Monitoring of environmental radiation on the Spratly Islets in the South China Sea

The concentration of radionuclides in environmental samples and the environmental radiation level (including cosmic rays) was monitored on Spratly Islets in South China Sea prior to the commercial operation of nearby Chinese nuclear power plants. Samples of coral sand, sea food, vegetation, water, and accumulated fallout on the islet were obtained and measured for radioactivity. Except for some exposure originating from minute amounts of⁶⁰Co and¹³⁷Cs, the radiation background is mainly emitted from naturally occurring radionuclides. Radiation levels including beta, gamma, and neutron on the islet have also monitored. Gamma dose rates for outdoor exposure averaged approximately 0.09 Sv/h; the neutron dose rate was about 0.003 Sv/h. Automatic radiation surveillance and a routine sampling program on the Spratly Islets are viewed as essential to provide an early warning in the Far East in case of a nuclear emergency.     

Biological monitoring of solar UV radiation at 17 sites in Asia, Europe and South America from 1999 to 2004

A small and robust dosimeter for determining the biologically effective dose of ambient UV radiation has been developed using UV-sensitive mutant spores of Bacillus subtilis strain TKJ6312. A membrane filter with four spots of the spores was snapped to a slide mount. The slide was wrapped and covered with two or more layers of polyethylene sheet to protect the sample from rain and snow and to reduce monthly-cumulative doses within the measurable range. From 1999, monthly data were collected at 17 sites for more than 1 year, and data for 4 to 6 consecutive years were obtained from 12 sites. Yearly total values of the spore inactivation dose (SID) ranged from 3200 at subarctic Oulu to 96000 at tropical Denpasar, and the mean yearly values of SID exhibited an exponential dependence on latitude in both hemispheres with a doubling for about every 14 degrees of change. During the observation period, increasing trends of UV doses have been observed at all sites with more than 5 years of data available. Year-to-year variations at high and middle latitude sites are considered due mostly to climatic variation. At three tropical sites, negative correlations between the yearly doses and the column ozone amounts were observed. The results verified the applicability of spore dosimetry for global and long-time monitoring of solar UV radiation, in particular at tropical sites where no monitoring is taking place.     

Variability of UVR effects on photosynthesis of summer phytoplankton assemblages from a tropical coastal area of the South China Sea

From June to September 2005, we carried out experiments to determine the ultraviolet radiation (UVR) -induced photoinhibition of summer phytoplankton assemblages from a coastal site of the South China Sea. Variability in taxonomic composition was determined throughout the summer, with a peak chlorophyll a (chl a approximately 20 microg chl a L(-1)) dominated by the diatom Skeletonema costatum that was detected early in the study period; the rest of the time samples were characterized by monads and flagellates, with low chl a values (1-5 chl a microg L(-1)). Surface water samples were placed in quartz tubes, inoculated with radiocarbon and exposed to solar radiation for 2-3 h to determine photosynthetic rates under three quality radiation treatments (i.e. PAB, 280-700 nm; PA, 320-700 nm and P, 400-700 nm) using different filters and under seven levels of ambient irradiance using neutral density screens (P vs E curves). UVR inhibition of samples exposed to maximum irradiance (i.e. at the surface) varied from -12.2% to 50%, while the daytime-integrated UVR-related photoinhibition in surface seawater varied from -62% to 7%. The effects of UVR on the photosynthetic parameters P(B)(max) and E(k) were also variable, but UV-B accounted for most of the observed variability. During sunny days, photosynthesis of microplankton (>20 microm) and piconanoplankton (<20 microm) were significantly inhibited by UVR (mostly by UV-B). However, during cloudy days, while piconanoplankton cells were still inhibited by UVR, microplankton cells used UVR (mostly UV-A) as the source of energy for photosynthesis, resulting in higher carbon fixation in samples exposed to UVR than the ones exposed only to photosynthetically active radiation (PAR). Our results indicate that size structure and cloudiness clearly condition the overall impact of UVR on phytoplankton photosynthesis in this tropical site of South China. In addition, model predictions for this area considering only PAR for primary production might have underestimated carbon fixation due to UVR contribution.     

