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1.
George F. Schäppi Philip E. Taylor Josephine Kenrick Ian A. Staff Cenk Suphioglu 《Aerobiologia》1998,14(1):29-37
In Melbourne, Australia, grass pollen is the predominant cause of hayfever in late spring and summer. The grass pollen season
has been monitored in Melbourne, using a Burkard spore trap, for 13 years (1975–1981, 1985 and 1991–1997). Total counts for
grass pollen were highly variable from one season to the next (approximately 1000 to >8000 grains/m3). The daily grass pollen counts also showed a high variability (0 to approximately 400 grains/m3). In this study, the grass pollen counts of the 13 years (12 grass pollen seasons, extending from October to January) have
been compared with meteorological data in order to identify the conditions that can determine the daily amounts of grass pollen
in the air. It was found that the seasonal total of grass pollen was directly correlated with the rainfall sum of the preceding
12 months (1 September–31 August): seasonal total of grass pollen (counts/m3)=18.161 × rainfall sum of the preceding 12 months (mm) −8541.5 (r
s=0.74,P<0.005,n=12). The daily amounts of grass pollen in the air were positively correlated with the corresponding daily average ambient
temperatures (P<0.001). The daily amount of grass pollen which was to be expected with a certain daily average temperature was linked to
the seasonal total of grass pollen: in years with high total grass pollen counts, a lower daily average temperature was required
for a high daily pollen count than in years with low total grass pollen counts. As the concentration of airborne grass pollen
determines the severity of hayfever in sensitive patients, an estimation of daily grass pollen counts can provide an indication
of potential pollinosis symptoms. We compared daily grass pollen counts with the reported symptomatic responses of hayfever
sufferers in November 1985 and found that hayfever symptoms were significantly correlated to the grass pollen counts (P<0.001 for nasal,P<0.005 for eye symptoms). Thus, a combination of meteorological information (i.e. rainfall and temperature) allows for an
estimation of the potential daily pollinosis symptoms during the grass pollen season. Here we propose a symptom estimation
chart, allowing a quick prediction of eye and nasal symptoms that are likely to occur as a result of variations in meteorological
conditions, thus enabling both physicians and patients to take appropriate avoidance measures or therapy. 相似文献
2.
Studies on Ambrosia pollen concentrations were carried out in Lublin in the period 1995–2004. The effects of a number of meteorological factors were analysed. In the first period of the study, the gravimetric method was used (1995–1999), while in the second period, the volumetric method was applied. The results show an increasing trend in the amount of airborne pollen. The Ambrosia pollen season in Lublin lasts from August to October. Over a period of 5 years, the highest number of pollen grains was recorded in September (53%), followed by August (44%) and October (3%). There were wide variations in annual totals. The annual total pollen counts was 167–1180 grains, with the peak value in 2002. Maximum daily pollen concentrations (56–312 pollen grains m−3) were recorded in the first half of August and in the first half of September. On the days when high Ambrosia pollen concentrations occurred, the temperature was above 21°C and the winds were mainly from the southeast, south and east. Maximum intradiurnal concentrations of pollen grains occurred in the afternoon hours. These results indicate, to some degree, that Ambrosia pollen is transported for long distances before descent. 相似文献
3.
Reproducibility between counts of airborne allergenic pollen from two cities in the East Midlands,UK
Catherine H. Pashley Abbie Fairs Richard E. Edwards John P. Bailey Julie M. Corden Andrew J. Wardlaw 《Aerobiologia》2009,25(4):249-263
Historically in the East Midlands, UK, airborne pollen has been monitored in two cities, Derby and Leicester, situated 41 km
(25 miles) apart. The aim of the present study was to compare aerobiological data from both sites to determine if a forecast
based on data from one site would be sufficient for both, and to address the wider issue of reproducibility between geographically
separated sites. Pollen types recorded could be split into two groups according to annual abundance, maximum daily concentration
and the number of high count days. Six taxa made up the abundant group; ash, birch, grass, oak, nettle-type and yew-type,
representing 90 and 88% of the total air spora for Derby and Leicester, respectively. Three consecutive years of grass and
nettle pollen data are presented, supported by one year of abundant tree pollen data. There were highly significant positive
correlations between the counts obtained. Line charts showing the average number of pollen grains m−3 air day−1 show similar trends, and Bland–Altman plots show little discrepancy between the amounts of pollen counted on any given day.
