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2010 Vol.30 Issue.9,Published 2010-09-20
1153 The mean concentration and chemical reactivity of VOCs of typical processes over Pearl River Delta Region
DENG Xue-Jiao, WANG Xin-Ming, ZHAO Chun-Sheng, RAN Liang, LI Fei, TAN Hao-Bo, DENG Tao, WU Dui, ZHOU Xiu-Ji
The diurnal features of VOCs in relative pollution and clean processes in autumn over Pearl River Delta (PRD) are analyzed. The mass concentration of VOCs under pollution circumstances can be 2.2 times as high as that with clean process. Contributed to pollution enrichment are the pollutants of toluene, xylene, ethylbenzene, butane, pentane, propane, acetylene and ethane, etc. The isoprene emitted from nature has the diurnal features of lower concentration in the morning and evening versus higher concentration during daytime, indicating characteristics of botanic photosynthesis, while toluene from anthropogenic emission has the diurnal features which basically reveal the effects of diurnal changes of meteorological condition and source emission, with obvious pollution enrichment in the morning and lower concentration in the afternoon under relative pollution circumstances. Relatively more active reactivity pollutants include alkene (trans-2-butene, isoprene, cis-2-pentene) and aromatic hydrocarbon (m/p-xylene, toluene), of which alkene has the lowest mass percentage while having the highest chemical reactivity percentage.
2010 Vol. 30 (9): 1153-1161 [Abstract] ( 329 ) [HTML 1KB] [ PDF 649KB] ( 1172 )
1162 Aircraft study of cloud water chemistry over Jilin Province in Northeast China
XUE Li-Kun, DING Ai-Jun, REN Yu, GAO Jian, WANG Tao, WANG Wen-Xing, WANG Xue-Zhong, LEI Heng-Chi, JIN De-Zhen
24 cloud water samples were collected aboard an aircraft over Jilin province during June-July 2007. The pH values and concentrations of major water-soluble ions were analyzed. The results showed that the cloud water was obviously acidified, with a mean pH value of 4.93. The dominant ions were SO42-, NH4+, Ca2+, and NO3-, with mean concentrations of 109.7, 74.8, 71.9, and 51.4meq/L, respectively. The equivalent ratio of SO42-/NO3- was 2.1, which is comparable to that of the precipitation at Longfengshan. The concentrations of ions in cloud water were mainly affected by synoptic weather condition and long-range transport patterns. Ensemble trajectory analysis revealed that the cloud water with the highest ion concentrations was affected by the regional transport of air pollution from the North China Plains. Comparison of cloud water with rain water samples at ground level suggests that the acidity of rainfalls can be neutralized during the washout process.
2010 Vol. 30 (9): 1162-1167 [Abstract] ( 263 ) [HTML 1KB] [ PDF 708KB] ( 776 )
1168 Divergence characteristics and formation mechanism of wind field appropriate for the cyanobacteria bloom in Taihu Lake
WANG Cheng-Lin, CHEN Li-Ming, PAN Wei-Yu, QIAN Xin
Based on conventional observational data from the 17 meteorological stations in 7 years around Taihu Lake, a cluster analysis is carried out. The analysis indicates that there is divergence wind field (DWF) above the water surface under the weather condition of high temperature and gentle breeze, which is suitable for the cyanobacteria bloom. Being driven by DWF, the transportation of the algae must be different with the situation under the single wind field. Based on this phenomenon, typical cases are selected for the numerical simulation. The simulation result shows that nonuniform diabatic heating process causes local thermodynamic sub-circulation which is superimposed upon weak background wind field. It is the formation mechanism of DWF. The intensity of the DWF depends on the lake-land thermal difference and the speed of the background wind field.
