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1.
Pierre Sicard Patrice Coddeville Stéphane Sauvage Jean-Claude Galloo 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):49-58
The long-term monitoring of precipitation and its chemical composition are important for identifying trends in rain quality
and for assessing the effectiveness of pollution control strategies. A statistical test has been used to the atmospheric concentrations
measured in the French rural monitoring network (MERA) in order to bring out spatio-temporal trends in precipitation quality
in France over the period 1990–2003. The non-parametric Mann–Kendall test which has been developed for detecting and estimating
monotonic trends in the time series was used and applied in our study at annual values of wet-only precipitation concentrations.
The emission data suggest that SO2 and NO
x
emissions decreased (−3.3 and −2.0% year−1, respectively) contrary to NH3 emissions that increased slightly (+0.2% year−1) over the period 1990–2002 in France. On the national scale, the pH values have a significant decreasing trend of −0.025 ± 0.02
unit pH year−1. and concentrations in precipitation have a significant decreasing trend, −3.0 ± 1.6 and −3.3 ± 0.6% year−1, respectively, corresponding with the downward trends in SO2 emissions in France (−3.3% year−1). A good correlation (R
2 = 0.84) between SO2 emissions and concentrations was obtained. The decreasing trend of was more significant (−5.4 ± 5.2% year−1) than that of (−1.3 ± 2.4% year−1). Globally, the concentration of the major ions showed a clear downward trend including marine and alkaline ions. In addition,
the relative contribution of HNO3 to acidity precipitation increased by 51% over the studied period. 相似文献
2.
Regular additions of NH4NO3 (35–140 kg N ha−1 yr−1) and (NH4)2SO4 (140 kg N ha−1 yr−1) to a calcareous grassland in northern England over a period of 12 years have resulted in a decline in the frequency of the
indigenous bryophyte species and the establishment of non-indigenous calcifuge species, with implications for the structure
and composition of this calcareous bryophyte community. The lowest NH4NO3 additions of 35 kg N ha−1 yr−1 produced significant declines in frequency of Hypnum cupressiforme, Campylium chrysophyllum, and Calliergon cuspidatum. Significant reductions in frequency at higher NH4NO3 application rates were recorded for Pseudoscleropodium purum, Ctenidum molluscum, and Dicranum scoparium. The highest NH4NO3 and (NH4)2SO4 additions provided conditions conducive for the establishment of two typical calcifuges – Polytrichum spp. and Campylopus introflexus, respectively. Substrate-surface pH measurements showed a dose-related reduction in pH with increasing NH4NO3 deposition rates of 1.6 pH units between the control and highest deposition rate, and a further significant fall in pH, of
>1 pH unit, between the NH4NO3 and (NH4)2SO4 treatments. These results suggest that indigenous bryophyte composition may be at risk from nitrogen deposition rates of
35 kg N ha−1 yr−1 or less. These effects are of particular concern for rare or endangered species of low frequency. 相似文献
3.
Johan Bergholm Hooshang Majdi Tryggve Persson 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):225-234
A nitrogen (N) budget was constructed for a period of 6 years (1988–1993) in a Norway spruce stand with current deposition
of 19 kg N and 22 kg S ha−1 year−1. The stand was fertilized annually by addition of 100 kg N and 114 kg S ha−1 (NS). Above and below ground biomass, litterfall, fine- root litter production, soil solution and net mineralization were
measured to estimate pools, fluxes and accumulation of nitrogen. The average needle litterfall in control (C) and NS plots
in 1993 was 2.2 and 2.5 ton ha−1 year−1, respectively. The fine root litter production prior to treatment (1987) was 4.4 ton ha−1 year−1 and after treatment (1993) it was 4.5 and 3.9 ton ha−1 year−1 in C and NS plots, respectively. Net N mineralization in the soil profile down to 50 cm was estimated to be 86 and 115 kg
ha−1 year−1 in C and NS plots, respectively in 1992. During the treatment period the uptake of N in the needle biomass in C and NS plots
was 29 and 77 kg ha−1 year−1, respectively. No N was accumulated in needles of C plot where the NS plots accumulated 34 kg ha−1 year−1. Of the annually added inorganic N to NS plots 47% was accumulated in the above and below ground biomass and 37% in the soil.
