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1.
The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved (DMSPd) and particulate fractions (DMSPp) were determined in the seasurface microlayer and corresponding subsurface water of the Jiaozhou Bay, China and its adjacent area in May and August 2006. The concentrations of all these components showed a clear seasonal variation, with higher concentrations occurring in summer. This can be mainly attributed to the higher phytoplankton biomass observed in summer. Simultaneously, the enrichment extents of DMSPd and DMSPp in the microlayer also exhibited seasonal changes, with higher values in spring and lower ones in summer. Higher water temperature and stronger radiant intensity in summer can enhance their solubility and photochemical reaction in the microlayer water, reducing their enrichment factors (the ratio of concentration in the microlayer to that in the corresponding subsurface water). A statistically significant relationship was found between the microlayer and subsurface water concentrations of DMS, DMSP and chlorophyll a, demonstrating that the biogenic materials in the microlayer come primarily from the underlying water. Moreover, our data show that the concentrations of DMSPp and DMS were significantly correlated with the levels of chlorophyll a, indicating that phytoplankton biomass might play an important role in controlling the distributions of biogenic sulfurs in the study area. The ratios of DMS/chlorophyll a and DMSPp/chlorophyll a varied little from spring to summer, suggesting that there was no obvious change in the proportion of DMSP producers in the phytoplankton community. The mean sea-to-air flux of DMS from the study area was estimated to be 5.70 μmol/(m2·d), which highlights the effects of human impacts on DMS emission.  相似文献   

2.
The thermal entanglement of a two-qutrit spin-1 anisotropic Heisenberg XXZ chain in an inhomogeneous magnetic field is studied in detail. The effects of the external magnetic field (B), a parameter b which controls the inhomogeneity of B, and the bilinear interaction parameters Jx=Jy≠Jz on the thermal variation of the negativity are studied in detail. It is found that negativity N decreases when the values of magnetic field, inhomogeneity b and temperature are increasing. In addition, N remains at higher temperatures for higher values of Jz and lower values of B and b.  相似文献   

3.
Vortex-shedding flow induced by the vertical oscillation of a cylinder with bottom-attached disks of different diameter ratio Dd/Dc and thickness ratio td/Dc is studied by a 3D (three-dimensional) numerical model developed in this paper, and compared with the results obtained through 2D (two-dimensional) numerical model. The high-order upwind scheme is applied to stabilize the computation, and convergence is accelerated by the multi-grid method. Qualitative and quantitative analyses of the differences between the 2D and 3D simulation results reveal the 3D effect on the flow field characteristics and hydrodynamic coefficients of the vertically oscillating cylinder with a bottom-attached disk. The 3D effect on the fluid field is mainly reflected in the significance of three vortex-shedding patterns: ωx has a greater effect on the flow fields around the sharp edges relative to the vortices generated in the 2D simulation. In the slice along the axial orientation, the vortex effect of ωy along the radial axis is smaller than that of ωx along the circumferential direction, indicating the radial effect on the velocity more pronounced than the circumferential effect around the sharp edges of the disk. The rotational interaction ωz of the fluid in the horizontal plane during the heave motion is insignificant. Based on the 2D and 3D simulation results, the turning points that separate the increasing regimes of the added mass coefficient and damping ratio are identified. The dependence of the turning point on the diameter ratio Dd/Dc and thickness ratio td/Dc are discussed in detail.  相似文献   

4.
Soft computing tools in the form of combination of multiple nonlinear regression and M5'' model tree were used for estimation of overtopping rate at the vertical coastal structures. For reliable and precise estimation of overtopping rate, the experimental data available in the database CLASH were used. The dimensionless overtopping rate was estimated in terms of conventional dimensionless parameters including the relative crest freeboard Rc/Hs, seabed slope tanθ, deep water wave steepness Som, surf similarity ξom and local relative water depth ht/Hs. The accuracy of the new model was compared with other existing models and also evaluated with some field measurements. The results indicated that the model presented in this paper is more accurate than other existing models. With statistical parameters, it is shown that the accuracy of predictions in the new model is better than that of other models.  相似文献   

