Soluble Salt Content Research Articles

Dynamics of soluble salts in cooling systems of circulating water supply

A model of the dynamics of soluble salts in the water of cooling systems of circulating water supply was developed based on mass balance principles. The proposed model is expressed in a general form under the assumption of a constant volume of circulating water and non-stationary input and output flows. The model accounts for scenarios where the concentration of soluble salts exceeds their concentration in the circulating water, thereby considering the technological necessity to change the system's power source in the event of an emergency at the feedwater treatment facilities. The developed model enables accurate prediction of the water-chemical regime in both existing and new recirculating cooling systems, sufficient for engineering calculations. It also facilitates the selection of optimal management strategies for such systems, including stabilization methods for recirculating water, feedwater preparation, blowdown volumes, etc. The model was validated under laboratory conditions for cases of concentration and dilution of highly soluble NaCl salt, with an observed error margin not exceeding 2%, attributed to experimental and instrumental factors. The variation in the concentration factor was analyzed for different blowdown rates, assuming initial equality of soluble salt concentrations in feedwater and circulation water. It was shown that establishing dynamic equilibrium between the circulation and feed waters can require dozens or even hundreds of circulation cycles for blowdown rates of 1–4%, and this system inertia must be considered during operation and when forecasting the performance of cooling systems with circulating water supply.

Evaluating the impact threshold of soluble salts on preservation of earthen site in Emperor Qin Shi Huang’s mausoleum

The recurrent crystallization and subsequent volumetric expansion of soluble salts pose significant risks to earthen sites, particularly those with archaeological remains on their surfaces. Therefore, timing interventions based on salt content is crucial. This study focuses on the effects of soluble salt content on the earthen site within the burial pits of the Qin Mausoleum, with a particular emphasis on defining safe salinity levels. A mixture of Na2SO4/NaCl salts in a 1:1 mass ratio was added to remodelled soil cakes, which were then aged in a climate chamber for several months. The area of salt expansion on the soil cakes’ surfaces was measured using a deep-focus microscope to assess damage. The results indicate a sudden increase in salt expansion when salinity exceeded 0.1%. Additionally, re-evaluations of these soil cakes years later allowed for the exploration of mechanisms and the feasibility of assessing soil surface expansion and friability at different stages of the earthen site’s lifecycle, including excavation and display. These findings provide preliminary scientific bases and novel methodologies for the further preventive conservation of heritage earthen sites.

Distribution and growth potential of wild Pittosporum tobira in the subtropical supratidal zone

The use of local native plant species for ecological restoration and rehabilitation is considered an important strategy for nature-based solutions. To achieve this goal, the key work is to understand the distribution of local native plants and their limiting factors. Pittosporum tobira is a keystone species of the vegetation community in subtropical coastal areas, and it plays an essential role in the function and stability of the coastal vegetation buffer zone. The aim of this study was to identify the factors that restrict the growth of P. tobira in the subtropical supratidal zone. We investigated the growth and development of P. tobira plants at three field sites, Dongtou Island (DT), Yuhuan Island (YH), and Cangnan County (CN), in Zhejiang Province, China. To investigate the key factors restricting the growth of this species, we sampled soils from both the supratidal zone and the P. tobira habitat zone. Soils in the supratidal zone showed typical characteristics of sodium chloride-type saline-alkali soil, and the soluble salts content showed wide fluctuations. Some soils in the supratidal zone showed severe salinization. The soil pH and soluble salts contents were higher, but soil organic matter content was lower, in the supratidal zone than in the P. tobira habitat zone. Among the three wild P. tobira habitat sites, DT had the lowest soil nutrient contents. In soil from the DT site, the soluble salts content was 150 % higher and soil organic matter content was 50 % lower than those in soils from the YH and CN sites. Compared with P. tobira growing at the CN and YH sites, those growing at the DT site showed higher antioxidant enzyme activity, higher organic osmotic regulatory substances content, and lower malondialdehyde content in the leaves and roots. These results suggest that the growth and distribution of P. tobira are affected by the organic matter content, pH, and soluble salts content in soil. Among the three P. tobira populations studied here, the population at DT was the most tolerant to the highly saline conditions in this subtropical coastal area, and has potential applications in landscape restoration of the supratidal zone.

Impacts of Varying Sowing Dates on the Profitability and Production of Cultivars of Pigeonpea (Cajanus cajan L. Mill sp.)

