Can salt marsh plants influence levels and distribution of DDTs in estuarine areas?

Sediments are depositories of toxic substances such as organochlorine pesticides and there is a global need for their removal in contaminated environments. Studies that combine contaminated sediments and phytoremediation are relatively recent and their number has been increasing. This work aimed to investigate whether salt marsh plants (sea club-rush Scirpus maritimus, sea rush Juncus maritimus and sea purslane Halimione portulacoides) can favor DDT and metabolites remediation in estuarine environment. For this purpose the levels of DDT, DDE and DDD were compared in vegetated and non-vegetated sediments from an estuary in the North of Portugal (in-situ study) and from another in the South of Portugal (ex-situ study). Results obtained both in the in-situ study, involving S. maritimus and J. maritimus, and in the ex-situ study, involving H. portulacoides, indicated that these plants did not have a significant role in DDTs removal and/or degradation. Therefore, it seems that the tested plants cannot influence levels and distribution of DDTs in estuarine areas.     

Particulate n-alkanes and fatty acids in the Changjiang river system

Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream.     

Studies on the absorption and utilization of amino acids in the test diets by the prawn Penaeus orientalis

This experiment was conducted to study the characteristics of absorption of amino acids by different regions of the alimentary tract and the utilization of free amino acids in the test diets of the prawn, Penaeus oricntolis.The midgut gland is the principal site of nutrient absorption. In the foregut, the digestibility coefficient of 15 amino acids tested accounted for 52.5% of the total digestibility coefficient in the entire alimentary tract. In the midgut, the digestibility coefficient was 47.5 % of the total. There was no evidence of the hindgut assimilating amino acids.The free amino acid in the test diet, methionine, was almost absorbed before entering the midgut. Methionine could not be absorbed synchronously with other amino acids bound in the dietary protein, but it did affect the synchronization of other essential amino acids. [3H]-lysine, incorporated into the test diet, was almost totally assimilated within the midgut gland. Five and a half hours after feeding, the labelled amino acid had be     

Particulate amino acids in Wadden Sea waters — seasonal and tidal variations

Particulate amino acids (THAA) were measured in the East Frisian Wadden Sea at monthly intervals from February to December 1995. Each time two tidal cycles were sampled at hourly intervals. THAA made up between 3 and 50% (mean 15±7%) of the particulate organic carbon and between 9.3 and 104% (mean 49±20%) of the total nitrogen pools. Seasonal variations of THAA followed the development of phytoplankton in the water column while tidal variability was controlled largely by physical forcing such as tidal current velocities and wave action. The overall molar composition of the THAA pool appears to be dominated by a detrital signal originating from erosion of surface sediments.     

Fatty acids associated with the frustules of diatoms and their fate during degradation—A case study in Thalassiosira weissflogii

Diatoms are major actors in the export of organic carbon out of the euphotic zone. Yet, the processes linking biogenic silica and carbon sedimentation fluxes to deep oceanic layers remain unclear. Analysing organic fractions in biominerals is challenging because efficient cleaning often led to structural alteration of organic molecules. Hence, although lipids are widely used as biogeochemical markers in ocean flux study, few studies have dealt with the lipids that are associated with frustules. In the present study, a protocol was set up to extract and quantify the fatty acids associated to the frustule of the diatom species Thalassiosira weissflogii. The protocol involves solvent extraction of diatom external lipids, followed by clean frustule dissolution by 4% NaOH during 1 h at 95 °C and subsequent solvent re-extraction of frustule-associated lipids. Results confirmed that this protocol was efficient first, to isolate the frustule from the rest of the cellular organic carbon and second to extract and quantify fatty acids (FA) associated to frustules of this species. FA composition of the frustules was significantly different from that of the whole cells consisting primarily of 14:0, 16:0 and 18:0 FA, as well as a smaller portion of 16:1 and 18:1 unsaturated FA. Frustule-associated FA constituted 7% of the total FA and 1.8% of the total POC. The 30 days T. weissflogii degradation/dissolution experiment suggested that frustule FA 14:0 and 16:0 were mainly associated with the bSiO₂ phase dissolving slowly as no degradation of this pool was measured despite 78% frustule dissolution. At the end of the degradation experiment, this pool constituted 5.8% of the remaining total POC suggesting an effective protection by the frustule through strong interaction with the biogenic silica which is consistent with the correlation observed at depth between Si and POC sedimentation fluxes.     