2010 Vol. 30 (9): 1168-1176 [Abstract] ( 323 ) [HTML 1KB] [ PDF 999KB] ( 966 )
1177 Sorption and sorption kinetics of nitrobenzene and sevin on activated carbon
ZHOU Yan-Mei, ZHANG Qiong, DIAO Xiao-Hua, LI Xiao-Yue
Pore structure, surface property and chemical constitution of activated carbon were determined and analyzed. The sorption isotherms and kinetics of nitrobenzene and sevin on activated carbon were examined, respectively. The data demonstrate that Polanyi-Manes model and two-stape dynamics equation fit best with the highest regression coefficients (R2), implying that sorption may be a multi-process reaction with dominating dynamic of dispersion force. The sorption capacity and rate of sevin onto activated carbon are lower than those of nitrobenzene, and the difference between fast and slow sorption stage is more obvious, indicate that adsorbate molecular size and adsorbent pore structure significantly influence the adsorption. The effect of Na+ concentration on sorption is slight, possible due to little effect of medium ionic strength on dispersion force among moleculars.
2010 Vol. 30 (9): 1177-1182 [Abstract] ( 230 ) [HTML 1KB] [ PDF 587KB] ( 803 )
1183 Static adsorption property of dimethylamine on ion exchange resin
MENG Yuan-Yuan, HU Qin-Hai, SUN Tong-Xi, LU Qiao-Zhi, XIONG Yun-Long
The fine grained resin ZGSPC106 was used to adsorb dimethylamine (DMA) from aqueous solution in the present research. Batch experiments were performed to analyze the thermodynamics and kinetics of adsorption. Results showed the equilibrium adsorption data were conformed satisfactorily to the Langmuir equation. The evaluation based on Langmuir isotherm gave the maximal static saturated adsorption capacity of 138.89mg/g at 293K. Various thermodynamic parameters such as free energy (ΔGo), enthalpy (ΔHo) and entropy (ΔSo) showed that the adsorption was spontaneous, endothermic and feasible. DMA adsorption on ZGSPC106 fitted well to the pseudo-second-order kinetic model and mainly controlled by the intraparticle diffusion. Furthermore, the adsorption mechanism was discussed by Fourier transform infrared spectroscopy (FT-IR) analysis.
2010 Vol. 30 (9): 1183-1188 [Abstract] ( 221 ) [HTML 1KB] [ PDF 492KB] ( 1113 )
1189 Effect of pipe materials on disinfection byproduct generated by monochloramine and biological stability of water quality
FU Jun, TENG Man, XIAO Hua
A simulated distribution system was employed to investigate water quality of effluent in one plant in Shanghai, and effect of five kinds of pipes and monochloramine dose on water quality were studied. Generally, decay rate of monochloramine in different pipes fitted with the following trend: galvanized pipe > copper pipe > stainless steel pipe > PE pipe > PPR pipe. The season had much effect on decay rate of monochloramine, which was much lower in autumn and winter than that in other two seasons. The formation of trihalomethanes (THMs) and haloacetic acids (HAAs) followed degressive order: PE ~ PPR > glass > stainless steel > copper > galvanized pipe. The value of heterotrophic plate counts (HPC) followed the decending order: galvanized pipe >> PE > stainless steel > PPR > copper. Concentration of assimilable organic carbon (AOC) in copper and PE pipe was much higher than that in other pipes.
2010 Vol. 30 (9): 1189-1194 [Abstract] ( 279 ) [HTML 1KB] [ PDF 445KB] ( 853 )
1195 Biological nutrients removal from domestic wastewater with low carbon-to-nitrogen ratio in A2O-BAF system at low temperature
WANG Jian-Hua, CHEN Yong-Zhi, PENG Yong-Zhen
Operational performance of A2O-BAF was investigated when treating domestic wastewater with low carbon-to-nitrogen ratio at low temperature. Under the condition of average temperature of 14.2℃ and carbon-to-nitrogen radio of 4.81, enhanced nitrogen and phosphorus removal was achieved. Average effluent total nitrogen and total phosphorus concentrations were 13.21mg/L and 0.23mg/L, respectively. The removal efficiencies of COD, ammonium nitrogen, total nitrogen and total phosphorus were 86.2%, 99.8%, 96.6% and 81.5%, respectively. The effluent quality could satisfy the first level A criteria specified in the discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002). Although the system was operated under low temperature, good settle ability with SVI of 85.4 mL/g was obtained. Moreover, pH and oxidation reduction potential could be used as control parameters for process control of A2O-BAF system. It was suggested that the operational state could be well known according to the changes of simple online sensors.