At the experimental farm of the College of Agriculture, Badnapur, VNMKV, Parbhani, a suitable range of field experiments were done during the kharif season, with an optimal time of sowing. The experiment was carried out using five varieties in the sub plot, V1-BSMR-736, V2-BSMR-853, V3-BDN-711, V4-BDN-708, and V5-Vipula, and four sowing dates in the main plot, D1: (15 th June), D2: (30 th June), D3: (15 th July), and D4: (30th July). The soil had a medium-black color, a clayey texture, a high base saturation level, an alkaline reaction, and a higher concentration of total soluble salts. It also had low levels of nitrogen and phosphorus and high levels of potassium and lime. The dibbling method of sowing was used. According to the experiment's results, sowing of pigeonpea on June 15 th was the best date to achieve greater yield metrics, specifically number of pods per plant, pod weight plant-1 (g), grain weight plant-1 (g), and test weight (g). in addition to economic indicators including GMR (119080 Rs ha-1), NMR (96573 Rs ha-1), and B:C (5.29), in addition to harvest index (HI), biological yield (kg ha-1) and seed yield (kg ha-1). Comparatively speaking to the other kinds, the pigeonpea variety BSMR-736 was shown to be very prolific.

Salt-Tolerant Plant Growth-Promoting Bacteria (ST-PGPB): An Effective Strategy for Sustainable Food Production.

Soil is the backbone of the agricultural economy of any country. Soil salinity refers to the higher concentration of soluble salts in the soil. Soil salinity is a ruinous abiotic stress that has emerged as a threatening issue for food security. High salt concentration causes an ionic imbalance that hampers water uptake, affecting photosynthesis and other metabolic processes, ultimately resulting in inferior seed germination and stunted plant growth. A wide range of strategies have been adopted to mitigate the harmful effects of salinity such as efficient irrigation techniques, soil reclamation, habitat restoration, flushing, leaching or using salt-tolerant crops, but all the methods have one or more limitations. An alternative and effective strategy is the exploitation of salt-tolerant plant growth-promoting bacteria (ST-PGPB) to mitigate salt stress and improve crop productivity. ST-PGPB can survive in salinity-tainted environments and perform their inherent plant growth-promoting and biocontrol functions effectively. Additionally, ST-PGPB can rescue plants via stress-responsive mechanisms including production of growth regulators, maintenance of osmotic balance, aminocyclopropane-1-carboxylate (ACC) deaminase activity, exopolysaccharides (EPS) activity, improvement in photosynthesis activity, synthesis of compatible solutes, antioxidant activity and regulation of salt overly sensitive (SOS) signaling pathway. Several well-known ST-PGPB, specifically Azospirillum, Bacillus, Burkholderia, Enterobacter, Pseudomonas and Pantoea, are used as bioinoculants to improve the growth of different crops. The application of ST-PGPB allows plants to cope with salt stress by boosting their defense mechanisms. This review highlights the impact of salinity stress on plant growth and the potential of ST-PGPB as a biofertilizer to improve crop productivity under salt stress.

Effect of Different Sowing Dates on the Growth of Pigeonpea (Cajanus cajan L. Millsp.) Varieties

The field investigation conducted during kharif season, at experimental farm, College of Agriculture, Badnapur, VNMKV, Parbhani. The experiment conducted with four sowing dates in main plot viz, D1 : (15th June) , D2: (30th June) , D3 : (15th July), D4 : (30th July) and five varieties in sub plot viz, V1-BSMR-736, V2-BSMR-853, V3-BDN-711, V4-BDN-708 and V5-VIPULA. The soil was medium black, clay in texture, alkaline in reaction and higher in total soluble salt concentration, low in nitrogen and phosphorus and rich in potassium and lime, alkaline in reaction with high base saturation. Sowing was done by dibbling method. From the result of experiment, it can be concluded that, among different sowing dates for pigeonpea, the sowing on 15th June, was found optimum for achieving higher seed yield. The pigeonpea variety BSMR-736 was found to be highly productive as compared to rest of the varieties.

A Comparative Analysis of Bacterial and Fungal Communities in Coastal and Inland Pecan Plantations.

