Gamma-rays induction of mutation in conchocelis ofPorphyra yezoensis

Free-living conchocelis ofPorphyra yezoensis Ueda (Bangiales, Rhodophyta) were treated with⁶⁰Co-γ rays of different doses (ranging from 100 Gy to 1000 Gy) to induce mutation. Most of the conchocelis maintained the capability of penetrating into shells, growing and forming colonies in shells, but their vitality was seriously impaired by the irradiation of γ-rays. A few conchocelis pigments were mutagenized directly into different color pigment mutants whose progeny-conchospores and foliose thalli had the same colors. However, some irradiated conchocelis did not show the change in color at the conchocelis stage. The pigment mutation could be observed only after the conchospores of these conchocelis had germinated into young foliose thalli. Irradiation of low dose (100 Gy) promoted the growth of thallus and many with altered morphology were observed. Conchospores of the irradiated conchocelis attached to the culture nets were cultured in the sea, and growth of these progenies was observed and measured.     

UV-B辐射对绿色巴夫藻生长及抗氧化酶的影响

研究了不同辐照强度的UV-B辐射对绿色巴夫藻(Pavlova viridis Tseng)生长、光合色素和两种抗氧化酶的影响。结果表明,(1)低强度辐射处理的绿色巴夫藻在正常培养后生长有所恢复,经辐照强度为2μW/cm2的UV-B处理的藻在培养第10天的吸光度与对照接近,大于6μW/cm2的UV-B处理的藻基本无法恢复生长;(2)处理组叶绿素a(Chla)含量均低于对照,且随辐射强度的增大不断下降,辐照强度为12μW/cm2处理组比对照下降了85.20%;(3)类胡萝卜素(CAR)含量和超氧化物歧化酶(SOD)活性均随辐射强度的增大先升高后下降,最高含量分别比对照提高了38.55%和49.41%;(4)过氧化物酶(POD)活性随辐射强度的增大不断升高,辐照强度为12μW/cm2处理组是对照的7.98倍。UV-B辐射对绿色巴夫藻生长产生了明显的抑制作用,CAR,SOD和POD可能在绿色巴夫藻抵抗UV-B辐射中起着保护作用。     

铜和镁离子对卵圆卡盾藻生长、光合色素和溶血活性的影响

本研究探索了不同浓度的铜和镁离子对卵圆卡盾藻(Chattonella ovata)光合色素含量及其溶血活性的影响,并探讨了溶血活性与光合色素间的关系.结果表明,当铜和镁离子浓度分别为7.84μg/dm3和18.79 g/dm3时,卵圆卡盾藻达到最佳生长状态.不同浓度的铜离子(3.92、5.88、7.84、9.80μg/...     

硅灰石质白色颜料的研制

针对硅灰石作为白色颜料的主要不利因素，对其进行超细粉碎和表面化学改性处理，改进硅灰石粉体粒度、粉体表面组成和表面结构，提高粉体的白度和折射率，进而提高遮盖力。改性后的硅灰石超细粉体具有良好的高级白色颜料性能。     

青藏高原湖泊沉积物色素与湖泊环境的响应

本文通过对青藏高原湖泊表层沉积物色素、有机碳含量和环境因子的测定和分析,初步探讨了青藏高原湖泊中色素的来源特征和该地区湖泊浮游植物群落组成结构等信息。结果表明,青藏高原湖泊沉积物TOC含量多在4%~6%之间,藻类植物是沉积物色素的重要来源。颤藻科和蓝藻科在青藏高原湖泊浮游植物中生长优势明显,颤藻科在数量上相对蓝藻科有明显优势。青藏高原湖泊溶解氧(DO)、电导率(SC)对湖泊中藻类生长状况影响明显,其中SC的升高对该地区湖泊中藻类生长有抑制作用。     

海洋沉积物中色素生物标志物研究进展

海洋沉积物中的光合色素包含着水体、沉积物中浮游和底栖植物以及微生物群落的丰富信息,能表征特定生物来源,在埋藏到沉积物甚至发生某些改变之后仍然保留其源信息,是一类重要的化学生物标志物.结合总有机碳、总氮等其他海洋地球化学参数,沉积色素可用来研究海洋浮游植物和光合细菌的群落组成和丰度,反演海洋初级生产、水体富营养化水平及其历史趋势,指示水体和沉积物氧化还原条件,揭示海域气候条件等现状及其历史变化.沉积色素的研究,对于掌握海洋中碳的生物地球化学循环过程,回溯古环境、古海洋、古生态以及古气候记录,制定合理的海洋管理政策具有十分重要的意义.阐述了沉积物中色素的分类、来源、性质和分析方法,分析了色素在沉积物中的保存和变化规律,探讨总结了沉积色素作为化学生物标志物在海洋学研究中的应用.     

Environmental influence on phytoplankton communities in the northern Benguela ecosystem

An investigation of surface phytoplankton communities was undertaken on the shelf of the northern Benguela upwelling ecosystem during austral autumn (May) and spring (September), along latitudinal transects at 20° S and 23° S, from 2 to 70 nautical miles offshore, as well as on a zigzag grid located between these transects. Microscopic identification of the phytoplankton and CHEMTAX analysis of pigment biomarkers were used to characterise the community composition. During May 2014, warmer, more-saline water with a shallower upper mixed layer corresponding to periods of less-intense offshore Ekman transport was encountered on the shelf. Satellite imagery indicated high phytoplankton biomass extending for a considerable distance from the coast, and CHEMTAX indicated diatoms as dominant at most of the stations (52–92%), although dinoflagellates were dominant at some inshore localities (57–74%). Species of Chaetoceros, Bacteriastrum and Cylindrotheca were the most abundant, with abundance of the Pseudo-nitzschia ‘seriata-group’ being particularly high at a number of stations. In September 2014, more-intense wind-forcing resulted in a deeper upper mixed layer and stronger upwelling of colder, less-saline water. Elevated phytoplankton biomass was confined close to the coast, where diatoms accounted for most of the population (54–87%), whereas small flagellates, such as prasinophytes, haptophytes and cryptophytes, as well as the cyanobacterium Synechococcus, dominated the communities (58–90%) farther from the coast. It is hypothesised that stronger upwelling and deeper vertical mixing in September of that year were not conducive for widespread diatom growth, and that small flagellates populated the water column by being entrained from offshore onto the shelf in the upwelled water that moved in towards the coast.     