2010 Vol. 30 (9): 1195-1200 [Abstract] ( 285 ) [HTML 1KB] [ PDF 497KB] ( 1029 )
1201 Anaerobic ammonium oxidation (ANAMMOX) for biological ntrogen removal from coking wastewater
LIN Lin, LI Yu-Ping, CAO Hong-Bin, LI Qing-Yu, LI Hai-Bo
Anaerobic ammonium oxidation (ANAMMOX) for the biological treatment of coking wastewater was investigated. An ANAMMOX reactor was successfully started up after 115d, at 34℃ and pH 7.5~8.5, with a hydraulic retention time (HRT) of 33h. The volume loading of total nitrogen (TN) up to 160 mg/(L·d) was obtained with 80 mg/L NH4+-N and 90 mg/L NO2--N in the influent. The maximum removal of TN, ammonia nitrogen and nitrite nitrogen reached 75%, 86% and 98%, respectively. The organic composition of influent and effluent of ANAMMOX reactor was investigated with GC-MS measurement, and the results showed that phenols were of easily-biodegraded organics in coking wastewater and low-concentration phenols from shortcut nitrification process could be removed in ANAMMOX reactor.
2010 Vol. 30 (9): 1201-1206 [Abstract] ( 241 ) [HTML 1KB] [ PDF 883KB] ( 904 )
1207 Cooperation effect between non-thermal plasma and flocculants for treatment dyeing wastewater
CHEN Ming-Gong, QI Yong-Tao, ZHANG Xin-Min, LIU Tao, YAN Ling-Yan, GAO Dao-He-Ze, SHUI Ye-Zhang
The cooperation effects of non-thermal plasma assisted with flocculants to clean dyeing wastewater have been investigated in this paper. The new way can shorten the dealing time and improve the rate of de-colorization and de-COD. The results showed the de-colorization and de-COD ratios increased with the increasing of input voltage and discharge time. The distance between discharge electrodes, initial concentration of dyeing wastewater and air flow to input wastewater have a significant impact on purification efficiency. The effect of discharge in gas phase is better then in liquid phase. When the anode pole is up the water level about 8mm the treatment can get good result. When the other operation conditions are unchanged, the ratio of de-colorization and de-COD increased and then decreased with the increasing of the initial concentration and air flow. The initial concentration and air flow has a peak value, respectively. The effect of dyeing wastewater treatment by adding flocculants into wastewater after discharged is better than by putting flocculants before discharged and only by plasma discharged. In this experiment when the wastewater initial value of CODcr is 572, input voltage 40kV, discharge time 20min, the anode pole up level 8mm, air flow 16L/h and associates with flocculants the ratio of de-colorization and de-COD reach 96% and 63%, respectively.
2010 Vol. 30 (9): 1207-1212 [Abstract] ( 238 ) [HTML 1KB] [ PDF 465KB] ( 597 )
1213 Synthesis and performance of a novel catalyst applied to the CWPO decolorization of direct blending purple (D-BL) on wastewater
LU Tang-Jun, LI Jian-Chao, SUN Hong-Xia, ZHANG Ai-Xia, ZHANG Xiao-Wei
A novel kind of Cu-La-Mo zeolite catalyst (Z/CLM) was prepared with impregnation and calcination hybrid method. A series of static and dynamic experiments was carried out to investigate the catalytic capability of prepared Z/CLM catalyst in the decolorization reaction, and direct blending purple D-BL was selected as target reactant. The experimental results gave out the optimum catalyst preparation conditions as, zeolite particle size of 60~80 mesh, calcination of 600℃ and 0.5h. In the static tests, the highest direct blending purple D-BL decolorization percentage was about 95.15% under the optimum condition, H2O2 8.33mL/L, pH 7.10. Further experiments revealed that the increase of the temperature and the NaCl concentration of wastewater will accelerate the decolorization reaction, and improve the removal efficiency. Besides, the dynamic fluidized bed experiment was implemented in a lab-scale reactor, and the experimental results confirm the removal capability of Z/CLM being 37.82mg/g to direct blending purple D-BL.
