排序方式： 共有33条查询结果，搜索用时 15 毫秒
31.
O. Popovicheva E. Kireeva N. Persiantseva T. Khokhlova N. Shonija V. Tishkova B. Demirdjian 《Atmospheric Research》2008,90(2-4):326-ICNAA07
More than 3000 water droplets with soot particles immersed were monitored individually to identify the effect of heterogeneous freezing and establish the link between soot properties and freezing efficiency. A set of soot samples from many combustion sources, including an aircraft engine combustor were examined. The list of key soot properties affecting freezing were determined. It appears that soot effectiveness in causing the droplets to freeze mainly depends on the soot behaviour in water defined by the mass density of soot agglomerates, size and wetting. When large mass particles were homogeneously distributed through droplets and were stable to sedimentation effects median freezing temperatures of such droplets were significantly warmer than pure water droplets. The long-term presence of large soot agglomerates in water leads to an increase in the freezing efficiency over time because of the slow kinetics of wetting. Small sizes of soot agglomerates stimulate aggregative instability in droplets with large soot mass which decreases the total soot surface area and the freezing temperature. The highest freezing efficiency is found for homogeneously distributed soot agglomerates of high porosity. A gradual increase of the freezing temperature in correspondence with number density of active oxygen-containing sites is observed for soots having surfaces of low or intermediate polarity. However, highly soluble surface compounds, such as sulfates, may be easily dissolved in water leading to a decrease in the potential freezing efficiency. This was the case found for aircraft engine combustor generated soot. Therefore relatively hydrophobic soot with a significant number of oxygen-containing functional groups but not covered totally by hydrophilic sites and soluble compounds is proposed to act as the most efficient immersion freezing nuclei in the atmospheric cloud droplets. 相似文献
32.
This paper discusses conditions of hydrochemical inverse section formation in the lower layers of the sedimentary cover in
West Siberia and on the South Vietnam shelf. A significant role of endogenic fluids in the formation of chemical composition
of low-mineralized hydrocarbonate-sodium waters is verified. An increase in the boron-bromine ratio is accepted as the main
criterion of the high-temperature endogenic water supply into the lower horizons of the sedimentary cover. 相似文献
33.
Yu. K. Vasil’chuk E. P. Rets Ju. N. Chizhova I. V. Tokarev N. L. Frolova N. A. Budantseva M. B. Kireeva N. A. Loshakova 《Water Resources》2016,43(6):847-861
The formation of snowmelt runoff from the Dzhankuat glacier has been considered and the hydrograph of the Dzhankuat R. has been separated with the use of isotope and ionic balance. Isotope variations of runoff at the outlet section of the Dzhankuat R. have been studied for two ablation seasons of 2013 and 2014. The separation of 2014 hydrograph was based on δ18O and mineralization values obtained for various sources of Dzhankuat R. recharge: precipitation, snow of different seasons, firn, ice, and groundwater. The isotopic separation of the hydrograph has shown that, in June, a considerable portion (15–20%) of Dzhankuat R. total runoff is due to the melting snow cover that has formed during spring snowfalls. In June, the proportion of this component in the total daily runoff can reach 36%. The contribution of the runoff originating from winter-snow melting varies from 20% in the early to 50% in the late June. In August and September, the share of groundwater varies from 30 to 100%; the share of precipitation, from 0 to 30% (on the average for the period, 6%); and the share of water from melting firn and ice, from 0 to 70% (on the average, 38.6%). 相似文献