Seasonal responses of monthly mean sea levels in the Bohai Sea to hydrometeorological forcing and their double screening regression models

-In this paper, the maximum entropy spectral, the cross-spectral and the frequency response analyses are madeon the basis of the data of monthly mean sea levels at coastal stations in the Bohai Sea during 1965-1986. The results show that the annual fluctuations of the monthly mean sea levels in the Bohai Sea are the results of the coupling response of seasonal variations of the marine hydrometeorological factors. Furthermore, the regression prediction equation is obtained by using the double screening stepwise regression analysis method . Through the prediction test , it is proved that the obtained results are desirable.     

Determination of trophic levels of marine fish in the Yellow Sea and northern East China Sea using nitrogen stable isotope(δ15N)analysis of otoliths

Fish otolith δ15N(δ15Noto)is a demonstrated source of information of dietary history for marine fish as it is available in otolith archives and sedimentary depo...     

The air–water sloshing problem: Fundamental analysis and parametric studies on excitation and fill levels

The problem of liquid sloshing has gained recent attention with the proliferation of liquefied natural gas (LNG) carriers transporting liquids in partially filled tanks. Impact pressures caused by sloshing depend on the tank fill level, period and amplitude of oscillation of the tank. In this paper, we first present the rudiments of a linear potential theory for sloshing motions in a two-dimensional rectangular tank, due to small amplitude sway motions. Although this topic is fundamental, we clarify inconsistencies in the published literature and texts.Numerical investigations were carried out on the sloshing motions in a two-dimensional tank in the sway excitation. The fluid domain was modeled using a finite volume approximation, and the air–water interface was tracked using a volume-of-fluid (VOF) technique. Computational results for free surface elevation and impact pressure are found to be in good agreement with theory and published data. The fill levels were varied from 10% to 95%, and the excitation time periods were varied from 0.8 to 2.8 s for a constant sway amplitude of 0.25 m (peak–peak) at 1:30 scale. The results of the parametric study are compared with theoretical predictions and suggestions are made on incorporating sloshing effects in standard seakeeping analysis for LNG carriers.     

Effects of tributyltin at environmental levels on monooxygenase system of digestive gland in hard clam Meretrix meretrix

The effects on ethoxyresorufin O-deethylase (EROD), NADPH-cytochrome c reductase and NADH cytochrome b5 reductase activities of digestive gland in Meretrix meretrix exposed to tributyltin (TBT) at environmental levels (0.1,1.0, 10.0 ng/dm3 as stannum concentration), in experimental condition, were evaluated. The EROD, NADH cytochrome b5 reductase activities were significantly inhibited after exposure to 10.0 ng/dm3 TBT for 8 and 20 d, the NADPH cytochrome c reductase activities were significantly inhibited after exposure to 0.1,1.0 and 10.0 ng/dm3 TBT for 8 d and to 1.0 and 10.0 ng/dm3 for 20 d, as compared with the matched control, while NADH cytochrome b5 reductases and NADPH cytochrome c reductase activities were induced after exposure to 10.0 ng/dm3 TBT for 2 d. The EROD activity in the 10 ng/dm3 group, and the NADH cytochrome b5 reductases activities in 1.0 and 10.0 ng/dm3 groups, were significantly induced when transferred to clean recovery tanks for 7 d. The three enzymic activities in the clams exposed to TBT were recovered to the level corresponding to that of the control group after transfer to clean recovery tanks for 20 d. NADPH cytochrome c reductase activity in Meretrix meretrix seems to be more sensitive to exposure of TBT than that of the EROD and NADH cytochrome b5 reductases. The results suggest that induction and inhibition by TBT to the monooxygenase system enzymic activity in Meretrix meretrix would simultaneously exist. The enzymic activities were inhibited by exposure for a long time. The results suggest that inhibition of the monooxygenase system should be an indication of the exposure to environmentally relevant concentrations of TBT for a long time.     