Each day was classified according to the UK accepted threshold levels for grass. Weighted kappa statistics showed substantial
or almost perfect agreement between the forecast classifications. With the caveat that this would not apply in a region with
restrictions to air flow such as a mountain range or with extreme fluctuations such as a coastline site, this study suggests
that data from a single site is suitable for forecasting a distance of up to 41 km. 相似文献
4.
G. F. Schäppi Philip E. Taylor Ian A. Staff Cenk Suphioglu R. Bruce Knox 《Sexual plant reproduction》1997,10(6):315-323
Allergenic proteins present in pollen grains, when inhaled, interact with the airways to cause an attack of asthma in susceptible
humans. In one system, grass pollen grains rupture osmotically in rainfall, releasing allergen-containing inhalable particles
into the atmosphere. In contrast, birch tree pollen grains do not rupture under these conditions, yet the major allergen,
Bet v 1, has been detected in the atmosphere in inhalable particles of unknown origin. It is possible that Bet v 1 may diffuse
from intact settled pollen grains and the allergenic material may again become airborne, interacting with settled fine particles
from other sources prior to resuspension. This study investigates the mechanism for the release of birch pollen allergen-containing
inhalable particles from pollen grains. We propose the hypothesis that (1) airborne birch pollen grains settle on nearby leaf
surfaces; (2) then, following light rainfall, the grains germinate and, (3) later, pollen tubes burst, releasing inhalable
particles carrying Bet v 1 into the atmospheric aerosol. We used microscopic analyses of pollen behaviour following anther
opening, a Burkard volumetric trap for pollen counts and a high volume air sampler with a two-stage cascade impactor for quantitative
immunochemical analyses of Bet v 1. On dry days of high birch pollen count (48 grains/m3, 1.5 ng/m3 of Bet v 1), we found that the surfaces of birch leaves became coated with pollen. This ”pollen rain” is a source of secondary
emission of allergens into the atmosphere. We observed that following light rainfall (<1 mm per day), about 80% of the birch
pollen grains germinated, producing pollen tubes, especially in the sticky surface secretions of leaf glands. These pollen
tubes may grow up to 300 μm in length prior to rupturing, each releasing about 400 starch granules coated with allergen molecules
that may, after drying, be dispersed into the aerosol. On these days following light rainfall, the highest atmospheric levels
of Bet v 1 (1.18 ng/m3) are associated with inhalable particles. Following heavy rainfall, both pollen and inhalable particles are washed from the
atmosphere. Immunoprinting studies show that Bet v 1 is associated with starch granules rather than the smaller orbicules.
Bet v 1 is present in the atmosphere in large particles, i.e. in particular pollen grains and in inhalable particles, i.e.
in particular starch granules.
Received: 28 May 1997 / Revision accepted: 18 August 1997 相似文献
5.