N fluxes via fine-root litter production in the C plots were much higher (54 kg ha−1 year−1) than that via litterfall (29 kg ha−1 year−1). The corresponding values in the NS plots were 65 and 43 kg ha−1 year−1, respectively. Most of the net N mineralization occurred in the FH layer and upper mineral soil. It is concluded that fine
root litter and litterfall play an important role in the cycling of N. Despite a high N uptake the losses of N in litterfall
and fine root litter resulted in an incorporation of N in soil organic matter. 相似文献
4.
Tatsuro Nakaji Takuya Kobayashi Mihoko Kuroha Kumiko Omori Yuko Matsumoto Tetsushi Yonekura Katsuhiko Watanabe Jarkko Utriainen Takeshi Izuta 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):277-287
To evaluate the effect of increasing nitrogen (N) deposition and tropospheric ozone (O3) concentrations on N-saturated forest ecosystems, we investigated the response of Japanese red pine (Pinus densiflora), an N-saturation sensitive tree species, to increasing N load under elevated O3 concentrations. One-year-old seedlings of red pine were treated with three levels of N supply (0, 50 and 100 mg N L-1 fresh soil volume) under two levels of atmospheric O3 concentration (< 5 and 60 ppb) for two growing seasons. Nitrogen treatment did not stimulate dry matter production of the seedlings. Growth inhibition was observed in the highest N treatment under low O3 and in the two higher N treatments under elevated O3. Irrespective of the O3 concentration, increasing N supply negatively affected root growth and mycorrhizal development in fine roots, resulting in a reduction in P and Mg uptake from the soil. Net photosynthetic rate was significantly reduced by both the highest N treatment under low O3 and the two higher N treatments under elevated O3, together with decreased N-availability to Rubisco. Nitrogen assimilated from NO3 - to amino acid in the needles was not affected by the treatments. However, needle protein concentration was reduced by the highest N-treatment under low O3 and by the two higher N-treatments under elevated O3. These results suggest that elevated O3 potentially disturbs the N-availability in the form of protein including Rubisco, and may advance the negative effects of excessive N-deposition on N-sensitive plant species in N-saturated forests. 相似文献
5.
Shaodong Xie Yuanhang Zhang Li Qi Xiaoyan Tang 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):217-229
In the Beijing area, March and April have the highest frequency of sand-dust weather. Floating dust, blowing sand, and dust
storms, primarily from Mongolia, account for 71%, 20%, and 9% of sand-dust weather, respectively. Ambient air monitoring and
analysis of recent meteorological data from Beijing sand-dust storm periods revealed that PM10 mass concentrations during dust storm events remained at 1500 μg m−3, which is five to ten times higher than during non-dust storm periods, for fourteen hours on both April 6 and 25, 2000. During
the same period, the concentrations in urban areas were comparable to those in suburban areas, while the concentrations of
gaseous pollutants, such as SO2, NO
x
, NO2, and O3, remained at low levels, owing to strong winds. Furthermore, during sand-dust storm periods, aerosols were created that consisted
not only of many coarse particles, but also of a large quantity of fine particles. The PM2.5 concentration was approximately 230 μg m−3, accounting for 28% of the total PM10 mass concentration. Crustal elements accounted for 60–70% of the chemical composition of PM2.5, and sulfate and nitrate for much less, unlike the chemical composition of PM2.5 on pollution days, which was primarily composed of sulfates, nitrates, and organic material. Although the very large particle
specific surface area provided by dust storms would normally be conducive to heterogeneous reactions, the conversion rate
from SO2 to SO4
2− was very low, because the relative humidity, less than 30%, was not high enough. 相似文献
6.
