The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August2001, through three cruises and a 15 d continuous observation. This investigation indicates that d...The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August2001, through three cruises and a 15 d continuous observation. This investigation indicates that diatom cell abundance increasedsharply following the end of a spring tide, from 9 cells/cm3 to a peak of 94 cells/cm3. The dominant species composition andabundance show a quick species sequence from spring to neap tide, and the dominant species at the start phase is Skeletomenacostatum, then changes to Chaetoceros curvisetus, finally it changes to Eucampia zodiacus. Silicate concentration increasesduring spring tide, as a result of nutrient replenishment from the watersediment interface, its initial average concentration inneap tide is 1.39 mmol/dm3 and reached the peak average concentration of 8.40 mmol/dm3 in spring tide. But the nitrogenconcentration dropped due to dilution by the low nitrogen seawater from the Huanghai Sea, its initial average concentration inneap tide is 67 mmol/dm3 and decreased to the average concentration of 54 mmol/dm3 in spring tide. The degree of siliconlimitation was decreased and phytoplankton, especially diatoms, responds immediately after nutrient replenishment in thewater column. Skeletonmea costatum, as one of the dominant species in the Jiaozhou Bay, shows a quicker response tonutrient availability than Eucampia zodiacus and Chaetoceros curvisetus. It is proposed that dominant species compositionand water column stability synchronously determine the development of phytoplankton summer blooms in the Jiaozhou bay.展开更多
Rock weathering plays an important role in studying the long-term carbon cycles and global climatic change. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled by eva...Rock weathering plays an important role in studying the long-term carbon cycles and global climatic change. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled by evaporite and carbonate weathering, which were responsible for over 90% of total dissolved ions. As compared with the Huanghe River basin, dissolved load of the Changjiang (Yangtze) River was mainly originated from the carbonate dissolution. The chemical weathering rates were estimated to be 39.29t/(km(2).a) and 61.58t/(km(2).a) by deducting the HCO3- derived from atmosphere in the Huanghe River and Changjiang River watersheds, respectively. The CO2 consumption rates by rock weathering were calculated to be 120.84 x 10(3)mol/km(2) and 452.46 x 10(3)mol/km(2) annually in the two basins, respectively. The total CO2 consumption of the two basins amounted to 918.51 x 10(9)mol/a, accounting for 3.83% of the world gross. In contrast to other world watersheds, the stronger evaporite reaction and infirm silicate weathering can explain such feature that CO2 consumption rates were lower than a global average, suggesting that the sequential weathering may be go on in the two Chinese drainage basins.展开更多
The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl r...The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl ref . The Cl ref of 41 97 μmol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of precipitation and river water, two approaches sea salt correction and precipitation correction were proposed in order to correct the contribution proportions of atmospheric precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the atmospheric contribution ratios fluctuate from ～5% to ～20% of TDS(total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO - 3 and cation Ca 2+ and Na\++ dominating the major compositions in this basin. The estimated chemical weathering rate of 15 78—23 48 t/(km 2·a) is only 40%—60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the precipitation chemistry has never been quantified in detail.展开更多
Tidal cycle measurements of tidal currents, salinity and water tempe rature, and suspended sediment concentrations were measured at four stations, to gether with surveys along two profiles short core collection within...Tidal cycle measurements of tidal currents, salinity and water tempe rature, and suspended sediment concentrations were measured at four stations, to gether with surveys along two profiles short core collection within the Yalu Riv er estuary. Grain size analysis of the three core sediment showed that: 1) the s ediment from B1 to B3 became finer, worse sorting and positively skewed; 2) the diversification of matter origin became more and more evident from east to west; 3) the sediments over the region were of the same origin, as indicated by their similar colors and grain sizes. The data indicated that stratification occurred in the flood season, from upstream to downstream, and a salt wedge was formed. The water column was well mixed, but the longitudinal gradient of the salinity w as larger on spring tide. The results also showed that the dominating mechanism of suspended sediment transport in the Yalu River estuary was T1, T2, T3 and T5. The non-tidal steady advection transport was restricted by the net transport o f suspended sediment induced by mass Stoked drift directed to landwards, then th e net sediment transport rate were decreased and the turbidity maxima was also f avored to forming and extending.展开更多