Pecan forests (Carya illinoinensis) are significant contributors to both food and oil production, and thrive in diverse soil environments, including coastal regions. However, the interplay between soil microbes and pecan forest health in coastal environments remains understudied. Therefore, we investigated soil bacterial and fungal diversity in coastal (Dafeng, DF) and inland (Guomei, GM) pecan plantations using high-throughput sequencing. The results revealed a higher microbial diversity in the DF plantation than in the GM plantation, significantly influenced by pH and edaphic factors. The dominant bacterial phyla were Proteobacteria, Acidobacteriota and Bacteroidota in the DF plantation, and Acidobacteriota, Proteobacteria, and Verrucomicrobiota in the GM plantation. Bacillus, Nitrospira and UTCFX1 were significantly more abundant bacterial genera in DF soil, whereas Candidatus Udaeobacter, HSB_OF53-F07 and ADurbBin063-1 were more prevalent in GM soil. Basidiomycota dominated fungal sequences in the GM plantation, with a higher relative abundance of Ascomycota in the DF plantation. Significant differences in fungal genus composition were observed between plantations, with Scleroderma, Hebeloma, and Naucoria being more abundant in DF soil, and Clavulina, Russula, and Inocybe in GM soil. A functional analysis revealed greater carbohydrate metabolism potential in GM plantation bacteria and a higher ectomycorrhizal fungi abundance in DF soil. Significantly positive correlations were detected between certain bacterial and fungal genera and pH and total soluble salt content, suggesting their role in pecan adaptation to coastal environments and saline-alkali stress mitigation. These findings enhance our understanding of soil microbiomes in coastal pecan plantations, and are anticipated to foster ecologically sustainable agroforestry practices and contribute to coastal marshland ecosystem management.

Using organic amendments in disturbed soil to enhance soil organic matter, nutrient content and turfgrass establishment

Disturbed soils, including manufactured topsoils, often lack physical and chemical properties conducive to vegetation establishment. As a result, efforts to stabilize disturbed soils with vegetation are susceptible to failure. Urban organic waste products such as wood mulch, composted leaf and yard waste, and biosolids are widely distributed as organic amendments that enhance sustainability and plant establishment. Correct use can be determined by examining soil properties such as pH; the concentration of soluble salts (SS); and plant available nutrients — particularly N, C and P; as well as root and shoot growth. This research examined the effects of three typical organic amendments on fertility, establishment, and nutrient loss. A manufactured topsoil was used as the base soil for all treatments, including a control unamended soil (CUT), and soil amended with either mulch (MAT), composted leaf and yard waste (LAT), or biosolids (BAT). A 2 % organic matter concentration increase was sought but not achieved due to difficulty in reproducing lab results at a larger scale. Results showed that LAT improved soil fertility, particularly N-P-K concentrations while maintaining a good C:N ratio, pH, and SS concentration. BAT was the most effective at enhancing shoot growth but results suggest that improved growth rates could result in increased maintenance. Additionally, biosolids were an excellent source of nutrients, especially N-P-K and S, but diminished root growth and N leachate losses indicate that N was applied in excess of turfgrass requirements. Therefore, biosolids could be used as fertilizer, subject to recommended rates for turfgrass establishment to prevent poor root growth and waterborne N pollution. To ensure establishment efforts are successful, MAT is not recommended without a supplemental source of soluble N. Altogether, study results and conclusions could inform others seeking to improve specifications for disturbed soil where turfgrass establishment is needed to stabilize soil.

On the contribution of tidal floods on damp walls of Venice

The city of Venice, Italy, has historically coped with tidal flooding and is an example of a resilient system, but today the disruptive effects of relative sea level rise pose even more complex challenges. Some of the most significant damage to the city's historic architectural assets is related to the effects of salty water on masonry due to rising damp and tidal flooding. This paper evaluates the entity and distribution of rising damp in seven Venetian brick masonries by quantifying moisture content, soluble salt content, and ion distribution. The distribution is compared with previous literature data and related to tidal and meteorological data recorded prior to sampling. The results show that frequent tidal flooding exacerbates rising damp phenomena within building masonry, resulting in higher moisture contents both in height and depth. Possible future scenarios of relative sea level based on models and the effects of countermeasures such as the MOSE dam are discussed about the likely damage to masonry exposed to rising damp and tidal flooding.