Ulf Sikström 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):137-142
Liming and/or application of specific nutrients have been proposed as countermeasures to the acidification of forest soils
in southern Sweden. In this study the stem growth of Picea abies (L.) Karst. growing on acidic mineral soils in SW Sweden was investigated 10 years after additions of lime (Ca; 3000 kg lime
ha−1), lime plus P (25 kg ha−1) and K (80 kg ha−1), or N in low doses (2 × 10 kg ha−1 yr−1) (treatments: CaPK, Ca, N, CaPKN, and 2Ca2P2K, respectively). Compared with the control, stem growth was increased following
all treatments involving lime additions, including liming alone. The PK addition did not seem to affect growth. The most plausible
cause of the observed growth increases was that the lime additions indirectly increased the supply of plant-available N. The
annual low-dose N addition did not significantly affect growth. This suggests that air-borne deposition of N, which supplies
very small doses of N throughout the year, has a minor or even negligible influence on P. abies growth. 相似文献
7.
Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003.
PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10 (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles
were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM2.5 and PM10 mass measured were 37.3 ± 16.2 μg m−3 and 60.8 ± 29.5 μg m−3, respectively. The sum of ionic chemical species concentrations for PM2.5 and PM10 was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m3, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM2.5 − 10) particles, but less reduction was found for fine (PM2.5) mass concentration. SO4
2−, NH4
+, and K+ predominated in fine particulate mode, NO3
− and Cl− predominated in fine particle mode and coarse particle mode, but Na+, Mg2+, and Ca2+ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized
sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass
concentrations of PM10 in daytime and at night were 57.6 and 70.0 μg m−3, and those of PM2.5 were 35.4 and 42.5 μg m−3, respectively. NO3
− and Cl− in both PM2.5 and PM10 were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night
than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and
low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow
dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations.
In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea,
along with a relatively low PM concentration. 相似文献
8.
J. A. Carfrae L. J. Sheppard J. A. Raven I. D. Leith W. Stein A. Crossley M. Theobald 《Water, Air, & Soil Pollution: Focus》2004,4(6):229-239
This paper reports data from a field study investigating the impacts of elevated ammonia (NH3) deposition on Calluna vulgaris growing on an ombrotrophic peat bog in S.E. Scotland. Shoot extension, foliar N concentrations, chlorophyll concentration and chlorophyll fluorescence were measured during the second growing season of exposure to a gradient of ammonia concentrations. Results indicate that NH3 increases growth between 150–200 kg N ha–1y–1 cumulative deposition. Foliar N content increased significantly in response to NH3 cumulative deposition up to 400 kg N ha–1 y–1 whereas chlorophyll a content significantly decreased. Measurements of Fv/Fm suggest that although NH3 exposure altered the growth and reduced chlorophyll a, the efficiency of photosystem II was insensitive to NH3-N deposition at this stage. 相似文献
9.
Shaun A. Watmough Julian Aherne M. Catherine Eimers Peter J. Dillon 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):301-306
In response to reduced sulphur emissions, there has been a large decrease in sulphate (; −0.97 μeq l−1 year−1) and hydrogen (−1.18 μeq l−1 year−1) ion concentration in bulk precipitation between 1980 and 2000 at Plastic Lake in central Ontario. The benefit of this large
reduction in deposition on stream water chemistry was assessed using the gauged outflow from a conifer-forested catchment (PC1; 23.3 ha),
which is influenced by a small wetland located immediately upstream of the outflow. Sulphate concentrations declined, but
not significantly due to large inter-annual variation in concentration. Between 1980 and 2000, there were significant increases in dissolved organic carbon, ammonium and potassium
concentration likely reflecting increased mineralisation in the wetland. Calcium concentrations in PC1 decreased during the
two decade period (−2.24 μeq l−1 year−1), as a consequence there was no improvement in stream pH and the Ca:Al ratio in PC1 continued to decline. A similar response
was noted in an upland-draining sub-catchment of PC1-08 that has been monitored since 1987. Despite large reductions in deposition and almost complete retention of nitrogen in soil, there has been no improvement (in terms of pH) in stream water
at PC1 due to a combination of soil acidification and climatic (droughts, increased mineralisation) perturbations. 相似文献
10.
