Biogenic origin of coastal honeycomb weathering

Honeycomb weathering occurs in two environments in Late Cretaceous and Eocene sandstone outcrops along the coastlines of south‐west Oregon and north‐west Washington, USA, and south‐west British Columbia, Canada. At these sites honeycomb weathering is found on subhorizontal rock surfaces in the intertidal zone, and on steep faces in the salt spray zone above the mean high tide level. In both environments, cavity development is initiated by salt weathering. In the intertidal zone, cavity shapes and sizes are primarily controlled by wetting/drying cycles, and the rate of development greatly diminishes when cavities reach a critical size where the amount of seawater left by receding tides is so great that evaporation no longer produces saturated solutions. Encrustations of algae or barnacles may also inhibit cavity enlargement. In the supratidal spray zone, honeycomb weathering results from a dynamic balance between the corrosive action of salt and the protective effects of endolithic microbes. Subtle environmental shifts may cause honeycomb cavity patterns to continue to develop, to become stable, or to coalesce to produce a barren surface. Cavity patterns produced by complex interactions between inorganic processes and biologic activity provide a geological model of ‘self‐organization’. Surface hardening is not a factor in honeycomb formation at these study sites. Salt weathering in coastal environments is an intermittently active process that requires particular wind and tidal conditions to provide a supply of salt water, and temperature and humidity conditions that cause evaporation. Under these conditions, salt residues may be detectable in honeycomb‐weathered rock, but absent at other times. Honeycomb weathering can form in only a few decades, but erosion rates are retarded in areas of the rock that contain cavity patterns relative to adjacent non‐honeycombed surfaces. Copyright © 2010 John Wiley & Sons, Ltd.     

Origin of honeycombs and related weathering forms in Oligocene Macigno Sandstone,Tuscan coast near Livorno,Italy

Two types of cavernous‐weathering features are exposed in the Oligocene Macigno Sandstone along 5 km of the Tuscan coast south of Livorno, Italy. Honeycomb cells (type 1 features) are typical closely spaced, more or less circular pits of centimetre scale that have been eroded 2 to 6 cm below the general surface of bedding planes or joints. ‘Aberrant honeycomb’ cells (type 2 features) are highly elongate, polygonal, or irregular ?at depressions of decimetre scale surrounded by walls rarely higher than 2 cm, some of which pass into long, free‐standing walls or tendrils. Thus, not all type 2 ‘honeycomb’ cells are fully enclosed. We measured the geometry of 551 honeycomb cells and examined various rock properties (microscopic texture and fabric, mineralogy, porosity, permeability, and chemical composition) to isolate factors that control the size, shape, distribution, and pattern of the honeycombs. Our goal was to narrow potential origins of the features and to understand their formation. The ubiquitous occurrence of sea salt in the honeycombs and scanning electron microscope evidence of physical weathering of silicates, especially micas, favours an origin for the honeycombs chie?y by salt weathering. Honeycombs do not form in siltstone, iron‐oxide‐impregnated sandstone, calcite‐cemented concretions, or in case‐hardened joints. Thus, salt weathering of type 1 and 2 honeycombs is not effective in very low permeability rocks. We propose for type 1 honeycombs that seawater is drawn into micropores of the sandstone and evolves into self‐organized diffusion cells (Turing patterns). Selective evaporation at the stationary nodes of diffusion cells, which form at the same site over time, leads to the precipitation of salt, then grains spall off, and pits are formed. The deepest pits (>40 mm) formed where Turing patterns consistently formed at the same sites. Although the walls are more porous and weathered than the host sandstone, they become selectively case hardened by an unidenti?ed component of low abundance. Initial honeycomb cell shape and gravity locally in?uenced type 1 honeycomb shapes. We suggest that type 2 honeycombs develop where diffusion‐controlled Turing patterns lead to case‐hardening along linear trends; gravity and rock fabric are important locally in in?uencing the orientation of the walls. Only type 2 cells are forming today, suggesting recent environmental changes. Gravity is not a fundamental control on honeycomb shape; in places it is a contributing factor. Pre‐existing depressions (quarry tool marks) have strongly in?uenced honeycomb shape locally. Copyright © 2004 John Wiley & Sons, Ltd.     