Kizilpinar I Civelek E Tuncer A Dogan C Karabulut E Sahiner UM Yavuz ST Sackesen C 《International journal of biometeorology》2011,55(4):623-631
Pollen plays an important role in the development and exacerbation of allergic diseases. We aimed to investigate the days
with highest counts of the most allergenic pollens and to identify the meteorological factors affecting pollen counts in the
atmosphere of Ankara, Turkey. Airborne pollen measurements were carried out from 2005 to 2008 with a Burkard volumetric 7-day
spore trap. Microscope counts were converted into atmospheric concentrations and expressed as pollen grains/m3. Meteorological parameters were obtained from the State Meteorological Service. All statistical analyses were done with pollen
counts obtained from March to October for each year. The percentages of tree, grass and weed pollens were 72.1% (n = 24,923), 12.8% (n = 4,433) and 15.1% (n = 5,219), respectively. The Pinaceae family from tree taxa (39% to 57%) and the Chenopodiaceae/Amaranthaceae family from weed taxa, contributed the highest percentage of pollen (25% to 43%), while from the grass taxa, only the Poaceae family was detected from 2005 to 2008. Poaceae and Chenopodiaceae/Amaranthaceae families, which are the most allergenic pollens, were found in high numbers from May to August in Ankara. In multiple logistic
regression analysis, wind speed (OR = 1.18, CI95% = 1.02–1.36, P = 0.023) for tree pollen, daily mean temperature (OR = 1.10, CI95% = 1.04–1.17, P = 0.001) and sunshine hours (OR = 1.15, CI95% = 1.01–1.30, P = 0.033) for grass pollen, and sunshine hours (OR = 3.79, CI95% = 1.03–13.92, P = 0.044) for weed pollen were found as significant risk factors for high pollen count. The pollen calendar and its association
with meteorological factors depend mainly on daily temperature, sunshine hours and wind speed, which may help draw the attention
of physicians and allergic patients to days with high pollen counts. 相似文献
6.
Accurate assessments of pollen counts are valuable to allergy sufferers, the medical industry, and health researchers; however,
monitoring stations do not exist in most areas. In addition, the degree of spatial reliability provided by the limited number
of monitoring stations is poorly understood. We developed and compared spatial models to estimate pollen concentrations in
locations without monitoring stations. Daily Acer, Quercus, and overall tree, grass, and weed pollen counts, in grains/m3, were obtained from 14 aeroallergen monitoring stations located in the northeastern and mid-Atlantic region of the United
States from 2003 to 2006. Pollen counts were spatially interpolated using ordinary kriging. Mixed effects and generalized
estimating equations incorporating daily and seasonal weather characteristics, pollen season characteristics and land-cover
information were also developed to estimate daily pollen concentrations. We then compared observed values from a monitoring
station to model estimates for that location. Observed counts and kriging estimates for tree pollen differed (p = 0.04), but not when peak periods were removed (p = 0.29). No differences between observed and kriging estimates of Acer (p = 0.46), Quercus (p = 0.24), grass (p = 0.31) or weed pollen (p = 0.29) were found. Estimates from longitudinal models also demonstrated good agreement with observed counts, except for
the extremes of pollen distributions. Our results demonstrate that spatial interpolation techniques as well as regression
methods incorporating both weather and land-cover characteristics can provide reliable estimates of daily pollen concentrations
in areas where monitors do not exist for all but periods of extremely high pollen. 相似文献
7.
Yuichi Takahashi Masaaki Aoyama Etsuko Abe Takeshi Aita Shigeto Kawashima Nobuo Ohta Masahiro Sakaguchi 《Aerobiologia》2008,24(1):53-59
We have developed a highly sensitive method for the measurement of airborne orchard grass (Dactylis glomerata: Dac g) pollen antigens using an electron spin resonance (ESR) radical immunoassay. In this immunoassay, the lowest detectable
level of Dac g antigen in a sample is 0.1 arbitrary unit; the amount of Dac g antigen in single pollen grains was found to
be as 1.84 units. Thus, Dac g antigens can be detected in amounts of 1/20th of that contained in the grain. This immunoassay
enables early detection of grass pollen antigens. Such information may be useful for patients with grass pollinosis, especially
for those who show symptoms when only low levels of the pollen antigens are present in air. In this study, minor amounts of
Dac g antigen (cross-reactive antigens) were detected in late March, after which the levels gradually increased. The levels
were detected to be 10 units/m3 until the middle of May and then increased after blooming of orchard grass. High levels were maintained until the middle
of June. Some patients who suffer from grass pollinosis show symptoms in late April and early May, when the airborne Dac g
antigen levels were found to be 5–10 units/m3. 相似文献
8.