Changes in serum thyroid hormone levels and thyroid gland activity of artificially maturing female Japanese eel(Anguilla japonica)

In order to evaluate the involvement of the thyroid gland in reproduction, thyroid functioning was described in female cultivated Japanese eel (Anguilla japonica) in progressive stages of sexual maturation induced by chum salmon pituitary homogenate (SPH) treatment. Serum thyroid hormones, thyroxine (T4) and triiodothyronine (T3) were also measured in each stage. Thyroid gland activity (epithelial cell height) was high before SPH injection (previtellogenic stage), further increasing at the early vitellogenic stage, thereafter decreasing to late vitellogenic and migratory nucleus stages. The profiles of both T3 and T4 changed during vitellogenesis, being high during previtellogenic and early vitellogenic stages, and subsequently declining, thus mimicking thyroid gland activity. These results suggest that the thyroid has relation with eel ovarian development during artificial maturation.     

Detection and assessment of cloud cover and precipitation parameters using data of scanning radiometers of polar–orbiting and geostationary meteorological satellites

Two multispectral threshold techniques have been developed and tested for the automatic classification of AVHRR/NOAA and SEVIRI/Meteosat-10 data. They provide day-and-night detection and the assessment of cloud-cover parameters, as well as the discrimination of precipitation zones and severe weather phenomena. The validation of output information products, which has been performed with ground-based conventional meteorological observations and radar data, as well as with independent satellite-based estimates of cloud cover and precipitation parameters, confirms the feasibility of developed techniques and reasonable accuracy of output products. Therefore, the technique is concurrent to those implemented in current foreign satellite centers.     

Dynamics of Sea Ice and Spectrum of Ice Force

Spectrum and self-excite characters are the two significant characters of the dynamics of sea ice. The spectrum character of sea ice is mainly shown by the spectrum of ice force. The spectrum character of the sea ice is its intrinsic attributes. When the spectrum of ice force from the dynamic response of ice and structure interaction are evaluated, the effect of dynamic character of the structure must be eliminated. In this paper, the ice force spectrum at Bohai Bay and Liaodong Bay is evaluated from the displacement and strain responses of a single degree and a multi-degree freedom structure. The evaluated ice force spectrum can be used to define the spectrum character of ice in the analysis of ice induced vibration.     

Oscillating Quaternary water levels of the Marmara Sea and vigorous outflow into the Aegean Sea from the Marmara Sea–Black Sea drainage corridor

Detailed interpretation of single-channel air-gun and deep-tow boomer profiles demonstrates that the Marmara Sea, Turkey, experienced small-amplitude (∼70 m) fluctuations in sea level during the later Quaternary, limited in magnitude by the sill depth of the Strait of Dardanelles. Moderate subsidence along the southern shelf and Quaternary glacio-eustatic sea-level variations created several stacked deltaic successions, separated by major shelf-crossing unconformities, which developed during the transitions from global glacial to interglacial periods. Near the Strait of Dardanelles, a series of sand-prone deposits are identified beneath an uppermost (Holocene) transparent mud drape. The sandy deposits thicken into mounds with the morphology and cross-sectional geometries of barrier islands, sand waves, and current-generated marine bars. All cross-stratification indicates unidirectional flow towards the Dardanelles prior to the deposition of the transparent drape which began ∼7000 years BP, in strong support of the notion that the Marmara Sea flowed westwards into the Aegean Sea through the Dardanelles at times of deglaciation in northern Europe. The global sea-level curve shows that, at ∼11,000 and ∼9500 years BP, sea level rose to the sill depths of the Straits of Dardanelles and Bosphorus, respectively. The effect from ∼11,000 to ∼9500 years BP was seawater incursion into the Marmara Sea, drowning and formation of algal-serpulid bioherms atop lowstand barrier islands, and transgression of shelves and lowstand deltas. At ∼9500 years BP, glacial meltwater temporarily stored in the Black Sea lake, developed into a vigorous southward flow toward the Aegean Sea, forming west-directed sandy bedforms in the western Marmara Sea and initiating deposition of sapropel S1 in the Aegean Sea. This strong outflow persisted until ∼7000 years BP, after which a mud drape began to accumulate in the Marmara Sea and euryhaline Mediterranean mollusks successfully migrated into a progressively more saline Black Sea where sapropel deposition began. Most eastern Mediterranean sapropels from S1 to S11 appear to correlate with periods of rising sea level and breaching, or near-breaching, of the Bosphorus sill. These events are believed to coincide with times of vigorous outflow of low-salinity (?fresh) surface waters transiting the Black Sea–Marmara Sea corridor, and ultimately derived from melting of northern European ice sheets.     