We used laboratory experiments to investigate surface resistance (R
c) to dry deposition of ozone (O3) on different types of soil samples collected from the arid deserts and the Loess Plateau of northern China. Furthermore,
we measured the factors that affected R
c, which depends on the physical and chemical interaction between trace constituents and the deposition surface, and evaluated
deposition velocity (V
d). There was little influence of geometric surface area, soil weight, or O3 concentration on V
d of O3. The effect of relative humidity (RH) (i.e. moisture content of the soil) on O3 uptake was in agreement with results reported in the literature: a distinct RH dependence of V
d and little uptake under water-saturated conditions were observed. R
c values for all the soil samples examined were in the range 0.21–3.3 s mm−1 and were exponentially related to the surface area of the particles and the organic carbon content of each soil sample at
RH of both <10 and 60%. 相似文献
11.
Armelle Braud Karine Jézéquel Emilie Vieille Adrien Tritter Thierry Lebeau 《Water, Air, & Soil Pollution: Focus》2006,6(3-4):261-279
Partly because of the low bioavailability of metals, the soil cleaning-up using phytoremediation is usually time-consuming.
In order to enhance the amount of metals at the plant's disposal, the soil bioaugmentation coupled together with phytoextraction
is an emerging technology. In this preliminary work, two agricultural soils which mainly differed in their Cr, Hg and Pb contents
(LC, low-contaminated soil; HC, high-contaminated soil) were bioaugmented in laboratory conditions by either bacterial (Bacillus subtilis, Pseudomonas aeruginosa, Pseudomonas fluorescens or Ralstonia metallidurans) or fungal inocula (Aspergillus niger or Penicillium simplicissimum) and incubated during three weeks. The LC soil pots bioaugmented with A. niger and P. aeruginosa contained higher concentrations of Cr (0.08 and 0.25 mg.kg−1 dw soil) and Pb (0.25 and 0.3 mg.kg−1 dw soil) in the exchangeable fraction F1 (extraction with MgCl2) by comparison with the non-bioaugmented soil where neither Cr nor Pb was detected. Conversely, immobilization of Cr and
Pb in the soil were observed with the other microorganisms. The soil bioaugmentation not only modified the metal speciation
for the most easily extractable fractions but also modified the distribution of metals in the other fractions, to a lesser
extent nevertheless. The difference in microbial concentrations between the bioaugmented or not HC soils reached up to 1.8
log units. Thus the microorganisms that we chose for the soil bioaugmentation were competitive towards the indigenous microflora.
The PCA analysis showed close positive relationships between the microorganisms which potentially produced siderophores in
the soil and the amount of Cr and Pb in the fraction F1. 相似文献
12.
Characterizing sorption processes is essential to understand the environmental distribution and toxicity potential of endocrine
disruptors in terrestrial and aquatic systems. The sorption behaviors of three endocrine disruptors (bisphenol A (BPA), 17β-estradiol
(E2), and 17α-ethynylestradiol (EE2)) on sediments were investigated using batch techniques. Samples were taken from some
representative reaches in several major Chinese rivers. More attention has been paid to the effect of sediment organic components
on the sorption of BPA, E2, and EE2. The results show that the sediment organic carbon-normalized partition coefficients (K
oc
(sed)) for three endocrine disruptors are in the order of EE2 > E2 > BPA, which corresponds to the octanol-water partitioning
coefficients (logK
ow) of the compounds. Moreover, the K
oc
values for humic substances (K
oc
(hs)) are comparable with the K
oc
(sed) values and highly dependent on the physico-chemical properties of humic substances in sediments. The UV absorptivity
at 272 nm (A
272), which suggests the abundance of aromatic rings in humic substance structure, correlates well with the K
oc
(hs) values. In addition, the infrared spectra of the humic substances extracted from sediments show four strong bands centered
at 3,400 cm−1, 1,625 cm−1, 1,390 cm−1, and 1,025 cm−1. The K
oc
(hs) values have a positive linear relation with the peak area ratio for peak at 1,025 cm−1 and a negative linear relation with the peak area ratio between peaks at 1,625 cm−1 and 1,025 cm−1. Hence, the hydrogen bonds play a critical role to the sorption of selected endocrine disruptors. 相似文献
13.
