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KM Cawley KD Butler GR Aiken LG Larsen TG Huntington DM McKnight 《Marine pollution bulletin》2012,64(8):1678-1687
Using fluorescence spectroscopy and parallel factor analysis (PARAFAC) we characterized and modeled the fluorescence properties of dissolved organic matter (DOM) in samples from the Penobscot River, Androscoggin River, Penobscot Bay, and the Gulf of Maine (GoM). We analyzed excitation-emission matrices (EEMs) using an existing PARAFAC model (Cory and McKnight, 2005) and created a system-specific model with seven components (GoM PARAFAC). The GoM PARAFAC model contained six components similar to those in other PARAFAC models and one unique component with a spectrum similar to a residual found using the Cory and McKnight (2005) model. The unique component was abundant in samples from the Androscoggin River immediately downstream of a pulp mill effluent release site. The detection of a PARAFAC component associated with an anthropogenic source of DOM, such as pulp mill effluent, demonstrates the importance for rigorously analyzing PARAFAC residuals and developing system-specific models. 相似文献
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Fluorescence and UV‐VIS techniques were employed for the investigation of natural organic matter (NOM) of a tropical lake. The relationships of absorbance/dissolved organic carbon (A/DOC), fluorescence intensity/dissolved organic carbon (FI/DOC), fluorescence ratio (FR), and peak wavelength with the highest intensity (PW) were used to distinguish the pedogenic or aquagenic origin of NOM. The values of FR, PW and A285/DOC of high waters (HW) or flooded period samples and of low waters (LW) period samples of the dry season, except for September 2002, confirm the predominance of pedogenic material. The spectra of water were similar to the standard fulvic acid (FA), and the spectra of FA from the lake were similar to the nearby soils, indicative of pedogenic predominance. The results confirm that the dissolved NOM of Patos Lagoon – MS (Brazil), in all sampling periods, predominantly consisted of humic substances (FA) of pedogenic origin. 相似文献
5.
Guang-hui Cai Hang Wu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(1-2):1-5
Let {Y, Y
i
, −∞ < i < ∞} be a doubly infinite sequence of identically distributed and asymptotically linear negative quadrant dependence random
variables, {a
i
, −∞ < i < ∞} an absolutely summable sequence of real numbers. We are inspired by Wang et al. (Econometric Theory 18:119–139, 2002) and Salvadori (Stoch Environ Res Risk Assess 17:116–140, 2003). And Salvadori (Stoch Environ Res Risk Assess 17:116–140, 2003) have obtained Linear combinations of order statistics to estimate the quantiles of generalized pareto and extreme values
distributions. In this paper, we prove the complete convergence of under some suitable conditions. The results obtained improve and generalize the results of Li et al. (1992) and Zhang (1996). The results obtained extend those for negative associated sequences and ρ*-mixing sequences.
CIC Number O211, AMS (2000) Subject Classification 60F15, 60G50
Research supported by National Natural Science Foundation of China 相似文献
6.
The earthquakes in Uttarkashi (October 20, 1991, M
w 6.8) and Chamoli (March 8, 1999, M
w 6.4) are among the recent well-documented earthquakes that occurred in the Garhwal region of India and that caused extensive
damage as well as loss of life. Using strong-motion data of these two earthquakes, we estimate their source, path, and site
parameters. The quality factor (Q
β
) as a function of frequency is derived as Q
β
(f) = 140f
1.018. The site amplification functions are evaluated using the horizontal-to-vertical spectral ratio technique. The ground motions
of the Uttarkashi and Chamoli earthquakes are simulated using the stochastic method of Boore (Bull Seismol Soc Am 73:1865–1894,
1983). The estimated source, path, and site parameters are used as input for the simulation. The simulated time histories are
generated for a few stations and compared with the observed data. The simulated response spectra at 5% damping are in fair
agreement with the observed response spectra for most of the stations over a wide range of frequencies. Residual trends closely
match the observed and simulated response spectra. The synthetic data are in rough agreement with the ground-motion attenuation
equation available for the Himalayas (Sharma, Bull Seismol Soc Am 98:1063–1069, 1998). 相似文献
7.
John E. Hathaway Richard O. Gilbert John E. Wilson Brent A. Pulsipher 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(2):253-261
After site clean-up teams have removed all of what they believe to be UXO within a specific impact area, statistical compliance
sampling is a possible method for verifying with a specified probability that this area has been cleaned to specifications.