5.
This study examines wave interactions with multiple semi-immersed Jarlan-type perforated breakwaters. A numerical model based on linear wave theory and an eigenfunction expansion method has been developed to study the hydrodynamic characteristics of breakwaters. The numerical results show a good agreement with previous analytical results and experimental data for limiting cases of double partially immersed impermeable walls and double and triple Jarlan-type breakwaters. The wave transmission coefficient CT; reflection coefficient CR, and energy dissipation coefficient CE coefficients and the horizontal wave force exerted on the front and rear walls are examined. The results show that CR reaches the maximum value when B/L = 0.46n while it is smallest when B/L=0.46n+0.24 (n=0, 1, 2,...). An economical triple semi-immersed Jarlan-type perforated breakwater can be designed with B/L = 0.25 and CR and CT ranging from 0.25 to 0.32 by choosing a relative draft d/h of 0.35 and a permeability parameter of the perforated front walls being 0.5 for an incident wave number kh nearly equal to 2.0. The triple semi-immersed Jarlan-type perforated breakwaters with significantly reduced CR, will enhance the structure’s wave absorption ability, and lead to smaller wave forces compared with the double one. The proposed model may be used to predict the response of a structure in the preliminary design stage for practical engineering.  相似文献   

6.
Four indexes of species diversity (H''), species richness (d), species evenness (J) and species dominance (D2) are used in this paper to analyse the.characteristics of the benthic faunal community structure in the soft-bottom intertidal zone along the northern coast of the Hang-zhou Bay.The results show a rather simple benthic faunal community structure in the survey area, with the average values of the four indexes from the five transects, namly, H''=2.06, d=3.34, J=0.46 and D2=0.73.Different degrees of the seasonal and regional variations have been observed from each index per transect.  相似文献   

7.
During CREAMS expeditions, fCO2 for surface waters was measured continuously along the cruise tracks. The fCO2 in surface waters in summer varied in the range 320–440 μatm, showing moderate supersaturation with respect to atmospheric CO2. In winter, however, fCO2 showed under-saturation of CO2 in most of the area, while varying in a much wider range from 180 to 520 μatm. Some very high fCO2 values observed in the northern East Sea (Japan Sea) appeared to be associated with the intensive convection system developed in the area. A gas-exchange model was developed for describing the annual variation of fCO2 and for estimating the annual flux of CO2 at the air-sea interface. The model incorporated annual variations in SST, the thickness of the mixed layer, gas exchange associated with wind velocity, biological activity and atmospheric concentration of CO2. The model shows that the East Sea releases CO2 into the atmosphere from June to September, and absorbs CO2 during the rest of the year, from October through May. The net annual CO2 flux at the air-sea interface was estimated to be 0.032 (±0.012) Gt-C per year from the atmosphere into the East Sea. Water column chemistry shows penetration of CO2 into the whole water column, supporting a short turnover time for deep waters in the East Sea. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
The purpose of this study was to investigate the accumulation behavior of two typical PAHs,phenanthrene(PHE) and fluoranthene(FLA),uptaken by the mangrove Kandelia candel in various treated sandy soils.The experiment lasted for three months.Soil and plant samples were collected after 3,6,9 and 13 weeks of the incubation and the levels of PAHs were analyzed using a GC/MS(HP6890-5975B).The results showed that the root accumulations of PHE and FLA were elevated with the increase of the PAH concentrations in the soil.With prolonged exposure time,PHE and FLA concentrations of the roots increased significantly in comparison with the control.PHE and FLA concentrations of root after 13 weeks of treatment ranged from 0.28 to 4.36 μg·g-1 and 0.79 to 35.76 μg·g-1,respectively.The calculated mean values of the root concentration factors were 0.58 for PHE and 0.71 for FLA.This indicated that root accumulation of FLA was greater than PHE,which would result from the higher octanol-water partition coefficient(Kow) of FLA.These results underline the ability of mangroves to remove PAHs from contaminated marine substrates and hence their potential use in bioremediation and the removal of PAHs from the marine food chain.  相似文献   

