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111.
Cell density, chemical composition and toxicity of Chrysochromulina polylepis (Haptophyta) in relation to different N:P supply ratios 总被引:2,自引:0,他引:2
The influence of different N:P supply ratios on cell accumulation, chemical composition and toxicity of the marine haptophyte
Chrysochromulina polylepis was examined in semi-continuous cultures. A non-axenic strain of C. polylepis was exposed to five different N:P supply ratios (N:P = 1:1, 4:1, 16:1, 80:1 and 160:1, by atoms), in order to create a range
of N- and P-limited conditions. The toxicity per cell in C. polylepis was determined on four occasions at steady state cell density using the haemolytic activity of the cells expressed as saponin
nanoequivalents. Haemolytic activity was demonstrated in all treatments, and increased in the algae when cell growth was nutrient
limited (N:P = 1:1, 4:1, 80:1 and 160:1), compared to cells grown under non-limiting conditions (N:P = 16:1). This occurred
regardless of the growth-limiting nutrient (N or P) and became more pronounced as nutrient limitation increased. In P-limited
cultures the haemolytic activity per cell increased linearly with the cellular N:P ratio, whereas the N-limited cultures showed
an opposite trend. The haemolytic activity per cell showed an inverse relationship with both cellular N and cellular P content.
Cells limited by P showed a higher haemolytic activity than cells limited by N. The results suggest that toxicity in C. polylepis is strongly influenced by the physiological state of the algae. This may partially explain the large variability previously
observed in the toxicity of C. polylepis blooms. The potential ecological significance of our findings is also discussed.
Received: 18 November 1998 / Accepted: 5 July 1999 相似文献
112.
Christer Johansson Michael Norman Lars Burman 《Atmospheric environment (Oxford, England : 1994)》2009,43(31):4681-4688
Quantifying the emissions and concentrations of heavy metals in urban air is a prerequisite for assessing their health effects. In this paper a combination of measurements and modelling is used to assess the contribution from road traffic emissions. Concentrations of particulate heavy metals in air were measured simultaneously during 1 year at a densely trafficked street and at an urban background site in Stockholm, Sweden. Annual mean concentrations of cadmium were 50 times lower than the EU directive and for nickel and arsenic concentrations were 10 and six times lower, respectively. More than a factor of two higher concentrations was in general observed at the street in comparison to roof levels indicating the strong influence from local road traffic emissions. The only compound with a significantly decreasing trend in the urban background was Pb with 9.1 ng m?3 in 1995/96 compared to 3.4 ng m?3 2003/04. This is likely due to decreased emissions from wear of brake linings and reduced emissions due to oil and coal combustion in central Europe.Total road traffic emission factors for heavy metals were estimated using parallel measurements of NOx concentrations and knowledge of NOx emission factors. In general, the emission factors for the street were higher than reported in road tunnel measurements. This could partly be due to different driving conditions, since especially for metals which are mainly emitted from brake wear, more stop and go driving in the street compared to in road tunnels is likely to increase emissions. Total emissions were compared with exhaust emissions, obtained from the COPERT model and brake wear emissions based on an earlier study in Stockholm. For Cu, Ni and Zn the sum of brake wear and exhaust emissions agreed very well with estimated total emission factors in this study. More than 90% of the road traffic emissions of Cu were due to brake wear. For Ni more than 80% is estimated to be due to exhaust emissions and for Zn around 40% of road traffic emissions are estimated to be due to exhaust emissions. Pb is also mainly due to exhaust emissions (90%); a fuel Pb content of only 0.5 mg L?1 would give similar emission factor as that based on the concentration increment at the street. This is the first study using simultaneous measurements of heavy metals at street and roof enabling calculations of emission factors using a tracer technique. 相似文献
113.
114.
Stef Bokhorst Stine Højlund Pedersen Ludovic Brucker Oleg Anisimov Jarle W. Bjerke Ross D. Brown Dorothee Ehrich Richard L. H. Essery Achim Heilig Susanne Ingvander Cecilia Johansson Margareta Johansson Ingibjörg Svala Jónsdóttir Niila Inga Kari Luojus Giovanni Macelloni Heather Mariash Donald McLennan Gunhild Ninis Rosqvist Atsushi Sato Hannele Savela Martin Schneebeli Aleksandr Sokolov Sergey A. Sokratov Silvia Terzago Dagrun Vikhamar-Schuler Scott Williamson Yubao Qiu Terry V. Callaghan 《Ambio》2016,45(5):516-537
115.