Salt distribution and alkalinity characterization in bauxite residue disposal areas from the spatial scale range

Bauxite residue (red mud) has high alkalinity and salinity, which seriously restricts its reuse. It is crucial to understand the salt distribution pattern and alkalinity characteristics in the bauxite residue disposal area (BRDA), which can provide a theoretical basis for realizing the salinity and alkalinity regulation and reuse of bauxite residue. In this paper, samples from different locations and depths of the BRDA were used for the determination of soluble salts content, pH, and electrical conductivity (EC), and the correlation between the indicators was analyzed. The results show that bauxite residue has a high content of soluble salts, and the spatial distribution of soluble salts in the BRDA is relatively complex, with moderate variability, but does not show an obvious regularity. The major cations are Na+, K+ and the major anions are CO32−, HCO3−. Through cluster analysis, the soluble ions in bauxite residue can be divided into two main groups, one is Na+, CO32−, HCO3−, and the other is Ca2+, Mg2+, K+, Cl− and SO42−. PH has a significant positive correlation with Na+, K+, CO32− and HCO3−, and a negative correlation with Ca2+. And its alkalinity depends to a large extent on carbonate and bicarbonate, and the Na+ content can be predicted from EC, thus reflecting the concentration of alkaline residues in the bauxite residue.

Effect of methyl jasmonate and GA3 on canola (Brassica napus L.) growth, antioxidants activity, and nutrient concentration cultivated in salt-affected soils

Salinity stress is a significant challenge in agricultural production. When soil contains high salts, it can adversely affect plant growth and productivity due to the high concentration of soluble salts in the soil water. To overcome this issue, foliar applications of methyl jasmonate (MJ) and gibberellic acid (GA3) can be productive amendments. Both can potentially improve the plant’s growth attributes and flowering, which are imperative in improving growth and yield. However, limited literature is available on their combined use in canola to mitigate salinity stress. That’s why the current study investigates the impact of different levels of MJ (at concentrations of 0.8, 1.6, and 3.2 mM MJ) and GA3 (0GA3 and 5 mg/L GA3) on canola cultivated in salt-affected soils. Applying all the treatments in four replicates. Results indicate that the application of 0.8 mM MJ with 5 mg/L GA3 significantly enhances shoot length (23.29%), shoot dry weight (24.77%), number of leaves per plant (24.93%), number of flowering branches (26.11%), chlorophyll a (31.44%), chlorophyll b (20.28%) and total chlorophyll (27.66%) and shoot total soluble carbohydrates (22.53%) over control. Treatment with 0.8 mM MJ and 5 mg/L GA3 resulted in a decrease in shoot proline (48.17%), MDA (81.41%), SOD (50.59%), POD (14.81%) while increase in N (10.38%), P (15.22%), and K (8.05%) compared to control in canola under salinity stress. In conclusion, 0.8 mM MJ + 5 mg/L GA3 can improve canola growth under salinity stress. More investigations are recommended at the field level to declare 0.8 mM MJ + 5 mg/L GA3 as the best amendment for alleviating salinity stress in different crops.

Effect of Lithium Slag Application on Saline–Alkali Soil Amelioration and Vegetable Growth

Increased attention has been attracted to saline–alkali soil amelioration due to the growing serious salinization of soils in the world. Lithium slag (LS) is an acid by-product of lithium production with potential properties to ameliorate alkalinity in saline–alkali soils. In this study, LS was reused as a saline–alkali soil amendment and potted plant experiments in a greenhouse were performed to evaluate the effect of LS application on the soil amelioration and the growth of vegetables (roquette and radish) in the saline–alkali soil during the 5-week growth period. LS was added at the amount of 0.5%, 1.0%, 2.0%, 5.0%, 8.0% and 10.0% (w/w) levels. Results showed that saline–alkali soil pH dropped obviously with the increase in LS application. Accordingly, the germination, survival and growth of roquette and radish were significantly improved by LS addition, especially at the optimum amount of 0.5% and 1.0% (w/w) in the saline–alkali soil. In contrast to the untreated saline–alkali soil, LS addition at 0.5% and 1.0% (w/w) levels increased the roquette’s height by 49.7% and 36.1% and increased the radish’s height by 54.6% and 53.7%, respectively. However, the soil electrical conductivity (EC) and soluble salt content increased with the addition of LS, and the salt stress induced by excessive LS (over 5.0% level) could inhibit the growth of plants. This study proposes a new way for the effective application of LS in the amelioration of saline–alkali soil in order to realize environment and resource sustainability.