A COMPARISON OF EVAPORATION FROM SNOW AND SOIL SURFACES

ABSTRACT

During the spring of 1961, evaporation from snow and soil surfaces was measured in the central Rocky Mountains near Fraser, Colorado. Measurements were made in natural forest openings at 9,000 feet elevation. Evaporation from wet soil surfaces greatly exceeded evaporation from nearby snow. There was little evidence of transfer of vapor from soil to nearby patches of snow, but as areas of bare, wet soil increased and evaporation amounts from such surfaces increased, evaporation from snow decreased. It was concluded that, as greater amounts of water evaporated from soils, the vapor pressure of the air was raised sufficiently to reduce evaporation from snow. Since transfer of vapor from soil to snow appeared small at best, evaporation losses from snow and soil surfaces essentially constituted a total moisture loss from the area.     

鄱阳湖夏季水面蒸发与蒸发皿蒸发的比较

水面蒸发是湖泊水量平衡要素的重要组成部分.基于传统蒸发皿观测蒸发不能代表实际水面蒸发,而实际水面蒸发特征仍不清楚.本研究基于涡度相关系统观测的鄱阳湖水体实际水面蒸发过程,在小时和日尺度分析了水面蒸发的变化规律及其主要影响因子,并与蒸发皿蒸发进行比较.研究表明,实际水面蒸发日变化波动剧烈,变化范围在0~0.4 mm/h之间.水面蒸发的日变化特征主要受风速的影响.鄱阳湖8月份日水面蒸发量与蒸发皿蒸发量在总体趋势上具有很好的一致性.8月份平均日水面蒸发速率(5.90 mm/d)比蒸发皿蒸发速率(5.65 mm/d)高4.6%.水面日蒸发量与蒸发皿蒸发量的比值在8月上、中、下旬平均值分别为1.24、1.00、0.92,呈现下降的趋势.鄱阳湖夏季水面日蒸发量与风速和相对湿度相关性显著,而蒸发皿蒸发与净辐射、气温、饱和水汽压差和相对湿度均呈显著相关.这是由于蒸发皿水体容积小,与湖泊相比其水体热存储能力小,因此更容易受到环境因子的影响.     

Modelling evaporation processes in soils from the Huasco salt flat basin,Chile

The need to understand and simulate hydrological phenomena and their interactions, and the impact of anthropogenic and climate changes on natural environments have promoted the study of evaporation from bare soils in arid climates. In closed Altiplano basins, such as those encountered in arid and hyper arid basins in northern Chile, evaporation from shallow groundwater is the main source of aquifer depletion, and thus, its study is crucial for water resources management. The objective of this work is to understand the mechanisms of evaporation in saline soils with shallow water tables, in order to better quantify evaporation fluxes and improve our understanding of the water balance in these regions. To achieve this objective, a model that couples fluid flow with heat transfer was developed and calibrated using column experiments with saline soils from the Huasco salt flat basin, Chile. The model enables determination of both liquid and water vapour fluxes, as well as the location of the evaporation front. Experimental results showed that salt transport inside the soil profile modified the water retention curve, highlighting the importance of including salt transport when modelling the evaporation processes in these soils. Indeed, model simulations only agreed with the experimental data when the effect of salt transport on water retention curves was taken into account. Model results also showed that the evaporation front is closer to the soil surface as the water table depth reduces. Therefore, the model allows determining the groundwater level depth that results in disconnection of liquid fluxes in the vadose zone. A sensitivity analysis allowed understanding the effect of water‐flux enhancements mechanisms on soil evaporation. The results presented in this study are important as they allow quantifying the evaporation that occurs in bare soils from Altiplano basins, which is typically the main water discharge in these closed basins. Copyright © 2016 John Wiley & Sons, Ltd.     

