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1.
The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sedi- ment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollu-tion and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel elec- trophoresis （DGGE） techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually en-hanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and con- sequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation.  相似文献   

2.
Polyphenols from the ethanol extracts of Sargassum tenerrimum （ST） with potent antiallergic effects were studied to optimize separation process through column chromatography. The adsorption and desorption characteristics of three widely used adsorbents： macroporous resin, silica gel, and polyvinylpolypyrrolidone （PVPP）, were critically evaluated respectively and studied for the optimization of preparative separation of polyphenols. Static operations on these adsorbents showed that macroporous resin had the best adsorption and desorption capability among the three adsorbents. Dynamic adsorption and desorption with macroporous resin packed column were also conducted to optimize the parameters such as： with the optimal values shown in brackets, the concen- tration of extract solution （4 times diluted）, pH value （6-7）, adsorption speed （3BVh-1, bed volumes/per hour）, concentration of ethanol （80%）, elution speed （3 BV ht） and elution volume （7 BV）. The chromatographic process so optimized gave a purity of 62.43% from the crude polyphenols, providing a promising basis for large scale preparation of bioactive polyphenols upon further scaling up tests.  相似文献   

3.
Optimal stocking densities were investigated for the sea cucumber Apostichopusjaponicus Selenka under feed-supplement and non-feed-supplement regimes in net enclosures for 333 d. Substantial weight loss occurred during the aestivation phase （AE）. Decreased growth rates were also observed during the winter phase （WT）. In contrast, sea cucumbers showed rapid growth during the spring （SP） and autumn （AU） phases. Feeding regimes considerably influenced the growtb performance, i.e., sea cucumbers grew faster under feed-supplement regime than under non-feed-supplement regime （P 〈 0.05）. The average survival rates of sea cucumbers under feed-supplement regime were higher than those under non-feed-supplement regime for both the autumn phase and spring phase, but the differences were only significant for the latter phase （P〈 0.05）. The fitted B-N curves showed that the optimal stocking densities, in terms of net production, were 22.3 ind. m^-2 for feed-supplement regime and 14.1 ind. m^-2 for non-feed-supplement regime.  相似文献   

4.
The toxic effects of benzo[α]pyrene （B[α]P） at different concentrations （0.1, 0.5, 1, 2.5 and 7.5 μgL^-1） on scallop （Chlamys farreri） immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity （P〈0.05）, while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL^-1·B[α]P decreased significantly （P〈0.05）. Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]E Bactenolytic activity in 0.1 μgL^-1 B[α]P treatment group and antibacterial activity in 0.1 ggLl and 0.5 μgL^-1 B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group （P〈0.05）, except for antibacterial activity in 0.1 μgLl B[α]P treatment group （P〉0.05）. Thus, B[α]P has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and lmmunomodulation in aquatic organisms.  相似文献   

5.
Autumn photoproduction of carbon monoxide in Jiaozhou Bay,China   总被引：1，自引：0，他引：1  
Carbon monoxide(CO) plays a significant role in global warming and atmospheric chemistry. Global oceans are net natural sources of atmospheric CO. CO at surface ocean is primarily produced from the photochemical degradation of chromophoric dissolved organic matter(CDOM). In this study, the effects of photobleaching, temperature and the origin(terrestrial or marine) of CDOM on the apparent quantum yields(AQY) of CO were studied for seawater samples collected from Jiaozhou Bay. Our results demonstrat that photobleaching, temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The concentration, absorbance and fluorescence of CDOM exponentially decreased with increasing light dose. Terrestrial riverine organic matter could be more prone to photodegradation than the marine algae-derived one. The relationships between CO AQY and the dissolved organic carbon-specific absorption coefficient at 254 nm for the photobleaching study were nonlinear, whereas those of the original samples were strongly linear. This suggests that: 1) terrestrial riverine CDOM was more efficient than marine algae-derived CDOM for CO photoproduction; 2) aromatic and olefinic moieties of the CDOM pool were affected more strongly by degradation processes than by aliphatic ones. Water temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The photoproduction rate of CO in autumn was estimated to be 31.98 μmol m-2 d-1 and the total DOC photomineralization was equivalent to 3.25%- 6.35% of primary production in Jiaozhou Bay. Our results indicate that CO photochemistry in coastal areas is important for oceanic carbon cycle.  相似文献   