The weak pre-edge features in the Mn K-edge X-ray absorption near-edge structure (XANES) spectrumof manganese monoxide (MnO) were investigated by comparing experimental data with dipolar and quadrupolarcross-section c...The weak pre-edge features in the Mn K-edge X-ray absorption near-edge structure (XANES) spectrumof manganese monoxide (MnO) were investigated by comparing experimental data with dipolar and quadrupolarcross-section calculations in the framework of multiple-scattering theory. We assign the first pre-edge feature to a di-rect quadrupolar transition from Is core state to 3d molecular orbitals of the central atom, e.g., the lowest in energy,due to the more effective attraction of the core hole. The second peak in this region arises unambiguously from thehybridization between p-orbitals of the central atom with higher-shell metal octahedral orbitals.展开更多
Polyoxometallates Co(en) 3PMo 12O 40·8H 2O(+,-)[abbreviated as PMo 12-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time. They were c...Polyoxometallates Co(en) 3PMo 12O 40·8H 2O(+,-)[abbreviated as PMo 12-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time. They were characterized by means of elemental analyses, IR spectrometry and X-ray diffraction. The images of scanning electron microscopy(SEM) and the results of calculation by using the Scherrer equation for the line widths of the XRD patterns were used to estimate the average particle size of the powder products, which was 40 nm. The results show that the nanoparticle size was affected by starting materials′ concentrations. The particles had a small size and a narrow distribution, when the concentrations of H 3PMo 12O 40·24H 2O and Co(en) 3I 3·H 2O were around 1.7×10 -4 and 1.0×10 -3 mol/L, respectively. When the concentration was increased, there was no significant increase in the particle size, but more polydisperse Co(en) 3(PMo 12O 40) (+, -) were obtained. In poly(ethylene glycol)(PEG) with an average molecular weight(M W) of 600 g/mol and containing LiClO 4[n(O)/n(Li)=100∶1] as the supporting electrolyte, the conductivity of the composite system increases upon the addition of PMo 12-Co(+ or -) nanoparticles, which was measured by the a.c. impedance technique. The interactions among PEG, LiClO 4, PMo 12, and Co can be used to explain that the PMo 12-Co(+ or -) nanoparticles could promote the conductivity of the PEG-LiClO4-PMo12-Co system.展开更多
Image segment is a primary step in image analysis of unexploded ordnance (UXO) detection by ground p enetrating radar (GPR) sensor which is accompanied with a lot of noises and other elements that affect the recogniti...Image segment is a primary step in image analysis of unexploded ordnance (UXO) detection by ground p enetrating radar (GPR) sensor which is accompanied with a lot of noises and other elements that affect the recognition of real target size. In this paper we bring forward a new theory, that is, we look the weight sets as target vector sets which is the new cues in semi-automatic segmentation to form the final image segmentation. The experiment results show that the measure size of target with our method is much smaller than the size with other methods and close to the real size of target.展开更多
基金This study was supported by the National Natural Science Foundation of China under contract Nos 40036010,40206020 and 40306025.
文摘The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August2001, through three cruises and a 15 d continuous observation. This investigation indicates that diatom cell abundance increasedsharply following the end of a spring tide, from 9 cells/cm3 to a peak of 94 cells/cm3. The dominant species composition andabundance show a quick species sequence from spring to neap tide, and the dominant species at the start phase is Skeletomenacostatum, then changes to Chaetoceros curvisetus, finally it changes to Eucampia zodiacus. Silicate concentration increasesduring spring tide, as a result of nutrient replenishment from the watersediment interface, its initial average concentration inneap tide is 1.39 mmol/dm3 and reached the peak average concentration of 8.40 mmol/dm3 in spring tide. But the nitrogenconcentration dropped due to dilution by the low nitrogen seawater from the Huanghai Sea, its initial average concentration inneap tide is 67 mmol/dm3 and decreased to the average concentration of 54 mmol/dm3 in spring tide. The degree of siliconlimitation was decreased and phytoplankton, especially diatoms, responds immediately after nutrient replenishment in thewater column. Skeletonmea costatum, as one of the dominant species in the Jiaozhou Bay, shows a quicker response tonutrient availability than Eucampia zodiacus and Chaetoceros curvisetus. It is proposed that dominant species compositionand water column stability synchronously determine the development of phytoplankton summer blooms in the Jiaozhou bay.
基金Undertheauspicesof Ministry of Science and Technology Project of China (No. G1999043075)
文摘Rock weathering plays an important role in studying the long-term carbon cycles and global climatic change. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled by evaporite and carbonate weathering, which were responsible for over 90% of total dissolved ions. As compared with the Huanghe River basin, dissolved load of the Changjiang (Yangtze) River was mainly originated from the carbonate dissolution. The chemical weathering rates were estimated to be 39.29t/(km(2).a) and 61.58t/(km(2).a) by deducting the HCO3- derived from atmosphere in the Huanghe River and Changjiang River watersheds, respectively. The CO2 consumption rates by rock weathering were calculated to be 120.84 x 10(3)mol/km(2) and 452.46 x 10(3)mol/km(2) annually in the two basins, respectively. The total CO2 consumption of the two basins amounted to 918.51 x 10(9)mol/a, accounting for 3.83% of the world gross. In contrast to other world watersheds, the stronger evaporite reaction and infirm silicate weathering can explain such feature that CO2 consumption rates were lower than a global average, suggesting that the sequential weathering may be go on in the two Chinese drainage basins.