Evaporites: Relative humidity control of primary mineral facies revisited

It is widely accepted that the deposition of mineral facies of evaporite basins is controlled by the average annual relative humidity of the contiguous atmosphere, which dictates the equilibrium activity of the evaporating brine. This concept has far reaching implications in salt works and for the investigation of paleoenvironmental settings affecting depositional sequences within evaporite basins. The above concept, which dominated the scientific thought of evaporite basin investigations, suffers from two serious flaws: (a) the assumption of a static decoupled atmosphere and (b) the total neglect of energy input and thermodynamic feedbacks resulting from evaporation suppression. The present investigation will resolve the underlying mechanisms controlling the equilibrium activity of hypersaline solutions using a theoretical framework that combines energy and mass transport across the surface–atmosphere boundary. Calculations of the equilibrium activity of hypersaline solutions under isothermal conditions, as implied in the original concept, are not in line with the basic physical principles defining heat and mass exchange across the brine–atmosphere boundary and lead to substantial overestimation of actual evaporation and the activity itself. It is demonstrated that in addition to atmospheric relative humidity, the activity of hypersaline solutions is determined by numerous meteorological forcings along with hydrological, geochemical, and thermodynamic feedback mechanisms. Evaporation suppression resulting from a drop in brine activity causes substantial increase in brine temperature, which enhances vapour pressure differential across the interface, leading to more evaporation. This negative feedback shifts the brine activity downward for equilibrium to be attained. It is also demonstrated that evaporation from a brine surface usually proceeds when the relative humidity of the contiguous atmosphere is similar or even higher than that of the brine due to energy input and the strong negative feedback caused by evaporation suppression. The present investigation re‐establishes a new paradigm concerning the processes controlling evaporite basin sedimentation and palaeoclimate reconstruction as deduced from evaporite/hypersaline basin deposits. Findings have operational ramifications in the industrial applications of dissolved salt mineral extraction.     

Proposing a formula for evaporation measurement from salt water resources

Evaporation involves the change in state of a liquid to a vapour. The evaporation rate from salt‐water resources depends mostly on saturated vapour pressure above its surface. On the other hand, the saturated vapour pressure is affected by the ion activity coefficient, which stems from the chemical salt concentration of water. Thus, an increase in concentration of water results in a reduction of saturated vapour pressure. In order to acquire the actual rate of evaporation from salt‐water resources, a uniform set of evaporation pans with different but specified salt concentrations were used, in a meteorological station under the same conditions. The difference in evaporation rate of each pan can only stem from the difference in chemical salt concentration and, indeed, the molar fraction of water in each saline solution. Therefore, by applying the water molar fraction in the pressure term of fresh‐water evaporation measurement formulas, these equations were developed further for determination of evaporation rate from salt‐water resources. The proposed formulas using very simple terms seem to be suitable for determination of evaporation rate from any water (typically saline, semi‐saline and fresh water) with a satisfactory precision. Copyright © 2007 John Wiley & Sons, Ltd.     

水面蒸发与散热系数公式研究(二)

根据自1976年以来全国水面蒸发与散热研究协作组在我国各典型地区的原体与室内实验资料和大量水文站历史资料,通过理论分析和统计检验,确定了影响水面蒸发的诸因子及其非线性相互作用,引入了新的无量纲参数和公式结构,用实测资料统计确定了公式中的常系数,得到了用开敞湖面一般水文气象资料计算逐日蒸发和散热系数的公式。经全国务典型气候带内务季节湖泊(水库)和受热污染水体上原体观测和室内专题实验共1860组日平均检验,公式的精度高于现有其他公式。全文分两部分,本文刊出第二部分,内容包括:公式的检验;水文气象要素对α的影响;水面散热系数的计算和结语。     

Artificial neural networks and empirical equations to estimate daily evaporation: application to Lake Vegoritis,Greece

ABSTRACT

Evaporation is one of the most important components in the energy and water budgets of lakes and is a primary process of water loss from their surfaces. An artificial neural network (ANN) technique is used in this study to estimate daily evaporation from Lake Vegoritis in northern Greece and is compared with the classical empirical methods of Penman, Priestley-Taylor and the mass transfer method. Estimation of the evaporation over the lake is based on the energy budget method in combination with a mathematical model of water temperature distribution in the lake. Daily datasets of air temperature, relative humidity, wind velocity, sunshine hours and evaporation are used for training and testing of ANN models. Several input combinations and different ANN architectures are tested to detect the most suitable model for predicting lake evaporation. The best structure obtained for the ANN evaporation model is 4-4-1, with root mean square error (RMSE) from 0.69 to 1.35 mm d^?1 and correlation coefficient from 0.79 to 0.92.

