Determining the soil-water retention curve using mercury intrusion porosimetry test in consideration of soil volume change

It is well-known that a close link exists between soil-water retention curve(SWRC)and pore size distribution(PSD).Theoretically,mercury intrusion porosimetry(MIP)test simulates a soil drying path and the test results can be used to deduce the SWRC(termed SWRCMIP).However,SWRCMIP does not include the effect of volume change,compared with the conventional SWRC that is directly determined by suction measurement or suction control techniques.For deformable soils,there is a significant difference between conventional SWRC and SWRCMIP.In this study,drying test was carried out on a reconstituted silty soil,and the volume change,suction,and PSD were measured on samples with different water contents.The change in the deduced SWRCMIP and its relationship with the conventional SWRC were analyzed.The results showed that the volume change of soil is the main reason accounting for the difference between conventional SWRC and SWRCMIP.Based on the test results,a transformation model was then proposed for conventional SWRC and SWRCMIP,for which the soil state with no volume change is taken as a reference.Comparison between the experimental and predicted SWRCs showed that the proposed model can well consider the influence of soil volume change on its water retention property.

A low-cost bromine-fixed additive enables a high capacity retention zinc-bromine batteries

In recent years,more and more efforts are devoting to clean energy,renewable energies in particular to achieving net zero carbon dioxide emissions[1].However,renewable energies,like solar power and wind power,are generally intermittent and random,hindering their wide application[2,3].To address this problem,there is an urgent need in effective and reliable energy storage device.

Influence of Dry Density on Soil-Water Retention Curve of Unsaturated Soils and Its Mechanism Based on Mercury Intrusion Porosimetry

The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller interconnected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens.

Effect of temperature on soil-water characteristics and hysteresis of compacted Gaomiaozi bentonite

Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively. The effect of temperature on the soil-water characteristics of the highly-compacted GMZ bentonite was analyzed. The results show that the water retention capacity of the highly-compacted GMZ bentonite decreases as the temperature increases under unconfined and confined conditions. At a certain temperature,the constraint conditions have little influence on the water retention capacity of the compacted bentonite at high suction,but the water retention capacity of the confined specimen is lower than that of the unconfined specimen at low suction. Under unconfined conditions,the hysteretic behaviour of the compacted bentonite decreases with increasing temperature. At high suction(>4 MPa) ,the hysteretic behaviour of the unconfined bentonite tends to increase with the decrease of the suction. In summary,the hysteretic behaviour of the compacted bentonite is not significant.

Soil-water characteristics of Gaomiaozi bentonite by vapour equilibrium technique

Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states is obtained in drying and wetting process.At high suctions,the hysteresis behaviour is not obvious in relationship between water content and suction,while the opposite holds between degree of saturation and suction.The suction variation can change its water retention behaviour and void ratio.Moreover,changes of void ratio can bring about changes in degree of saturation.Therefore,the total change in degree of saturation includes changes caused by suction and that by void ratio.In the space of degree of saturation and suction,the SWRC at constant void ratio shifts to the direction of higher suctions with decreasing void ratio.However,the relationship between water content and suction is less affected by changes of void ratio.The degree of saturation decreases approximately linearly with increasing void ratio at a constant suction.Moreover,the slope of the line decreases with increasing suction and they show an approximately linear relationship in semi-logarithmical scale.From this linear relationship,the variation of degree of saturation caused by the change in void ratio can be obtained.Correspondingly,SWRC at a constant void ratio can be determined from SWRC at different void ratios.

Dust Retention Ability of Plants as a Factor Improving Environment Air

It is well known that air in industrial cities contains a significant amount of dust particles, smoke, and toxic gases. The increased number of vehicles has a direct impact on air quality resulting in the emission of exhaust gases, and the increase of dust concentration in air. In this article, we are describing the dust retention ability of plants depending on their leaf structure. Plant species were classified into three groups according to their dust-holding capacities. Dust retaining ability of plant species in conditions of high, average and low dust conditions described.

QSRR Study on the Relationship between the Chromatographic Capacity Factor and Lipophilicity and Structure Parameters of Halogenated Thiophenols

The capacity factors （k＇） of fourteen types ofhalogenated thiophenols in different phases of methanol-water eluent were determined by reversed phased high-performance liquid chromatography （RP-HPLC） and the relationships between the logarithm of capacity factor lgK＇ and methanol ratio ψ were analyzed. A fair linear relationship is found between lgK＇ and ψ, and the correlation coefficients R2 of the constructed linear equations are all greater than 0.990. Relationship between the chromatographic data lgKw＇ when extrapolated to pure water and n-octanol/water partition coefficient lgKow obtained by the group contribution method has shown a good linear correlation with R2= 0.956. The structure parameters of fourteen halogenated thiophenols were calculated by using DFT, and the correlation equation of lgKw＇ and structure parameters was obtained by using SPSS, lgKw＇ = -0.409 ＋ 0.039a and R2 = 0.981, meaning that lgKw＇ is mainly determined by the polarizability α.