9.
Concentration and stable isotopic compositions (δ 18O) of dissolved O2 were measured in seawater samples collected from the Philippine Sea in June 2006. The in-situ O2 consumption rate and the isotopic fractionation factor (α r ) during dissolved O2 consumption were obtained from field observations by applying a vertical one-dimensional advection diffusion model to the deep water mass of about 1000–4000 m. The average O2 consumption rate and α r were, respectively, 0.11 ± 0.07 μmol kg−1yr−1 and 0.990 ± 0.001. These estimated values agree well with values from earlier estimations of Pacific deep water. The in-situ O2 consumption rates are two or more times higher north of 20°N, although the value of α r was not significantly different between the north and south. Its levels varied rapidly in the water mass of less about 2000 m depth. These results suggest that organic matter from the continent imparts a meaningful contribution to the upper water in the northern part of the area; it might produce the strong O2 minimum that is evident in the water mass from about 1000–2000 m in the northern part of the Philippine Sea.  相似文献   

10.
The performance of the “version 2” Global Imager (GLI) standard atmospheric correction algorithm, which includes empirical absorptive aerosol correction and sun glint correction, was evaluated using data collected with handheld above-water SIMBADA radiometers during 23 cruises of opportunity (research vessels, merchant ships), mostly in the North Atlantic and European seas. A number of 100 match-up data sets of GLI-derived and SIMBADA-measured normalized water-leaving radiance (nL W ) and aerosol optical thickness (AOT) were sorted out, using objective selection criteria, and analyzed. The Root-Mean-Square (RMS) difference between GLI and SIMBADA nL W was about 0.32 μW/cm2/nm/sr for the 412 nm band, showing improvement by 30% in RMS difference with respect to the conventional “version 1” GLI atmospheric correction algorithm, and the mean difference (or bias) was reduced significantly. For AOT, the RMS difference was 0.1 between GLI estimates and SIMBADA measurements and the bias was small (a few 0.01), but the ?ngstr?m exponent was systematically underestimated, by 0.4 on average, suggesting a potential GLI calibration offset in the near infrared. The nL W differences were not correlated to AOT, although performance was best in very clear conditions (AOT less than 0.05 in the 865 nm band). Despite the relatively large scatter between estimated and measured nL W , the derived chlorophyll-a concentration estimates, applying the same ratio algorithm (GLI OC4V4) to GLI and SIMBADA, were consistent and highly correlated in the range of 0.05–2 μg/l. The large variability in chlorophyll-a concentration estimate for clear clean water areas (e.g. with the concentration range lower than about 0.05 μg/l) turns out to be due to the nature of the “band ratio” based in-water algorithm.  相似文献   

11.
本研究对成年雄性孔鳐(Okamejei kenojei)的生殖系统进行解剖学和组织学观察,结果表明,孔鳐的生殖系统主要由精巢、附睾、输精管、储精囊、间质腺、鳍脚腺和鳍脚组成。其中孔鳐的精巢中的精小囊,按照成熟度依次由中心向小叶外周辐射状排列,其精子发育成熟过程根据精巢支持细胞的位置、精小囊的大小和精小囊中的生精细胞所处的状态可划分为7个时期:精巢支持细胞未迁移期、精巢支持细胞迁移期、精巢支持细胞定植早期、精巢支持细胞定植晚期、精子变形期、精子迁移期、精子聚拢期。变态成熟的精子最终每59~64根精子组成精子束进入附睾。精子束在附睾中经历“游离-聚拢-游离”3个过程后,最终储存在储精囊中。鳍脚是孔鳐的外生殖器,主要有鳍扇、扇盾等结构组成,它与储精囊相连,是将精液输送至体外的器官。  相似文献   