Bradshaw SD Bradshaw FJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):569-580
A method is described, based on the simultaneous turnover of both stable (18O) and radioactive isotopes (3H and 22Na), whereby the daily nectar and pollen intake of free-ranging marsupial honey possums (Tarsipes rostratus) may be estimated. The field metabolic rate is measured using doubly labelled water and nectar intake is estimated independently
from the measured water and sodium fluxes. The method assumes that free-water intake is negligible (but may be accounted for
if not the case), that virtually all dietary sodium is derived from nectar rather than from pollen, and that the animals are
in energetic balance over the period of measurement. These assumptions have been tested and found to be robust, except during
periods of heavy rain when significant intakes of free-water were recorded. Leaching experiments with pollen grains suggest
that less than 10% of the sodium ingested by honey possums is derived from pollen and calculations thus assumed a 90%:10%
split between nectar and pollen. Nectar intake averaged 5.9 ± 0.6 ml · day−1 and regressing nectar intake on daily change in body mass predicts an intake of approximately 7 ml · day−1 nectar to maintain balance for a 9 g honey possum. Estimates of pollen intake averaged 660 ± 156 mg · day−1 and a similar regression analysis of the data predicts that a daily intake of approximately 1 g pollen would be needed to
maintain mass balance of honey possums. Estimated nectar and pollen intakes did not differ significantly between males and
females, but nectar intake was higher in winter compared with dry periods of the year. The sugar content of nectar falls during
winter, however, and the overall energy derived from nectar thus remains roughly constant. Estimates of pollen and nectar
intake for individual animals were not significantly correlated, suggesting that honey possums forage selectively for these
two food items.
Accepted: 19 August 1999 相似文献
9.
E. J. Olguín S. Galicia R. Camacho G. Mercado T. J. Pérez 《Applied microbiology and biotechnology》1997,48(2):242-247
The use of untreated sea water supplemented with anaerobic effluents from digested pig waste and sodium bicarbonate was evaluated
as a low-cost medium for semi-continuous cultivation of a mixed culture of two Spirulina strains in outdoor raceways under temperate climatic conditions (pond temperature in the range 21–26 °C and light intensity
in the range 225–957␣μE m−2 s−1). The mixed culture had a predominant population (86.6 ± 3.9%) of an atypical Spirulina strain consisting of straight filaments, which appeared spontaneously after the strain with helicoidal trichomes had been
subcultured. Morphological studies for the identification of the type and size of trichomes of the two strains (HF and SF)
were carried out. The proportions of the two strains were observed to be stable during the monitoring period (30 days). Three
different sets of semicontinuous cultures were carried out. Sets 1 and 2 were operated under regime 1 (a single addition of
anaerobic effluents at time zero and no pH control) during the same season (June and July) of different years. Set 3 was operated
under regime 2 (semi-continuous addition of anaerobic effluents and pH control) during the autumn. A minimum productivity
of 3.6 g m−2 day−1 was obtained at one of the lowest temperatures (22.1 °C) and light intensities (245 μE m−2 s−1) and a maximum productivity of 10.9 g m−2 day−1 was observed at the highest temperature (25 °C) and highest average light intensity (618 μE m−2 s−1) registered for sets 1 and 2. The protein content in the Spirulina biomass harvested from these two sets varied from 17% to 65.6%. In set 3, a maximum productivity of 9.0 g m−2 day−1 was recorded at an average temperature of 24.4 °C and at an average light intensity of 668 μE m−2 s−1. The protein content in this set under regime 2 varied within a narrower range than in set 1 and set 2 (from 34.8% to 49.1%),
apparently because of a continuous availability of ammonia nitrogen at a level of 30–50 mg l−1. However, in terms of the removal of ammonia nitrogen and chemical oxygen demand, regime 1 was more efficient than regime␣2.
Received: 3 September 1996 / Received revision: 19 February 1997 / Accepted: 7 March 1997 相似文献
10.
Time-varying parametric linear and time-varying nonparametric regression models as well as a time-varying nonparametric median
regression model are developed to predict the daily pollen concentration for Szeged in Hungary using previous-day meteorological
parameters and the daily pollen concentration. The models are applied to rainy days and non-rainy days, respectively. The
most important predictor is the previous-day pollen concentration level, and the only other predictor retained by a stepwise
regression procedure is the daily mean global solar flux for rainy days and the daily mean temperature for non-rainy days.