Decrease in Cation Exchange Capacity of Zeolites at Neutral pH: Examples and Proposals of a Determination Method

Cation exchange capacity (CEC) is an important characteristic of zeolites, especially when they are used as adsorbents in the aqueous system. However, no international standard method exists for the determination of CEC of zeolites. We determined CEC of Linde-type A and Na-P1 type zeolites at various pH (4 to 10) with a simple method, where Na+-saturated zeolites were prepared, and then various amounts of HCl were added. CEC was simply calculated by subtracting the amount of Na+ in the final supernatant from the content of Na+ of the Na+-saturated zeolites. CEC of the zeolites decreased with decreasing pH and with decreasing Na+ concentration of the final supernatant. The concentration of Na+ of the supernatant, CEC of the zeolites began to decrease at weakly alkaline or neutral pH, and that of the Linde-type A zeolite became about half at pH around 6. When CEC was plotted against pH-pNa;where pNa is negative logarithm of the activity of Na+;CEC of each zeolite was expressed by a curve. It indicates that the CEC or the amount of Na+ retention is univocally determined by the ratio of activities of Na+ and proton.

Correlation between Chromatograph Capacity Factors and Structural Parameters of Indole Derivatives

Sixteen indole derivatives have been computed at B3LYP/6-31 IG^＊＊ level using density functional theory （DFF）. Based on linear solvation energy theory, the structural parameters were employed to present correlation between the parameters of chromatograph capacity factor （CCF） and molecular structural parameters. As a result, the correlation equation of the reversed phased high performance liquid chromatograph capacity factor to the intercept lgk＇w and slope S of CCF were obtained, from which the correlation coefficients of lgk＇w to the structural parameters are r^2 = 0.9596 and q^2 = 0.9262. While the correlation coefficients of the parameter S r^2 q^2 with structures are = 0.9750 and = 0.9252. Moreover, the effect of water as solvent on the present two models was also considered using SCRF method, and the result shows that the predicting capacity of correlation equation of lgkw＇ increases, while that of the model for S decreases slightly. Both two correlation equations achieved in this work are more advantageous than those using theoretical descriptors from molecular connectivity indices.

Pedoecological Regularities of Organic Carbon Retention in Estonian Mineral Soils

Soil organic carbon (SOC) retaining capacities of epipedon (EP), subsoil (SS) and soil cover (SC) as a whole, are soil type specific. Depending on individual and sites characteristics, the generalized humus status indices of soil types (EP and SC thickness and SOC stocks) may vary. Land use and land use change primarily influence the properties and fabric of the EP, but the humus status (SOC concentration and stock, fabric of horizons) of the SS remains practically unchangeable. The mean mineral soils SOC stocks, EP quality and SOC distribution in soil profiles depend mainly on the water regime, mineral composition (texture, calcareousness), development of eluvial processes and the land use peculiarities of soils. The mean area weighted SC SOC stock of Estonian mineral soils is 99.9 Mg ha–1, thereby the mean hydromorphic soils SOC retention capacity considerably exceeds the SOC retention capacity of automorphic soils (means are accordingly 127.5 and 78.9 Mg ha–1). The sustainable management of SOC is based on adequate information about actual SOC stocks and theoretically established or optimal humus status levels of soil types. The aggregate of SOC retained in the mineral soils of Estonia (3,235,100 ha) amounts to 323 ± 46 Tg (1 Tg = 1012 g). Approximately 42% of this is sequestered into stabilized humus, 40% into instable raw-humous material and 18% into forest (grassland) floor and shallow peat layers.

黑鱼片复配水分保持剂配方优化

为得到一种复配水分保持剂以降低磷酸盐用量并提高持水性,以黑鱼为对象,通过单因素试验探究不同浓度的三聚磷酸钠、焦磷酸钠、碳酸钠和柠檬酸对鱼片的增重率、解冻及熟化损失率和感官的影响。在此基础上,采用响应面法对各因素进行优化。结果表明,三聚磷酸钠浓度、焦磷酸钠浓度、碳酸钠浓度和柠檬酸浓度均对黑鱼片的品质影响显著。最佳条件为三聚磷酸钠浓度1.3%、焦磷酸钠浓度1%、碳酸钠浓度0.7%、柠檬酸浓度0.5%。在此条件下,增重率、解冻损失率、熟化损失率及感官评分分别为56.01%、3.93%、11.37%和7.6,具有磷酸盐较低、增重率较高、解冻和熟化损失率较低的优点。研究表明,该复配水分保持剂可提高黑鱼片持水性、降低磷酸盐用量。

Preparation of carbon-based material with high water absorption capacity and its effect on the water retention characteristics of sandy soil