12.
泥蚶、缢蛏和僧帽牡蛎呼吸与排泄的周年变化   总被引：1，自引：1，他引：0  
于2005年5月至2006年3月对浙江沿岸重要的3种经济贝类泥蚶、缢蛏和僧帽牡蛎的呼吸率与排泄率进行了周年研究。结果表明:泥蚶、缢蛏和僧帽牡蛎耗氧率的变化范围分别为0.11~5.05 mg/（g·h）、0.77~5.97 mg/（g·h）和0.33~5.47 mg/（g·h）,排氨率的变化范围分别为21.51~1 078.63 μg/（g·h）,26.97~990.73 μg/（g·h）和32.12~1 378.67 μg/（g·h）;耗氧率与排氨率9月份最高,1月份最低。经单因素方差分析发现,3种实验贝类月际间的耗氧率与排氨率均存在极显著差异（p<0.01）,经配对T检验发现,缢蛏（SC）和僧帽牡蛎（SCA）之间的耗氧率存在着显著差异T（SC-SCA）=3.184,p=0.024）,泥蚶（TG）与缢蛏、僧帽牡蛎的耗氧率之间都不存在差异（T（TG-SC）=1.887,p=0.118;T（TG-SCA）=0.246,p=0.815）,泥蚶、缢蛏和僧帽牡蛎之间的排氨率的差异均不显著（T（TG-SC）=0.977,p=0.373;T（TG-SCA）=2.369,p=0.064;T（SC-SCA）=1.002,p=0.362）。3种贝类的耗氧率与排氨率均随温度的升高而升高,经回归分析发现,耗氧率和排氨率与温度的变化均呈较显著的幂指数性相关lnY=lna+blnT（Y=aebT）。泥蚶呼吸排泄O:N变化范围为4.69~28.55,缢蛏和僧帽牡蛎的O:N变化范围分别为:4.68~37.89和3.04~10.27。  相似文献   

13.
微藻固碳是一种新型节能减排技术，具有长期可持续发展的潜力。本文对两株富油微藻（球等鞭金藻和微拟球藻）进行了富碳培养下生长特性及中性脂积累特性的研究。两株富油微藻的最佳培养条件为10%CO2浓度和f培养基。本研究对两株富油微藻的最大生物量产率、总脂含量、最大油脂产率、微藻的C含量和CO2固定率进行了测定。球等鞭金藻的各参数指标分别为：142.42±4.58g/（m2·d），39.95%±0.77%，84.47±1.56g/（m2·d），45.98%±1.75%和33.74±1.65g/（m2·d）。微拟球藻的各参数指标分别为：149.92±1.80g/（m2·d），37.91%±0.58%，89.90±1.98g/（m2·d），46.88%±2.01%和34.08±1.32g/（m2·d）。实验结果显示，两株海洋微藻均属于高固碳优良藻株，适合应用于微藻烟气减排技术开发，具备用于海洋生物质能耦合CO2减排开发的潜力。  相似文献   

14.
余为  陈新军  易倩 《海洋学报》2016,38(2):64-72
海洋初级生产力在海洋生态中扮演重要角色,其变化影响了海洋渔业的潜在产量。本文根据2004-2013年中国鱿钓组提供的西北太平洋柔鱼(Ommastrephes bartramii)捕捞数据和海洋遥感净初级生产力数据,研究了柔鱼冬春生西部群体资源量变动与净初级生产力的关系。结果发现,柔鱼渔场范围内净初级生产力在经度方向上呈明显的季节性变化,冬春季低,夏秋季高。捕捞月份7-11月对应的适宜净初级生产力范围分别为500~700 mg/(m2·d)(以碳计),500~800 mg/(m2·d),500~1000 mg/(m2·d),500~800 mg/(m2·d)和300~500 mg/(m2·d),最适净初级生产力分别为700 mg/(m2·d),600 mg/(m2·d),700 mg/(m2·d),600 mg/(m2·d)和400 mg/(m2·d)。7-11各月最适净初级生产力平均纬度与捕捞努力量纬度重心呈显著正相关关系(P<0.05),说明了捕捞努力量位置在渔场中不是随机分布,可能受最适净初级生产力的纬度分布的影响。柔鱼年间资源丰度与各年3月份净初级生产力以及7-11月份平均净初级生产力大小显著正相关(P<0.05)。推测每年柔鱼资源量大小可能是由3月份产卵场海域和7-11月捕捞月份渔场净初级生产力水平交互作用的结果。研究表明,异常环境条件(厄尔尼诺和拉尼娜事件)对柔鱼产卵场和渔场的净初级生产力具有显著影响,但调控机制不同。  相似文献   

