我国煤矸石山的水分研究进展

关于煤矸石山生态恢复最重要的限制因子——煤矸石山水分的科学研究,将为煤矸石山的植被恢复与生态重建提供科学的依据。分别从水分特征、入渗规律和立地条件对水分的影响3个方面,介绍了我国煤矸石山的水分研究进展,并指出了我国现有的煤矸石水分研究中存在的问题以及亟待研究的方面。

我国煤矸石山水分研究进展

水分是煤矸石山生态恢复最重要的限制因子。对煤矸石山水分的科学研究,将为其植被恢复与生态重建提供科学的依据。从水分特征、入渗规律和立地条件等方面,介绍了我国煤矸石山的水分研究进展,指出了我国现有的煤矸石水分研究中存在的问题和亟待研究的方面。

白榆不同地理种源水分生理特性初步研究

全国的白榆区划为北、中、南三大种源区。通过对不同种源区的白榆进行生理测定的结果表明,白榆的含水量、水势、相对含水量、蒸腾速率等指标南方区均大于北方区,而水分亏缺和持水力则北方区大于南方区。

尿素成品低水分调控技术研究及应用

甘肃刘化(集团)有限责任公司300 kt/a CO_(2)汽提法尿素装置于2009年12月投产,总体运行情况较好,尿素成品质量大多数时候可保证为优等品,尿素成品质量偶有不佳主要表现为易结块,分析认为原因在于尿素成品水分含量较高。为此,刘化集团组织工程技术人员等成立项目课题组,对客户使用体验进行调查,制定降低尿素成品水分含量的研究方案,并对尿素蒸发系统一段、二段温度与真空度进行调整试验。研究试验结果表明,尿素装置尿素成品水分含量的主要影响因素为蒸发系统真空度、温度,并确定了蒸发系统真空度、温度的最佳工艺操作区间。本研究成果应用后,尿素成品水分含量可控制在0. 35%以下,尿素成品各项指标均优于《尿素》(GB/T 2440—2017)优等品标准。

汇集雨水补灌农技措施研究初报

采用试验与示范相结合，对汇集雨水补灌农技措施进行了系统研究。结果表明：在干旱少雨，蒸发量大，气候冷凉的定西地区，实行地膜和秸秆覆盖加滴灌的农技措施，能有效减少土壤水分蒸发，增加作物生长需要的有效积温；实行垄沟种植，发展间套，进行雨水有限补灌，能充分发挥雨水资源的生态经济效益。

Orientation and Motion of Water Molecules at Air/Water Interface

Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation （SFG） vibrational peak of the free O-H stretching band at 3700 cm^-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interracial water molecule is tilted around 33°from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interracial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orient, ational motion of a liquid interface by Wei et al. （Phys. Rev. Lett. 86, 4799, （2001）） using single SFG experimental configuration.

Research on soil salt transfer under freeze-thawing condition

Soil salt transformation plays an important role in the freeze-thawing process,which is also one of basic problems of cryopedology. The very special law is made up of the two time salt-moisture transfer under freeze-thawing condition. Based on the latest research at home and abroad,through the investigation of soil moisture-salt change in the freeze-thawing process,the conclusion is made that the soil water potential gradient is the main driving force of soil salt movement and the factors are of quantities. The research shows that,when freezing,temperature drops,salt and moisture move towards frozen layer. All make the salinity content of the frozen layer increase significantly. In the thawing process,salinity and moisture in the soil move up again with evaporation and makes the salt second migration.

Porosity Distribution Characteristics and Geological Analysis of Brine Storage Medium in the Qaidam Basin, Western China

Underground brine is an unusual water resource that contains abundant mineral resources. It is distributed widely in the Qaidam Basin, western China, a hyperarid inland basin located in the northern Tibetan Plateau. Pores in the brine storage medium act as storage space and transmission channels of underground brine. Therefore, the porosity of brine storage medium determines its ability to store brine. In this study, Mahai Salt Lake was used as the research area as a modern saline lake located in the north area of the Qaidam Basin. A total of 100 porosity samples were collected from eight sampling points in two profiles of the research area at sampling depths of 1.30–314.78 m. The porosity distribution characteristics and influencing factors in brine storage medium were analysed according to the measured porosity data. Based on analysis of the pore structure characteristics, the brine storage medium contains intercrystalline pores, unlike conventional freshwater storage mediums. Moreover, the primary salt rock is susceptible to dissolution by lighter brine, facilitating the formation of secondary porosity. Due to the formation of secondary pores, a porosity greater than 20% remains even at buried depths greater than 100 m. Based on the geological statistical analysis, due to the geographic location, salt formation time, and depositional environment, the porosity values of Mahai Salt Lake do not exhibit a wider distribution, but also show more extreme values than a nearby salt lake. Based on the porosity characteristics by depth, due to the presence of secondary pores, flooding, stratigraphic static pressure, and other factors, porosity shows fluctuations with increasing depth.