Algal populations and characteristics of oxygen exchange of effluent samples from a facultative oxidation pond

Algal populations in a facultative oxidation pond were monitored over a 12 month period. The relationships between cell counts of individual species and characteristics of oxygen exchange, determined from changes in dissolved oxygen concentration in response to varying light flux density, were investigated by correlation analysis. These measurements were made in the laboratory at a constant temperature (15°C). Microalgae (Chlorella spp.) usually made up at least 80% of the total cell numbers, whereas Euglena acus, E. gracilis, and Ankistrodesmus falcatus var. acicularis separately made up less than 10% of the total counts. However, when cell volumes were considered, E. acus usually made the greatest contribution, and this species accounted for 86% (=r²) of the variation in total cell volume. The detectable pigment concentration in the water was closely related to the numbers of E. acus present (r=0.81, P <0.001) but not to the numbers of microalgae (r=0.00). Cell counts of E. acus were highly correlated with the light saturated rate of net oxygen production (P_{n max}) and to the rate under limiting light supply (6) because of the high detectable pigment contribution from this species. It was calculated that E. acus contributed, on average, about 44% of the total rate of net oxygen production, whereas the proportion attributed to the microalgae was 8%.     

The nature and origin of pigments in black opal from Lightning Ridge,New South Wales,Australia

Abstract

Black opal (opal-AG) owes its dark coloration to a fine-grained pigment commonly inferred to be mainly carbon, yet chemical compositions for black opals suggest there may be additional components. Here we search for such components in pigment concentrates prepared by dissolving black opal nodules (nobbies) from Lightning Ridge (NSW) in hydrofluoric acid, using electron microscopy (scanning electron microscopy, transmission electron microscopy), X-ray diffraction and laser-ablation ICP-MS. The results demonstrate the presence of sulfides—predominantly pyrite and chalcopyrite, with minor galena and Ti-oxide phases, as additional components of the pigment. ATR-FTIR analysis indicates the presence of C=O and C–H groups, consistent with an organic origin. Transmission electron microscopy images of pigment show variously deformed, originally spherical ～100?nm particles rich in sulfide and carbon, which are interpreted as thin coatings of pigment on now dissolved opaline silica spheres. Laser-ablation ICP-MS analysis identifies remnant silica in pigment concentrates, which may be interpreted as opaline silica surviving HF treatment protected as inclusions in sulfides. When examined within the context of petrographic observations from more than 1000 opal nodules (nobbies) at Lightning Ridge, these new results suggest that pigment carbon and sulfides in the nodules formed microbially under initially anoxic groundwater conditions, within pre-existing cavities concurrently being filled with silica sol ultimately derived from chemical weathering of feldspar-rich volcaniclastic sediment. Intensely black pigment layers observed at the floor of many nodules indicate settling of dark, high-density (sulfide–Ti-oxide-rich) pigment within cavities, with the implication that sulfate-reducing bacterial (SRB) activity commences early during the silica sol-gel ripening process. Microbial activity may persist until after the cavity has completely filled with the silica sol, as illustrated by abundant black opals with uniformly distributed pigment. Pigment formed at this stage may no longer be able to settle out within the ripening and increasingly viscous silica gel, thus forming pigmentation throughout the opal cavity. The existence of ‘amber’, pigment-poor opal with intensely black basal pigment layers is interpreted as signalling a lack of sulfate to sustain further SRB activity, or a change to more oxidising conditions, possibly related to interaction with surface waters within a downward-penetrating weathering front. A change in redox conditions would shut off activity of SRB and thus sulfide pigment production and allow development of aerobic microbial activity as described by others.     

Phytoplankton composition and its ecological effect in subsurface cold pool of the northern Bering Sea in summer as revealed by HPLC derived pigment signatures

CHEMTAX analysis of high-performance liquid chromatography(HPLC) pigment was conducted to study phytoplankton community structure in the northern Bering Sea shelf, where a seasonal subsurface cold pool emerges. The results showed that fucoxanthin(Fuco) and chlorophyll a(Chl a) were the most abundant diagnostic pigments, with the integrated water column values ranging from 141 to 2 160 μg/m2 and 477 to 5 535 μg/m2, respectively. Moreover, a diatom bloom was identified at Sta. BB06 with the standing stock of Fuco up to 9 214 μg/m3. The results of CHEMTAX suggested that the phytoplankton community in the northern Bering Sea shelf was dominated by diatoms and chrysophytes with an average relative contribution to Chl a of 80% and 12%, respectively, followed by chlorophytes, dinoflagellates, and cryptophytes. Diatoms were the absolutely dominant algae in the subsurface cold pool with a relative contribution exceeding 90%, while the contribution of chrysophytes was generally higher in oligotrophic upper water. Additionally, the presence of a cold pool would tend to favor accumulation of diatom biomass and a bloom that occurred beneath the halocline would be beneficial to organic matter sinks, which suggests that a large part of the phytoplankton biomass would settle to the seabed and support a rich benthic biomass.