First documented southern transatlantic migration of a blue shark Prionace glauca tagged off South Africa     

《African Journal of Marine Science》2013,35(3):639-642

The first documented recapture of a South African-tagged juvenile blue shark Prionace glauca off Uruguay lends weight to the hypothesis of a single blue shark population in the South Atlantic. The presence of neonate blue sharks with umbilical scars and females with post-parturition scars, as well as the high frequency of small juveniles in research longline catches, confirm the existence of a parturition and nursery area off South Africa. The final positions of three tagged sharks suggest that large-scale movement patterns in the South Atlantic are a mirror image of movements in the North Atlantic, with sharks using the north-westerly Benguela Drift to migrate into the tropics and ultimately across into South American waters. The confirmed existence of a parturition and nursery area off the south coast of South Africa and the movement of sharks into both adjacent ocean basins suggest that the southern African blue sharks are part of a single stock that straddles the South Atlantic and Indian oceans, and possibly the entire Southern Hemisphere.  相似文献   

Insights into zooplankton‐cyanobacteria interactions derived from enclosure studies     

Carolyn W. Burns 《新西兰海洋与淡水研究杂志》2013,47(3):477-482

Few workers have used enclosures specifically to study interactions between zoo‐plankton and cyanobacteria. Differences among studies in enclosure size, nutrient level, plankton abundance and species composition, presence or absence of fish, and length of experiments make generalisations difficult. Zooplankton had no direct effect on the growth of ungrazed cyanobacteria (Anabaena flos‐aquae, Aphanizomenon flos‐aquae, large Microcystis colonies) in short‐term (<5 days) and long‐term (> 1 month) enclosure studies. When large cyanobacteria were abundant, some Daphnia spp. snowed reduced reproduction and development. When large grazers were abundant they suppressed the growth of edible, colonial cyanobacteria (Aphanizomenon elenkinii, small Microcystis colonies). By altering the ambient light and nutrient environment, large zooplankton may suppress cyanobacteria; evidence for the importance of grazers in promoting cyanobacterial dominance by removing competing phytoplankton species is equivocal. Zooplankton may suppress nitrogen fixation by cyanobacteria through ammonia excretion and may promote a change in dominance from diatoms to cyanobacteria through recycling phosphorus but not silicon.  相似文献   

Light‐dependence of photosynthesis and growth in cyanobacteria: Implications for their dominance in eutrophic lakes     

Max M. Tilzer 《新西兰海洋与淡水研究杂志》2013,47(3):401-412

In eutrophic lakes cyanobacteria are favoured relative to other phytoplankton, both under stratified and mixed conditions. During stratification, gas vacuole formation allows the accumulation of dense surface scums which attain the highest possible area‐specific photosynthetic rates in aquatic environments owing to high irradiances, near‐complete harvesting of impinging light, and minimal light inhibition and photo‐oxidation. During moderate mixing, high yields of biomass can be achieved by effective light harvesting for photosynthesis (aided by phycobilin pigments) and low maintenance energy requirements at low mean irradiances. Howevrr, nitrogen fixation competes for energy and reductant with photosynthesis, and leads to a decline of light‐saturated maximum growth rates. Wind‐driven vertical mixing and lateral advection are the main causes for the instability of cyanobacterial blooms in hyper‐eutrophic lake ecosystems.  相似文献   

磷锑钼蓝光度法测定红土镍矿中磷量          下载免费PDF全文

司银奎 《山东国土资源》2012,28(12):52-54

试样经烘干处理后,利用硫酸和氢氟酸溶矿,硝酸提取,加氨水以氢氧化铁为载体沉淀磷酸盐,分离镍、铬、钴、铜等干扰离子,制备成硝酸溶液。中和后,以钼酸铵—酒石酸锑钾为显色剂,以抗坏血酸为还原剂,显色,在700nm处测量吸光度,利用计算机拟合标准曲线计算磷含量。此方法精密度与加标回收率均能满足质量要求。  相似文献   

