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1.
M. Jerrett K. B. Newbold R. T. Burnett G. Thurston R. Lall C. A. Pope III R. Ma P. De Luca M. Thun J. Calle D. Krewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(5):511-522
Assessing the long-term benefits of marginal improvements in air quality from regulatory intervention is methodologically
challenging. In this study, we explore how the relative risks (RRs) of mortality from air pollution exposure change over time
and whether patterns in the RRs can be attributed to air quality improvements. We employed two-stage multilevel Cox models
to describe the association between air pollution and mortality for 51 cities with data from the American Cancer Society (ACS)
cohort (N = 264,299, deaths = 69,819). New pollution data were computed through models that predict yearly average fine particle (PM2.5) concentrations throughout the follow-up (1982–2000). Average PM2.5 concentrations from 1999 to 2000 and sulfate concentrations from 1980 were also examined. We estimated the RRs of mortality
associated with air pollution separately for five time periods (1982–1986, 1987–1990, 1991–1994, 1995–1998, and 1999–2000).
Mobility models were implemented with a sub-sample of 100,557 subjects to assist with interpreting the RR estimates. Sulfate
RRs exhibit a large decline from the 1980s to the 1990s. In contrast, PM2.5 RRs follow the opposite pattern, with larger RRs later in the 1990s. The reduction in sulfate RR may have resulted from air
quality improvements that occurred through the 1980s and 1990s in response to the acid rain control program. PM2.5 concentrations also declined in many places, but toxic mobile sources are now the largest contributors to PM in urban areas.
This may account for the heightened RR of mortality associated with PM2.5 in the 1990s. The paper concludes with a three alternative explanations for the temporal pattern of RRs, each emphasizing
the uncertainty in ascribing health benefits to air quality improvements. 相似文献
2.
H.K. Lai H. Tsang J. Chau C.H. Lee S.M. McGhee A.J. Hedley C.M. Wong 《Marine pollution bulletin》2013,66(1-2):158-163
Global marine vessels emissions are adversely affecting human health particularly in southeast Asia. But health burdens from both ocean- and river-going vessels in Pearl River Delta (PRD) regions are not quantified. We estimated the potential health impacts using pooled relative risks of mortality and hospital admissions in China, and the model derived concentrations of sulfur dioxide (SO2), particulate matter (PM10), nitrogen dioxide (NO2) and ozone (O3) due to vessels emissions. SO2 concentrations due to marine emissions in Hong Kong were 13.6 μgm?3 compared with 0.7 μgm?3 in PRD regions that were far from the marine vessels. In PRD regions, the estimated annual numbers (per million people) of excess deaths from all natural causes and hospital admissions from cardiorespiratory causes attributable to SO2, NO2, O3 and PM10 combined from marine emissions were 45 and 265 respectively. Marine emission control measures could contribute a large reduction in mortality and hospital admissions in PRD regions especially in Hong Kong. 相似文献
3.
Débora C. Marié Marcos A. E. Chaparro Claudia S. G. Gogorza Ana Navas Ana M. Sinito 《Studia Geophysica et Geodaetica》2010,54(1):135-152
In this work, we carried out a preliminary study of traffic-derived pollutants from primary sources (vehicles), and on roads
(paved area), road borders and surroundings areas. The study is focussed on the identification, distribution and concentration
of pollutants and magnetic carriers. Magnetic parameters and their analyses suggest that the magnetic signal of vehicle-derived
emissions is controlled by a magnetite-like phase. Magnetic grain size estimations reveal the presence of fine particles (0.1–5
μm) that can be inhaled and therefore are dangerous to human health. Magnetic susceptibility results (about 175 × 10−5 SI) show a higher magnetic concentration — magnetic enhancement — in the central area of the tollbooth line that is related
to higher traffic. In addition, magnetic susceptibility was computed on several roadside soils along a length of 120 km and
used to generate a 2-D contour map, which shows higher magnetic values (100–200 10−5 SI) near the edge of the road. The observed distribution of magnetic values indicates that magnetic particles emitted by
vehicles are accumulated and mainly concentrated within a distance of several meters (1–2 m) from the edge of the road. In
consequence, the magnetic susceptibility parameter seems to be a suitable indicator of traffic-related pollution. Non-magnetic
studies show an enrichment of some trace elements, such as Ba, Cr, Cu, Zn and Pb, that are associated with traffic pollution.
