Analysis of Yellow Sea low-frequency current variation

Low frequency (LF) current (period>25 hour) variation at 5 stations in Jiaozhou Bay. Shijiousuo, and the central part of the Yellow Sea were studied by analyzing the observed long-period current data series in the study area.1) There are obvious periods of 3 and 5 days in the LF current spectra. The energy spectral value of LF current of a 5 day period is remarkably larger than that of a 3 day period. These periods reflect the correlations between the LF current variation and the LF water level variation.2) The feet that the 15-day period in the LF current spectra corresponds to the semi-monthly celestial tide period indicates that the tide-induced residual current is an important and most evident LF current component in the bay.3) The LF current spectral energy density in the northward direction is much larger than that in the eastward direction. This shows the frequency and strength of the wind field in the northward direction are evidently larger than that in the eastward direction.     

Geochemistry of re and trace elements in ferromanganese nodules and their genesis

Trace and RE element geochemistry and genesis have been studied with respect to ferromanganese nodules from the sediments of the Pacific, Atlantic and Indian oceans.     

Bioreactor technology for production of valuable algal products

INTRODUCTIONManystudiesonvascularplantSduringthenontwperiodhavedrireP0redinChinaandabroad.TherearefeWreportSonwhethertherearesomevasctilarplantS,andhowmanyspedessurvive,underice,andontheirbiomassesandphotosyntheticproduCtivitiesduringwinter,espedal1yduringbeAfpinchLillyamepe0ylenctal.,l976,Liuetal.,l994).WeimtlycarriedoutaseadriontheunderforvascularplantsdurinwinderinsomewaterbodieswherevascularplantSgrowluxdrianhydurinInildareonsinnorthemareas,soastoimproveourknowedgeofvascularplaflt…     

Characteristics of organic geochemistry of sediments in the northern part of the South Huanghai Sea

It is known that the organic matter in the upper layer of sediments gets lost fast, but not in the South Huanghai Sea (Yellow sea). Some of the major characteristics of organic geochemistry of sediments in the South Huanghai Sea can be summarized as follows:1. The contents of organic carbon and bitumen increase with the decrease in grain size.2.Loss of organic matter is closely related to grain size but less so in clay sediments.3.The contents of bitumen and hydrocarbon are low, about n ×102 ppm for bitumen and n ×10 ppm for hydrocarbon.A scattered show of organic matter does not necessarily indicate the presence of petroleum in recent marine sediments.In research into the genesis of petroleum, people pay more attention to the study of the organic geochemistry of recent marine sediments. How much organic materials was lost during the deposition up to the diagenesis ? The problem is as important as the study on the transformation of organic matter. This study on the organic geochemistry of the sediment     

Palynological assemblages from the holocene sediments of the Changjiang (Yangtze) River Delta and its implications

The palynolpgical study on the Quaternary sediments of 42 cores in the region of the Yangtze River Delta and the sections of 4 relics had been done since 1960. Palynological assemblages from the region of the Yangtze River Delta, showing obviously .common characteristics but with slight differences because of the vast areas covered, can be divided into five spores and pollen zones and three subzones in ascendant order:I.Quercus alienc-Pinus-Cupressaceae-Chenopodiaceae spores and pollen zone reflecting the cool, then cold and dry climate--Preboreal.II.Quercus dentata-Quefcus acutissima-Pinus-Castanea-Artemisia spores and pollen zone reflecting the temperate and cool, but a little dry climate--Boreal.III.Quercus glauca-Caslanopsis-Myrica-Caslanea spores and pollen zone reflecting the hot and moist climate--Atlantic.IV.Quercus acutissima-Pinus-Castanea-Quercus glauca- Chenopodiaceae spores and pollen zone reflecting the warm, and a little dry climate--Subboreal.V.Quercus acutissima-Costarica-Quercus glauca     

Distribution and migration of the common squidTodarodes pacificus in the Yellow Sea