EDITOR M.C. Acreman

ASSOCIATE EDITOR not assigned     

Evaporation from seasonally frozen bare and vegetated ground at various groundwater table depths in the Ordos Basin,Northwest China

In cold climates, the process of freezing–thawing significantly affects the ground surface heat balance and water balance. To better understand the mechanism of evaporation from seasonally frozen soils, we performed field experiments at different water table depths on vegetated and bare ground in a semiarid region in China. Soil moisture and temperature, air temperature, precipitation, and water table depths were measured over a 5‐month period (November 1, 2016, to March 14, 2017). The evaporation, which was calculated by a mass balance method, was high in the periods of thawing and low in the periods of freezing. Increased water table depth in the freezing period led to high soil moisture in the upper soil layer, whereas lower initial groundwater levels during freezing–thawing decreased the cumulative evaporation. The extent of evaporation from the bare ground was the same in summer as in winter. These results indicate that a noteworthy amount of evaporation from the bare ground is present during freezing–thawing. Finally, the roots of Salix psammophila could increase the soil temperature. This study presents an insight into the joint effects of soil moisture, temperature, ground vegetation, and water table depths on the evaporation from seasonally frozen soils. Furthermore, it also has important implications for water management in seasonally frozen areas.     

An improved methodology to measure evaporation from bare soil based on comparison of surface temperature with a dry soil surface

Accurate estimation of the resistances to water vapor movement is a major difficulty in evaluating evaporation from soil. By including the temperature of a dry soil surface (the temperature of the surface of a dry soil column buried in the field), a method for estimating evaporation from soil is proposed. The necessary input variables for the suggested method are temperature, net radiation, and soil heat flux. There are three advantages of the proposed method over the conventional methods. First, soil surface resistance and aerodynamic resistance are not required. Second, the variables included are fewer. Third, measurement and analysis of the parameters involved are relatively easy. Sensitivity analysis shows that the suggested method is sensitive to temperatures. Test experiments were conducted in a sandy field, where a weighing lysimeter was installed. Evaporation from soil, together with the variables specified above, were measured. For temperatures measured by thermocouples, experimental results showed that the mean absolute error (MAE) for the daily evaporation over 22 days was 0.17 mm day⁻¹. The regression between calculated and measured evaporation was highly significant (r²=0.89). Moreover, the intercept and slope of the regression equation were not significantly different from zero and unity, respectively, at the 0.05 probability level. Furthermore, by using the temperatures measured by infrared thermometers, the MAE between measured evaporation and estimated evaporation was 0.15 mm day⁻¹. The regression between them was highly significant (r²=0.94). In addition, the intercept and slope of the regression equation were not significantly different from zero and unity, respectively, at the 0.05 probability level. These results show that evaporation calculated using the proposed method is in good agreement with lysimeter measured values. By comparing with the temperature difference method, it was shown that the suggested method estimated soil evaporation more accurately than the temperature difference method. Therefore, it is concluded that the proposed method is not only a simple way for application, but also an accurate way to estimate soil evaporation.     

水面蒸发与散热系数公式研究(一)

根据自1976年以来全国水面蒸发与散热研究协作组在我国各典型地区的原体与室内实验资料和大量水文站历史资料,通过理论分析和统计检验,确定丁影响水面蒸发的诸因子及其非线性相互作用,引入了新的无量纲参数(w_e、Pv、Pe)和公式结构,用实测资料统计确定厂公式中的常系数,得到了用开敞湖面一般水文气象资料计算逐日蒸发和散热系数的公式。经全国各典型气候带内各季节湖泊(水库)和受热污染水体上原体观测和室内专题实验共1860组口平均资料检验,公式的精度高于现有其他公式。全文分两部分,这是第一部分,内容包括:影响水面蒸发的土要无量纲参数;感热输送和大气饱和度对蒸发影响的修正;水面蒸发计算公式的结构及其经验系数。     

Predicting evaporation from mountain streams

Evaporation can be an important control on stream temperature, particularly in summer when it acts to limit daily maximum stream temperature. Evaporation from streams is usually modelled with the use of a wind function that includes empirically derived coefficients. A small number of studies derived wind functions for individual streams; the fitted parameters varied substantially among sites. In this study, stream evaporation and above-stream meteorological conditions (at 0.5 and 1.5 m above the water surface) were measured at nine mountain streams in southwestern British Columbia, Canada, covering a range of stream widths, temperatures, and riparian vegetation. Evaporation was measured on 20 site-days in total, at approximately hourly intervals, using nine floating evaporation pans distributed across the channels. The wind function was fit using mixed-effects models to account for among-stream variability in the parameters. The fixed-effects parameters were tested using leave-one-site-out cross-validation. The model based on 0.5 m measurements provided improved model performance compared to that based on 1.5 m values, with RMSE of 0.0162 and 0.0187 mm h⁻¹, respectively, relative to a mean evaporation rate of 0.06 mm h⁻¹. Inclusion of atmospheric stability and canopy openness as predictors improved model performance when using the 1.5 m meteorological measurements, with minimal improvement when based on 0.5 m measurements. Of the wind functions reported in the literature, two performed reasonably while five others exhibited substantial bias.     