Furthermore, statistical correlations between the content of toxic trace metals and magnetic variables support the use of
magnetic parameters as potential proxies for traffic-related pollution in this study area. 相似文献
4.
Modelling air pollution data by the skew-normal distribution 总被引:3,自引:3,他引:0
Silvia Bartoletti Nicola Loperfido 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(4):513-517
Particulate matter with an aerodynamic equivalent diameter of up 10 μm is commonly referred to as PM10 and its harmful effects on human health are well known. We model annual means of daily concentrations of PM10 in Italy by the skew-normal distribution, giving theoretical as well as empirical motivations for the model’s choice. Its
adequacy is checked through Anderson–Darling statistic. The skew-normal distribution gives a very good fit to the data and
it is particularly useful in estimating probabilities of high PM10 concentrations. 相似文献
5.
Average mass concentrations of TSP, PM10 and PM2.5 in Erzurum urban atmosphere, Turkey 总被引:3,自引:3,他引:0
Hanefi Bayraktar F. Sezer Turalioğlu Gürdal Tuncel 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(1):57-65
In this study, particulate matters (TSP, PM10, PM2.5 and PM10–2.5) which are hazardous for environment and human health were investigated in Erzurum urban atmosphere at a sampling point from
February 2005 to February 2006. During sampling, two low volume samplers were used and each sampling period lasted approximately
24 h. In order for detection of representative sampling region and point of Erzurum, Kriging method was applied to the black
smoke concentration data for winter seasons. Mass concentrations of TSP, PM10 and PM2.5 of Erzurum urban atmosphere were measured on average, as 129, 31 and 13 μg/m3, respectively, in the sampling period. Meteorological factors, such as temperature, wind speed, wind direction and rainfall
were typically found to be affecting PMs, especially PM2.5. Air temperature did not seem to be significantly affecting TSP and PM10 mass concentrations, but had a considerably negative induction on PM2.5 mass concentrations. However, combustion sourced PM2.5 was usually diluted from the urban atmosphere by the speed of wind, soil sourced coarse mode particle concentrations (TSP,
PM10) were slightly affected by the speed of wind. Rainfall was found to be decreasing concentrations to 48% in all fractions
(TSP, PM10, PM10–2.5, PM2.5) and played an important role on dilution of the atmosphere. Fine mode fraction of PM (PM2.5) showed significant daily and seasonal variations on mass concentrations. On the other hand, coarse mode fractions (TSP,
PM10 and PM10–2.5) revealed more steady variations. It was observed that fine mode fraction variations were affected by the heating in residences
during winter seasons. 相似文献
6.
Reliance on motor vehicle travel and the internal combustion engine has provided mobility, but the public health costs are
substantial: Road deaths, adverse deleterious health effects from air pollution and noise, reduction in physical exercise,
and toxic hazards associated with the refining, transport, use and disposal of petrochemicals. For traumatic road injury,
kinetic energy is the pathogen. Risks for injury and death rise with the second and fourth power of increases in velocity
upon impact; emissions of many air pollutants also increase exponentially with speed. Models derived from vector transmission
in infectious diseases have proven useful for defining risks and designing interventive strategies. These models predict the
number of lives saved and injuries prevented from a package of low-cost, effective measures, which can be quickly implemented.
Eradication of road deaths and elimination of air pollution emissions are achievable public health goals.
Speed camera systems produce sustainable levels of detection deterring speeding, and thereby reducing human injury and environmental
damage. “Education” and building more roads, part of the scenario “predict and provide,” have not been shown to reduce injury
risks. Building more roads, which in the long run, promotes urban sprawl and congestion, does not reduce travel time.