Although the variance percentage explained by these two predictors is higher for non-rainy (55.2%) days than for rainy (51.9%)
days, the prediction rate is slightly better for rainy than for non-rainy days. Nonparametric regression yields substantially
better estimates, especially for rainy days indicating a nonlinear relationship between the predictors and the pollen concentration.
The explained variance percentage is 71.4 and 64.6% for rainy and non-rainy days, respectively. Concerning the mean absolute
error, the nonparametric median regression provides the best estimate. The quantile regression shows that probability distribution
of daily ragweed concentration is much more skewed for non-rainy days, while the more concentrated probability distribution
for rainy days exhibits relatively stable ragweed pollen concentrations. The possible lowest limits of concentrations are
also calculated. Under highly favorable conditions for peak concentrations, the pollen level reaches at least 350 grains m−3 and 450 grains m−3 for rainy and non-rainy days, respectively. These values again underline the excessive ragweed pollen load over the area
of Szeged. 相似文献
11.
Toluene vapour removal in a laboratory-scale biofilter 总被引:4,自引:0,他引:4
A bench-scale biofilter with a 0.5-m high filter bed, inoculated with a toluene-degrading strain of Acinetobacter sp. NCIMB 9689, was used to study toluene removal from a synthetic waste air stream. Different sets of continuous tests were
conducted at influent toluene concentrations ranging over 0.1–4.0 g m−3 and at superficial gas velocities ranging over 17.8–255 m h−1. The maximum volumetric toluene removal rate for the biofilter (242 g m−3 h−1) was obtained at a superficial gas velocity of 127.5 m h−1 (corresponding to a residence time of 28 s) and a toluene inlet concentration of 4.0 g m−3. Under these operating conditions, toluene removal efficiency was only 0.238, which suggested that effective operation required
higher residence times. Removal efficiencies higher than 0.9 were achieved at organic loads less than 113.7 g m−3 h−1. A macro-kinetic study, performed using concentration profiles along the bioreactor, revealed this process was limited by
diffusion at organic loads less than 100 g m−3 h−1 and by biological reaction beyond this threshold.
Received: 10 October 1999 / Received revision: 15 February 2000 / Accepted: 18 February 2000 相似文献
12.
Raúl Muñoz María Hernández Ana Segura Joao Gouveia Antonia Rojas Juan Luis Ramos Santiago Villaverde 《Applied microbiology and biotechnology》2009,83(1):189-198
The long-term performance and stability of Pseudomonas putida mt-2 cultures, a toluene-sensitive strain harboring the genes responsible for toluene biodegradation in the archetypal plasmid
pWW0, was investigated in a chemostat bioreactor functioning under real case operating conditions. The process was operated
at a dilution rate of 0.1 h−1 under toluene loading rates of 259 ± 23 and 801 ± 78 g m−3 h−1 (inlet toluene concentrations of 3.5 and 10.9 g m−3, respectively). Despite the deleterious effects of toluene and its degradation intermediates, the phenotype of this sensitive
P. putida culture rapidly recovered from a 95% Tol− population at day 4 to approx. 100% Tol+ cells from day 13 onward, sustaining elimination capacities of 232 ± 10 g m−3 h−1 at 3.5 g Tol m−3 and 377 ± 13 g m−3 h−1 at 10.9 g Tol m−3, which were comparable to those achieved by highly tolerant strains such as P. putida DOT T1E and P. putida F1 under identical experimental conditions. Only one type of Tol− variant, harboring a TOL-like plasmid with a 38.5 kb deletion (containing the upper and meta operons for toluene biodegradation), was identified. 相似文献
13.