Elizabeth K. O’Dea Edward Dwyer Valerie Cummins Dawn J. Wright 《Journal of Coastal Conservation》2011,15(4):607-627
A Coastal Web Atlas (CWA) is a valuable resource for a range of users including coastal managers as it provides easy access
to maps, spatial data, coastal information and tools. A trans-Atlantic workshop on “Potentials and Limitations of Coastal
Web Atlases”, held in Ireland in July 2006, brought together atlas developers and coastal data experts from Europe and the
United States to examine state-of-the-art developments in CWAs and future needs. This paper focuses on workshop outcomes,
including what defines a CWA and an overview of international, national, state and regional atlas case studies from both sides
of the Atlantic. Results of discussions are presented concerning issues related to design, data, technology and institutional
capacity for existing CWAs based on the collective experience of workshop participants. Directions in CWA development and
applications since the workshop are also discussed. A major outcome of the workshop was the initiation of an International
Coastal Atlas Network. The insights provided give a framework for CWA developers and a useful point of reference for coastal
managers and policy makers on atlas potentials and limitations. 相似文献
116.
Andreas Johansson Evalena Blomqvist Annika Ekvall Lennart Gustavsson Claes Tullin Bengt-Ake Andersson Mattias Bisaillon Tisse Jarlsvik Anders Assarsson Gunnar Peters 《Waste management & research》2007,25(3):296-300
This paper briefly describes waste treatment trends in Sweden and describes an example of state-of-the-art treatment in a local integrated waste treatment system (Bor?s). The focus is on treatment of household waste, to illustrate what can be done to establish a sustainable waste treatment system with high recovery of materials and energy. The various processes have resulted in a low amount of landfilled household waste, and high proportions of recovered energy and materials. Heat, electricity, vehicle fuel and fertilizers, metals and construction materials are recovered from the local waste in Bor?s, with less than 4% of domestic waste being sent to landfill. 相似文献
117.
C. Wretfors S.-W. Cho M. S. Hedenqvist S. Marttila S. Nimmermark E. Johansson 《Journal of Polymers and the Environment》2009,17(4):259-266
The next generation of manufactured products must be sustainable and industrially eco-efficient, making materials derived
from plants an alternative of particular interest. Wheat gluten (WG) is an interesting plant material to be used for production
of plastic similar materials due to its film-forming properties. For usage of plastics in a wider range of applications, composite
materials with improved mechanical properties are demanded. The present study investigates the possibilities of reinforcing
WG plastics with hemp fibers. Samples were manufactured using compression molding (130 °C, 1600 bar, 5 min). Variation in
fiber length, content (5, 10, 15 and 20 wt%) and quality (poor, standard, good) were evaluated. Mechanical properties and
structure of materials were examined using tensile testing, light and scanning electron microscopy. Hemp fiber reinforcement
of gluten plastics significantly influenced the mechanical properties of the material. Short hemp fibers processed in a high
speed grinder were more homogenously spread in the material than long unprocessed fibers. Fiber content in the material showed
a significant positive correlation with tensile strength and Young’s modulus, and a negative correlation with fracture strain
and strain at maximum stress. Quality of the hemp fibers did not play any significant role for tensile strength and strain,
but the Young’s modulus was significantly and positively correlated with hemp fiber quality. Despite the use of short hemp
fibers, the reinforced gluten material still showed uneven mechanical properties within the material, a result from clustering
of the fibers and too poor bonding between fibers and gluten material. Both these problems have to be resolved before reinforcement
of gluten plastics by industrial hemp fibers is applicable on an industrial scale. 相似文献
118.