2010 Vol. 30 (9): 1213-1218 [Abstract] ( 219 ) [HTML 1KB] [ PDF 585KB] ( 653 )
1219 The effect of carbon source on disintegrated aerobic granular during activity recovery.
LIU Jian-Mei, YANG Chang-Zhu, PU Wen-Hong, XU Jie, LUO Ying-Dong
This activity recovery of aerobic granular was investigated in SBR with three different carbon sources including glucose, sodium acetate and a mixture of glucose-sodium acetate for 30 days. The results indicated that carbon sources greatly influenced the physical characteristics of aerobic granular sludge and TN,TP removal during the recovery period. Conversely, the removal efficiencies of COD and NH3-N had been little influenced by carbon sources in the whole activity recovery period. And aerobic granular sludge activity for COD and NH3-N removal was recoveried fully after 10 days.. After the aerobic granular sludge reached the steady state, the aerobic granular with sodium acetate showed the best effect on nitrogen and phosphorus removal, the removal efficiency of TN and TP increased from 45% and 42% to 74% and 81% respectively after 20 days. While COD specific degradation rate can reach to 10.74kgCOD/(kgMLSS?d) with glucose-sodium acetate, which was 112% than that before aerobic granular was disintegrated. The nitrification and denitrification ability of aerobic granular sludge got best recovery with sodium acetate, the specific degradation rate of NH3-N and TN reached to 0.335kgNH3-N/(kgMLSS?d) and 0.272kgTN/(kgMLSS?d) respectively and the reactivation resumed to 97% and 101% respectively.
2010 Vol. 30 (9): 1219-1225 [Abstract] ( 234 ) [HTML 1KB] [ PDF 555KB] ( 632 )
1226 Comparison of amoA mRNA during inhibition of nitrifying activity by heavy metals
WANG Feng, LIU Yi, YANG Hai-Zhen
Comparison of amoA mRNA (ammonia mono-oxygenase encoding mRNA) was examined due to inhibition from Cd2+ (1, 5, 10mg/L) and Zn2+(5, 20, 50mg/L) during a short reaction period (6h). The real-time reverse transcription- PCR method was applied to detect profile of amoA mRNA in activated sludge quantificationally. Different performance of mRNA was observed during Cd2+ and Zn2+ inhibition test respectively, the highest inhibitory rate up to 53% at 10mg/L Cd2+ was discovered. The nitrifying inhibition was possibly performed through the impact on transcription of amoA mRNA by some heavy metals.
2010 Vol. 30 (9): 1226-1229 [Abstract] ( 230 ) [HTML 1KB] [ PDF 377KB] ( 652 )
1230 Effects and kinetics model of combined alkaline and thermal sludge treatment
LI Yang-Yang, JIN Yi-Ying, LI Huan, NIE Yong-Feng
The combined alkaline and thermal treatment was used to disintegrate the dewatered sludge. The treatment process was studied and a kinetics model was built. The results showed that alkaline application can significantly promote the sludge disintegration compared with the only thermal treatment, and NaOH has higher efficiency than Ca(OH)2. The best parameters of combined alkaline and thermal treatment are 140℃, 90minutes, and the alkaline dose of 0.25g/g total solid (TS). Under this condition, the soluble chemical oxygen demand (SCOD) has an increase of 41.26% or 198% and the mass reduction ratio can reach 50% and 57% respectively with the assistance of Ca(OH)2 or NaOH. The relationship of the SCOD variation and the treatment temperature (T), duration (t) and NaOH dosage (A) can be described with an exponential model: SCODNa=10178.17[ T ]0.43 [ A ]0.59 t 0.24.