15.
To investigate the effects of a polychlorinated biphenyl (PCB) mixture (Aroclor 1254) on reproductive neuroendocrine function, male Atlantic croaker (Micropogonias undulatus) were exposed to the PCB mixture in the diet (0.1 mg/100. g body wt/day) for 30 days during gonadal recrudescence. Concentrations of the monoamines (5-hydroxytryptamine (5-HT), dopamine (DA) and norepinephrine (NE)) and their major metabolites (5-hydroxyindolacetic acid, dihydroxyphenylacetic acid and 3-methoxytyramine) were measured in the preoptic-anterior hypothalamus (POAH) and medial and posterior hypothalamus (MPH) using HPLC with electrochemical detection. There was a significant decline in 5-HT and DA concentrations and an increase in their metabolite to parent amine ratios in both the POAH and MPH of Aroclor 1254-exposed fish. In addition, Aroclor 1254 exposure resulted in the loss of the in vitro gonadotropin (GtH) response to stimulation by a luteinizing hormone-releasing hormone analog (LHRHa). The reduced availability of 5-HT in the nerve terminals may be responsible for the loss of pituitary GtH response to stimulation by LHRHa. These results support the hypothesis that Aroclor 1254-induced alterations in pituitary gonadotropin release may be mediated, at least partially, by altered hypothalamic serotonergic activity.  相似文献   

16.
The biomass and size fraction of phytoplankton in terms of chlorophyll a(Chl a) was measured during four cruises conducted in April, July, October 2013 and January 2014 in mariculture area, the Sanggou Bay, China.Results show that total Chl a levels in the surface seawater of the Sanggou Bay generally range from 0.10 to 20.46μg/L, with an average value of 2.13 μg/L. Nano-phytoplankton was the most important size-fraction and accounted for about 65.1% of total Chl a. In order to evaluate the importance of the "protozoan trophic link" for energy transfer from the microbial loop to filter-feeding feeders, Zhikong scallop Chlamys farreri was then offered a natural planktonic community as potential prey. Results show that scallops obtained carbon source from natural plankton with the rate of 11 033.05 μg/(g·d). Protists(nanoflagellates and ciliates) were the dominant source of carbon retained by scallop(48.78%). The microbial loop provided 58.45% of the carbon source for farmed scallops. These results indicate that the microbial loop represent a valuable trophic resource in mariculture system of the Sanggou Bay.  相似文献   

17.
刘勇  孙耀  唐启升 《海洋学报》2006,28(6):139-143
在实验室大型玻璃钢水槽中,流水条件下投喂两种不同颗粒大小的卤虫,采用Eggers模型比较了黄海、渤海主要中上层小型鱼类玉筋鱼的摄食、生长和生态转换效率等生态能量学特征.结果表明:投喂颗粒小的幼体卤虫的排空率比投喂颗粒大的成体卤虫的大,分别为0.2136,0.1887.摄食小颗粒幼体卤虫的玉筋鱼的摄食率、生长率和生态转换效率分别为22.53g/(100g·d)(湿质量)或60.14kJ/(100g·d),3.63g/(100g·d)(湿质量)或14.86kJ/(100g·d),16.12%(以湿质量计)或24.70%(以能量计);而摄食大颗粒成体卤虫的玉筋鱼的摄食率、生长率和生态转换效率分别为27.54g/(100g·d)(湿质量)或51.69kJ/(100g·d),4.77g/(100g·d)(湿质量)或19.50(kJ/100g·d),17.31%(以湿质量计)或37.69%(以能量计).摄食成体卤虫的湿重比摄食幼体卤虫的多,而摄食幼体卤虫所含能量比成体卤虫的高;从玉筋鱼的生长情况来看,成体卤虫投喂的效果明显优于幼体卤虫,不管是用湿重还是用能含量来表示,摄食成体卤虫的生长都比摄食幼体的快,摄食成体的生态转化效率也都比摄食幼体的要高.  相似文献   