Junya Katagiri Siqingaowa Borjigin Toshiaki Yoshioka Tadaaki Mizoguchi 《Journal of Material Cycles and Waste Management》2010,12(2):136-146
The formation and decomposition of tetrafluoroborate ions (BF4−) in H3BO3-Al3+-F− solutions were investigated via experiments and thermodynamic calculations. The concentration of the formed BF4− increased with decreasing pH, raising the total fluoride concentration and lowering the total aluminum ion concentration.
Once formed, BF4− was stable under neutral and alkaline conditions. Fluoride in the form of BF4− was converted to fluoroaluminate ions by adding an aluminum compound under acidic conditions. A method for removing fluoride
in the form of BF4− is proposed whereby fluoroaluminate ions formed by the reaction of BF4− with aluminum are decomposed with calcium ions. This process was applied to the treatment of wastewater from flue gas desulfurization
plants, and resulted in a satisfying level of reduction in the range of the fluoride emission limit of 8 mg/l. 相似文献
14.
Hatam Godini Abbas Rezaee Ali Khavanin Afshin Nili Ahmadabadi Sayedomid Rastegar Hooshyar Hossini 《Journal of Polymers and the Environment》2011,19(1):283-287
The objective of this study was to investigate the feasibility of using a microbial biopolymer produced by Acetobacter xylinum as a carbon source for heterotrophic biological denitrification. The denitrification rate, COD availability and nitrite concentration
were response parameters. Under the experimental conditions, a denitrification rate of about 0.74 kg NO3
−N/m3d at 6 h retention time was achieved with microbial cellulose (MC). The reactor effluent contained significantly COD concentrations
(20–86 mg/L) so it was not carbon limited, and was receiving enough carbon to facilitate the denitrification process. The
maximum nitrite concentration in the effluent was found to be 0.4 mg/L. However, decreasing the retention time to 3 h significantly
reduced the efficiency. It can be concluded that the MC is a suitable carbon source for nitrate removal in a heterotrophic
biological denitrification process. 相似文献
15.
Shinsuke Iijima Morito Nakamura Akira Yokoi Mitsuhiro Kubota Liwei Huang Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2011,13(3):206-212
For an effective decomposition and removal of organic halogenated compounds, a packed-bed non-thermal plasma reactor with
in situ absorption of the resulting halogenated products by alkaline sorbent incorporated was proposed. In the plasma reactor,
α-Al2O3 particles of 1 and 3 mm (mean particle diameter) were packed as solid dielectric medium to enhance the plasma power density
in the reactor. Further, alkaline sorbent of Ca(OH)2 was doped onto the surface of α-Al2O3 particles, in order to remove halogenated products by in situ absorption with Ca(OH)2. A high-voltage and high-frequency pulsed power of −15 to 15 kV and 1 kHz was applied to the wire electrode of the plasma
reactor by means of a DC power source. In the present study, as the sample of an organic halogenated compound that is most
popularly used, we selected dichloromethane (CH2Cl2), and 500 ppm of the initial concentration of CH2Cl2 was fed into the reactor accompanied by air at a fixed flow rate of 500 × 10−6 m3 min−1 at room temperature. As a result, it was recognized that the amount of CH2Cl2 decomposed by non-thermal plasma in an α-Al2O3 particle bed increased with an increase in plasma input power. The ratio of decomposition of CH2Cl2 was almost 100% at 13 kV of electric power and 1 kHz frequency, and CO2, CH3Cl, COCl2, HCl, and Cl2 were observed as the major reaction products. On the other hand, when CH2Cl2 was introduced into the plasma reactor where α-Al2O3 particles doped with Ca(OH)2 were packed, the ratio of decomposition of CH2Cl2 became higher, compared to the case that α-Al2O3 particles were not doped with Ca(OH)2. Moreover, there were no halogenated by-product gases detected in the outlet gas from the reactor. As the solid reaction
products, CaClOH and Ca(ClO)2·4H2O were detected on Ca(OH)2 by X-ray diffraction. From these findings, it was recognized that CH2Cl2 was decomposed more effectively without producing unwanted harmful halogenated by-products in the proposed non-thermal plasma
reactor where α-Al2O3 particles doped with Ca(OH)2 sorbent were packed. 相似文献
16.