2010 Vol. 30 (9): 1230-1234 [Abstract] ( 222 ) [HTML 1KB] [ PDF 446KB] ( 737 )
1235 Effects of organic acids on zinc and lead leaching from contaminated sediments
LI Peng, ZENG Guang-Ming, XU Wei-Hua, ZHANG Chang, JIANG Min
The leaching characteristics of zinc and lead in two contaminated sediments were studied, and the effect of low molecular weight organic acids (LMWOAs) and pH value on the leaching of zinc and lead from two contaminated sediments were examined. The results showed that zinc and lead in the sediments were partly dissolved by three LMWOA solutions under different concentrations in batch experiment. The leaching of heavy metals from two sediments followed the descending order: citric acid> malic acid> tartrate acid (for zinc); citric acid> tartrate acid> malic acid (for lead). The leaching concentrations of heavy metals in solution were enhanced with the increasing of LMWOA concentration and the decreasing of pH value. In addition, all LMWOAs leached more heavy metals than inorganic salt did. The leaching capability under the condition of LMWOAs followed the order: zinc>lead.
2010 Vol. 30 (9): 1235-1240 [Abstract] ( 271 ) [HTML 1KB] [ PDF 400KB] ( 856 )
1241 Distribution of polycyclic aromatic hydrocarbons (PAHs) in different size fractions of sediments from intertidal zone of Bohai Bay, China
JIAO Li-Xin, MENG Wei, ZHENG Bing-Hui, ZHANG Lei, ZHAO Xing-Ru, QIN Yan-Wen
Concentrations of 16EPA polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC) and black carbon (BC) contents were investigated in different size fractions (0.063mm) of sediments from intertidal zone of Bohai Bay. The total PAHs (16-EPA) concentration in different size fractions of all sediments ranged from 714.28to 4869.71ng/g dry weight. The highest total PAHs concentration of Qikou estuary (TS3) sediment was measured in the 0.063mm size fractions. The lowest total PAHs concentrations were measured in the 0.031-0.063mm size fraction for all site sediments. However, TOC-normalized total PAHs concentrations trended to increase with increasing size of sediments. Furthermore, stronger correlations between total PAHs versus BC rather than versus OC (OC=TOC-BC) were found. Therefore, distribution of BC in different size fractions of sediments possibly played a more important role.
2010 Vol. 30 (9): 1241-1248 [Abstract] ( 253 ) [HTML 1KB] [ PDF 499KB] ( 727 )
1249 Pollution characterization of urban stormwater runoff on different underlying surface conditions.
欧Yang-Wei , WANG Wei, HAO Fang-Hua, SONG Kai-Yu, WANG Yun-Hui
Based on monitoring the runoff water quality on different underlying surface conditions in Beijing and analyzing the experiment data via Pearson statistical method, the paper covered the time-varying regularity of stormwater runoff pollutants and the even mean concentrations (EMCs) of stormwater runoff pollutants. Major factors for runoff water quality were also analyzed. The results showed that compared with asphalt road and bituminous roof, the green roof had lower flush effect, playing an important role in reducing the concentration of runoff pollutants. The initial EMCs values of COD, NH3-N, NO3-N and TP were higher than the fifth category of national surface water standard. Parts of them were even beyond the third category of emission discharge standard. The values of EMCs were positively correlated with dry weather deposits and runoff duration, and negatively correlated with precipitation and rainfall intensity. The analysis indicated that the controlling preliminary runoff pollution and surface clean-up can reduce the urban rainfall runoff pollution.
