Specificity of two temperate dinoflagellate–anthozoan associations from the north-western Pacific Ocean

Whilst many studies of symbiotic dinoflagellate diversity have focused on tropical reef environments, only a few have explored the degree and pattern of divergence of these endosymbionts at high latitudes. In this study, the genetic diversity and specificity of symbiotic dinoflagellates associated with two common anthozoan hosts in the north-western Pacific Ocean was studied in four different seasons during a period of 1 year. Partial nucleotide sequences of 28S and complete ITS1 ribosomal DNA regions were used to identify, genetically, the endosymbionts extracted from the scleractinian Alveopora japonica and the actinarian Heteractis sp. A. japonica harbours symbionts belonging to Symbiodinium of clade F, while Heteractis sp. associates with Symbiodinium of clade C. Moreover, no seasonal changes in the endosymbiont community were detected in these two associations during this study. This is the first evidence that these two temperate cnidarian–microalgae symbioses are stable. Furthermore, we tested the apparent specificity of the Heteractis sp.– Symbiodinium sp. clade C association, by performing alga-infection experiments with aposymbiotic hosts, and monitoring the uptake and persistence of homologous and heterologous symbionts. The findings confirm the association patterns detected in the field and show that Heteractis sp. only establishes a successful association with Symbiodinium cells of clade C, at least among the heterologous symbionts occurring in the study area. Our results are consistent with the idea that selective pressures in highly fluctuating temperate environments might have granted symbiosis-specificity an adaptive value.Communicated by T. Ikeda, Hakodate     

铁聚合反应速率研究

研究了聚合硫酸铁絮凝剂制备中亚铁的氧化反应速率，证明该速率对Ｆｅ＾２＋为零级，对ＮＯ２（ｇ）为一级，因此提高气相中ＮＯ２的分压可大大缩短制备时间。     

Blooms of the dinoflagellate Gyrodinium aureolum in a Long Island estuary:

A dense dinoflagellate bloom of Gyrodinium aureolum Hulburt in a shallow temperate zone estuary was monitored during the summers of 1982 and 1983. The bloom was typically extremely localized, its densest part exceeding 1000g chlorophyll a liter^-1 (2x10⁴ cells ml^-1). The bloom began at temperatures between 24.5° and 27°C, existed at as high as 30°C and terminated when water temperature dropped to between 19° and 22°C. The highest specific growth rate measured was 0.90d^-1 (1.3 divisions d^-1) and near the termination of the bloom decreased to 0.28d^-1 (0.4 divisions d^-1). A diel vertical migration of the bloom was observed. A box model analysis, based on division rates, vertical migration and water circulation patterns, indicated that the bloom must move downward at the estuary mouth to maintain itself in the estuary, either by means of a convergence system or by downward swimming. High growth rate, low grazing pressure, and a stratified water column are proposed to stimulate bloom formation. Decreasing growth rate appeared to reduce the intensity of the bloom and finally allowed its disappearance by estuarine flushing and mixing.Communicated by J. M. Shick, Orono     

Mechanisms of photoadaptation in three strains of the symbiotic dinoflagellate Symbiodinium microadriaticum

Mechanisms of photoadaptation of photosynthesis have been studied in three strains of the symbiotic dinoflagellate Symbiodinium microadriaticum. Algal strains isolated from the clam Tridacna maxima, the sea anemone Aiptasia pulchella, and the scleractinian coral Montipora verrucosa were maintained in the defined medium ASP-8A, and were grown at irradiances ranging from 22 to 248 μE m^-2 s^-1 on a 14 h:10 h (light:dark) photoperiod at 26°C. All algal cultures were analysed during log-phase of growth. At all light levels, rates of cell division and photosynthesis were determined, as were cell volumes, pigmentation (including chlorophyll a, chlorophyll c ₂, peridinin, β-carotene and xanthophylls), and carbon and nitrogen content. Low light-induced changes in pigmentation were evident to varying degrees in all three algal strains, although alterations in the photosynthesis-irradiance relations were distinctly different in each strain. The algae from T. maxima show the least photoadaptive capability, and seem to photoadapt by changing photosynthetic unit (PSU) size. Algae from A. pulchella appear to adapt by changing PSU number, while algae from M. verrucosa appear to photoadapt by changes in the activities of CO₂-fixing enzymes or electron transport systems. These are the first observations that demonstrate functional differences in different strains of S. microadriaticum. The adaptive capabilities of the algae appear to correlate well with the ecological distribution of their respective hosts. The study was made from July 1981 through December 1982.     