6.
Acila divaricata （Hinds, 1843） and A. mirabilis （Adams and Reeve, 1850） are common benthic bivalves in China. A number of researchers have proposed that the latter species is a junior synonym of the former species. Because of morphological similarities, it is difficult to distinguish these two species based on visual examination only. For better understanding of their taxon-omy, the mitochondrial CO1 gene fragments of five individuals of A. divaricata from the East China Sea and six individuals of A. mirabilis from the Yellow Sea were sequenced in this study. The phylogenetic relationships of the obtained COI sequences, together with nineteen sequences of three species of the genus Nucula, were analyzed. The pairwise intra- and inter-specific distances for the CO1 sequences ranged from 0.002 to 0.017 and from 0.128 to 0.134, respectively, and no overlap was found. Phylogenetically, A. divaricata and A. mirabilis form distinct clades and cluster into a sister to all other Nucula species. The results indicated that A. di-varicata and A. mirabilis are two distinct species. The differences in the morphology and distribution between the two species were briefly discussed.  相似文献   

7.
The increasing riverine pollutants have resulted in nutrient enrichment and deterioration of water quality in the coastal water of Guangxi Province, China. However, the quantitative relationship between nutrient loads and water quality responses, which is crucial for developing eutrophication control strategies, is not well studied. In this study, the riverine fluxes of nutrients were quan- tified and integrated with nutrient cycling and phytoplankton dynamics by using box models for Guangxi coastal bays. The model concepts and biogeochemical equations were the same; while most model parameters were specific for each bay. The parameters were calibrated with seasonal observations during 2006--2007, and validated with yearly averaged measurements in 2009. The gen-eral features of nutrient and phytoplankton dynamics were reproduced, and the models were proved feasible under a wide range of bay conditions. Dissolved inorganic nitrogen was depleted during the spring algal bloom in Zhenzhu Bay and Fangcheng Bay with relatively less nutrient inputs. Phosphorus concentration was high in spring, which decreased then due to continuous phytoplankton consumption. Chlorophyll-a concentration reached its annual maximum in summer, but was the minimum in winter. Eutrophication was characterized by both an increase in nutrient concentrations and phytoplankton biomass in Lianzhou Bay. Either about 80% re-duction of nitrogen or 70% reduction of phosphorus was required to control the algal bloom in Lianzhou Bay. Defects of the models were discussed and suggestions to the environmental protection of Guangxi coastal bays were proposed.  相似文献   

8.
The study of artificial slope stability has been a key item of geological engineering projects. Though more evaluation methods are available, result of stability evaluation simulation does not explain the actual problem owing to the diversified geological engineering factors and complexity. The author made a detailed study based on surveys of large amount of geological engineering research on Donggang Power Plant slope project, discussed the comprehensive factors influencing the project, and gave analytical calculation and evaluation to the improved response surface of the slope project. The study result shows that the slope is stable, which can provide scientific basis for designing the slope.  相似文献   

9.
Different culture methods may affect the intensive culture system of Pacific white shrimp （Litopenaeus vannamei） re- garding water quality and growth and economic performance. This study evaluated the potential effects of three culture methods through cultivation of juvenile shrimps under consistent tank management conditions for 84 d. The three methods involved shrimp cultivation in different tanks, i.e., outdoor tanks with cement bottom （mode-C）, greenhouse tanks with cement bottom （mode-G） and outdoor tanks with mud-substrate （mode-M）. Results showed that water temperature was significantly higher in mode-G than that in mode-C （P 〈 0.05）. In contrast to the other two treatments, mode-M had stable pH after 50 d cultivation of shrimps. In the mid-late period, the average concentrations of TAN, NO2-N, DIP and COD were significantly lower in mode-M and mode-G compared with those in mode-C （P 〈0.05）. Despite lack of differences in the final shrimp weight among different treatments （P 〉0.05）, mode-M had significantly higher shrimp yield, survival rate and feed conversion rate （P 〈 0.05） than other modes. There were significant dif- ferences in revenue and net return among different treatments （P 〈 0.05）. These demonstrated that the treatments of mode-G and mode-M were conductive to the intensive culture system ofL. vannamei.  相似文献   

10.
An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.  相似文献   

11.
Inducing lipid accumulation in microalgae cells without suppressing cell growth is vital to the economical production of biodiesel from microalgae. In two experiments, we demonstrate that the cell concentration and lipid content of marine microalgae Isochrysis galbana depend upon the iron concentration in the growth media. In Experiment I, adding chelated FeCl 3 to the medium at the late exponential growth phase prolonged this phase and increased the lipid content in I. galbana cells. The fi nal cell density and lipid content of I. galbana supplemented with chelated FeCl 3 was approximately 2 and 1.65 times higher than that of non-supplemented cultures, respectively. In Experiment II, I. galbana cells in the late exponential phase were collected and re-inoculated into new media containing Fe 3+ at various concentrations. The fi nal cell concentration and lipid content were maximized at the highest iron concentration(38% biomass by dry weight at 1.2×10-5 mol/L Fe 3+). In this study, intracellular neutral lipid storage was evaluated by fl uorescent spectrophotometry using fl uorochrome Nile red, and the measurement conditions were optimized.  相似文献   