High speed toll roads and circular beltways, which involve trade-offs among time-saving, risk of injury, and diversion of
traffic from population centers, need to be re-evaluated and compared to alternative strategies based on modal shifts. We
suggest that revenues resulting from massive use of speed cameras can serve as the first step for funding the first steps
of sustainable transportation policies based on developing alternatives to private vehicle use and trucking. Such alternatives
could lead to even further reductions in injury and death and adverse effects of air pollution. More involvement by epidemiologists
in overseeing and evaluating strategies can expedite progress towards the goal of eradication of deaths from road injury,
and at the same time, reduce emissions of air pollutants.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
《国际泥沙研究》2022,37(5):539-552
A detailed analysis of horizontal and vertical particulate matter (PM) fluxes during wind erosion has been done, based on measurements of PM smaller than 10, 2.5, and 1.0 μm, at windward and leeward positions on a measuring field. The three fractions of PM measurement are differently influenced by the increasing wind and shear velocities of the wind. The measured concentrations of the coarser fractions of the fine dust, PM10, and PM2.5, increase with wind and shear velocity, whereas the PM1.0 concentrations show no clear correlation to the shear velocity. The share of PM2.5 on PM10 depends on the measurement height and wind speed and varies between 4 and 12 m/s at the 1 m height ranging from 25% to 7% (average 10%), and at the 4 m height from 39% to 23% (average 30%). Although general relationships between wind speed, PM concentration, and horizontal and vertical fluxes could be found, the contribution of the measuring field was very low, as balances of incoming and outgoing fluxes show. Consequently, the measured PM concentrations are determined from a variety of sources, such as traffic on unpaved roads, cattle drives, tillage operations, and wind erosion, and thus, represent all components of land use and landscape structure in the near and far surroundings of the measuring field. The current results may reflect factors from the landscape scale rather than the influence of field-related variables. The measuring devices used to monitor PM concentrations showed differences of up to 20%, which led to considerable deviations when determining total balances. Differences up to 67% between the calculated fluxes prove the necessity of a previous calibration of the devices used. 相似文献
8.
Correlation between plasmid DNA damage induced by PM10 and trace metals in inhalable particulate matters in Beijing air 总被引:2,自引:0,他引:2
Lü Senlin Shao Longyi Wu Minghong T. P. Jones L. Merolla R. J. Richard 《中国科学D辑(英文版)》2006,49(12):1323-1331
Based on the study of Beijing PM10 bioreactivity with the newly developed plasmid DNA assay method, and analysis for trace elements of PM10, the cause of plasmid DNA damage by PM10 was investigated. The study showed that plasmid DNA oxidative damages by PM10 are of difference in different seasons at various areas. The concentrations of TM50 of PM10 in whole samples respectively collected at urban and comparison sites during winter were 900 μg mL−1 and 74 μg mL−1, while those in their corresponding soluble fractions were 540 μg mL−1 and 86 μg mL−1. In contrast, TM50 contents of PM10 from summer whole samples at urban areas and comparison sites were 116 μg mL−1 and 210 μg mL−1, whereas those in their soluble fractions were 180 μg mL−1 and 306 μg mL−1. The difference of bioreactivity of Beijing PM10 resulted from the variation of trace elements. The oxidative damage of plasmid DNA caused by Pb, Zn, As in PM10 (whole sample) was relatively strong. TM50 and Mn, V, Zn display stronger correlation in the soluble fraction. It implies
that Zn could be the major trace element in Beijing PM10 which contributes to oxidative damage to plasmid DNA. 相似文献
9.
During the period 2019–2020, size-segregated aerosol samples containing elemental and organic carbon (EC and OC) were investigated. These samples were collected weekly using an eight-stage cascade impactor from an urban site located at Aksaray University, Aksaray. The quantification of EC and OC was carried out through a thermal-optical transmission device. The results revealed consistent size distribution attributes of EC and OC between winter and summer. Although EC accounted for an insignificant percentage (4.4%) of particulate matter (PM) in the PM9.0–10.0 fraction during winter, a more substantial portion of OC in the same fraction (13.4%) comprised EC. Seasonal variations were distinct for EC but not significant for OC. Strong correlations between OC and EC were observed in coarse particle fractions, indicating a common source, with weaker correlations in fine particles. The highest OC/EC ratio was in the PM0.43–0.65 fraction, followed by PM2.1–3.3. The ratio of OC to EC in fine PM exceeded the threshold of 15 consistently. The observation indicates that as particle size increases, there is a noticeable decline in the OC to EC ratios. Secondary organic aerosols (SOA) accounted for 60.8% (winter) and 89.8% (summer) of OC values, emphasizing the substantial impact of SOA on Aksaray's atmosphere. Both seasons exhibited a multimodal distribution of ambient OC. In winter, the EC distribution was dominated by fine particles, with a bimodal pattern (PM1.1–2.1 and PM0.43–0.65 peaks). Common pollutant sources, including traffic emissions, road dust, biogenic emissions, and coal combustion, were identified for both seasons in coarse and fine particle fractions. These findings underscore the importance of emission control strategies targeting fine PM in Aksaray. 相似文献
10.