中国南海珊瑚化学研究新进展

本文综述了近年来中国南海珊瑚代谢产物中一些新的或有生理活住的物质，其中包括萜类、甾醇及含氮化合物等。     

Seasonal Impacts of Solar UV Radiation on Photosynthesis of Phytoplankton Assemblages in the Coastal Waters of the South China Sea

We carried out experiments to evaluate seasonal changes in the impacts of UV radiation (UVR, 280–400 nm) on photosynthetic carbon fixation of phytoplankton assemblages. Surface water samples were obtained in the coastal area of the South China Sea, where chlorophyll a ranged 0.72–3.82 μg L⁻¹. Assimilation numbers (photosynthetic carbon fixation rate per chl a) were significantly higher during summer 2005 than those in spring and winter 2004. The mean values obtained under photosynthetically active radiation (PAR) were 2.83 (spring 2004), 4.35 (winter 2004) and 7.29 μg C (μg chl a)⁻¹ h⁻¹ (summer 2005), respectively. The assimilation numbers under PAR + UVR were 1.58, 2.71 and 5.28 μg C (μg chl a)⁻¹ h⁻¹, for spring, winter and summer, respectively. UVR induced less inhibition of photosynthesis during summer 2005 than during the other seasons, in spite of the higher UVR during summer. The seasonal differences in the productivity and photosynthetic response to UV were mainly due to changes in water temperature, while irradiance and vertical mixing explained >80% of the observed variability. Our data suggest that previous studies in the SCS using UV-opaque vessels might have overestimated the phytoplankton production by about 80% in spring, 61% in winter and 38% in summer.     

南海海绵Axinyssa aplysinoides的化学成份研究(一)

从南海海绵Axinyssaaplysinoides中分离得到一甘油醚类化合物C2 7H54 O3。利用IR ,MS,NMR等分析手段确定了它的结构为 1 -( 1 7Z -二十四碳烯基 ) -甘油醚。     

Global forecast model to predict the daily dose of the solar erythemally effective UV radiation

A worldwide forecast of the erythemally effective ultraviolet (UV) radiation is presented. The forecast was established to inform the public about the expected amount of erythemally effective UV radiation for the next day. Besides the irradiance, the daily dose is forecasted to enable people to choose the appropriate sun protection tools. Following the UV Index as the measure of global erythemally effective irradiance, the daily dose is expressed in units of UV Index hours. In this study, we have validated the model and the forecast against measurements from broadband UV radiometers of the Robertson-Berger type. The measurements were made at four continents ranging from the northern polar circle (67.4 degrees N) to the Antarctic coast (61.1 degrees S). As additional quality criteria the frequency of underestimation was taken into account because the forecast is a tool of radiation protection and made to avoid overexposure. A value closer than one minimal erythemal dose for the most sensitive skin type 1 to the observed value was counted as hit and greater deviations as underestimation or overestimation. The Austrian forecast model underestimates the daily dose in 3.7% of all cases, whereas 1.7% results from the model and 2.0% from the assumed total ozone content. The hit rate could be found in the order of 40%.     

南中国海海藻刺状鱼栖苔的化学成分(Ⅲ)

采自南中国海刺状鱼栖苔的乙醇提取物经多种柱层析分离并鉴定出四种化合物,分别为:(24S) 5 烯 3β 谷甾醇、对羟基苯甲酸、黄酮类化合物槲皮素及类黄酮化合物(-) 表儿茶精.其结构通过各种波谱技术如IR,GC MS、FABMS、1HNMR、13CNMR(DEPT)、1H 1HCOSY和HMBC等加以证实.这些化合物均是首次从刺状鱼栖苔中检测到.其中槲皮素和(-) 表儿茶精是首次从红藻中检测到     

The role of solar UV radiation in the ecology of alpine lakes.

Solar ultraviolet radiation (UVR, 290-400 nm) is a crucial environmental factor in alpine lakes because of the natural increase of the UVR flux with elevation and the high water transparency of these ecosystems. The ecological importance of UVR, however, has only recently been recognized. This review, examines the general features of alpine lakes regarding UVR, summarizes what is known about the role of solar UVR in the ecology of alpine lakes, and identifies future research directions. Unlike the pattern observed in most lowland lakes, variability of UV attenuation in alpine lakes is poorly explained by differences in dissolved organic carbon (DOC) concentrations, and depends mainly on optical characteristics (absorption) of the chromophoric dissolved organic matter (CDOM). Within the water column of lakes with low DOC concentrations (0.2-0.4 mg l(-1)), UV attenuation is influenced by phytoplankton whose development at depth (i.e. the deep chlorophyll maximum) causes important changes in UV attenuation. Alpine aquatic organisms have developed a number of strategies to minimize UV damage. The widespread synthesis or bioaccumulation of different compounds that directly or indirectly absorb UV energy is one such strategy. Although most benthic and planktonic primary producers and crustacean zooplankton are well adapted to high intensities of solar radiation, heterotrophic protists, bacteria, and viruses seem to be particularly sensitive to UVR. Understanding the overall impact of UVR on alpine lakes would need to consider synergistic and antagonistic processes resulting from the pronounced climatic warming, which have the potential to modify the UV underwater climate and consequently the stress on aquatic organisms.     