The importance of the petrophysical properties and external factors in the stone decay on monuments

In this paper it is proposed to quantify the importance of some physical parameters responsible for stone decay on monuments. The most common decay process is the crystallisation of salt near the surface of the rocks or inside their porous network. Therefore, the water balance in rocks submitted to these special saturation and position conditions has been studied specifically, using the general concepts of water transfer in unsaturated porous media, and using the capillary imbibition kinetics of different rocks. Different parameters have been taken into account for the calculation of the salt crystallisation position: on one hand, several external parameters such as relative humidity, air convection and the presence of solute in solution, and on the other hand, the intrinsic water transfer properties of the rocks. Their relative importance is discussed, considering the potential values that each parameter can reach in nature.     

Building sandstone surface modification by biofilm and iron precipitation: emerging block‐scale heterogeneity and system response

Stone surfaces are sensitive to their environment. This means that they will often respond to exposure conditions by manifesting a change in surface characteristics. Such changes can be more than simply aesthetic, creating surface/subsurface heterogeneity in stone at the block scale, promoting stress gradients to be set up as surface response to, for example, temperature fluctuations, can diverge from subsurface response. This paper reports preliminary experiments investigating the potential of biofilms and iron precipitation as surface‐modifiers on stone, exploring the idea of block‐scale surface‐to‐depth heterogeneity, and investigating how physical alteration in the surface and near‐surface zone can have implications for subsurface response and potentially for long‐term decay patterns. Salt weathering simulations on fresh and surface‐modified stone suggest that even subtle surface modification can have significant implications for moisture uptake and retention, salt concentration and distribution from surface to depth, over the period of the experimental run. The accumulation of salt may increase the retention of moisture, by modifying vapour pressure differentials and the rate of evaporation. Temperature fluctuation experiments suggest that the presence of a biofilm can have an impact on energy transfer processes that occur at the stone surface (for example, buffering against temperature fluctuation), affecting surface‐to‐depth stress gradients. Ultimately, fresh and surface‐modified blocks mask different kinds of system, which respond to inputs differently because of different storage mechanisms, encouraging divergent behaviour between fresh and surface‐modified stone over time. Copyright © 2014 John Wiley & Sons, Ltd.     

Patterns of damage in igneous and sedimentary rocks under conditions simulating sea‐salt weathering

A saline‐spray artificial ageing test was used to simulate the effects produced in granites and sedimentary rocks (calcarenites, micrites and breccia) under conditions in coastal environments. Three main points were addressed in this study: the durability of the different kinds of rock to salt decay, the resulting weathering forms and the rock properties involved in the weathering processes. For this, mineralogical and textural characterization of each of the different rocks was carried out before and after the test. The soluble salt content at different depths from the exposed surfaces was also determined. Two different weathering mechanisms were observed in the granite and calcareous rocks. Physical processes were involved in the weathering of granite samples, whereas dissolution of calcite was also involved in the deterioration of the calcareous rocks. We also showed that microstructural characteristics (e.g. pore size distribution), play a key role in salt damage, because of their influence on saline solution transport and on the pressures developed within rocks during crystallization. Copyright © 2003 John Wiley & Sons, Ltd.     

Experimental investigation of injectivity alteration due to salt precipitation during CO2 sequestration in saline aquifers

Injection of CO₂ into saline aquifers causes the geochemical reaction of rock-fluid and salt precipitation due to the evaporation of water as a physical process. Well injectivity is an important issue in carbon capture and storage (CCS) projects because large volumes of CO₂ must be stored for a long time and salt precipitation can significantly reduce injectivity by reducing the permeability. The impact of salt precipitation on the injectivity must therefore be specified in order to maintain the security of CCS projects and enable them to perform at a high level of practicality. The objective of this work is to investigate the influence of the injection rate and brine salinity on injectivity reduction due to evaporation and salt precipitation. In this study, we injected supercritical CO₂ into a sandstone rock sample fully saturated with NaCl brine to characterize the salt precipitation induced by the evaporation process.Evaporation is investigated by mass measurement of the water and vapor produced. The extension in time of salt precipitation and the precipitation profile are analyzed by drying rate measurement, Capillary number and Peclet number. The consequences of salt precipitation on injectivity are specified by permeability and relative permeability analysis. The results show that a high drying rate in the early stage of injection induces rapid salt precipitation. The level of salt precipitation increases with salinity, within a permeability reduction range of 21–66%, and decreases with the injection rate, within a permeability reduction range of 43–62%. The relative permeability of CO₂ is affected by both the injection rate and salinity.     