V. Y. Hoang H. Jupsin V. C. Le J.-L. Vasel 《Journal of Material Cycles and Waste Management》2012,14(1):3-13
A process of partial nitrification and denitrification in a sequencing batch reactor (SBR) treating leachate was simulated
by applying a modified version of activated sludge model no. 3 (ASM3), named ASM3_2step. This model modifies the ASM3 model
by separating nitrification and denitrification into two steps with nitrite as an intermediate substrate. Three periods, including
long term period, steady state and cycle evolution, were used for calibration. Three main processes were observed, including
biomass production, nitrification (focusing on nitrite accumulation) and denitrification. The kinetic and stoichiometric parameters
(
m\textA_NH \mu_{{{\text{A\_NH}}}} ,
Y\textA_NH Y_{{{\text{A\_NH}}}} ,
Y\textA_\textNO2 Y_{{{\text{A}}\_{\text{NO}}_{2} }} ,
Y\textH_\textO2 Y_{{{\text{H}}\_{\text{O}}_{2} }} , b
A,
K\textA_NH K_{{{\text{A\_NH}}}} ), were determined from biokinetic and respirometry tests. Some of the default values of kinetic and stoichiometric parameters
available in the ASM3 model and in the literature were kept constant, while some others were adjusted step by step until observed
state variables fit with experimental data. The maximum specific growth rate of nitrite oxidizing bacteria (0.108 day−1) (simulated by the model) and that of ammonium oxidizing bacteria (0.61 day−1) (from biokinetic tests) are the parameters which have the highest influence on the nitrite accumulation, even more than
oxygen supply intensity or Kla value. Other important parameters were
K\textAO_NH K_{{{\text{AO\_NH}}}} and
K\textAO_\textNO2 K_{{{\text{AO}}\_{\text{NO}}_{2} }} , calibrated at the values of 1.37 and 1.59 mg O2/L, respectively. The modified model and values of the kinetic and stoichiometric parameters obtained from the modeling process
will be used for optimization of the partial nitrification in the next study. 相似文献
17.
Mohammad Taghi Taghizadeh Reza Abdollahi Naser Sadeghpour Orang 《Journal of Polymers and the Environment》2012,20(1):208-216
The degradation of chitosan by means of ultrasound irradiation and its combination with homogeneous photocatalysis (photo-Fenton)
was investigated. Emphasis was given on the effect of additive on degradation rate constants. 24 kHz of ultrasound irradiation
was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. To increase the efficiency of
degradation process, degradation system was combined with Fe(III) (2.5 × 10−4mol/L) and H2O2 (0.020–0.118 mol/L) in the presence of UV irradiation and the rate of degradation process change from 1.873 × 10−9−6.083 × 10−9 mol1.7 L s−1. Photo-Fenton process led to complete chitosan degradation in 60 min with the rate increasing with increasing catalyst loading.
Sonophotocatalysis in the presence of Fe(III)/H2O2 was always faster than the respective individual processes. A synergistic effect between ultrasound and ultraviolet irradiation
in the presence of Fenton reagent was calculated. The degraded chitosans were characterized by X-ray diffraction (XRD), gel
permeation chromatography (GPC) and Fourier transform infrared (FT-IR) spectroscopy and average molecular weight of ultrasonicated
chitosan was determined by measurements of intrinsic viscosity of samples. The results show that the total degree of deacetylation
(DD) of chitosan change, partially after degradation and the decrease of molecular weight led to transformation of crystal
structure. A negative order for the dependence of the reaction rate on total molar concentration of chitosan solution within
the degradation process was suggested. Results of this study indicate that the presence of catalyst in the reaction medium
can be utilized to reduce molecular weight of chitosan while maintaining the power of irradiated ultrasound and degree of
deacetylation. 相似文献
18.