2010 Vol. 30 (9): 1249-1256 [Abstract] ( 247 ) [HTML 1KB] [ PDF 624KB] ( 1395 )
1257 Identifying sources of particles organic matter in surface water based on stable isotope tracing on basin scale.
TANG Yan-Ling, ZHANG Guang-Xin
In order to assure the safety of surface drinking water, the sources of suspended particulate organic matter (POM) were studied in this paper by stable carbon and nitrogen isotopes analysis and elemental C/N ratios measure of POM. Soil and plant samples were collected in Shitoukoumen Reservoir Basin. The results showed that POM mainly sourced from soil organic matter which possessed 69.2%. Macrophyte was the second important contributor (23.1%). In addition, phytoplankton was also one of the sources of POM, accounting for 7.7%. The sources of POM existed seasonal and spatial variations. Over rainy season, the contributions of phytoplankton and Macrophytes to POM reached to 15.4%, respectively. While the contribution of Macrophyte to POM increased to 30.8% over dry season. Spatially, POM in surface water in the whole basin was from the soil organic matter in the lower reaches of Shuangyang river and Yinma river, owing to high soil erosion and the risk of non-point source (NPS) pollution in the regions. The phytoplankton, the main contributor of POM, possessed 86.3% and 94.8% in Chaluhe river and Xiaohuanghe river, respectively. And the soil organic matter contributed 13.7% and 5.2% in the two areas, respectively, where the low risk of NPS pollution showed low soil erosion. The most of POM from Macrophyte in reservoir indicated suspended particulates from the other sources may sink.
2010 Vol. 30 (9): 1257-1267 [Abstract] ( 220 ) [HTML 1KB] [ PDF 1033KB] ( 753 )
1268 Quantitative estimation of Taihu chlorophyll-a concentration using HJ-1A and 1B CCD imagery
KUANG Da, HAN Xiu-Zhen, LIU Xiang, ZHAN Ya-Ting, NIU Zheng, WANG Li-Juan
In this study, models estimating water chlorophyll-a concentration have been proposed and calibrated, based on the regression analysis between HJ-1 satellite CCD images and synchronous in-situ water quality monitoring data, ranging from September to December in 2008 on Taihu, Jiangsu Province. The red and near infrared bands of HJ-1A and 1B CCD data, with central wavelength at 660 nm and 830 nm respectively, have shown to be sensitive to the chlorophyll-a concentration. Three models has been built and validated. The results illustrate the high potentials of the models to estimate chlorophyll-a concentration in inland waters for operational applications from satellite HJ-1 satellite CCD data, which will be of immense value for environment monitoring. Among the three models been proposed, the one based on index R830/R660 has the highest estimation precision, 6.04mg/m3. This model has been applied to eight images of HJ-1 satellite CCD, generating chlorophyll-a concentration distributions from May to December 2009.
2010 Vol. 30 (9): 1268-1273 [Abstract] ( 261 ) [HTML 1KB] [ PDF 516KB] ( 1380 )
1274 Influences of nitrification inhibitor 3,4-dimethylpyrazole phosphate on nitrogen transformation and potential runoff loss in rice fields
YU Qiao-Gang, CHEN Ying-Xu
In a rice pot incubation experiment, the nitrogen transformation in the rice field surface water and potential nitrogen runoff loss risk were studied by applied urea with new nitrification inhibitor 3,4-dimethyl pyrazole phosphate (DMPP) in the powder soil and blue clayey paddy soil. The results showed that, in the powder soil and blue clayey paddy soil, the ammonium concentration were increased 24.8% and 16.7%, nitrate, nitrite and total inorganic nitrogen concentrations were declined 47.7% and 70.9%, 90.6% and 88.9%, 13.5% and 23.1% in the rice field surface water, respectively. So, the potential nitrogen runoff loss risk could greatly be decreased when the storm or field drainage happened. Furthermore, the electric conductivity value was also declined in the rice field surface water with the DMPP addition in the urea, decreasing the salt-ion runoff loss risk at the storm or field drainage and being beneficial for protecting the water body.