文摘The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl ref . The Cl ref of 41 97 μmol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of precipitation and river water, two approaches sea salt correction and precipitation correction were proposed in order to correct the contribution proportions of atmospheric precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the atmospheric contribution ratios fluctuate from ～5% to ～20% of TDS(total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO - 3 and cation Ca 2+ and Na\++ dominating the major compositions in this basin. The estimated chemical weathering rate of 15 78—23 48 t/(km 2·a) is only 40%—60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the precipitation chemistry has never been quantified in detail.
文摘Tidal cycle measurements of tidal currents, salinity and water tempe rature, and suspended sediment concentrations were measured at four stations, to gether with surveys along two profiles short core collection within the Yalu Riv er estuary. Grain size analysis of the three core sediment showed that: 1) the s ediment from B1 to B3 became finer, worse sorting and positively skewed; 2) the diversification of matter origin became more and more evident from east to west; 3) the sediments over the region were of the same origin, as indicated by their similar colors and grain sizes. The data indicated that stratification occurred in the flood season, from upstream to downstream, and a salt wedge was formed. The water column was well mixed, but the longitudinal gradient of the salinity w as larger on spring tide. The results also showed that the dominating mechanism of suspended sediment transport in the Yalu River estuary was T1, T2, T3 and T5. The non-tidal steady advection transport was restricted by the net transport o f suspended sediment induced by mass Stoked drift directed to landwards, then th e net sediment transport rate were decreased and the turbidity maxima was also f avored to forming and extending.
基金One of the authors(WU Zi-Yu)acknowledges the financial support of the 100-Talent Research Program of the Chinese Academy of Sciences and of the Outstanding Youth Fund(10125523)the Key Important Nano-Research Project(90206032)of the National Natural Science Founda tion of China.
文摘The weak pre-edge features in the Mn K-edge X-ray absorption near-edge structure (XANES) spectrumof manganese monoxide (MnO) were investigated by comparing experimental data with dipolar and quadrupolarcross-section calculations in the framework of multiple-scattering theory. We assign the first pre-edge feature to a di-rect quadrupolar transition from Is core state to 3d molecular orbitals of the central atom, e.g., the lowest in energy,due to the more effective attraction of the core hole. The second peak in this region arises unambiguously from thehybridization between p-orbitals of the central atom with higher-shell metal octahedral orbitals.
基金Supported by the National Natural Science Foundation of China(No.2 0 3710 0 7)
文摘Polyoxometallates Co(en) 3PMo 12O 40·8H 2O(+,-)[abbreviated as PMo 12-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time. They were characterized by means of elemental analyses, IR spectrometry and X-ray diffraction. The images of scanning electron microscopy(SEM) and the results of calculation by using the Scherrer equation for the line widths of the XRD patterns were used to estimate the average particle size of the powder products, which was 40 nm. The results show that the nanoparticle size was affected by starting materials′ concentrations. The particles had a small size and a narrow distribution, when the concentrations of H 3PMo 12O 40·24H 2O and Co(en) 3I 3·H 2O were around 1.7×10 -4 and 1.0×10 -3 mol/L, respectively. When the concentration was increased, there was no significant increase in the particle size, but more polydisperse Co(en) 3(PMo 12O 40) (+, -) were obtained. In poly(ethylene glycol)(PEG) with an average molecular weight(M W) of 600 g/mol and containing LiClO 4[n(O)/n(Li)=100∶1] as the supporting electrolyte, the conductivity of the composite system increases upon the addition of PMo 12-Co(+ or -) nanoparticles, which was measured by the a.c. impedance technique. The interactions among PEG, LiClO 4, PMo 12, and Co can be used to explain that the PMo 12-Co(+ or -) nanoparticles could promote the conductivity of the PEG-LiClO4-PMo12-Co system.
基金Supported by the Natural Science Foundation of Heilongjiang Province (F0201)
文摘Image segment is a primary step in image analysis of unexploded ordnance (UXO) detection by ground p enetrating radar (GPR) sensor which is accompanied with a lot of noises and other elements that affect the recognition of real target size. In this paper we bring forward a new theory, that is, we look the weight sets as target vector sets which is the new cues in semi-automatic segmentation to form the final image segmentation. The experiment results show that the measure size of target with our method is much smaller than the size with other methods and close to the real size of target.