亚甲蓝分光光度法测定地下水中硫化物的水样保存方法   总被引：3，自引：1，他引：2  

董建芳  李义  冯锐  赵婕  禹海清 《岩矿测试》2012,31(5):868-871

硫化物是评价地下水污染的重要特征指标之一。为了使硫化物的测定结果更加准确可靠,在硫化物水样采集过程中通常加入乙酸锌溶液和氢氧化钠溶液作为固定剂,以抑制硫离子被氧化生成硫化氢从水样中逸出。但已有的标准方法和文献中对加入乙酸锌溶液和氢氧化钠溶液的顺序和加入量不尽相同,回收率范围为65%～108%。本研究采用亚甲蓝分光光度法测定地下水中的硫化物,考察了采样时乙酸锌溶液和氢氧化钠溶液的加入顺序和加入量对硫化物回收率的影响。结果表明,在采样过程中应先加1.0 mL乙酸锌溶液,再加500 mL水样,最后加入2.0 mL氢氧化钠溶液,其低浓度和高浓度加标水样的回收率达到94.2%～98.0%,优于文献的回收率,硫的测定结果令人满意。对硫化物浓度高的水样,可增加乙酸锌溶液和氢氧化钠溶液的加入量,硫化物同样有着较高的回收率。  相似文献   

Solar Photocatalytic Decolorization and Detoxification of Industrial Batik Dye Wastewater Using P(3HB)‐TiO2 Nanocomposite Films     

Nanthini Sridewi  Liu‐Tzea Tan  Kumar Sudesh 《洁净——土壤、空气、水》2011,39(3):265-273

Solar photocatalytic decolorization and detoxification of batik dye wastewater using titanium dioxide (TiO₂) immobilized on poly‐3‐hydroxybutyrate (P(3HB)) film was studied. The effects of initial dye concentration, catalyst concentration, P(3HB) film thickness, and fabrication methods of the nanocomposite films were evaluated against methylene blue, a standard organic dye. It was observed that 0.4 g of P(3HB)‐40 wt% TiO₂ removed 96% of the color under solar irradiation. P(3HB) and TiO₂, mixed concurrently in chloroform followed by stirring for 24 h showed a more even distribution of the photocatalyst on the polymer surface and yielded almost 100% color removal. The photocatalytic films were able to completely decolorize real industrial batik dye wastewater in 3 h and induced a chemical oxygen demand (COD) reduction of 80%. Reusability of the 0.4 g P(3HB)‐40 wt% TiO₂ film in decolorizing the batik dye wastewater was also possible as it gave a high consistent value of decolorization percentage (>80%) even after the sixth repeated usage. Recovery step of the photocatalysts was also not required in this simple treatment system. The decolorized batik dye wastewater had less/no toxic effects on mosquito larvae, Aedes aegypti, and microalgae, Scenedesmus quadricauda indicating simultaneous detoxification process along with the decolorization process.  相似文献   

Numerical predictions of the behaviour of soft clay with two anisotropic elastoplastic models     

Paulo J. Venda Oliveira  Luís J.L. Lemos 《Computers and Geotechnics》2011

The numerical predictions obtained with the Melanie and MIT-E3 models are compared. Firstly, the performance of the constitutive models is checked against undrained triaxial tests. The models are then used to replicate the behaviour of an embankment built on soft clay. The numerical results are compared with the field data in terms of settlements, lateral displacements and excess pore pressures. Additionally, the numerical predictions are also analysed in terms of yield area, contours of vertical effective stresses, horizontal effective stresses and shear stresses and in terms of effective stress paths.  相似文献   

泉州市地下水功能区划分   总被引：1，自引：0，他引：1  

曹阳  滕彦国  王金生  翟远征  郑洁琼 《地球学报》2011,32(4):469-476

本文针对泉州市地下水资源的分布特点,依据全国地下水功能区划分技术大纲,选取了地下水系统中具有代表性的驱动因子、状态因子和响应因子,综合地下水的资源供给功能、生态环境维持功能和地质环境稳定功能,将地下水功能区划分为开发区、保护区和保留区,并以完整的水文地质单元为基础,以防止泉州地下水污染和海水入侵为控制目标,依据地下水的...  相似文献   

山东半岛蓝色经济区地质工作思路     

徐军祥  吴立进 《山东地质》2011,(2):1-3

提出山东半岛蓝色经济区地质工作部署原则,应坚持＂缺什么,补什么＂,突出海岸带,以环境地质工作为重点,以综合研究为主,增强成果实用性。具体实施内容为1∶10万地质调查评价、大比例尺基础地质调查、矿产资源潜力调查、地质环境监测和综合研究等,并就组织实施提出了保障措施建议。  相似文献   

Two contact binaries at different evolutionary stages in the globular cluster NGC 6397     

《New Astronomy》2013

  相似文献