三元体系K2B4O7-KBr-H2O在323K的相平衡研究

采用等温溶解平衡法研究了三元体系K2B4O7-KBr-H2O在323 K的相平衡关系及密度。研究发现,该三元体系为简单共饱和型,无复盐及固溶体形成。根据溶解度数据绘制了相图,相图中有一个共饱点,两条单变曲线,单变量曲线所对应的平衡固相分别为K2B4O7.4H2O和KBr;实验结果表明KBr对K2B4O7有较强的盐析作用。并简要讨论了密度变化规律。     

Land cover controls on depression‐focused recharge on the Oak Ridges Moraine,southern Ontario,Canada

The Oak Ridges Moraine (ORM) is a key hydrogeologic feature in southern Ontario. Previous research has emphasized the importance of depression‐focused recharge (DFR) for the timing and location of water recharge to the ORM's aquifers. However, the significance of DFR has not been empirically demonstrated, and the ORM's permeable surficial deposits imply that rainfall and snowmelt will largely recharge vertically rather than move laterally to topographic depressions. The exception may be during winter and spring, when concrete soil frost limits infiltration and encourages overland flow. The potential for DFR was examined for closed depressions under forest and agricultural land covers with similar soils and surficial geology. Air temperatures, precipitation, snow depth and water equivalent, soil water contents, soil freezing, and depression surface‐water levels were monitored during the winter and spring of 2012–2013 and 2013–2014. Recharge (R) was estimated at the crest and base of each depression using a 1‐dimensional water balance approach and surface‐applied Br^? tracing. Both forest and agricultural land covers experienced soil freezing; however, forest soils did not develop concrete frost. Conversely, agricultural fields saw concrete frost, overland flow, episodic ponding, and subsequent drainage of rain‐on‐snow and snowmelt inputs in open depressions. Recharge at the base of open depressions exceeded that in surrounding areas by an order of magnitude, suggesting that DFR is a significant hydrologic process during winter and spring under agricultural land cover on the ORM. Closed topographic depressions under agricultural land cover on the ORM crest may serve as critical recharge “hot spots” during winter and spring, and the ability of the unsaturated zone beneath these depressions to modify the chemistry of recharging water deserves further attention.     

Laboratory Studies of Bromide Oxidation in the Presence of Ozone: Evidence for a Glass-Surface Mediated Reaction

The reaction of sodium bromide particles in the presence of ozone was studied in a flow system both under dark conditions and with 254 nm radiation. We found that there was significant formation of gaseous bromine (probably Br₂) in the presence of ozone in the dark, and that bromide deposited to the walls of the Pyrex reaction flask was its source. The observed rate of gaseous bromine formation in these experiments was approximately 100–1000 times faster than expected based on the knownrate constant for aqueous reaction of bromide with ozone. While the mechanism responsible for this enhanced reactivity was not identified, based on previous reports we suggest that the glass surface converted ozone to more reactive species, such as hydroxyl radical, which in turn oxidized bromide. In the presence of 254 nm radiation, rates of gaseous bromine collection were further enhanced, likely as a result of increased radical production in the system, and wall-deposited bromide was also the source of the gaseous bromine. In these `light' experiments, there was a significant decline in ozone mixing ratios, consistent with bromine radical chemistry. These results suggest the possibility that ozone reacting with internally mixed silicate/sea-salt particles might be a significant mechanism for the oxidation of particulate halides, and subsequent release of photoactive halogen species, in the marine boundary layer.     

AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001

In situ AGAGE GC-MS measurements of methyl bromide (CH₃Br) and methyl chloride (CH₃Cl) at Mace Head, Ireland and Cape Grim, Tasmania (1998–2001) reveal a complex pattern of sources. At Mace Head both gases have well-defined seasonal cycles with similar average annual decreases of 3.0% yr⁻¹ (CH₃Br) and 2.6% yr⁻¹ (CH₃Cl), and mean northern hemisphere baseline mole fractions of 10.37 ± 0.05 ppt and 535.7 ± 2.2 ppt, respectively. We have used a Lagrangian dispersion model and local meteorological data to segregate the Mace Head observations into different source regions, and interpret the results in terms of the known sources and sinks of these two key halocarbons. At Cape Grim CH₃Br and CH₃Cl also show annual decreases in their baseline mixing ratios of 2.5% yr⁻¹ and 1.5% yr⁻¹, respectively. Mean baseline mole fractions were 7.94 ± 0.03 ppt (CH₃Br) and 541.3 ± 1.1 ppt (CH₃Cl). Although CH₃Cl has astrong seasonal cycle there is no well-defined seasonal cycle in the Cape Grim CH₃Br record. The fact that both gases are steadily decreasing in the atmosphere at both locations implies that a change has occurred which is affecting a common, major source of both gases (possibly biomass burning) and/or their major sink process (destruction by hydroxyl radical).     