Study of the distribution and migration of the common squid,Todarodes pacificus Steenstrup,basedon the index of important fishing ground(P) and fisheries statistics on the Yellow Sea and northern EastChina Sea during 1980—1991 showed that:1.Its catch in the fishing period(June to November) is 91.77% of the annual yield.The fishingground distributes over the northem and middle Yel1ow Sea and adjacent area of the Changjiang Estuary.2. It over-winters in the northem East China Sea and waters adjacent to Goto Island from De-cember to February and spawns in waters near Haijiao Is1and and west of Kyushu. The main stock mi-grates along 123°30′E to the ChangJiang Estuary, Haizhou Bay. offsea from Shidao to Qingdao,mideastern Yellow Sea, and offsea Weihai and Haiyang Island succesively for feeding after April. The sur-plus stock migrates again to the wintering ground in December.3.The favorable feeding temperature is 6-23℃(optimum of l3-20℃ in the Changjiang Estua-ry and 7-13℃ in the northern and middle Yel     

Chemical mass transfer from the Changjiang River to the sea

1. The nonanthropogenic SO₄ in the Changjiang River stems from weathering and oxidation of sulphate and sulphite minerals, while the anthropogenic SO₄ here is attributed to acid rain containing H₂SO₄ formed by atmospheric sulphur oxides derived from the burning of fossil fuels in the region of the lower reaches. Ca and Mg are probably derived from weathering of carbonate minerals, but possibly less from weathering of silicate minerals.
2. The Changjiang River estuary is characterized by two—layer flow based on the salinity section of the estuary, so a model of two—layer exchange of water—body in the Changjiang River estuary can be advanced.
3. The presence of SO₄ and K at stations H₁₄ and H₁₅ were found most likely to be due to the addition and removal processes, that of the other major consituents may be mainly controlled by physical mixing in this estuary.

     

An approach to the transgressive sedimentary pattern of the present continental shelf

On the basis of our study of the present sediments in the northern part of the continental shelf of the South China Sea, this article clarifies our views that a "three-zone pattern" is the basic feature of transgression-type sedimentation.The classification of transgression-type sedimentation of the present continental shelf is based on: the close relationships between the formation of the present continental shelf and the position of the low sea level of the Wiirrn glacial stage, the genetic types and environmental features of sedimentary zoning, the relationship between the formation of glauconite with different maturity and the migration of coastline, the speed of transgression, and the overlying speed of sedimentation. We put forward the genetic name of the "three-zone pattern" to denote:1.The inner zouu, river mouth-coastal current sedimentary area;2.The intermediate zone, coastal current-sea current scouring-sedimentary area;3.The outer zone, sea current scouring area.All these are of significance     

Vertical zonation of horticultural farming in the Alaknanda basin of Garhwal Himalaya, India

Introduction In the Alakananda Basin, undulating terrain constitutes the most fragile elements of the ecosystem. Traditional economy rests on the terraced cultivation with extremely limited viability to expansion and modernization. Consequently, low economic return remains the characteristic feature of the agrarian landscape. It is the common experience that the ecological conditions of the basin are more suited to fruit cultivation rather than cereal farming (Atkinson 1889). Along with frui…     

The internal hydrographic structure of the Huanghai cold water mass (HCWM) in summer

The deep and bottom water within the Huanghai Cold Water Mass (HCWM) in summer was, for a long time, considered as a homogeneous body of water. Various investigations in recent years showed this may not be true.After a detailed analysis of the most recently obtained refined CTD data and other historical hydrographic data at our disposal, some significant results have been obtained.1.It is definitely shown that the Huanghai Warm Current (HWC) did not enter the HCWM in summer. However, there exist two types of second class water masses within the HCWM in summer. They are: (1) a water mass with low temperature and low salinity, which was formed in the preceding winter by a vertical mixing process locally, and (2) a water mass of relatively high temperature and high salinity, which is the remanent body of the HWC that entered the HCWM in preceding seasons, but was completely cut off from its source in summer. The spreading of these two water masses, the existence of a frontal zone at the boundary of the two     