The prediction of PM2.5 concentrations with high spatiotemporal resolution has been suggested as a potential method for data collection to assess the health effects of exposure. This work predicted the weekly average PM2.5 concentrations in the Yangtze River Delta, China, by using a spatio-temporal model. Integrating land use data, including the areas of cultivated land, construction land, and forest land, and meteorological data, including precipitation, air pressure, relative humidity, temperature, and wind speed, we used the model to estimate the weekly average PM2.5 concentrations. We validated the estimated effects by using the cross-validated R2 and Root mean square error (RMSE); the results showed that the model performed well in capturing the spatiotemporal variability of PM2.5 concentration, with a reasonably large R2 of 0.86 and a small RMSE of 8.15 (μg/m3). In addition, the predicted values covered 94% of the observed data at the 95% confidence interval. This work provided a dataset of PM2.5 concentration predictions with a spatiotemporal resolution of 3 km × week, which would contribute to accurately assessing the potential health effects of air pollution. 相似文献
11.
YueChen Liu ZhiJun Wu TianYi Tan YuJue Wang YanHong Qin Jing Zheng MengRen Li Min Hu 《中国科学:地球科学(英文版)》2016,59(8):1683-1691
Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10~(-8)) ×RH~(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility. 相似文献
12.
Tom Koch Kenneth Denike 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(5):523-531
The problem is not uncertainty—proposed here as an inevitable condition—but the chimera of certainty asserted by most contemporary
researchers. Problems of data definition, collection, and their use are reviewed in terms of spatial epidemiology and health
data with examples drawn from several areas of contemporary health research. The argument is that preconceptions limit data
modeled in a manner assuming its completeness. The result, as the West Nile Virus example seeks to demonstrate, may obscure
other patterns and limit avenues of research. 相似文献
13.
Physicochemical and microbiological characteristics of the bathing waters in Varna’s Black Sea coastal area were investigated
during year 2007 at 23 monitoring stations. Most of the determined physicochemical parameters—pH, mineral oils, surface active
substances, phenols, dissolved oxygen, nutrients and microbiological parameters—“Total coliforms”, “Faecal coliforms”, “Faecal
streptococci” were in compliance with the guidline’ limits and exhibited good water quality. Ammonium and phosphate’s pollution
above the limits was determined at the South beach, Officers beach and Central beach situated in Varna’s central bathing zone.
For the period of 13.08 to 24.10.2007—70% of the South beach samples analyzed for NH4+ exceeded the limits 60 times and the concentrations of PO43− exceeded the limits 17.5 times. Some deviations from the guidline’ limits regarding the microbiology were exhibited at the
same beaches. A conclusion is made that the area of study is not yet seriously threatened, in spite of the rapid recreation
during the last years. 相似文献
14.
Cadet Héloïse Anne-Marie Duval Etienne Bertrand 《Bulletin of Earthquake Engineering》2012,10(2):451-489
This paper presents empirical correlations between amplification factors and simple site parameters derived from a large subset
of the KiK-net data. The amplification factor is estimated from the ratios between the surface and down-hole horizontal response
spectra, corrected for the varying depths and impedance of the down-hole sites (Cadet et al. in Site effect assessment using
KiK-net data—part 1—a simple correction procedure for surface/downhole spectral ratios, 2011). Several site parameters are selected on the basis of their simplicity and availability at relatively low cost. They are
the shallow time-average velocities VSZ, with z equal to 5, 10, 20 and 30 m, and the fundamental frequency f0. The amplification factors are then correlated with each of the individual site parameters; four other “twin-parameter”—couples
(f0, VSZ)—are also considered and the correlation with amplification factors is performed through a normalization of the frequencies
by each site fundamental frequency. The quality of the correlations is given by a misfit compared with the original data variance.
The largest variance reduction is obtained with twin-parameter characterizations, out of which the couple (f0, VS30) proves to provide the lower misfit. The performance of single parameter correlations is relatively lower; however, the best
single parameter proves to be the fundamental frequency, which provides smaller misfit than the Vsz parameters. A comparison
is also performed with the amplification factors recommended in European regulations, showing that it is possible right now
to significantly improve both the site characterization criteria and the associated amplification factors, for use in building
codes and microzonation studies. 相似文献
15.
