. 相似文献
15.
Recurrent climate‐induced mass mortality episodes have been recorded in the Mediterranean Sea over the past 15 years, affecting rocky benthic communities. In this study, we provide for the first time a report on the annual mortality events of benthic sessile invertebrates occurring in the eastern part of the Adriatic Sea. Over the course of 14 consecutive years, we studied the sea temperature gradient to a depth of 40 m and found an abnormal summer warming trend and an increased frequency of above‐average temperatures. Mortality events were recorded in the summers of 10 observed years, in particular in 2009, when the highest mortality rates were recorded. Late in summer 2009, extensive mass mortality of sessile invertebrates was observed in the entire Eastern Adriatic Sea. We performed an analysis of selected target benthic species associated with mass mortality events with inter‐regional differences in hydrological and temperature conditions. We were able to characterize the mortality event by studying five areas covering the northern, central and southern regions of the Eastern Adriatic Sea. The degree of impact on each study area was quantified at 28 sites by estimating the proportion of affected target species. According to the obtained data, the northern sites (Cres area) were the least affected, whereas sites in the Central and Southern Adriatic [Tela??ica and Lastovo Nature Parks, Mljet National Park (NP)] displayed the highest impact. In summer 2009, sea surface temperatures reached values of 28 °C in the Cres area and 30 °C in Mljet NP. These thermal conditions were concomitant with moderate to severe mass mortalities of benthic populations. Mass mortality events reached depths of 45 m in most parts of the affected areas. Amongst studied species, the scleractinian coral and gorgonian populations suffered the most extensive damage during the mass mortality events. 相似文献
16.
Copper complexing ligand concentrations in the Daya Bay, Qingdao coast, Jiaozhou Bay, South China Sea and Huanghe Estuary waters were determined by the anodic stripping voltammetry technique. The distribution regularity and the relationship with other parameters were discussed. The results were as follows： Copper complexing ligand concentrations of the South China Sea were a little higher than those of other sea areas, and they were apparently higher than those of the ocean. Compared with the subsurface layer （SSL） in the sea surface microlayer copper complexing ligand concentrations showed an enrichment phenomenon, of which the mechanism is similar to dissolved organic matter. The metal complexing ligand concentration profiles of the South China Sea showed that the value in the sea surface was the highest, then it decreased with depth accruing, and a higher value appeared at the bottom. Copper complex- ing ligand concentrations were higher than those of cadmium and lead. Ligands in each sea area exhibited a complicated property. In short, the distribution regularity of copper complexing ligand concentrations in China＇s coastal waters was consistent with that of other regions in the world. Meanwhile, the positive relationship between the copper complexing ligand concentrations and biological oxygen demand, chemical oxygen demand, dissolved organic carbon, and viscosity were found clearly. 相似文献
17.
Copper complexing ligand concentrations in the Daya Bay, Qingdao coast, Jiaozhou Bay, South China Sea and Huanghe Estuary waters were determined by the anodic stripping voltammetry technique. The distribution regularity and the relationship with other parameters were discussed. The results were as follows: Copper complexing ligand concentrations of the South China Sea were a little higher than those of other sea areas, and they were apparently higher than those of the ocean. Compared with the subsurface layer (SSL) in the sea surface microlayer copper complexing ligand concentrations showed an enrichment phenomenon, of which the mechanism is similar to dissolved organic matter. The metal complexing ligand concentration profiles of the South China Sea showed that the value in the sea surface was the highest, then it decreased with depth accruing, and a higher value appeared at the bottom. Copper complexing ligand concentrations were higher than those of cadmium and lead. Ligands in each sea area exhibited a complicated property. In short, the distribution regularity of copper complexing ligand concentrations in China' s coastal waters was consistent with that of other regions in the world. Meanwhile, the positive relationship between the copper complexing ligand concentrations and biological oxygen demand, chemical oxygen demand, dissolved organic carbon, and viscosity were found clearly. 相似文献
18.