Schilling [J Qual Technol 10(2):47–51, 1978, Acceptance sampling in quality control. Marcel Dekker, Inc., New York, 1982] developed a compliance sampling methodology based on the hypergeometric distribution. Bowen and Bennett (1987) also use compliance sampling where they provide an approximation for estimating the number of samples (n) required to state with desired probability that the entire population of sample units (N, where n < N) are in compliance with cleanup goals. This article describes two methods (anomaly and transect) for applying the Schilling
[J Qual Technol 10(2):47–51, 1978, Acceptance sampling in quality control. Marcel Dekker, Inc., New York, 1982] compliance sampling method to military training sites. After describing these methods, a simulation study is presented which
demonstrates the performance of transect compliance sampling calculations based on varied degrees of clustered UXO within
a specific impact area and different types of sampling routines. 相似文献
8.
Changes in habitat acoustics over the year can potentially affect fish hearing and orientation to sound, especially in temperate
climates. This is the first study where year-round changes in ambient noise in aquatic habitats were assessed. Seven different
European freshwater habitats were chosen for this study. Sound pressure level (SPL) and spectral composition of the ambient
noise varied in both quiet stagnant habitats (lakes, backwaters) and in flowing habitats (streams, rivers). Linear equivalent
SPL (LLeq, 60s) tended to be lower in stagnant habitats (means: 91.6–111.7 dB) than in flowing habitats (means: 111.2–133.4 dB). The changes
in SPL were smallest in the river (means: 4.2–4.4 dB, maxima: 8.5–10.1 dB), whereas significantly higher values were measured
in stagnant habitats and the stream (means: 9.9–14.9 dB, maxima: 25.1–30.9 dB). The spectral compositions of the ambient noise
determined at different times of the year were highly correlated to each other at the river sites (mean cross-correlation
coefficients: 0.85 and 0.94) and were weaker or not correlated at the other study sites (means: 0.24–0.76). The changes in
ambient noise spectra were negatively correlated to changes in SPL, indicating that large changes in SPLs were accompanied
by large changes in spectral composition and vice versa. Comparison of these eco-acoustical data with a preceding study (Amoser
and Ladich in J Exp Biol 208:3533–3542, 2005) indicates that the auditory sensitivity in hearing specialists is affected by changes in ambient noise levels and spectra
throughout a year and that this effect tends to be more pronounced in stagnant waters and the stream than at river sites.
On the other hand, absolute noise levels result in a higher degree of masking in flowing waters. 相似文献
9.
An automatic scheme for baseline correction of strong-motion records in coseismic deformation determination 总被引:2,自引:0,他引:2
Coseismic deformation can be determined from strong-motion records of large earthquakes. Iwan et al. (Bull Seismol Soc Am
75:1225–1246, 1985) showed that baseline corrections are often required to obtain reliable coseismic deformation because baseline offsets lead
to unrealistic permanent displacements. Boore (Bull Seismol Soc Am 91:1199–1211, 2001) demonstrated that different choices of time points for baseline correction can yield realistically looking displacements,
but with variable amplitudes. The baseline correction procedure of Wu and Wu (J Seismol 11:159–170, 2007) improved upon Iwan et al. (Bull Seismol Soc Am 75:1225–1246, 1985) and achieved stable results. However, their time points for baseline correction were chosen by a recursive process with
an artificial criterion. In this study, we follow the procedure of Wu and Wu (J Seismol 11:159–170, 2007) but use the ratio of energy distribution in accelerograms as the criterion to determine the time points of baseline correction
automatically, thus avoiding the manual choice of time points and speeding up the estimation of coseismic deformation. We
use the 1999 Chi-Chi earthquake in central Taiwan and the 2003 Chengkung and 2006 Taitung earthquakes in eastern Taiwan to
illustrate this new approach. Comparison between the results from this and previous studies shows that our new procedure is
suitable for quick and reliable determination of coseismic deformation from strong-motion records. 相似文献
10.