Brine formation in cold desert, shallow groundwater systems: Antarctic Ca-Cl brine chemistry controlled by cation exchange, microclimate, and organic matter

Groundwater in the McMurdo Dry Valleys of Antarctica is commonly enriched in calcium and chloride, in contrast to surface and groundwater in temperate regions, where calcium chemistry is largely controlled by the dissolution of carbonates and sulfates. These Antarctic Ca-Cl brines have extremely low freezing points, which leads to moist soil conditions that persist unfrozen and resist evaporation, even in cold, arid conditions. Several hypotheses exist to explain these unusual excess-calcium solutions, including salt deliquescence and differential salt mobility and cation exchange. Although the cation exchange mechanism was shown to explain the chemistry of pore waters in permafrost cores from several meters depth, it has not been evaluated for near-surface groundwater and wetland features (water tracks) in which excess-calcium pore-water solutions are common. Here, we use soluble salt and exchangeable cation concentrations to determine whether excess calcium is present in water-track brines and if cation exchange could be responsible for calcium enrichment in these cold desert groundwaters. We show that calcium enrichment by cation exchange is not occurring universally across the McMurdo Dry Valleys. Instead, evidence of the present-day formation of Ca-Cl−rich brines by cation exchange is focused in a geographically specific location in Taylor Valley, with hydrological position, microclimate, soil depth, and organic matter influencing the spatial extent of cation exchange reactions. Up-valley sites may be too cold and dry for widespread exchange, and warm and wet coastal sites are interpreted to host sediments whose exchange reactions have already gone to completion. We argue that exchangeable cation ratios can be used as a signature of past freeze-concentration of brines and exchange reactions, and thus could be considered a geochemical proxy for past groundwater presence in planetary permafrost settings. Correlations between water-track organic matter, fine sediment concentration, and cation exchange capacity suggest that water tracks may be sites of enhanced biogeochemical cycling in cold desert soils and serve as a model for predicting how active layers in the Antarctic will participate in biogeochemical cycling during periods of future thaw.

Ecophysiological response of Populus alba L. to multiple stress factors during the revitalisation of coal fly ash lagoons at different stages of weathering.

The enormous quantities of fly ash (FA) produced by thermal power plants is a global problem and safe, sustainable approaches to reduce the amount and its toxic effects are still being sought. Vegetation cover comprising long-living species can help reduce FA dump-related environmental health issues. However, the synergistic effect of multiple abiotic factors, like drought, low organic matter content, a deficit of essential nutrients, alkaline pH, and phytotoxicity due to high potentially toxic element (PTE) and soluble salt content, limits the number of species that can grow under such stressful conditions. Thus, we hypothesised that Populus alba L., which spontaneously colonised two FA disposal lagoons at the 'Nikola Tesla A' thermal power plant (Obrenovac, Serbia) 3 years (L3) and 11 years (L11) ago, has high restoration potential thanks to its stress tolerance. We analysed the basic physical and chemical properties of FA at different weathering stages, while the ecophysiological response of P. alba to multiple stresses was determined through biological indicators [the bioconcentration factor (BCF) and translocation factor (TF) for PTEs (As, B, Cr, Cu, Mn, Ni, Se, and Zn)] and by measuring the following parameters: photosynthetic efficiency and chlorophyll concentration, non-enzymatic antioxidant defence (carotenoids, anthocyanins, and phenols), oxidative stress (malondialdehyde (MDA) concentrations), and total antioxidant capacity (IC50) to neutralise DPPH free radical activity. Unlike at L3, toxic As, B, and Zn concentrations in leaves induced oxidative stress in P. alba at L11, shown by the higher MDA levels, lower vitality, and reduced synthesis of chlorophyll, carotenoids, and total antioxidant activity, suggesting its stress tolerance decreases with long-term exposure to adverse abiotic factors. Although P. alba is a fast-growing species with good metal accumulation ability and high stress tolerance, it has poor stabilisation potential for substrates with high As and B concentrations, making it highly unsuitable for revitalising such habitats.