南海海绵Biemna fortis化学成份的研究(一)

从中国南海海绵Biemnafortis的乙酸乙酯可溶部分中分离得到化合物 2 4 -甲基胆甾 - 7 2 2E -二烯 - 3β,5α -二羟基 - 6-酮 ,其结构由IR、MS、1 HNMR等分析手段得以确定     

南海海绵Axinyssa aplysinoides的化学成分研究(二)

从中国南海采集的海绵Axinyssaaplysinoides中分离得到一白色结晶 ,通过UV ,IR ,MS ,NMR等波谱方法和光谱技术 ,确定了它的结构为Δ2 2 (2 3 ) (E) - 2 4 ,2 6 ,2 6-三甲基 - 2 5(30 ) -亚甲基胆甾醇     

中国南沙群岛卡拉凹顶藻化学成分研究

中国南沙群岛卡拉凹顶藻化学成分研究钟永利，苏镜娱，曾陇梅，阎素君，罗秉浩（中山大学化学系，广州，５１０２７５）关键词红藻，卡拉凹顶藻，木糖甙，β－十六烷基－Ｄ－吡喃木糖甙，胆甾醇凹顶藻（Ｌａｕｒｅｎｃｉａ）含有非常丰富的次生代谢产物，主要包括萜类和含...     

中国南海海绵化学成分研究进展

综述了近十年来我国南海海绵化学成分的研究进展情况 ,主要包括萜类、含氮化合物、甾醇等 ,以及部分化合物的生理活性。     

南海佳丽鹿角珊瑚化学成分的研究(一)

从中国南海的一种石珊瑚一佳丽鹿角珊瑚（Acroporapuchro）的乙酸乙酯可溶部分获得两个有机化合物：正十六碳酸（Ⅰ）和（24S）－24-甲基胆甾醇（Ⅱ）。它们的结构是通过EIMS、IR、1HNMR、13CNMR和DEPT等实验分析确定的。其中纯的（24S）-24-甲基胆甾醇是首次从自然界大量获得。本文首次提供化合物（Ⅱ）的完整波谱数据。     

On the mechanism of air nitrogen fixation on activated carbon surface in water

High-performance liquid chromatography and gas chromatography were used to reveal formation of hydroxyl radicals in air-saturated water containing activated carbon. Probable mechanisms of OH^· formation are considered. The role of OH^· radicals in the formation of carbene centers on the activated carbon surface is discussed. For interpreting the experimental data on atmospheric nitrogen fixation on activated carbon surface, probable mechanisms of nitrogen activation are explored by quantum-chemical methods. Highly reactive OH^· radicals are unable to react with molecular nitrogen under mild conditions. A high reactivity of singlet and triplet carbenes of different nature on activated carbon surface with respect to N₂ molecules was revealed by density functional theory methods.     

南海软珊瑚Sarcophyton molle化学成分的研究

从中国南海软肉芝软珊瑚(Sarcophyton molle)中分离到七个化合物, 经紫外光谱(UV), 红外光谱(IR), 质谱(MS)和核磁共振光谱(1H NMR, 13C NMR)分析, 确定了其化学结构。它们是: 异新西松烯(1), (E, E, E)-7, 8-环氧-1-异丙基-4, 8, 12-三甲基-十四环-1,3, 11-三烯(2), 正十八烷酸(3), 鲨肝醇(4), 神经酰胺(5), 胸腺嘧啶(6), 胸腺嘧啶脱氧核苷(7)。其中化合物(2)为新化合物。本文是第一次报道软珊瑚Sarcophyton molle的化学成分。     

南海红树林内生真菌Cephalosporium sp．（2090#）次级代谢产物研究

海洋微生物是寻找海洋药物先导化合物的一个新的源泉,人们已经从海洋微生物的次级代谢产物中分离得到了很多结构新颖或强药理活性的化合物[1]。我们在对中国南海红树林内生真菌的研究中,发现了大量的生物活性化合物,这也揭示了我国南海海洋真菌具有极大的药用开发前景[2-5]。红     

A chemometric survey of three sites in Muggia Bay (Northern Adriatic Sea): meteorological effects on heavy metal patterns in surface coastal waters

Within research on the quality of the waters of the Gulf of Trieste, this study on patterns of trace metal contents in the inner part of the gulf (Muggia Bay) discusses data of Cu, Pb, Cd and Zn, determined voltammetrically (DPASV), and collected in three sites with a 10-day frequency over the period of one year. Two of the sites lie inside the dam system which protects the harbour of Trieste, while the third one is situated outside for comparison purposes. Principal component analysis pointed out different metal patterns inside and outside the dam system; PC scores were related to meteorological information: rain plays a major role in conditioning the estuarine inner site: wind stirring action was detectable for the outer site. Both univariate graphics and canonical correlation analysis suggest a diffuse source for Pb, probably atmospheric deposition. Received: 1 August 1997 / Revised: 20 November 1997 / Accepted: 23 November 1997