Sludge-grown algae for culturing aquatic organisms: Part I. Algal growth in sludge extracts

This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae (Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, aeration and shaking, it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher (P < 0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (µg/g): Zn 289–581, Cu 443–682, Ni 310–963, Mn 96–126, Cr 25–118, and Fe 438–653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.     

Influence of bacteria and diatoms in biofilms on metamorphosis of the marine slipper limpet <Emphasis Type="Italic">Crepidula onyx</Emphasis>

Larvae of the slipper limpet Crepidula onyx metamorphose in response to marine biofilms. In this study, we investigated how the percentage of larval metamorphosis in this species was affected by biofilms that differed in certain attributes. To manipulate bacterial and diatom cell densities and community composition, we developed biofilms in the laboratory (1) at different temperatures (16, 23 and 30°C) and salinities (20, 27 and 34‰), (2) with or without addition of antibiotics, and (3) in the light or in the dark. We also allowed biofilms to develop at three field sites with different prevailing environmental conditions so as to generate biofilms with different, but natural, attributes. Bacterial and diatom community composition in biofilms were determined using a DNA fingerprinting technique and microscopic examination, respectively. The effects of biofilms on metamorphosis were investigated in laboratory assays. The percentage of larval metamorphosis correlated with bacterial and diatom cell densities in only one of the three experiments conducted, but was substantially affected by differences in bacterial and diatom community composition in all three experiments. It also appears that metamorphosis of C. onyx depends on the simultaneous presence of both bacterial and diatom communities in biofilms.     

Developmental changes in body weight and elemental composition of laboratory-reared larvae of the red frog crab,Ranina ranina (Decapoda: Brachyura)

Ranina ranina larvae were reared at 29°C from hatching to the megalopa stage to measure daily changes in body weight, water content and elemental composition. Energy, estimated from carbon content, was also examined. The water content was 85 to 92% of body weight immediately after ecdysis but decreased with days after ecdysis. Gains in body weight, carbon, nitrogen, hydrogen and energy during each instar ranged from 52 to 245% and increased with instar after instar II (body weight and carbon), instar III (hydrogen and energy), and instar IV (nitrogen). Cumulative gains of these elements from hatching to 2 d before metamorphosis into megalopa ranged from 11 567% (carbon) to 12 209% (energy). Most cumulative gains (57 to 59%) in elemental composition were contributed by instar VII. Carbon, nitrogen and hydrogen content in body weight decreased to a minimum on the day of ecdysis and increased on the subsequent days. C:N ratios after instar IV were lowest on the day after ecdysis and reached a plateau by the second day. Energy, estimated as J mg^-1 dry weight (DW), decreased with instar and within a molt cycle, and was at a minimum on the day after ecdysis. Gains in elemental composition could be described by an exponential function of days after hatching and by a quadratic function in each instar.     

Differential timing of larval starvation effects on filtration rate and growth in juvenile Crepidula onyx

This study demonstrates that the timing of larval starvation did not only determine the larval quality (shell length, lipid content, and RNA:DNA ratio) and the juvenile performance (growth and filtration rates), but also determine how the latent effects of larval starvation were mediated in Crepidula onyx. The juveniles developed from larvae that had experienced starvation in the first two days of larval life had reduced growth and lower filtration rates than those developed from larvae that had not been starved. Lower filtration rates explained the observed latent effects of early larval starvation on reduced juvenile growth. Starvation late in larval life caused a reduction in shell length, lipid content, and RNA:DNA ratio of larvae at metamorphosis; juveniles developed from these larvae performed poorly in terms of growth in shell length and total organic carbon content because of “depletion of energy reserves” at metamorphosis. Results of this study indicate that even exposure to the same kind of larval stress (starvation) for the same period of time (2 days) can cause different juvenile responses through different mechanisms if larvae are exposed to the stress at different stages of the larval life.     

The role of black carbon as a catalyst for environmental redox transformation

Black carbon (BC) is an important class of geosorbents that control the fate and transport of organic pollutants in soil and sediment. We previously demonstrated a new role of BC as an electron transfer mediator in the abiotic reduction of nitroaromatic and nitramine compounds by Oh and Chiu (Environ Sci Technol 43:6983-6988, 2009). We proposed that BC can catalyze the reduction of nitro compounds because it contains microscopic graphitic (graphene) domains, which facilitate both sorption and electron transfer. In this study, we assessed the ability of different types of BC--graphite, activated carbon, and diesel soot--to mediate the reduction of 2,4-dinitrotoluene (DNT) and 2,4-dibromophenol (DBP) by H(2)S. All three types of BC enhanced DNT and DBP reduction. H(2)S supported BC-mediated reduction, as was observed previously with a thiol reductant. The results suggest that BC may influence the fate of organic pollutants in reducing subsurface environments through redox transformation in addition to sorption.     