12.
The generalized linear model （GLM） and generalized additive model （GAM） were applied to the standardization of catch per unit effort （CPUE） for Chilean jack mackerel from Chinese factory trawl fishing fleets in the Southeast Pacific Ocean from 2001 to 2010 by removing the operational, environmental, spatial and temporal impacts. A total of 9 factors were selected to build the GLM and GAM, i.e., Year, Month, Vessel, La Nifia and E1 Nifio events （ELE）, Latitude, Longitude, Sea surface temperature （SST）, SST anomaly （SSTA）, Nino3.4 index and an interaction term between Longitude and Latitude. The first 5 factors were significant components in the GLM, which in combination explained 27.34% of the total variance in nominal CPUE. In the stepwise GAM, all factors explained 30.78% of the total variance, with Month, Year and Vessel as the main factors influencing CPUE. The higher CPUE occurred during the period April to July at a SST range of 12-15℃ and a SSTA range of 0.2-1.0℃. The CPUE was significantly higher in normal years compared with that in La Nifia and E1 Nifio years. The abundance of Chilean jack mackerel declined during 2001 and 2010, with an increase in 2007. This work provided the relative abundance index of Chilean jack mackerel for stock as- sessment by standardizing catch and effort data of Chinese trawl fisheries and examined the influence of temporal, spatial, environ- mental and fisheries operational factors on Chilean jack mackerel CPUE.  相似文献   

13.
As an important marginal sea under the influences of both the Changjiang River and the Kuroshio, the East China Sea （ECS） environment is sensitive to both continental and oceanic forcing. Paleoenvironmental records are essential for understanding the long-term environmental evolution of the ECS and adjacent areas. However, paleo-temperature records from the ECS shelf are currently very limited. In this study, the U^K_37 and TEX86 paleothermometers were used to reconstruct surface and subsurface temperature changes of the mud area southwest of the Cheju Island （Site F10B） in the ECS during the Holocene. The results indicate that temperature changes of F 10B during the early Holocene （11.6-6.2 kyr） are associated with global climate change. During the period of 6.2-2.5 kyr, the similar variability trends of smoothing average of AT （the difference between surface and subsurface temperature） of Site F10B and the strength of the Kuroshio suggest that the Kuroshio influence on the site started around 6.2kyr when the Kuroshio entered the Yellow Sea and continued to 2.5 kyr. During the late Holocene （2.5-1.45 kyr）, apparent decreases of U^K_37 sea surface temperature （SST） and AT imply that the direct influence of the Kuroshio was reduced while cold eddy induced by the Kuroshio gradually controlled hydrological conditions of this region around 2.5 kyr.  相似文献   

14.
In order to determine the role of alginate-derived oligosaccharides （ADO） in drought stress resistance of tomato （Lycopersicon esculentum Miller） seedlings, the leaves were exposed to different concentrations of ADO （0.05%, 0.10%, 0.20%, 0.30% and 0.50%） after drought stress was simulated by exposing the roots to 0.6molL^-1 PEG-6000 solution for 6h. Changes in biomass, electrolyte leakage and malondialdehyde （MDA）, free proline, total soluble sugars （TSS） and abscisic acid （ABA）, the enzyme activities of catalase （CAT）, superoxide dismutase （SOD）, peroxidase （POD） and phenylalanine ammonia-lyase （PAL） were measured to investigate the effects of ADO treatment. The results showed that the treatment with an ADO concentration of 0.20% exhibited the highest performance of drought stress resistance in the tomato seedlings by decreasing the electrolyte leakage and the concentration of MDA, increasing the contents of free proline, TSS and ABA, and increasing the activities of CAT, SOD, POD and PAL after treatment with ADO. It is suggested that changes in electrolyte leakage, MDA, osmotic solutes, ABA, anti-oxidative enzyme and PAL activities were responsible for the increased drought stress resistance in tomato seedlings. To our best knowledge, this is the first report of the effect of ADO treatment on enhancing the drought stress resistance of tomato seedlings.  相似文献   