Biodiversity, distributions and adaptations of Arctic species in the context of environmental change 总被引:1,自引:0,他引:1
Callaghan TV Björn LO Chernov Y Chapin T Christensen TR Huntley B Ims RA Johansson M Jolly D Jonasson S Matveyeva N Panikov N Oechel W Shaver G Elster J Henttonen H Laine K Taulavuori K Taulavuori E Zöckler C 《Ambio》2004,33(7):404-417
The individual of a species is the basic unit which responds to climate and UV-B changes, and it responds over a wide range of time scales. The diversity of animal, plant and microbial species appears to be low in the Arctic, and decreases from the boreal forests to the polar deserts of the extreme North but primitive species are particularly abundant. This latitudinal decline is associated with an increase in super-dominant species that occupy a wide range of habitats. Climate warming is expected to reduce the abundance and restrict the ranges of such species and to affect species at their northern range boundaries more than in the South: some Arctic animal and plant specialists could face extinction. Species most likely to expand into tundra are boreal species that currently exist as outlier populations in the Arctic. Many plant species have characteristics that allow them to survive short snow-free growing seasons, low solar angles, permafrost and low soil temperatures, low nutrient availability and physical disturbance. Many of these characteristics are likely to limit species' responses to climate warming, but mainly because of poor competitive ability compared with potential immigrant species. Terrestrial Arctic animals possess many adaptations that enable them to persist under a wide range of temperatures in the Arctic. Many escape unfavorable weather and resource shortage by winter dormancy or by migration. The biotic environment of Arctic animal species is relatively simple with few enemies, competitors, diseases, parasites and available food resources. Terrestrial Arctic animals are likely to be most vulnerable to warmer and drier summers, climatic changes that interfere with migration routes and staging areas, altered snow conditions and freeze-thaw cycles in winter, climate-induced disruption of the seasonal timing of reproduction and development, and influx of new competitors, predators, parasites and diseases. Arctic microorganisms are also well adapted to the Arctic's climate: some can metabolize at temperatures down to -39 degrees C. Cyanobacteria and algae have a wide range of adaptive strategies that allow them to avoid, or at least minimize UV injury. Microorganisms can tolerate most environmental conditions and they have short generation times which can facilitate rapid adaptation to new environments. In contrast, Arctic plant and animal species are very likely to change their distributions rather than evolve significantly in response to warming. 相似文献
119.
A method for determination of antibiotics in hospital sewage water has been developed and validated. Analogue internal standards for fluoroquinolones, sulfonamides, trimethoprim, beta-lactams (penicillins and cephalosporins), nitroimidazoles and tetracyclines were successfully used for calibration and shown to generally improve precision compared to external calibration. Matrix components caused ion suppression/enhancement effects during the MS detection for all analytes studied. Two effects were observed: general suppression and short-term variations in the MS response. In the hospital sewage water large temporal variations in the analyte concentration were observed during the course of the sampling period (seven grab samples in 13 h). Analyte concentrations varied within the following ranges (in microg l(-1)): ciprofloxacin, 3.6-101.0; metronidazole, 0.1-90.2; sulfamethoxazole, 0.4-12.8; ofloxacin, 0.2-7.6; trimethoprim, 0.6-7.6; and doxycycline, 0.6-6.7. 相似文献
120.
The air quality in a newly built preschool was investigated in a longitudinal study. Typical air contaminants emanating from building materials were determined, their variation over time (0–18 months) was measured, and the influence of the ventilation system (81%–91% recirculation of return air) on contaminant concentrations was studied. Volatile organic compounds were sampled by adsorption on porous polymer, analysed by a GC/FID system, and identified by MS. A spatial build-up in concentration (ppb or μg/m3 levels) is evident for all the organic compounds, as well as for CO2, from the outdoor air, through the ventilation system, and through the rooms to the exhaust air. The longitudinal comparison over time shows that all the organic compounds decline in concentration mainly within the first 6 months of occupancy: 1-butanol 4–14 times, toluene and pentanal + hexanal 2–4 times, while formaldehyde remained at a constant low level of 90 ppb (110 μg/m3). It is difficult to believe that the problems of poor air quality in 100 preschools in Stockholm are caused by the organic compounds alone unless interactions occur. A preschool building needs to be gassed off during the first 6 months after its construction with no recirculation of return air allowed (outdoor air rate approx 4–5 ach). During at least 1–2 additional years, it is desired that the recirculation rate of return air is restricted, perhaps to 50%. 相似文献