Examining the Purification Effect of Euryale Ferox On Eutrophic Rivers Along the Huaihe River

We conducted a comprehensive analysis to assess the purification effect of Euryale ferox, a native aquatic plant, on eutrophic rivers in rural areas along the Huaihe River. This involved simulating variations in the total nitrogen (TN), ammonia nitrogen (NH4+-N), total phosphorus (TP), chemical oxygen demand (CODCr), pH, soluble salt content (SSC), and dissolved oxygen (DO) within the eutrophic river pool. Euryale ferox was cultivated in a eutrophic river pool within rural areas along the Huaihe River. Subsequently, an extensive analysis was conducted to assess the purification effects of Euryale ferox on river ecosystems. The results indicated that Euryale ferox, an indigenous aquatic plant in the Huaihe River, exerted a beneficial purifying influence on eutrophic rivers. This plant demonstrated a robust capacity to absorb NH4+-N and TP, ranging from 95.53% to 98.45% and 99.50% to 99.65%, respectively, in the water body during its growth, thereby achieving excellent purification performance. However, the purification of Euryale ferox for TN and CODCr in eutrophic rivers remains unclear. Notably, the pH in the aquatic environment demonstrated a noteworthy increase from 11.05% to 11.61%, while the EC value increased from 21.12% to 22%. Additionally, the DO levels exhibited a substantial increase, ranging from 3.82 to 21.77 times. It is essential to acknowledge that rural rivers are subject to various influences, including river velocity, submerged vegetation, aquatic fauna, and human activities. Further observation of practical applications is vital to comprehensively understand the implications of these findings.

Роль биомелиорантов в снижении электропроводности и засоленности почв

This study aimed to evaluate the impact of biomeliorants on soil electrical conductivity and salinity under the arid conditions of the Syrian Arab Republic. Field experiments were conducted using compost, biopreparations based on Bacillus bacteria, and their combination. Electrical conductivity was measured at four depths: 0-25 cm, 26-50 cm, 51-75 cm and 76-100 cm. The methodology included the use of graphite electrode cells and a conductometer calibrated with standard potassium chloride (KCl) solutions. Soil samples were collected from various depths, dried at 105°C, sieved through a 2 mm sieve, mixed with distilled water in a 1:2 ratio, stirred, and left for 24 hours. Three measurements of electrical conductivity were then taken for each sample. The results showed a significant reduction in soil electrical conductivity with the application of biomeliоrants particularly at the 0-25 cm depth. Two-factor ANOVA and Tukey’s test confirmed statistically significant differences between the experimental treatments. The combination of compost and biopreparations demonstrated the greatest effectiveness in reducing electrical conductivity. These findings indicate the high efficiency of biomeliorants in improving soil conditions and reducing salinity, which is crucial for sustainable agriculture in arid regions. The introduction of biomeliorants helped reduce the content of soluble salts and improve soil structure, ultimately leading to increased crop yields.

Characteristics of anion and cation in rhizosphere soil of saline grassland in North China under different nitrogen addition levels

We investigated the effects and mechanisms of nitrogen additions (0, 1, 2, 4, 8, 16, 24, 32 g N·m-2·a-1) on contents of anion and cation in rhizosphere soil, bulk soil, and mixed rhizosphere and bulk soil in the heavily salinized grassland in the agro-pastoral ecotone of North China. The results showed that pH of rhizosphere, mixed and bulk soils decreased significantly with the increases of nitrogen addition levels. Moreover, pH of three soil types under the 32 g N·m-2·a-1 treatment decreased by 1.2, 0.9, and 0.6, respectively, while pH of rhizosphere soil decreased by 0.44 compared with the bulk soil. Na+ content of rhizosphere, mixed and bulk soils significantly decreased, while the NO3- content significantly increased. The proportion of Na+ content in total soluble salt content in rhizosphere soil decreased by 14% and that in bulk soil decreased by 12% after the 32 g N·m-2·a-1 addition. NO3- content increased by 29% in rhizosphere soil and by 26% in bulk soil. There was significant negative correlation between pH and NO3- content, and significant positive correlation between pH and Na+ content. The total soluble salt content of rhizosphere soil under the 32 g N·m-2·a-1 treatment was significantly reduced by 31.5%. Collectedly, nitrogen deposition could reduce soil pH and total soluble salt content of rhizosphere soil and alleviate saline-alkali stress.