Cadmium flux and genotoxicity in an experimental marine food chain

Cadmium flux through a lab food chain (Phaeodactylum tricornutum Bohlin- Penaeus orientate Kishinouye- Hexagrammos otakii Jordan et Starks) and its genotoxicity were investigated. The results are as follows:1. High doses of cadmium (>0.003 mol / L) induced flocculation and quick precipitation of Phaeodactylum tricornutum; lower doses of cadmium could be adsorbed on and absorbed by P. tricornutum without delaying its growth. Cadmium concentrations in algae increased with dosage, and cadmium ions removed from the medium were in proportion to dosage. In vivo chelation and organizable combination of absorbed cadmium ions by metabolites of P. tricornutum can be considered as bio-detoxification.2. Cadmium concentration decreased in the transfers from P. tricornutum to P. orientalis and from the latter to H. otakii. Transfer coefficient of cadmium in the first flux was 66.6% and 29.9% in the second. Results of t tests showed that mutagenicity of ashed internal organs of experimental prawns was significantly hi     

Secondary metabolites of a deep sea derived fungus Aspergillus versicolor CXCTD-06-6a and their bioactivity

In order to obtain novel secondary metabolites, a deep sea inhabiting fungus Aspergillus versicolor CXCTD-06-6a was investigated. One new diketopiperazine brevianamide W(1a), as well as five known diketopiperazine alkaloids, diketopiperazine V(1b), brevianamide Q(2), brevianamide R(3), brevianamide K(4), and brevianamide E(5), were isolated from the Et OAc extract of the fermentation broth. Their structures were elucidated by spectroscopy techniques(NMR, MS). The six compounds exhibited moderate radical scavenging activity against DPPH with clearance ratio of 55.0%(1a and 1b), 53.7%(2), 46.2%(3), 61.4%(4) and 19.3%(5) at a concentration of 13.9 μmol L-1, respectively; while the positive control ascorbic acid showed a ratio of 70.3% at the concentration of 28.4 μmol L-1.     

Effects of Anthropogenic Disturbance on Sediment Organic Carbon Mineralization Under Different Water Conditions in Coastal Wetland of a Subtropical Estuary

The changes in soil organic carbon(C) mineralization as affected by anthropogenic disturbance directly determine the role of soils as C source or sink in the global C budget. The objectives of this study were to investigate the effects of anthropogenic disturbance(aquaculture pond, pollutant discharge and agricultural activity) on soil organic C mineralization under different water conditions in the Minjiang River estuary wetland, Southeast China. The results showed that the organic C mineralization in the wetland soils was significantly affected by human disturbance and water conditions(P 0.001), and the interaction between human disturbance activities and water conditions was also significant(P 0.01). The C mineralization rate and the cumulative mineralized carbon dioxide-carbon(CO_2-C)(at the 49th day) ranked from highest to lowest as follows: Phragmites australis wetland soil aquaculture pond sediment soil near the discharge outlet rice paddy soil. This indicated that human disturbance inhibited the mineralization of C in soils of the Minjiang River estuary wetland, and the inhibition increased with the intensity of human disturbance. The data for cumulative mineralized CO_2-C showed a good fit(R~2 0.91) to the first-order kinetic model C_t = C_0(1 – exp(–kt)). The kinetic parameters C_0, k and C_0 k were significantly affected by human disturbance and water conditions. In addition, the total amount of mineralized C(in 49 d) was positively related to C_0, C_0 k and electrical conductivity of soils. These findings indicated that anthropogenic disturbance suppressed the organic C mineralization potential in subtropical coastal wetland soils, and changes of water pattern as affected by human activities in the future would have a strong influence on C cycling in the subtropical estuarine wetlands.     

Effects of nitrogen specification and culture method on growth of Enteromorpha prolifera

Eutrophication, which is the enrichment of a water mass with inorganic and organic nutrients that support plant growth, is a key factor in stimulating phytoplankton growth. In this study, we determined the effects of various nitrogen sources, different nitrogen concentrations in the culture medium, and two culture methods on the growth of the green alga, Enteromorpha prolifera. The relationship between the specific growth rate of E. prolifera and NO3--N concentration was consistent with that estimated using the Monod equation (R2 = 0.9713, P < 0.01). In the NO3--N medium, the maximum specific growth rate was calculated to be 0.1634/d and the semi-saturation constant was calculated to be 16.86 μmol/L. Our results show that E. prolifera can effectively utilize NH4+-N, NO3--N, and NO2--N and urea-N in the range of 5 to 50 μmol/L. NH4+-N was preferentially assimilated by E. prolifera, and urea-N was favorable for long-term growth.     

Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192,an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa,resulted in the isolation of nine known secondary metabolites,including four indole-diterpenoids:penijanthine A(1),paspaline(2),paspalinine(3),and penitrem A(4);three tricycloalternarene derivatives:tricycloalternarene 3a(5),tricycloalternarene 1b(6),and tricycloalternarene 2b(7);and two alternariol congeners:djalonensone(8) and alternariol(9).The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature.The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum,with inhibition zone diameters of 8 and 9 mm,respectively,at 100 μg/disk.To the best of our knowledge,this is the first report on the secondary metabolites of mangrove-derived Alternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus Alternaria.     

Chemical profile of the secondary metabolites produced by a deep-sea sediment-derived fungus Penicillium commune SD-118

Bioassay-guided fractionation of the crude extract from Penicillium commune SD-118, a fungus obtained from a deep-sea sediment sample, resulted in the isolation of a known antibacterial compound, xanthocillin X (1), and 14 other known compounds comprising three steroids (2-4), two ceramides (5 and 6), six aromatic compounds (7-12), and three alkaloids (13-15). Xanthocillin X (1) was isolated for the first time from a marine fungus. In the bioassay, xanthocillin X (1) displayed remarkable antimicrobial activity against Staphylococcus aureus and Escherichia coli, and significant cytotoxicity against MCF-7, HepG2, H460, Hela, Du145, and MDA-MB-231 cell lines. Meleagrin (15) exhibited cytotoxicity against HepG2, Hela, Du145, and MDA-MB-231 cell lines. This is the first report of the cytotoxicity of xanthocillin X (1).     

Screening and isolation of the algicidal compounds from marine green alga <Emphasis Type="Italic">Ulva intestinalis</Emphasis>

Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae Heterosigma akashiwo and Prorocentrum micans. Inhibitory effects of fresh and dried tißsues of green alga Ulva intestinalis were assessed and the main algicidal compounds were isolated, purified, and identified. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/mL of U. intestinalis dissolved in media significantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate (EtOAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/mL, respectively, were fatal to H. akashiwo, while its water and EtOAc extracts in excess of 0.96 and 0.32 mg/mL, respectively, were lethal to P. micans. Three algicidal compounds in the EtOAc extracts were identified as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid (I), (6E,9E,12E)-(2-acetoxy-β-D-glucose)-octadecatrienoic acid ester (II) and hexadecanoic acid (III). Of these, compound II displayed the most potent algicidal activity with IC₅₀ values of 4.9 and 14.1 µg/mL for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC₅₀ values of 13.4 and 24.7 µg/mL for H. akashiwo and P. micans, respectively. These findings suggested that certain macroalgae or products therefrom could be used as effective biological control agents against red tide algae.     

Biodeposition,respiration, and excretion rates of an introduced clam <Emphasis Type="Italic">Mercenaria mercenaria</Emphasis> in ponds with implications for potential competition with the native clam <Emphasis Type="Italic">Meretrix meretrix</Emphasis> in Shuangtaizi estuary,China

This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of M. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates of M. mercenaria were 0.06–0.37 g/ (ind.·d), and the respiration rates were 0.31–14.66 mg/(ind.·d). The ammonia and phosphate excretion rates were 0.18–36.70 and 1.44–14.87 μg/(ind.·d), respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1×10⁵ t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10³ t O₂ from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food if M. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.     

Effect of dry density on the liquefaction behaviour of Quaternary silt

Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt (dry density ρ_d=1.460 g/cm³) and dense silt (ρ_d=1.586 g/cm³) under different cyclic stress ratios (CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure (EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the “fast-stable” and “fast-gentle-sharp” growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.