Chlorophyll a and nutrient concentrations along with temperature and salinity values were measured at 22 CTD stations along a 735-km transect
running to the northwest of the island of South Georgia, Southern Ocean. Measurements were repeated during five summer surveys
(January and February 1994, January 1996, December 1996, January 1998) and one spring survey (October 1997). The transect
sampled Sub-Antarctic Zone water in the north, Polar Frontal Zone water and Antarctic Zone water in the south. Chlorophyll
a concentrations were lowest to the north of the transect and frequently high (up to 17 mg m−3) in the deep open ocean of the Antarctic Zone. Sub-surface peaks were measured in all zones and chlorophyll a was detectable to a depth of 150 m. There was a clear latitudinal temperature gradient in the near-surface waters (0–50 m),
the warmest water occurring in the north (∼12 °C), and the coolest in the Antarctic Zone (∼2 °C). There was also a well-defined
latitudinal gradient in summer near-surface silicate concentrations (∼2, 4, and 10 mmol m−3 in the Sub-Antarctic Zone, the Polar Frontal Zone and the Antarctic Zone, respectively), increasing to >20 mmol m−3 near South Georgia. Distinct differences in silicate concentrations were also evident in all three zones to a depth of 500 m.
Near-surface nitrate and phosphate concentrations were relatively low to the north of the transect (∼14 and 1 mmol m−3, respectively) and higher in the Polar Frontal Zone and Antarctic Zone (∼18 and 1.4 mmol m−3, respectively). Ammonium and nitrite were restricted to the upper 200 m of the water column, and exhibited sub-surface concentration
peaks, the lowest being in the Sub-Antarctic Zone (0.68 and 0.25 mmol m−3, respectively) and the highest in the Antarctic Zone (1.72 and 0.29 mmol m−3, respectively). Surface (∼6 m) spring nutrient measurements provided an indication of pre-bloom conditions; ammonium and
nitrite concentrations were low (∼0.27 and 0.28 mmol m−3, respectively), while silicate, nitrate and phosphate concentrations were high and similar to previously measured winter
values (e.g. ∼26, 23, 2 mmol m−3, respectively in the Antarctic Zone). Although the values measured were very variable, and there was some evidence of a seasonal
growth progression, the chlorophyll a and nutrient distribution patterns were dominated by intercruise (interannual) factors. Approximate nutrient depletions (spring
minus summer) appeared similar in the Polar Frontal Zone and Antarctic Zone for nitrate and phosphate, while silicate showed
a marked latitudinal increase from north to south throughout the transect. Highest chlorophyll a concentrations coincided with the highest apparent silicate depletions over the deep ocean of the Antarctic Zone. In this
area, relatively warm, easterly flowing Antarctic Circumpolar Current water meets cooler, westerly flowing water that is influenced
by the Weddell-Scotia Confluence and is rich in nutrients, especially silicate.
Accepted: 27 November 1999 相似文献
14.
To test the hypothesis that the contribution of phosphoribulokinase (PRK) to the control of photosynthesis changes depending
on the light environment of the plant, the response of transgenic tobacco (Nicotiana tabacum L.) transformed with antisense PRK constructs to irradiance was determined. In plants grown under low irradiance (330 μmol m−2 s−1) steady-state photosynthesis was limited in plants with decreased PRK activity upon exposure to higher irradiance, with a
control coefficient of PRK for CO2 assimilation of 0.25 at and above 800 μmol m−2 s−1. The flux control coefficient of PRK for steady-state CO2 assimilation was zero, however, at all irradiances in plant material grown at 800 μmol m−2 s−1 and in plants grown in a glasshouse during mid-summer (alternating shade and sun 300–1600 μmol m−2 s−1). To explain these differences between plants grown under low and high irradiances, Calvin cycle enzyme activities and metabolite
content were determined. Activities of PRK and other non-equilibrium Calvin cycle enzymes fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase
and ribulose-1,5-bisphosphate carboxylase-oxygenase were twofold higher in plants grown at 800 μmol m−2 s−1 or in the glasshouse than in plants grown at 330 μmol m−2 s−1. Activities of equilibrium enzymes transketolase, aldolase, ribulose-5-phosphate epimerase and isomerase were very similar
under all growth irradiances. The flux control coefficient of 0.25 in plants grown at 330 μmol m−2 s−1 can be explained because low ribulose-5-phosphate content in combination with low PRK activity limits the synthesis of ribulose-1,5-bisphosphate.