Coastal and oceanic surface microlayer samples were collected using a stainless steel screen, along with subsurface bulk seawater, and were analyzed for low-molecular-weight (LMW) carbonyl compounds, including formaldehyde, acetaldehyde, propanal, glyoxal, methylglyoxal, glyoxylic acid and pyruvic acid. The enrichment factor in surface microlayer compared to corresponding subsurface seawater ranged from 1.2 to 21. A time-series measurement at a coastal site showed strong diurnal variations in concentrations of the LMW carbonyl compounds in the surface microlayer and in the enrichment factor, with maxima in the early afternoon and minima in the early morning. Exposure of samples to sunlight resulted in the higher yields of these compounds in the surface microlayer than in the bulk seawater, by a factor of 1.1–25, suggesting that the higher photoproduction rate of LMW carbonyl compounds in the surface microlayer accounts for the majority of the observed enrichment in these samples. Potential sinks include biological uptake and mixing. Air-sea exchange may be a source for soluble compounds and a sink for less soluble compounds. The enrichment of the LMW carbonyl in surface microlayer may alter their net air-sea exchange direction e.g., from the ocean as a potential sink to a source for atmospheric acetaldehyde and acetone. The residence times of the LMW carbonyl compounds in the microlayer were estimated to be on the order of tens of seconds to minutes using a modified two-layer model. However, to maintain the observed microlayer enrichment factor, the residence time should be on the order of ˜ 1 hour. This prolonged residence time may be due to organic enrichment in the surface microlayer (‘organic film’) which inhibited molecular transfer of carbonyl compounds into and out of the microlayer. The deviated behavior from model prediction may also be due to changes in the apparent partition coefficients of these species as a result of thier physical and chemical interactions with organic matrix in the surface microlayer. 相似文献
19.
Biogeochemistry of Dimethylsulfoniopropionate (DMSP) in the Surface Microlayer and Subsurface Seawater of Funka Bay,Japan 总被引：1，自引：0，他引：1
Twenty-eight sea surface microlayer samples, along with subsurface bulk water samples were collected in Funka Bay, Japan during October 2000–March 2001 and analyzed for dimethylsulfoniopropionate, dissolved (DMSPd) and particulate (DMSPp), and chlorophyll a. The aim of the study was to examine the extent of enrichment of DMSP in the microlayer and its relationship to chlorophyll a, as well as the production rate of dimethylsulfide (DMS) from DMSP and the factors that influence this. The enrichment factor (EF) of DMSPd in the surface microlayer ranged from 0.81 to 4.6 with a mean of 1.85. In contrast, EF of DMSPp in the microlayer varied widely from 0.85–10.5 with an average of 3.21. Chlorophyll a also appeared to be enriched in the microlayer relative to the subsurface water. This may be seen as an important cause of the observed enrichment of DMSP in the microlayer. The concentrations of DMSPp in the surface microlayer showed a strong temporal variation, basically following the change in chlorophyll a levels. Moreover, the microlayer concentrations of DMSPp were, on average, 3-fold higher than the microlayer concentrations of DMSPd and there was a significant correlation between them. Additionally, there was a great variability in the ratios of DMSPp to chlorophyll a over the study period, reflecting seasonal variation in the proportion of DMSP producers in the total phytoplankton assemblage. It is interesting that the production rate of DMS was enhanced in the microlayer and this rate was closely correlated with the microlayer DMSPd concentration. Microlayer enrichment of chlorophyll a and higher DMS production rate in the microlayer provide favorable evidence supporting the view that the sea surface microlayer has a greater biological activity than the underlying water. 相似文献
20.
Alexander Theocharis Efstathios Balopoulos Soterios Kioroglou Harilaos Kontoyiannis Athanassia Iona 《Progress in Oceanography》1999,44(4):1
Four seasonal oceanographic cruises were carried out in the Eastern Mediterranean Sea, within the framework of the CEC/MAST-MTP Project PELAGOS, during 1994–1995. The surveys covered the South Aegean Sea and the adjacent open sea regions (southeastern Ionian, northwestern Levantine). Analysis of CTD data revealed that a multiscaled circulation pattern prevails in the area. It differs from the circulations detected during the 1986–87, thus indicating interannual variability. Cyclonic and anticyclonic gyres and eddies are interconnected by currents and jets variable in space and time. Most of the features are persistent, others seem transitional or recurrent. The hydrological structure is also complex and apart from the upper layer does not present basinwide any significant seasonality. Dynamical and hydrological regimes are variable in the upper and intermediate layers at the Straits of the Cretan Arc, while the deep regime seems rather constant. Topographic control is evident on the flows through the straits. The new very dense deep water mass, namely the Cretan Deep Water (CDW) and a well-defined intermediate layer of minimum temperature and salinity, the so-called Transition Mediterranean Water (TMW), consists the new important structural elements of the South Aegean Sea. The CDW outflows towards the deep and bottom layers of the Eastern Mediterranean, thus considerably contributing to the formation of the new, denser Deep and Bottom Water of the Eastern Mediterranean, which sinks and displaces the Eastern Mediterranean Deep Water of Adriatic origin in the adjacent sea regions outside the Aegean Sea. 相似文献