18.
人工参礁在中国刺参(Apostichopus japonicus (Selenka))养殖业中被广泛应用,本文调查了2008年春、秋季刺参池塘中一种塑料人工礁表面的生物群落结构.采用沉积物捕捉器的方法调查了刺参池塘人工礁表面碳、氮、磷的循环及参礁的生态特征.结果表明,春季礁体底栖动物生物量及生物多样性高于秋季,底栖动物均集中在礁体外表面的缝隙内,4月礁体表面颗粒物,底泥沉积物总有机碳(TOC)平均含量分别为41.9 mg/g 和2.45 mg/g;总氮(TN)平均含量分别为4.1 mg/g 和0.2 mg/g.10月礁体表面颗粒物,底泥沉积物 TOC 含量分别为27.5 mg/g 和3.1 mg/g; TN 平均含量分别3.1 mg/g 和0.3 mg/g.4月 TOC, TN 沉积量分别达到711.2 mg/(m2·d)和70.7 mg/(m2·d);10月 TOC, TN 沉积量分别为804.9 mg/(m2·d)和87.3 mg/(m2·d).4月人工礁表面叶绿素/脱镁叶绿素(Chl a/Pheophytin)>1,表明礁体活体藻类较多.10月人工礁表面 Chl a/Pheophytin<1表明礁体表面降解颗粒物质较多.人工礁为刺参提供遮蔽场所,其表面生物膜为刺参提供优质食物,同时可增加池塘底面积,增强养殖系统稳定性.  相似文献   

19.
为了探究盐度和氨氮对方斑东风螺生理代谢的影响,本文采用实验生态学方法,研究了不同盐度和氨氮浓度条件下方斑东风螺(Babylonia areolata)的存活以及能量收支变化。结果显示,方斑东风螺的存活率随着盐度上升呈现先上升后下降的趋势,当盐度为25和30时,方斑东风螺的存活率为100%,低盐96hLC50为10.14,高盐为44.36;方斑东风螺存活率随氨氮浓度上升逐渐下降,当氨氮质量浓度为0~20mg/L时,存活率均为100%;氨氮96hLC50为253.83mg/L。盐度和氨氮对方斑东风螺的摄食率、排粪率、耗氧率和排氨率均具有显著影响(P<0.05)。盐度实验中,方斑东风螺的摄食率、排粪率和排氨率在盐度30时达到最大值,分别为20.50、8.62和0.07mg/(g·h),耗氧率在盐度35时达到最大值,为1.84mg/(g·h)。氨氮实验中,摄食率和排粪率在10mg/L时达到最大值,分别为23.58和10.42mg/(g·h),耗氧率和排氨率在20mg/L时达到最大值,分别为2.49和0.13mg/(g·h)。通过能量收支方程发现,随着盐度和氨氮浓度的上升,方斑东风螺生长能占比均呈现先上升后下降的趋势,其在盐度30和氨氮浓度5mg/L时达到最大值。本研究首次从能量收支角度出发,探讨了盐度和氨氮对方斑东风螺生理代谢的影响,可为其工厂化养殖提供参考。  相似文献   

20.
温度对墨西哥湾扇贝耗氧率及排泄率的影响   总被引：63，自引：2，他引：61       下载免费PDF全文
于1996年12月至1997年1月在实验室内研究了温度对墨西哥湾扇贝(Argopecten irradians concentricus)的耗氧率和排泄(NH4-N)率的影响,实验在投饵后6h,静水(盐度32)条件下进行,溶氧量和氨氮量分别采用Winkler滴定法和次溴酸盐氧化法测定.实验结果表明,在实验温度(10～31℃)条件下,不同规格(壳高1.6～4.8cm,软体部干重0.0342～0.6908g)的墨西哥湾扇贝耗氧率的总平均值为2.35mg/(g·h).排泄率总平均值为350.89μg/(g·h).墨西哥湾扇见的耗氧量和排氧量都与扇贝体重呈明显的幂函数关系.在10～28℃范围内,不同规格的扇贝耗氧率都随温度的升高而增加;当水温继续升高到31℃时,耗氧率反而下降.在实验温度(10～31℃)条件下,扇贝的排泄率随着温度的升高而增加,温度对墨西哥湾扇贝的耗氧率和排泄率的影响都可用指数方程表示.本实验证实,高温(31℃)将进一步提高墨西哥湾扇贝蛋白质的代谢水平.耗氧量(O)和排氨量(N)与温度(t)、扇贝软体部干重(W)二元线性回归方程分别为:O=-587.804+36.787t+1697.864W;N=-92.344 9+4.534 1t+276.781 8W.复相关系数r分别为0.880 6和0.8035 ; F检验表明,两个回归方程均极显著(F>F0.01).  相似文献   

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