This communication describes the use of differential absorbance spectroscopy to explore the intermediates formed during halogenation of natural organic matter (NOM). The differential spectra of chlorinated NOM comprise two contributions. The primary component is negative and has a peak near 270 nm. The shape of this band is independent of chlorine dose, and its intensity increases monotonically with Cl2 dose. The second component is positive, with a well‐defined peak near 280 nm and another, broader band in the 340...380 nm range. The second component is noticeable at low chlorine concentrations but disappears with increasing Cl2 dose. We attribute this component to aromatic chlorinated intermediates formed prior to the release of identifiable smaller species such as haloacetic acids. We believe that this component of the differential spectra can be used to probe the identity, formation and breakdown of the halogenated intermediates. 相似文献
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Selection and ranking of ground motion models for seismic hazard analysis in the Pyrenees 总被引:1,自引:0,他引:1
Stéphane Drouet Frank Scherbaum Fabrice Cotton Annie Souriau 《Journal of Seismology》2007,11(1):87-100
The issue addressed in this paper is the objective selection of appropriate ground motion models for seismic hazard assessment
in the Pyrenees. The method of Scherbaum et al. (2004a) is applied in order to rank eight published ground motion models relevant to intraplate or to low deformation rate contexts.
This method is based on a transparent and data-driven process which quantifies the model fit and also measures how well the
underlying model assumptions are met. The method is applied to 15 accelerometric records obtained in the Pyrenees for events
of local magnitude between 4.8 and 5.1, corresponding to moment magnitudes ranging from 3.7 to 3.9. Only stations at rock
sites are considered. A total of 720 spectral amplitudes are used to rank the selected ground motion models. Some control
parameters of these models, such as magnitude and distance definitions, may vary from one model to the other. It is thus important
to correct the selected models for their difference with respect to the magnitude and distance definitions used for the Pyrenean
data. Our analysis shows that, with these corrections, some of the ground motion models successfully fit the data. These are
the Lussou et al. (2001) and the Berge-Thierry et al. (2003) models. According to the selected ground motion models, a possible scenario of a magnitude 6 event is proposed; it predicts
response spectra accelerations of 0.08–0.1 g at 1 Hz at a hypocentral distance of 10 km. 相似文献
12.
Depth profiles of fluorescence at several excitation and emission wavelengths were measured along with CTD data during the
cruise So119 of RV Sonne in the Arabian Sea from 12 May to 10 June 1997. In addition to chlorophyll fluorescence from phytoplankton in the near-surface
layer, the profiles in the oxygen minimum region well below the euphotic zone show enhanced red fluorescence. Red fluorescence
intensity is inversely related to the oxygen concentration in intermediate and deep waters. A relationship to characteristic
water masses of the region cannot be found in the data, and this holds also with chemical data such as DOC. Absorbance spectra
of water samples taken in the oxygen minimum zone show an absorption band at 420 nm wavelength with about 50 nm bandwidth,
much weaker than gelbstoff absorbance in the same wavelength range. The absorption band remains stable after sample filtration
with 0.45 μm glass fibre filters. Hence, the size of the absorbing matter is in the range of dissolved molecules or particles
much smaller than 1 μm. Fluorescence spectra of unfiltered samples with 420 nm excitation show a weak emission band at 600
nm and a more pronounced one at 660 nm wavelength. The trailing edge of the 660 nm band falls into the range of chlorophyll
emission, thus giving rise to the observed depth profiles of red fluorescence in the oxygen minimum zone. Red fluorescence
measured on samples remain stable during a few hours after sampling even in the presence of oxygen. It is not detectable after
several weeks of sample storage in the dark and cannot be reproduced even after depletion of dissolved oxygen.
Received: 22 May 2002 / Accepted: 18 February 2003
Responsible Editor: Andreas Oschlies
Acknowledgements. This work was supported by a grant from the Federal Minister of Education and Technology, Bonn, within the frame work of
the JGOFS Arabian Sea program. We are grateful to the captain and the crew of RV Sonne for their support. We are indebted to Mrs. Kirsten Neumann from the Institute of Marine Chemistry and Biogeochemistry of
the University of Hamburg for providing the oxygen data, and to Mr. Nikolai Delling from the same institute for making the
DOC and chlorophyll data available to us. 相似文献
13.