Kinetic investigation of the OH + CH3Br reaction between 248 and 390 K

The rate parameters for the reaction of the OH radical with CH₃Br have been measured using the discharge flow-electron paramagnetic resonance method. The result isk ₁=(1.86±0.48)×10^–12 exp[–(1230±150)/T] cm³ molecule^–1 s^–1. This value is compared to earlier data and is found to be in excellent agreement with the most recent results, which greatly increases the accuracy of the ozone depletion potential of CH₃Br which can be derived from these kinetic data.     

The contribution of old and new water to a storm hydrograph determined by tracer addition to a whole catchment

Two tracer experiments have been carried out at an enclosed catchment in southern Norway. The catchment was brought to steady state with respect to rainfall and runoff prior to the tracer addition. A known concentration of lithium bromide was then added to the rainfall for the duration of each event. The tight control on tracer concentration and rainfall amount enabled assessment of the contribution of old and new water to runoff, the dominant flow pathways and soil water residence times during a storm event. A significant volume of ‘old’ water contributes to runoff despite the hydrologically responsive nature of the catchment and several hours of tracer injected rainfall are required before ‘new’ water becomes the dominant runoff source. After 34 h of tracer injection, ‘new’ water apparently contributes c. 83% to instantaneous flow and c. 55% of the total tracer input to the catchment has been lost in runoff. Recovery of the tracer from soil water indicates that the organic soil surface layer is the dominant flow pathway for rainwater through the catchment and that a significant pathway also exists at the soil–bedrock interface. New water is retained in deep pockets of soil for several days. Assessment of the conservative behaviour of the tracer suggests that 10–14% of the input Br⁻ is retained in the soil and the tracer is not conservative. Laboratory experiments indicate that sorption of Br⁻ to organic soil is the likely mechanism of retention. This process is probably concentration dependent and will have occurred predominantly during the initial period of tracer application. Copyright © 2000 John Wiley & Sons, Ltd.     

溴化锂的生产工艺综述

综述了国内外溴化锂生产方法,并指出了每种方法的优缺点,同时展望了今后溴化锂生产方法的发展方向。     

钼－氨三乙酸－溴邻苯三酚红－溴化十六烷基三甲基铵体系的显色反应及其应用

在ｐＨ２．５的氯乙酸缓冲介质中，有溴化十六烷基三甲基铵（ＣＴＭＡＢ）存在下，Ｍｏ（Ⅵ）与氨三乙酸（ＮＴＡ）及溴邻苯三酚红（ＢＰＲ）形成胶束混配配合物，该配合物最大吸收波长在６００ｎｍ，摩尔吸光系数为７．２７×１０￣４Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１），配合物组成为Ｍｏ（Ⅵ）：ＮＴＡ：ＢＰＲ：ＣＴＭＡＢ＝１：１：２：４。Ｍｏ（Ⅵ）量在０～１．０ｇ／ｍｌ范围内符合比尔定律。由于ＮＴＡ的存在，改善了方法的选择性，可直接分光光度测定矿石及钢中微量Ｍｏ。     

相转移催化合成增塑剂邻苯二甲酸丁苄酯的研究

以CTMAB为相转移催化剂，苯酐、正丁醇和苄氨为原料合成BBP的新方法。通过设计正交实验，对原料配比、反应时间、催化荆用量、pH值和加水量等影响因素以及催化荆的回收利用进行了研究。实验结果表明，苯酐：正丁醇：CT．MAB：苄氨为1：1．33：0．04：1．2，pH值为9，反应时间为3h，反应过程中的加水量为1％时最高酯产率可达到80％以上。本方法操作简单，耗时少，成本低，催化荆可回收利用，产品质量好，无“三废”污染，并易于工业化生产。     

Tracer and hydrometric study of preferential flow in large undisturbed soil cores from the Georgia Piedmont,USA

We studied the temporal patterns of tracer throughput in the outflow of large (30 cm diameter by 38 cm long) undisturbed cores from the Panola Mountain Research Watershed, Georgia. Tracer breakthrough was affected by soil structure and rainfall intensity. Two rainfall intensities (20 and 40 mm hr⁻¹) for separate Cl⁻ and Br⁻ amended solutions were applied to two cores (one extracted from a hillslope soil and one extracted from a residual clay soil on the ridge). For both low and high rainfall intensity experiments, preferential flow occurred in the clay core, but not in the hillslope core. The preferential flow is attributed to well‐developed interpedal macrochannels that are commonly found in structured clay soils, characteristic of the ridge site. However, each rainfall intensity exceeded the matrix infiltration capacity at the top of the hillslope core, but did not exceed the matrix infiltration capacity at the middle and bottom of the hillslope core and at all levels in the clay core. Localized zones of saturation created when rainfall intensity exceeds the matrix infiltration capacity may cause water and tracer to overflow from the matrix into macrochannels, where preferential flow occurs to depth in otherwise unsaturated soil. Copyright © 1999 John Wiley & Sons, Ltd.