A simple approach to modeling microbial biomass in the rhizosphere

Microorganisms make an important contribution to the degradation of contaminants in bioremediation as well as in phytoremediation. An accurate estimation of microbial concentrations in the soil would be valuable in predicting contaminant dissipation during various bioremediation processes. A simple modeling approach to quantify the microbial biomass in the rhizosphere was developed in this study. Experiments were conducted using field column lysimeters planted with Eastern gamagrass. The microbial biomass concentrations from the rhizosphere soil, bulk soil, and unplanted soil were monitored for six months using an incubation–fumigation method. The proposed model was applied to the field microbial biomass data and good correlation between simulated and experimental data was achieved. The results indicate that plants increase microbial concentrations in the soil by providing root exudates as growth substrates for microorganisms. Since plant roots are initially small and do not produce large quantities of exudates when first seeded, the addition of exogenous substrates may be needed to increase initial microbial concentrations at the start of phytoremediation projects.     

Uranium Accumulation of Crop Plants Enhanced by Citric Acid

Citric acid was applied to soil to enhance U accumulation in four crop plants. While the highest enhanced U accumulation of aboveground tissues (a.c. 2000 mg kg⁻¹ dry weight) occurred in the leaves of Indian mustard (Brassica juncea), the highest enhanced U accumulation of roots (a.c. 3500 mg kg⁻¹ dry weight) occurred in canola (Brassica napus var. napus). Uranium translocation among tissues of test plants is in the relation of roots>shoots ≅ leaves. The flowers of sunflower (Helianthus annuus) contained similar or higher U concentrations than those found in shoots, but concentrations in seeds are close to zero. In conclusion, Indian mustard is recommended as a potential species for phytoextraction for U-contaminated soil due to its high U accumulation of aboveground biomass (a.c. 2200 μg per plant). There is no evidence that two types of soils cause a significant difference of the enhanced U accumulation (p<0.05). Results, however, indicate that additional citric acid may result in downward U migration that may contaminate groundwater. Speciation of U that is taken up by plants is also discussed in the end.     

城市污水脱氮除磷方法探讨

本文综述了城市污水脱氮降磷工艺的几种主要方法，指出生物法因工艺简单、处理能力强、运行方式灵活等优点已成为近年来一种污水处理的重要方法，得到广泛应用。     

1420Al-Li合金超塑特性及微成形

采用最大载荷法研究了 14 2 0Al Li合金的超塑特性 ,根据试验获得的超塑特性参数 ,采用两种形式的模具对 14 2 0Al Li合金的微成形性进行了研究。分析了成形压力、保压时间对微成形的影响 ,采用扫描电镜和金相显微镜分析了成形件的微观形貌 ,更好地理解了材料在微成形时的行为。     

Using sustainable development indicators as a supplementary measure for the integrated management of environmental information system in Taiwan

Environmental Information System (EIS) transfers environmental data and information to audiences in any field of knowledge or activity interested in environmental problems. Currently, numerous conventional EISs or Environmental Databases (EDs) are available in Taiwan. However, they fail to adequately address the strong correlations among the environmental, social and economic components. Notably, Sustainable Development Indicators (SDIs) combine environmental, social and economic dimensions, as well as illustrate the links among systems. Subsequently, developing a set of SDIs will provide an excellent opportunity to systematically consolidate the information scattered among many archives, as well as promoting an integrated EIS. This work presents an experimental model referred to as the 'Sustainable Development Information System of the Island Taiwan' (SDISIT). This system was developed to assist the integrated management of either EIS or ED. The Factor Analysis Method (FAM) is one tool that may prove useful in easing the developing process. Furthermore, by examining the correlations between the indicators, this method can apply existing SDIs to identify the structure of interrelationships among indicators.     

Abatement of sulfur hexafluoride emissions from the semiconductor manufacturing process by atmospheric-pressure plasmas

Sulfur hexafluoride (SF6) is an important gas for plasma etching processes in the semiconductor industry. SF6 intensely absorbs infrared radiation and, consequently, aggravates global warming. This study investigates SF6 abatement by nonthermal plasma technologies under atmospheric pressure. Two kinds of nonthermal plasma processes--dielectric barrier discharge (DBD) and combined plasma catalysis (CPC)--were employed and evaluated. Experimental results indicated that as much as 91% of SF6 was removed with DBDs at 20 kV of applied voltage and 150 Hz of discharge frequency for the gas stream containing 300 ppm SF6, 12% oxygen (O2), and 40% argon (Ar), with nitrogen (N2) as the carrier gas. Four additives, including Ar, O2, ethylene (C2H4), and H2O(g), are effective in enhancing SF6 abatement in the range of conditions studied. DBD achieves a higher SF6 removal efficiency than does CPC at the same operation condition. But CPC achieves a higher electrical energy utilization compared with DBD. However, poisoning of catalysts by sulfur (S)-containing species needs further investigation. SF6 is mainly converted to SOF2, SO2F4, sulfur dioxide (SO2), oxygen difluoride (OF2), and fluoride (F2). They do not cause global warming and can be captured by either wet scrubbing or adsorption. This study indicates that DBD and CPC are feasible control technologies for reducing SF6 emissions.