Comprehensive evaluation of regional flood frequency analysis by L- and LH-moments. I. A re-visit to regional homogeneity 总被引:1,自引:0,他引:1
Ali Meshgi Davar Khalili 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(1):119-135
As part I of a sequence of two papers, previously developed L-moments by Hosking (J R Stat Soc Ser B Methodol 52(2):105–124,
1990), and the LH-moments by Wang (Water Resour Res 33(12):2841–2848, 1997) are re-visited. New relationships are developed for regional homogeneity analysis by the LH-moments, and further establishment
of regional homogeneity is investigated. Previous works of Hosking (J R Stat Soc Ser B Methodol 52(2):105–124, 1990) and Wang (Water Resour Res 33(12):2841–2848, 1997) on L-moments and LH-moments for the generalized extreme value (GEV) distribution are extended to the generalized Pareto
(GPA) and the generalized logistic (GLO) distributions. The Karkhe watershed, located in western Iran is used as a case study
area. Regional homogeneity was investigated by first assuming the entire study area as one regional cluster. Then the entire
study area was designated “homogeneous” by the L-moments (L); and was designated “heterogeneous” by all four levels of the
LH-moments (L1 to L4). The k-means method was used to investigate the case of two regional clusters. All levels of the L- and LH-moments designated the
upper watershed (region A), “homogeneous”, and the lower watershed (region B) “possibly-homogeneous”. The L3 level of the GPA and the L4 level of the GLO were selected for regions A and B, respectively. Wang (Water Resour Res 33(12):2841–2848, 1997) identified a reversing trend in improved performance of the GEV distribution at the LH-moments level of L3 (during the goodness-of-fit test). Similar results were also obtained in this research for the GEV distribution. However,
for the case of the GPA distribution the reversing trend started at L4 for region A; and at L2 for region B. As for the case of the GLO, an improved performance was observed for all levels (moving from L to L4); for both regions. 相似文献
14.
A reappraisal of shear wave splitting parameters from Italian active volcanic areas through a semiautomatic algorithm 总被引:1,自引:0,他引:1
Shear wave splitting parameters represent a useful tool to detail the stress changes occurring in volcanic environments before
impending eruptions. In the present paper, we display the parameter estimates obtained through implementation of a semiautomatic
algorithm applied to all useful datasets of the following Italian active volcanic areas: Mt. Vesuvius, Campi Flegrei, and
Mt. Etna. Most of these datasets have been the object of several studies (Bianco et al., Annali di Geofisica, XXXXIX 2:429–443,
1996, J Volcanol Geotherm Res 82:199–218, 1998a, Geophys Res Lett 25(10):1545–1548, 1998b, Phys Chem Earth 24:977–983, 1999, J Volcanol Geotherm Res 133:229–246, 2004, Geophys J Int 167(2):959–967, 2006; Del Pezzo et al., Bull Seismol Soc Am 94(2):439–452, 2004). Applying the semiautomatic algorithm, we confirmed the results obtained in previous studies, so we do not discuss in much
detail each of our findings but give a general overview of the anisotropic features of the investigated Italian volcanoes.
In order to make a comparison among the different volcanic areas, we present our results in terms of the main direction of
the fast polarization (φ) and percentage of shear wave anisotropy (ξ). 相似文献
15.
Use of spectral acceleration data for determination of three-dimensional attenuation structure in the Pithoragarh region of Kumaon Himalaya 总被引:1,自引:0,他引:1
Three-dimensional attenuation structures are related to the subsurface heterogeneities present in the earth crust. An algorithm
for estimation of three-dimensional attenuation structure in the part of Garhwal Himalaya, India has been presented by Joshi
(Curr Sci 90:581–585, 2006b; Nat Hazards 43:129–146, 2007). In continuation of our earlier approach, we have presented a method in which strong motion data have been used to estimate
frequency-dependent three-dimensional attenuation structure of the region. The border district of Pithoragarh in the Higher
Himalaya, India, lies in the central seismic gap region of Himalaya. This region falls in the seismic zones IV and V of the
seismic zoning map of India. A dense network consisting of eight accelerographs has been installed in this region. This network
has recorded several local events. An algorithm based on inversion of strong motion digital data is developed in this paper
to estimate attenuation structure at different frequencies using the data recorded by this network. Twenty strong motion records
observed at five stations have been used to estimate the site amplification factors using inversion algorithm defined in this
paper. Site effects obtained from inversion has been compared with that obtained using Nakamura (1988) and Lermo et al. (Bull Seis Soc Am 83:1574–1594, 1993) approach. The obtained site amplification term has been used for correcting spectral acceleration data at different stations.