Identifying surface water evaporation loss of inland river basin based on evaporation enrichment model

Accurately quantifying the evaporation loss of surface water is essential for regional water resources management, especially in arid and semi-arid areas where water resources are already scarce. The long-term monitoring of stable isotopes (δ¹⁸O and δ²H) in water can provide a sensitive indicator of water loss by evaporation. In this study, we obtained surface water samples of Shiyang River Basin from April to October between 2017 and 2019. The spatial and temporal characteristics of stable isotopes in surface water show the trend of enrichment in summer, depletion in spring, enrichment in deserts and depletion in mountains. The Local Evaporation Line (LEL) obtained by the regression of δ²H and δ¹⁸O in surface water has been defined by the lines: δ²H = 7.61δ¹⁸O + 14.58 for mountainous area, δ²H = 4.19δ¹⁸O − 17.85 for oasis area, δ²H = 4.08δ¹⁸O − 18.92 for desert area. The slope of LEL shows a gradual decrease from mountain to desert, indicating that the evaporation of surface water is gradually increasing. The evaporation loss of stable isotopes in surface water is 24.82% for mountainous area, 32.19% for oasis area, and 70.98% for desert area, respectively. Temperature and air humidity are the main meteorological factors affecting the evaporation loss, and the construction of reservoirs and farmland irrigation are the main man-made factors affecting the evaporation loss.     

An automated tunnel evaporation measurement system for confined spaces

An automated tunnel evaporation‐rate measurement system (TEMS) has been designed to measure automatically the evaporation from a cylinder 0·30 m in diameter and ～0·10 m tall. This cylinder continuously maintains a constant height of water, with losses to evaporation replenished from a stilling cylinder connected to a water reservoir. The evaporation rate is measured by a transducer located at the bottom of the stilling well. The TEMS was tested over a period of 3 months in an underground research facility with relatively strong wind effects, changing temperature, and changing humidity. During this period, the TEMS continued to function uninterrupted, automatically measuring the evaporation amounts along a tunnel and an enclosed niche. These observations suggest that this tool can be useful for investigations of evaporation processes both in enclosed and ventilated environments. Published in 2002 by John Wiley & Sons, Ltd.     

Effect of salt types on salt precipitation and water transport in saline sandy soil

Salt precipitation on the surface of porous media significantly affects water transport processes. Most studies on salt precipitation mainly focused on single salts, but in nature, salt precipitation usually occurs as mixtures. Consequently, information on the crystallization of salt mixtures and its effect on water transport remains scarce. This study investigated the precipitation of mixtures (the mass ratios of NaCl:Na₂SO₄ were 3:7, 5:5, and 7:3, respectively) of NaCl (typical efflorescence) and Na₂SO₄ (typical subflorescence) in the initially saturated sandy soil columns and its effect on evaporation and compared it with the cases of the two salts individually. The results showed that salt mixtures exhibited a mixed pattern of crystals including both efflorescence and subflorescence, and the efflorescence showed granular aggregation, unlike the mono-salts. The crystallization coverage of the salt mixtures was smaller than that of NaCl mono-salt; high (7:3) and low (5:5 and 3:7) proportions of NaCl led to larger and smaller crystallization coverage than that of Na₂SO₄ mono-salt, respectively. While the salt mixtures had less crystallization coverage than the mono-salts, they showed lower evaporation because the salt mixtures formed a denser crystallization structure of efflorescence-subflorescence-soil layer, this crystallization structure exhibited greater inhibition of water vapour diffusion, thus reducing evaporation. In addition, the crystallization of the salt mixtures with higher NaCl proportion afforded greater resistance of evaporation. The mixed crystallization pattern formed by the salt mixtures significantly enhances the crystallization resistance to evaporation.