Distribution of dominant species and abundance of nannofossils in surface sediments of the central and northern parts of the South China Sea——Comparison and discussion

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Effects of tributyltin at environmental levels on monooxygenase system of digestive gland in hard clam Meretrix meretrix

The effects on ethoxyresorufin O-deethylase （EROD）, NADPH-cytochrome c reductase and NADH cytochrorne b5 reductase activities of digestive gland in Meretrix meretrix exposed to tributyltin （TBT） at environmental levels （0.1,1.0,10.0 ng/dm as stannum concentration）,in experimental condition, were evaluated. The EROD, NADH cytochrorne b5 reductase activities were significantly inhibited after exposure to 10.0 ng/dm^3 TBT for 8 and 20 d, the NADPH cytochrorne c reductase activities were significantly inhibited after exposure to 0.1,1.0 and 10.0 ng/dm TBT for 8 d and to 1.0 and 10.0 ng/dm for 20 d, as compared with the matched control, while NADH cytochrorne b5 reductases and NADPH cytochrome c reductase activities were induced after exposure to 10.0 ng/dm^3 TBT for 2 d. The EROD activity in the 10 ng/dm^3 group,and the NADH cytochrome b5 reductases activities in 1.0 and 10.0 ng/dm groups, were significantly induced when transferred to clean recovery tanks for 7 d. The three enzymic activities in the clams exposed to TBT were recovered to the level corresponding to that of the control group after transfer to clean recovery tanks for 20 d. NADPH cytochrome c reductase activity in Meretrix meretrix seems to be more sensitive to exposure of TBT than that of the EROD and NADH cytochrome b5 reductases. The results suggest that induction and inhibition by TBT to the monooxygenase system enzymic activity in Meretrix meretrix would simultaneously exist. The enzymic activities were inhibited by exposure for a long time. The results suggest that inhibition of the monooxygenase system should be an indication of the exposure to environmentally relevant concentrations of TBT for a long time.     

Observations and Estimations of Directional Spectrum of Sea Waves

The directional spectrum is one of the basic characteristics of sea waves. The observations of directional spectrum of sea waves were successfully conducted at platform Bohai 8 during 1991 and 1992 using a wave gage array for the first time in China. Based on the field data, the directional spectrum which depends on the wave growth is given in this paper. Before observations, the effects of the type of gage array, the distance between the gages and the platform itself on the measured results and the precision of some methods for estimating the directional spectrum were investigated and compared with the methods of numerical simulations and model tests of multi-direcitonal irregular waves. This ensures the quality of the observations and estimations of the directional spectrum.     

A study of anchoring geographic coordinates and calculating zenith and azimuth of sun and scanner for oceanic satellite data

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Construction and implementation of multisource spatial data management system of China''s coastal zone and offshore

To meet the increasing demand of national spatial database infrastructure construction and application, a concept model of China‘ s coastal zone scientific data platform is established based on the information feature analysis of a compound dataset, consisting of remote sensing data and conventional data. Based on this concept model, the detailed logical database structure and the storage strategy of remote sensing data and their metadata using ArcSDE are designed. The complicated technology of multisources data combination in this research is crucial to the future coastal zone and offshore database construction and practical running, which will provide intelligent information analysis and technological service for coastal zone and offshore investigation, research, development and management.     

Studies on the prevention and treatment of mycosis and ciliate disease of larval penaeid shrimp

This paper deals mainly with etiology, pathology, sympotomatology, harmfulness, preventive measures and treatment of larval mycosis (caused by Lagenidium sp. ) and of ciliate disease (caused by Zoothamnium sp. ) of penaeid shrimp larvae.