This limitation is overcome in high-light-grown plants because of the large relative increase in activities of sedoheptulose-1,7-bisphosphatase
and fructose-1,6-bisphosphatase under these conditions, which facilitates the synthesis of larger amounts of ribulose-5-phosphate.
This potential limitation will have maintained evolutionary selection pressure for high concentrations of PRK within the chloroplast.
Received: 15 November 1999 / Accepted: 27 January 2000 相似文献
15.
Simultaneous nutrients and carbon removal during pretreated swine slurry degradation in a tubular biofilm photobioreactor 总被引:1,自引:0,他引:1
Ignacio de Godos Cristina González Eloy Becares Pedro A. García-Encina Raúl Muñoz 《Applied microbiology and biotechnology》2009,82(1):187-194
The biodegradation potential of an innovative enclosed tubular biofilm photobioreactor inoculated with a Chlorella sorokiniana strain and an acclimated activated sludge consortium was evaluated under continuous illumination and increasing pretreated
(centrifuged) swine slurry loading rates. This photobioreactor configuration provided simultaneous and efficient carbon, nitrogen,
and phosphorous treatment in a single-stage process at sustained nitrogen and phosphorous removals efficiencies ranging from
94% to 100% and 70–90%, respectively. Maximum total organic carbon (TOC), NH4
+, and PO4
3− removal rates of 80 ± 5 g C mr
−3 day−1, 89 ± 5 g N mr
−3 day−1, and 13 ± 3 g P mr
−3 day−1, respectively, were recorded at the highest swine slurry loadings (TOC of 1,247 ± 62 mg L−1, N–NH4
+ of 656 ± 37 mg L−1, P–PO4
3+ of 117 ± 19 mg L−1, and 7 days of hydraulic retention time). The unusual substrates diffusional pathways established within the phototrophic
biofilm (photosynthetic O2 and TOC/NH4
+ diffusing from opposite sides of the biofilm) allowed both the occurrence of a simultaneous denitrification/nitrification
process at the highest swine slurry loading rate and the protection of microalgae from any potential inhibitory effect mediated
by the combination of high pH and high NH3 concentrations. In addition, this biofilm-based photobioreactor supported efficient biomass retention (>92% of the biomass
generated during the pretreated swine slurry biodegradation). 相似文献
16.
Microstegium vimineum (Trin.) A. Camus, a shade-tolerant C4 grass, has spread throughout the eastern United States since its introduction in 1919. This species invades disturbed understory
habitats along streambanks and surrounding mesic forests, and has become a major pest in areas such as Great Smoky Mountains
National Park. The focus of this study was to characterize the photosynthetic induction responses of M. vimineum, specifically its ability to utilize low light and sunflecks, two factors that may be critical to invasive abilities and
survival in the understory. In addition, we were curious about the ability of a grass with the C4 photosynthetic pathway to respond to sunflecks. Plants were grown under 25% and 50% ambient sunlight, and photosynthetic
responses to both steady-state and variable light were determined. Plants grown in both 25% and 50% ambient sun became 90%
light saturated between 750–850 μmol m−2 s−1; however, plants grown in 50% ambient sun had significantly higher maximum steady-state photosynthetic rates (16.09 ± 1.37 μmol m−2 s−1 vs. 12.71 ± 1.18 μmol m−2 s−1). Both groups of plants induced to 50% of the steady-state rate in 3–5 min, while it took 10–13 min to reach 90% of maximum
rates, under both flashing and steady-state light. For both groups of plants, stomatal conductance during induction reached
maximum rates in 6–7 min, after which rates decreased slightly. Upon return to low light, rates of induction loss and stomatal
closure were very rapid in both groups of plants, but were more rapid in those grown in high light. Rapid induction and the
ability to induce under flashing light may enable this species to invade and dominate mesic understory habitats, while rapid
induction loss due to stomatal closure may prevent excess water loss when low light constrains photosynthesis. The C4 pathway itself does not appear to present an insurmountable barrier to the ability of this grass species to respond to sunflecks
in an understory environment.
Received: 21 February 1997 / Accepted: 10 October 1997 相似文献
17.