T. D. Blackall M. R. Theobald C. Milford K. J. Hargreaves E. Nemitz L. J. Wilson J. Bull P. J. Bacon K. C. Hamer S. Wanless M. A. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):279-285
Ammonia emissions from two contrasting seabird colonies in Scotland were measured, based on the determination of atmospheric concentrations downwind of the colonies. Atmospheric concentrations of ammonia (NH3) across the downwind plume were compared with the inverse application of a Gaussian dispersion model (ID) to calculate the modelled NH3 emission that would generate the measured cross-wind-integrated plume concentration. In parallel, a tracer gas (sulphur hexafluoride, SF6) was released from the colonies with air samples taken to allow determination of SF6 concentrations. On the basis of the known emission rate of SF6, the magnitude of ammonia emissions was estimated by the cross-wind-integrated tracer ratio (TR) of NH3/SF6 concentrations. Coupled with data on annual bird attendance, the measurements indicate annual emissions from the Isle of May and the Bass Rock of 18 and 132 tonnes NH3-N year–1, respectively. The measured NH3 emissions were compared with estimates of seabird nitrogen excretion to estimate the proportion of excreted N that is volatilised as NH3 (FNr). The emission estimates of the two methods compared favourably, giving 4 and 6 kg NH3-N h–1 (FNr = 15%) for the Isle of May for the ID and TR methods, respectively, and 21 and 25 kg NH3-N h–1 (FNr = 50%) for the Bass Rock for the ID and TR methods, respectively. The results provide the first measurement-based estimates to allow regional up scaling of ammonia emissions from seabirds. 相似文献
19.
A. G. Triantafyllou S. Zoras V. Evagelopoulos S. Garas 《Water, Air, & Soil Pollution: Focus》2008,8(1):77-87
Measurements of indoor and outdoor PM10, as well as indoor O3 and CO concentrations were conducted and are presented here. These measurements were carried out at an institute building,
located in a suburban industrial area in Greece. Both indoor and outdoor PM10 samples were also collected and their elemental
composition was identified by ED-XRF analysis. Twenty seven major, minor and trace elements were identified. The measurements
took place generally in different periods of institute operation, from June 2004 to February 2005. The indoor PM10 concentrations
which were measured during the normal operation period of the institute were found to be many times higher than the respective
outdoor PM10 concentrations of the same periods. On the contrary, the indoor PM10 concentrations which were measured during
the holiday period were found to be lower than their corresponding outdoor values. Indoor O3 and CO concentrations were found to be in low level. Indoor PM10 concentrations were found to be in a relative good correlation
with O3 (r = 0.45) and in high correlation (r = 0.98) with CO concentrations. On average, total elements concentrations were much higher indoors relative to outdoors.
Based on above findings we attempted to determine the pollution sources of the indoor environment and to investigate some
parameters or chemical processes that affect indoor pollutants’ levels. 相似文献
20.
Ping-Ping Shen Hong Zhou Ho-Yan Lai Ji-Dong Gu 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):575-581
Benthic infaunal communities at Mai Po Inner Deep Bay mudflat, Hong Kong were investigated between August 2002 and August
2003. A total of 55 species belonging to 8 Phyla from more than 99,074 specimens were recorded. The species richness varied
between 13 at Station B in August 2002 and 28 at Station D in August 2003 with an average of 21 across the mudflat and the
species diversity was low [H′(log2) = 0.7–3.5 with an average H′ = 2.4]. Seasonal variations were also observed through abundance and biomass across the mudflat among the seasons. The abundance
density was between 8,977 individuals m−2 at Station D in February 2003 and 77,256 individuals m−2 at Station B in November 2002 and the overall average density was 25,274 individuals m−2 for the four stations. The benthic infauna were dominated by pollution tolerant species at this wetland mudflat. 相似文献