2010 Vol. 30 (9): 1274-1280 [Abstract] ( 230 ) [HTML 1KB] [ PDF 575KB] ( 894 )
1281 Combined phytoremediation effect of several plants in PCBs contaminated farmland soils
SUN Xiang-Hui, TENG Ying, LUO Yong-Ming, WU Long-Hua, LI Zhen-Gao
A field microzone experiment was carried out to study the co-remediation effect of PCBs contaminated farmland soils under different planting models for using three plant species, alfalfa( Medicago sativa L), Elsholtzia splendens and Sedum plumbizincicola. The results indicated that mixed croppings of alfalfa with Elsholtzia splendens or Sedum plumbizincicola could enhance PCBs removal in soils compared to the monoculture with alfalfa. About 43.0% of PCBs were removed from the soils in mixed cropping of alfalfa and Elsholtzia splendens at the end of the 120d experiment, and 47.8% in mixed cropping of three plants. The mixed croppings of alfalfa with Elsholtzia splendens or Sedum plumbizincicola could increase the total biomass of plants, facilitate the uptake and accumulation of the PCBs in plants. Analysis of PCBs composition showed that the planted treatments could decrease the concentration of lower chlorinated PCBs in soils, and multi-species phytoremediation could improve the transformation of higher chlorinated PCBs into lower chlorinated PCBs. The mixed croppings of alfalfa with Elsholtzia splendens or Sedum plumbizincicola show a good potential in the remediation of PCBs contaminated farmland soils.
2010 Vol. 30 (9): 1281-1286 [Abstract] ( 259 ) [HTML 1KB] [ PDF 391KB] ( 738 )
1287 Spectral models for estimating grassland vegetation coverage on Hulunbeier Grassland, Inner Mongolia, China.
CHEN Yan-Mei, GAO Ji-Xi, DIAO Zhao-Yan, 吕Shi-Hai , CHANG Xue-Li, FENG Chao-Yang
During July and August 2009, an ASD Fieldspec3 spectroradiometer and a Japanese Fuji digital camera were used to measure hyperspectral data and vegetation coverage on the Hulunbeier Grassland, Inner Mongolia, China. Regression analysis methods were used to establish a ground spectral relationship between the local measured vegetation coverage and normalized difference vegetation (ASD NDVI). Then, the relationship between NDVI got from MODIS/TERRA (MODIS NDVI) and ASD NDVI was analyzed to establish a MODIS Spectral Model to estimate vegetation coverage with MODIS NDVI. Finally, the accuracy of MODIS spectral model was validated. The MODIS Spectral Model was just a linear equation but had higher prediction accuracy than sub-pixel models with 11.58% standard error and 88.75% average prediction accuracy.
2010 Vol. 30 (9): 1287-1292 [Abstract] ( 209 ) [HTML 1KB] [ PDF 520KB] ( 930 )
1293 Distribution of far-field power density and planning control distance of mobile base stations
DI Guo-Qing, ZHOU Bing, JIA Li, CAO Yong, YANG Wei-Geng
In order to investigate power density distribution regularity and determine planning control distance reasonably, 2057 mobile communication base stations with various network types and carrier wave numbers in urban district of Hangzhou were selected, and the radiofrequency field power density around the antenna was measured when mobile phone traffic was in peak period. Results indicated that far-field power density of GSM base stations S∝ under the condition of distortion field (S∝ under the condition of non-distortion field), and the determination coefficient (R2) is 0.80; in the range of 20m away from antenna, about 85.91% of measured power density values around base stations is less than theoretical values, which can be calculated according to antenna nominal power and antenna gain under the condition of non-distortion field. In addition, the frequency statistical results indicated that, in the range of 1~15m away from antenna, S10 (10% of measured values are higher than the value of S10) of base stations which belong to A operator is 10.00% higher than B operator; in the range of 1~30m away from antenna, the statistical power density values S10 of base stations with double and ternate networks are 50.31% and 57.10% higher than base stations with single network respectively. So the planning control distance of mobile communication base stations determined accordingly should be 15m. Out of this range, only 0.11% of base stations power density values are above 8μW/cm2.
2010 Vol. 30 (9): 1293-1296 [Abstract] ( 225 ) [HTML 1KB] [ PDF 359KB] ( 1677 )
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