Following the collapse of the New York World Trade Center (WTC) towers on September 11, 2001, Local, State, and Federal agencies initiated numerous air monitoring activities to better understand the ongoing impacts of emissions from the disaster. The collapse of the World Trade Center towers and associated fires that lasted for several weeks resulted at times in a noticeable plume of material that was dispersed around the Metropolitan New York City (NYC) area. In general, the plume was only noticeable for a short period of time following September 11, and only apparent close to the World Trade Center site. A study of the estimated pathway which the plume of WTC material would likely follow was completed to support the United States Environmental Protection Agency’s 2002 initial exposure assessments. In this study, the WTC emissions were simulated using the CALMET-CALPUFF model in order to examine the general spatial and temporal dispersion patterns over NYC. This paper presents the results of the CALPUFF plume model in terms of plume dilution and location, since the exact source strength remains unknown. Independent observations of PM2.5 are used to support the general dispersion features calculated by the model. Results indicate that the simulated plume matched well with an abnormal increase (600–1000% of normal) in PM2.5 two nights after the WTC collapse as the plume rotated north to southeast, towards parts of NYC. Very little if any evidence of the plume signature was noted during a similar flow scenario a week after September 11. This leads to the conclusion that other than areas within a few kilometers from the WTC site, the PM2.5 plume was not observable over NYC’s background concentration after the first few days. 相似文献
16.
Black carbon aerosols and their radiative properties in the Pearl River Delta region 总被引:13,自引:0,他引:13
Dui Wu JieTai Mao XueJiao Deng XueXi Tie YuanHang Zhang LiMin Zeng Fei Li HaoBo Tan XueYan Bi XiaoYing Huang Jing Chen Tao Deng 《中国科学D辑(英文版)》2009,52(8):1152-1163
The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative
properties of the aerosols are one of the important parameters in assessing climatic change. Here we studied the black carbon
concentration and absorption coefficient measured with aethalometers, scattering coefficient measured with nephelometers,
and single scattering albedo derived at an atmospheric composition watch station in Guangzhou from 2004 to 2007. Our main
results are as follows. The data of black carbon concentration and absorption coefficients measured with instruments cannot
be directly used until they are measured in parallel with internationally accepted instruments for comparison, calibration,
and reduction. After evaluation of the data, the result shows that the monthly mean of BC concentration varies 3.1–14.8 μg·m−3 and the concentration decreases by about 1 μg·m−3 in average over the four years; It is higher in the dry season with a multi-year mean of 8.9 μg/m3 and lower in the rainy season with a multi-year mean of 8.0 μg·m−3; The extreme maximum of monthly mean concentration occurred in December 2004 and extreme minimum in July 2007, and a 4-year
mean is 8.4 μg·m−3. It is also shown that monthly mean scattering coefficient derived varies 129 −565 Mm−1, monthly mean absorption coefficient 32–139 Mm−1, and monthly mean single scattering albedo 0.71–0.91, with annual mean values of 0.80, 0.82, 0.79 and 0.84 for 2004, 2005,
2006 and 2007, respectively. Three instruments were used to take simultaneous measurements of BC in PM10, PM2.5, and PM1 and the results showed that PM2.5 took up about 90% of PM10 and PM1 accounted for about 68% of PM2.5, and BC aerosols are mainly present in fine particulates. The variability of BC concentrations is quite consistent between
the Nancun station (141 m above sea level) and the Panyu station (13 m above sea level), which are 8 km apart from each other.
The concentration in higher altitude station (Panyu) is consistently lower than the lower altitude station (Nancun), and the
difference of annual mean is about 4 μg·m−3.
Supported by Natural Science Foundation of China (Grant Nos. U0733004, 40375002, 40418008, 40775011), National High Technology
R & D Program of China (Grant Nos. 2006AA06A306 and 2006AA06A308) and National Basic Research Program of China (Grant No.
2005CB422207) 相似文献
17.