Although the prevalence of asthma and allergic rhinitis has been increasing in tropical regions, little is known about the
allergenicity of pollens from tropical plant families or the importance of ongoing environmental changes. We investigated
associations between daily average pollen counts of several tropical plant families and sales of medications for the treatment
of allergic rhinitis in Darwin, Australia—a tropical setting in which grass abundance has increased due to increased fire
frequencies and the introduction of African pasture grasses. Daily pollen counts with detailed identification of plant species
were undertaken in conjunction with a weekly survey of flowering plant species from April 2004 to November 2005. Five pharmacies
provided daily sales data of selected medications commonly used to treat allergic rhinitis. We used generalized linear modeling
to examine outcomes. All analyses accounted for the potential confounding effects of time trends, holidays, respiratory viral
illnesses, meteorological conditions, and air pollution. The peak total pollen count was 94 grains/m3. Despite the low levels of Poaceae (grass) pollen (maximum daily count, 24 grains/m3), there was a clear association with daily sales of anti-allergic medications greatest at a lag of 1 day. Sales increased
by 5% with an interquartile range rise (3 grain/m3) in Poaceae pollen (5.07%, 95%CI 1.04%, 9.25%). No associations were observed with pollen from other plant families. Although
further testing is required, we suggest that an overlooked aspect of the “grass-fire cycle” that is degrading many tropical
landscapes, could be an increase in the prevalence of allergic rhinitis. 相似文献
18.
A. Q. Hurtado A. T. Critchley A. Trespoey G. Bleicher-Lhonneur 《Journal of applied phycology》2008,20(5):551-555
Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different
durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan
content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly
(P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower
stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise,
decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period
produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values
of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content
and molecular weight. 相似文献
19.
Particle size effects in bioleaching of pyrite by acidophilic thermophile Sulfolobus metallicus (BC) 总被引:4,自引:0,他引:4
The effect of mineral particle size on the bioleaching of pyrite by the acidophilic thermophile Sulfolobus metallicus was investigated in a batch bioreactor. Decreasing the particle size from a mean diameter of 202 micron (size fraction: 150–180 micron)
to a mean diameter of 42.5 micron (size fraction: 25–45 micron) enhanced the bioleaching rate from 0.05 kg m−3 h−1 to 0.098 kg m−3 h−1. The particle size distribution of the mineral in this range did not influence the morphology and growth kinetics of the
cells. The values of specific growth rate (μ) and yield factor (Y) were 0.018–0.025 h−1 and 0.67 × 1011–1.45 × 1011 cells (g iron)−1, respectively. Decreasing the particle size of the mineral to a mean diameter of 6.40 micron (size fraction <25 micron) adversely
influenced the activity of the cells. The presence of fine particles apparently damaged the structure of the cells, resulting
in their inability to oxidise pyrite.
Received: 11 December 1998 / Accepted: 9 April 1999 相似文献
20.
Codium fragile (Suringar) Hariot is an edible green alga farmed in Korea using seed stock produced from regeneration of isolated utricles
and medullary filaments. Experiments were conducted to reveal the optimal conditions for nursery culture and out-growing of
C. fragile. Sampling and measurement of underwater irradiance were carried out at farms cultivating C. fragile at Wando, on the southwestern coast of Korea, from October 2004 to August 2005. Growth of erect thalli and underwater irradiance
were measured over a range of depths for three culture stages. During the nursery cultivation stage (Stage I), growth rate
was greatest at 0.5 m depth (0.055 ± 0.032 mm day−1), where the average midday irradiance over 60 days was 924 ± 32 μmol photons m−2 s−1. During the pre-main cultivation stage (Stage II), the greatest growth rate occurred at a depth of 2 m (0.113 ± 0.003 mm day−1) with an average irradiance of 248 ± 116 μmol photons m−2 s−1. For the main cultivation stage (Stage III) of the alga, thalli achieved the greatest increase in biomass at 1 m depth (7.2 ± 1.0 kg
fresh wt m−1). These results suggest that optimal growth at each cultivation stages of C. fragile could be controlled by depth of cultivation rope. 相似文献