Sedimentary Pigments and Organic Matter in Relation to Benthic Fauna in the Tan-Shui Estuary,Taiwan

The benthic ecological structure of the Tan-Shui estuary, Taiwan is changed due to long term effects of dumping of urban wastewater and of engineering actions. to monitor these changes, we sampled and analyzed benthos and sediment from 12 stations on the estuary.

The composition of the dominant species of benthos varied seasonally, with molluscan and crustacean species having greater numbers and higher frequencies of occurrence than other species. the dominant taxa during winter were Nassarius sp. and Maldanidae at two stations. Analysis using Simpson's index and Shannon's index showed the benthic community varied more in coastal areas than in offshore areas.

Physicochemical analysis showed that most of the Tan-Shui estuary consisted of sandy sediment. the variations in concentrations of organic carbon and total nitrogen at each station were small. Although the concentrations of chlorophyll-a and carotenoid at all stations were generally low, the two stations had the highest concentrations, and we concluded that the concentration of pigments in these sediments was related to the abundance of benthos. the community structure of the benthos reflected the characteristics of the sediments, and benthic species exhibited selection of and adaptation to specific sedimentary environments.     

A survey of international urban search-and-rescue teams following the Ji Ji earthquake

On 21 September 1999, the Ji Ji earthquake killed 2,347 people. In the immediate aftermath the international community, mobilised rapidly and sent urban search-and-rescue (US&R) teams to the scene. This paper will present an annotated survey of the expertise and standard of equipment of international US&R teams following that earthquake which could serve as a blueprint for the establishment of US&R teams elsewhere at risk from earthquakes.     

Reductive transformation of dieldrin under anaerobic sediment culture

A pathway of dieldrin transformation to aldrin by epoxide reduction was found in this study. Investigation of dieldrin degradation under anaerobic conditions was performed with a mixed culture containing indigenous microorganisms obtained from sediment of the Er-Jen River in Taiwan. During the incubation, the transformation of dieldrin to aldrin was analyzed by GC-ECD and GC-MS. Effects of incubation factors including dieldrin concentrations, incubation temperatures and kinds of carbon sources on the degradation of dieldrin were also studied. Original concentrations (from 0.5 to 10 microg ml(-1)) of dieldrin affect the transformation rate of dieldrin, and lower concentrations indicated the higher degradation rates. But once the concentration higher than 100 microg ml(-1), almost no degradation occurred. The optimal temperature for degradation in mixed culture was found at 40 degrees C in this study. Dieldrin transformation rates varied with the type of major carbon sources in the mixed culture and were in order of yeast extract > sodium acetate > glucose. In addition, the denaturing gradient gel electrophoresis (DGGE) fingerprint revealed that four microbials evolved in dieldrin-amended cultures, but not in the dieldrin-free cultures. Partial sequence of 16S rDNA for these four organisms exhibited 94-99% similarity to those of genera Clostridium, Acidaminobacter and an uncultured bacterial group. These results suggest that the four microbials might promote the dieldrin transformation.     

中国废水排放量预测研究

文章在综合分析中国废水排放量影响因素的基础上,结合ARMA、多元线性回归方法构建了中国废水排放量预测模型,并对2013年-2015年中国废水排放量进行了预测,结果表明:2013年-2015年中国废水排放量将分别达到729.98亿吨、768.97亿吨、810.71亿吨;造纸印刷及文教用品制造业、化学工业等行业废水排放量及单位增加值废水排放量均较大,相关部门需对减排的各个过程进行规范和严格的监督。     

基于压电纤维复合材料的风沙冲击力传感器研究∗

沙尘暴是一种多发于沙漠等干旱地区的灾害天气，建（构）筑物常受其影响被侵蚀甚至产生破坏，这种破坏的本质是风沙两相流中沙粒对结构表面冲击产生细微损伤的积累。为了深入探索这种风沙两相流对结构的冲击作用和沙粒冲击力在结构表面的分布规律，研究了采用压电纤维复合材料作为力传感器来测量风沙流场中沙粒冲击力的方法，通过标定试验建立了压电传感器所受沙粒冲击力与其输出电信号之间的数学模型，构建了基于压电纤维复合材料的风沙冲击力传感器。分别采用高频测力天平和压电传感器测量低矮房屋迎风面在风沙风洞试验中所受到的沙粒冲击力，验证压电传感器测量沙粒冲击力的适用性和准确性。结果显示：两种测力方式的结果总体相差在-4.72%~5.80%，两种试验结果吻合良好；建筑物迎风面内侧所受到的沙粒冲击力大于外侧所受到的沙粒冲击力，沙粒冲击力的分布与表面风压力分布具有一定相关关系。研究成果可为结构防风沙灾害的相关研究提供参考。