HUANG XiaoFeng YUN Hui GONG ZhaoHeng LI Xiang HE LingYan ZHANG YuanHang HU Min 《中国科学:地球科学(英文版)》2014,57(6):1352-1362
PM2.5 is the key pollutant in atmospheric pollution in China.With new national air quality standards taking effect,PM2.5 has become a major issue for future pollution control.To effectively prevent and control PM2.5,its emission sources must be precisely and thoroughly understood.However,there are few publications reporting comprehensive and systematic results of PM2.5 source apportionment in the country.Based on PM2.5 sampling during 2009 in Shenzhen and follow-up investigation,positive matrix factorization(PMF)analysis has been carried out to understand the major sources and their temporal and spatial variations.The results show that in urban Shenzhen(University Town site),annual mean PM2.5 concentration was 42.2μg m?3,with secondary sulfate,vehicular emission,biomass burning and secondary nitrate as major sources;these contributed30.0%,26.9%,9.8%and 9.3%to total PM2.5,respectively.Other sources included high chloride,heavy oil combustion,sea salt,dust and the metallurgical industry,with contributions between 2%–4%.Spatiotemporal variations of various sources show that vehicular emission was mainly a local source,whereas secondary sulfate and biomass burning were mostly regional.Secondary nitrate had both local and regional sources.Identification of secondary organic aerosol(SOA)has always been difficult in aerosol source apportionment.In this study,the PMF model and organic carbon/elemental carbon(OC/EC)ratio method were combined to estimate SOA in PM2.5.The results show that in urban Shenzhen,annual SOA mass concentration was 7.5μg m?3,accounting for 57%of total organic matter,with precursors emitted from vehicles as the major source.This work can serve as a case study for further in-depth research on PM2.5 pollution and source apportionment in China. 相似文献
18.
Relationship between coral growth rate and sea surface temperature in the northern part of South China Sea during the past 100 a 总被引:4,自引:0,他引:4
Baofu Nie Tegu Chen Meitao Liang Youqiang Wang Jinliang Zhong Yuanzhi Zhu 《中国科学D辑(英文版)》1997,40(2):173-182
To research the relationship between coral growth rate and sea surface temperatnre (Tss), 5 cores of livingPorites lutea were collected from the Xisha Islands and the southern Hainan Island waters and measured. The results of the study show that
there is an obviously positive correlation between the coral growth rates and theTss records from the northern part of South China Sea. The annual growth rates of the five samples ofPorites lutea during the past 100 a are in the range of 7—15 mm/a, and their mean value is 11 mm/a. The correlation coefficients between
the coral growth rates and the Tss records from the waters during 1961—1993 are in the range of 0.77—0.89. As a result, a thermometer of the coral growth rate
is established. A hindcasting Tss, in the waters from 1993 to 1961 has been obtained with an error of about 0.12—0.17°C. Based upon the calculated result,
the rising rate of Tss in the northern part of South China Sea during the past 100 a is 0.20°C. which is higher than that of the air temperature
in China (0.09°C/100 a), but lower than that of the global temperature and that of Tss in the tropical western Pacific Ocean.
Project supported by the National Nutural Science Foundation of China and the Multidesciplinary Oceanographic Expedition Team
of Chinese Academy of Sciences to the Nansha Islands. 相似文献
19.
Roberto Carniel Marta Tárraga Fausto Barazza Alicia García 《Bulletin of Volcanology》2008,70(9):1113-1121
Continuous seismic noise is recorded in the volcanic island of Tenerife (Canary Islands, Spain). The origin of this noise,
strongly augmented by anthropogenic contamination, is still under debate. In this paper, we discuss the relationship between
this noise and the occurrence of local tectonic events in the same area. In particular, transitions are sought in the time
evolution of dynamic parameters computed on the seismic noise, and examples are shown where abrupt transitions may be associated
with the occurrence of tectonic events. These transitions provide further evidence of the existence of a natural origin for
at least part of the seismic noise, which is strongly contaminated—if not dominated—by anthropogenic sources. 相似文献
20.
The source parameters of the Bohai Sea earthquake, July 18, 1969 and Yongshan, Yunnan earthquake, May 11, 1974 were determined
by full — wave theory synthetic seismograms of teleseismic P waves. P+pP+sP wereform were calculated with WKBJ approximation
and real integral paths. One — dimensional unilateral, finite propagation source was also considered. By trail — and — error
in comparing the theoretical seismograms with the observational ones of WWSSN stations, the source parameters were obtained
as follow: for Bohai earthquake, φ=195°, δ=85°, λ=65°,M
o=0.9×1019Nm,L=59.9km.V
R=3.5km/s, ∧
R
=160°; for Yongshan earthquake, φ=240°, δ=80°, ∧=150°,M
o=1.3×1018Nm,L=48.8km,V
R=3km/s, ∧
R
=−10°, where φ is strike, δ dip angle, λ slip angle,M
o seismic moment,L rupture length,V
R rupture propagation speed. As III type fractures the faulting propagated along the fault planes, and ∧
R
is the angle from the strike to the propagation direction. Yongshan earthquake showed complexity in its focal process, having
four sub—ruptures during the first 60 seconds.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 1–8, 1991. 相似文献