The corrected spectral acceleration data have been used as an input to the developed algorithm to avoid effect of near-site
soil amplification term. The attenuation structure is estimated by dividing the entire area in several three-dimensional block
of different frequency-dependent shear wave quality factor Q
β
(f). The input to this algorithm is the spectral acceleration of S phase of the corrected accelerogram. The outcome of the algorithm
is given in terms of attenuation coefficient and source acceleration spectra. In the present study, this region has been divided
into 25 rectangular blocks with thickness of 10 km and surface dimension of 12.5 × 12.1 km, respectively. Present study gives
three-dimensional attenuation model of the region which can be used for both hazard estimation and simulation of strong ground
motion. 相似文献
16.
This paper presents the analysis of measurements of long waves at the harbor of Marina di Carrara, Italy. Nine pressure gauges
(eight in the inner harbor and one outside the harbor) were used to record continuously the water surface elevation, for about
3 years; incoming short waves were measured using a directional buoy at about 500 m offshore the breakwaters. The analysis
is carried out splitting the energy of the long waves into two bands, i.e., very long waves (VLW; f < 0.003 Hz) and long waves (LW; 0.003 < f < 0.030 Hz); it is found that LW energy is strongly correlated with the energy of the incoming short waves while no correlation
(or very poor) is found for VLW. During energetic sea states, surface elevation spectra of VLW and LW, normalized against
the wave energy of each frequency band, appear to be autosimilar; this suggests that the spectra of the incoming long waves
have a mostly constant shape. Simple numerical computations of harbor resonance, carried out using a mild-slope equation linearized
model, indicate that the amplification of the height of the incoming LW generated by short waves (calculated using empirical
formulae from previous researches by Melito et al. 2007) inside the harbor can be reasonably predicted using such simple approach, assuming that the LW spectra are rectangular.
The shape of the amplification diagram calculated by the numerical model shows reasonable (but not perfect) agreement with
the shape of the normalized measured spectra inside the harbor. 相似文献
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The vernal pool fairy shrimp (Branchinecta lynchi) (Eng et al. in J Crustac Biol 10:247–277, 1990) is broadly distributed throughout California’s Central Valley with disjunct populations in southern California and southern
Oregon. A survey of genetic variation at the mitochondrial cytochrome c oxidase subunit I (COI) gene was conducted from individuals
collected throughout the range of the species. Phylogenetic analysis of unique haplotypes could not resolve any significant
genetic partitions below the species level. A detailed analysis of samples from two pools indicates that sample sizes underestimate
overall variation, but that the general phylogeographic pattern still holds. Evidence was found for a putative long-distance
dispersal event between Central Valley sites and the Oregon site. These results indicate that geographically limiting stochastic
colonization followed by local diversification may be important in governing current genetic structure for this species. Future
and current conservation/restoration efforts should recognize the geographic limitations to population structure for this
species and focus on local endemic genetic variation. 相似文献
20.
蓝藻水华暴发和衰亡对太湖有色可溶性有机物的影响 总被引:1,自引:1,他引:0
利用平行因子分析(PARAFAC)技术对藻华暴发季节太湖梅梁湾和开敞区水样中有色可溶性有机物(CDOM)的三维荧光光谱进行分析,获得代表类酪氨酸、类色氨酸和类腐殖酸等3种荧光组分,这3个组分的荧光得分值均与叶绿素a浓度呈极显著正相关,其中类腐殖酸物质荧光得分值占总分值的比例也与叶绿素a浓度极显著正相关,由此可以推测,蓝藻水华可能是太湖CDOM的一个重要来源,并极大地影响了湖泊CDOM的组成结构.为进一步探索蓝藻水华对湖泊CDOM的影响,于太湖梅梁湾湖岸进行藻华暴发和衰亡模拟试验.PARAFAC结果显示,模拟试验水样CDOM的三维荧光图谱同样含有3个组分,其中类酪氨酸和类色氨酸荧光峰位置与湖泊水样基本相同,而类腐殖酸物质荧光峰则有一定程度的蓝移,表明培养试验中有新的内源类腐殖酸物质产生.利用PARAFAC模型中的得分值计算后发现,初始叶绿素a浓度越高,类腐殖酸物质所占比例越大,而实验结束时添加了高浓度和中等浓度藻的2个处理中类腐殖酸物质对荧光的贡献率也有显著提高.因此,藻华的长期暴发可以显著改变湖泊CDOM的组成,导致类腐殖酸物质比例提高. 相似文献