Moisturizing an analogous earthen site by ultrasonic water atomization within Han Yangling Museum, China

Dry cracking and salt enrichment are common deterioration of earthen sites being exposed to soil‒air coupled environments. The deterioration of earthen sites cannot be completely prevented by simply maintaining a high relative humidity (RH) of air environment, especially in the absence of supplemental liquid water, because of one-way migration of moisture from earthen sites to air environment. In the current work, a protection strategy of constructing a mist atmosphere over the surface of earthen sites, of which near-saturated air with micron-sized moisture droplets by an ultrasonic water atomization, was proposed to enhance the back diffusion of liquid moisture into earthen sites, and thereby inhibit the deterioration of earthen sites. The experimental moisturizing system with an ultrasonic atomization unit was built in an analogous earthen site exhibition hall in the field of Han Yangling Museum of Xi'an City, China. A series of tests were conducted to evaluate the feasibility and safety of the moisturizing system for earthen sites. The results showed that the moisture content of earthen site topsoil after moisturizing can be recovered to a level close to that prior to excavation of earthen sites, and the fractures once occurring on the surface of earthen site was effectively inhibited; The soluble salt content of earthen site topsoil was significantly reduced, and no salt damage occurred. It is anticipated that this study has a great potential for application to resist the one-way migration of moisture from earthen sites to air environment, and the salt damage and fracture of earthen sites.

Evaluating the Application Potential of Acid-Modified Cotton Straw Biochars in Alkaline Soils Based on Entropy Weight TOPSIS

As a good carbon source and soil conditioner, biochar is widely used in acidic soils but seldom in alkaline soils due to its high pH. In this study, cotton straw biochar was modified with five different acidic materials to obtain wood-vinegar- (WBC), monosodium-glutamate (MSG)-wastewater- (MBC), citric-acid- (CBC), phosphoric-acid- (PBC), and nitric-acid-modified biochars (NBC), and three dosages were used for each modifier. The pristine and modified biochars were characterized with scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. The biochar properties such as pH, specific surface area (SSA), and elemental contents were measured. In addition, the technique for order preference by similarity to ideal solution (TOPSIS) model based on entropy weight was used to evaluate the application potential of the biochars in alkaline soils. The FTIR spectra showed that modification with the five acidic materials, MSG wastewater in particular, resulted in more oxygen-containing functional groups such as O-H, C=O, and C-O on the biochar surface. In addition, acid modification greatly decreased the pH: phosphoric acid modification significantly decreased the pH of cotton straw biochar by 5.71–7.88 units. For the same modifier, a higher dosage (i.e., a smaller biochar:modifier ratio) led to a larger decrease in the pH of cotton straw biochar. The magnitudes of increase in total soluble salt content followed the general order of CBCs > PBCs > WBCs > NBCs > MBCs. The SSA, average pore diameter, and total pore volume of biochar were changed as well. Modification using wood vinegar and MSG wastewater significantly decreased the SSA of cotton straw biochar by 15.58–16.24 m2 g−1 (82.7–86.2%) and 15.87–16.80 m2 g−1 (84.2–89.2%), respectively, whereas modification using citric acid and nitric acid significantly increased the SSA of cotton straw biochar by 4.51–4.66 m2 g−1 (23.9–24.7%) and 0.55–54.21 m2 g−1 (2.9–287.7%). The evaluation based on entropy weight TOPSIS model suggested that the MBCs have the highest potential for application in alkaline soils. This study presents a theoretical basis for evaluation of biochar application potential, demonstrates a way of improving biochar application potential, and provides a support for beneficial utilization of agricultural and industrial wastes such as cotton straw, wood vinegar, and MSG wastewater.

Desalination of Hamipterus tianshanensis fossil by electrokinetic method: evaluation for treatment of clay-rich sandstone

The fossils of Hamipterus tianshanensis (Wang et al. in Curr Biol 24:1323–1330, 2014) and their eggs have important scientific significance because they can provide unique information about the reproduction, development, and evolution of pterosaurs. The fossils and the rock surrounding them have, however, been weathered, which including powdering and flaking, since they were relocated from Xinjiang to Beijing. The high content of soluble salts is a significant factor in fossil deterioration because the dissolution–recrystallization process can generate tremendous pressure and lead to decreased mechanical strength. This study evaluated the electrokinetic desalination performance for the fossils, and two types of poultices employed including paper pulp from Bioline® and CKS121 (cellulose: kaolin: sand = 1:2:1, w/w). Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), ion chromatography (IC), and other methods were applied to evaluate the desalination effect. The surface salt content reduction by applied direct current (DC) was about 70%, and the inner salt content reduction was about 80%. The experimental results suggest that the electrokinetic method is a promising way to desalinate fossils. Nonetheless, cracks appeared in the surrounding rock crack after electrokinetic desalination, which can be explained by the montmorillonite swelling-induced stresses. Pre-consolidation, especially for electro-chemical method may solve the cracking problem for the clay-rich sandstone desalination.