Formation and Transportation of High-Salinity Water Produced in Polynyas South of the St.Lawrence Island

The authors studied variations of temperature and salinity in seawater under sea ice using hydrologic data collected from polynyas south of the St.Lawrence Island during March of 2008 and 2009.The results indicate that the high-salinity water found during the cruises of 2008 and 2009 was due to the formation of polynyas.The salinity observed in 2008 was higher than that in 2009 as a result of higher salt production in 2008.The spatial distributions of high-salinity cores differed between the two cruises.In March 2008, a southeastward flow was formed under the persistent northerly wind in the observation region, which transported the high-salinity water produced by the polynyas to the southeast.The similar flow, however, did not exist in March 2009 because the northerly wind over the study area was interrupted by a southerly wind.Accordingly, the polynyas and the high-salinity water pro-duced by them existed for a short time.As a result, the high-salinity water in 2009 did not spread very far, and stayed within the polynyas.In addition, during the 2009 cruise, two stages of observations in the polynyas showed the core of high-salinity water was shifted to the southwest of the St.Lawrence Island.This result suggested that a southwestward flow might have existed in the area at the onset of the northerly wind, which was consistent with the alongshore and/or offshore flows caused by the northerly wind.

Numerical investigation on freeze-drying of aqueous material frozen with pre-built pores

Freeze-drying of the initially porous frozen material with pre-built pores from liquid material was found experimentally to save drying time by over 30% with an initial saturation being 0.28 compared with the conventional operation with the initial saturation being 1, using mannitol as the solid material. In order to understand the mass and heat transfer phenomena of this novel process, a two-dimensional mathematical model of coupled mass and heat transfer was derived with reference to the cylindrical coordinate system. Three adsorption–desorption equilibrium relationships between the vapour pressure and saturation value namely, power-law, Redhead's style and Kelvin's style equation, were tested. Kelvin's style in exponential form of adsorption equilibrium relation gave an excellent agreement between the model prediction and experimental measurement when the equation parameter, γ, of 5000 was applied. Analyses of temperature and ice saturation profiles show that additional heat needs to be supplied to increase the sample temperature in order to promote the desorption process. Simulation also shows that there is a threshold initial porosity after which the drying time decreased with the increase in the initial porosity. Enhanced freeze-drying is expected to be achieved by simultaneously enhancing mass and heat transfer of the process.

A hydrochemical study of the Hammam Righa geothermal waters in north-central Algeria

This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal field, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 ℃ and the hot waters from 32.1 to 68.2 ℃. All waters exhibited a near-neutral pH of 6.0-7.6. The thermal waters had a high total dis- solved solids （TDS） content of up to 2527 mg/l, while the TDS for cold waters was 659.0-852.0 mg/l. Chemical analyses suggest that two main types of water exist： hot waters in the upflow area of the Ca-Na-SO4 type （Ham- mam Righa） and cold waters in the recharge zone of the Ca-Na-HCO3 type （Zaccar Mount）. Reservoir tempera- tures were estimated using silica geothermometers and fluid/mineral equilibria at 78, 92, and 95℃ for HR4, HR2, and HRI, respectively. Stable isotopic analyses of the δ18O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge infiltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1-2.2 km. The hotwaters then interact at depth with Triassic evaporites located in the hydrothermal conduit （fault）, giving rise to the Ca-Na-SO4 water type. As they ascend to the surface, the thermal waters mix with shallower Mg-rich ground- water, resulting in waters that plot in the immature water field in the Na-K-Mg diagram. The mixing trend between cold groundwaters from the recharge zone area （Zaccar Mount） and hot waters in the upflow area （Hammam Righa） is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 〈 R 〈 29.2 %. We summa- rize these results with a geothermal conceptual model of the Hammam Righa geothermal field.