15.
The nitrogen(N) and phosphorus(P) budget and the ecological efficiency of a polyculture system of sea cucumber(Apostichopus japonicus), jellyfish(Rhopilema esculenta) and shrimp(Fenneropenaeus chinensis) were studied in a cofferdam, 120.2 ha in size. The nutrients were supplied by spring tide inflow. In total, 139600 kg N yr-1 and 9730 kg P yr-1 input to the system; while 118900 kg N yr-1 and 2840 kg P yr-1 outflowed from the system concurrently, thus the outflow was 85.7%(N) and 29.2%(P) of inflow. The production of N and P was 889.5 kg yr-1 and 49.28 kg yr-1(sea cucumber) and 204 kg yr-1 and 18.03 kg yr-1(jellyfish and shrimp), respectively. The utilization rate of N and P by polycultured animals was 7.8‰ and 6.9‰, respectively, 21.9% and 38% higher than that of monocultured sea cucumber. Our results indicated that the polyculture system was an efficient culture system of animals and a remediation system of coastal environment as well; it scavenged 14.3% and 70.8% of N and P, respectively. Such an ecological efficiency may be improved further by increasing either the stocking density or the size of sea cucumber or both.  相似文献   

16.
Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and pro- teins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions.  相似文献   

17.
In this study we assessed the current status of coral reefs along the Saudi Arabian coast of the Red Sea. Among the three growth forms of Acroporid corals, the branching forms were found to dominate in the Farassan Islands （44.55%±11.10% cover） fol-lowed by tabular forms in the Doga Islands （ranging between 18%±6.47% and 18.30%±9.47% cover）. Digitate forms were rarely found along the coast except at Maqna. Among the five growth forms of non-Acroporid corals, we observed maximum cover of branching forms in the Yanbu offshore area （58.89%±15.11% cover） followed by the Jeddah coast （24.76%±14.04% cover）. The Millepora spp., a non-Scleractinian coral, was abundant at all the near-shore sites, such as Jeddah （10.70%±8.21%） and A1-Wajh （9.81%±6.69%）. The live coral cover （including both Scleractinian and non-Scleractinian corals） of Saudi Red Sea coast was seen to be higher in the north and gradually decrease towards the south. Principal Component analysis showed that the contribution of Acro- porid corals was greater in the southern region than in the northem and middle regions, but vice-versa in the case of non-Acroporid corals. Bray-Curtis cluster analysis categorized all the study sites into two major clusters with 60% similarity. Among them, one cluster-forming sites from Maqna to Masturah （Northem region） and the second one comprised the middle and southem regions （Jeddah to Farassan Islands）, and one outlier Rabigh.  相似文献   

18.
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19.
According to topography of Yemen, most areas and villages are located at obligated crest, toe of mountain and under cliffs. Therefore Al-Huwayshah consisting of Tawilah sandstone group is characterized by steep slope reach to 90℃ in some areas. This area is affected by strong tectonic movements and faults that occurred during the geological epochs. This effect enhances to find out fractures and joints as well as the rocks become brittle and ready to slide depending on the position of area. And there are some fractures and joints on the surface of the areas due to tectonic movement associated with opening the Red Sea and Gulf of Aden. The rainfalls, fractures, joints, earthquakes, gravity, vegetations, temperatures and human activities play a big role in the processes of rockfalls and landslides in this area. All those factors are considered as the basic causes and catalyzed factors for occurrence of rockfall in the studide area. In addition, the authors carried out laboratory test for many rock samples to get the physical properties of the rocks.  相似文献   

20.
For sustainable water resource management,it is important to determine the relationship between streamfl ow and other variables that infl uence availability of water resources.However,many catchments do not have suffi cient data to allow for a more detailed study of these relationships.We faced a similar challenge in the Chengcun Basin(limited historical data: from 1986–1999); and therefore we used a new approach to overcome this.We found that,using nonparametric trend methods in conjunction with the climate elasticity analyses and the 2D visualization of hydrologic data,it is possible to assess the relationships between streamfl ow and other hydro-climatic variables.In the past,streamfl ow trends in the basin were more correlated with precipitation than with potential evapotranspiration(PET).In addition,there is a gradual shift in the hydrological regime of the catchment,which may affect the occurrence of available water resources and activities that depend on them.In addition,based on our climate sensitivity analyses,the streamfl ow is dependent and more sensitive to variations in precipitation than to PET(δQ=0.79δP+0.42δE; precipitation elasticity,ε P=1.32; PET elasticity,ε E=-2.10).Therefore pending more detailed studies,the use of our approach will provide a rapid means to assess the variation of water resources(streamfl ow)in a watershed.In the future,we hope to carry out related research in other watersheds and also perform a more detailed studies to improve upon the results of this study.  相似文献   

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