Biochar has the potential to provide a multitude of benefits when used in soil remediation and increasing soil organic matter enrichment.Nevertheless,the intricated,hydrophobic pores and groups weaken its water-holding capacity in dry,sandy soils in arid lands.In order to combat this issue,starch-carbon-based material(SB),sodium alginate-carbon-based material(SAB),and chitosan-carbon-based material(CB)have been successfully synthesized through the graft-polymerization of biochar(BC).A series of soil column simulations were used to scrutinize the microstructure of the carbon-based material and explore its water absorption properties and its effects on sandy soil water infiltration,water retention,and aggregation.The results indicated that SB,SAB,and CB achieved water maximum absorption rates of 155,188,and 172 g g^(−1),respectively.Considering their impact on sandy soils,SB,SAB,and CB lengthened infiltration times by 1920,3330,and 3880 min,respectively,whilst enhancing the water retention capabilities of the soil by 18%,25%,and 23%in comparison to solely adding BC.The utilization of these innovative materials notably encouraged the formation of sandy soil aggregates ranging from 2.0 to 0.25 mm,endowing the aggregates with enhanced structural stability.Findings from potting experiments suggested that all three carbonbased materials were conducive to the growth of soybean seeds.Thus,it is evident that the carbon-based materials have been fabricated with success,and they have great potential not only to significantly augment the water retention capacities and structural robustness of sandy soils in arid areas,but also to bolster the development of soil aggregates and crop growth.These materials possess significant application potential for enhancing the quality of sandy soils in arid and semi-arid regions.

Methods and mechanisms for enhancing the water retention properties of Jiuzhaigou disintegrated rubble soils

Rubble deposits with a high concentration of rock debris were created after the powerful earthquakes in Jiuzhaigou.Because of the restricted soil resources,water leaks,and nutrient deficits,these deposits pose serious obstacles for vegetation regeneration.The purpose of this study was to investigate the main mechanisms controlling soil water retention and evaluate the effects of different amendments on the hydraulic characteristics and water-holding capacity of collapsed rubble soils.Finegrained soil,forest humus,crushed straw,and organic components that retain water were added to the altered soils to study the pore structure images and soil-water characteristic curves.Comparing understory humus to other supplements,the results showed a considerable increase in the soil's saturated and wilting water content.The saturated water content and wilting water content rose by 17.9%and 4.3%,respectively,when the percentage of understory soil reached 30%.Additionally,the enhanced soil's microporosity and total pore volume increased by 45.33%and 11.27%,respectively,according to nuclear magnetic imaging.It was shown that while clay particles and organic matter improved the soil's ability to adsorb water,they also increased the soil's total capacity to store water.Fine particulate matter did this by decreasing macropores and increasing capillary pores.These results offer an essential starting point for creating strategies for soil repair that would encourage the restoration of plants on slopes that have been damaged.

泰乐菌素在黄土中的吸附持留能力及影响因素研究

兽药抗生素(Veterinary antibiotics,VAs)通过多种途径进入土壤,极易对土壤及地下水环境带来严重危害。探究VAs在土壤中的吸附过程,对于深入了解土壤环境中VAs的污染与防控具有重要意义。选取兽药泰乐菌素(Tylosin,TYL)为目标污染物,采用批平衡实验法探讨其在3种不同类型黄土(灰钙土、棕黄土和黄绵土)中的吸附/解吸特性以及关键环境因素(温度、初始浓度、pH、离子强度等)对TYL吸附持留的影响,并结合动力学、热力学模型探究其作用机制。结果表明:TYL在3种黄土中的吸附平衡时间均在120 min内,吸附动力学过程符合准二级动力学模型(R^(2)>0.995),吸附热力学过程可以用Freundlich等温吸附模型描述(R^(2)>0.985),表明黄土有机质疏水分配和阳离子交换作用对TYL的吸附过程起到关键作用,土壤黏粒含量和pH也有一定影响。此外,解吸实验结果显示,解吸滞后系数(HI)在0.270~0.573之间,且解吸量始终大于50%,表明TYL吸附的不可逆性较低,在土壤中表现出的滞后现象不明显,容易解吸,会对地下水环境造成潜在威胁。随TYL初始浓度的增加,其在3种黄土中的吸附平衡时间延长,吸附容量也随之增大。吸附体系为酸性时有助于土壤对TYL的吸附;吸附体系为碱性时,灰钙土、棕黄土和黄绵土由于静电引力减弱,导致其对TYL的吸附量分别由0.264、0.341、0.289 mg/g显著降至0.105、0.077、0.078 mg/g。相对于K^(+)、NH_(4)^(+),高价态离子(如Ca^(2+)、Mg^(2+))及浓度较高离子的存在对TYL的吸附有明显抑制作用。研究显示,黄土对TYL的吸附主要与土壤有机质含量和阳离子交换容量有关,其主要吸附机制是阳离子交换作用和疏水作用。

设施土壤磷素固持材料的选择与应用研究进展

我国设施土壤磷素高量积累继而流失是造成相邻水体富营养化的一个重要原因。施用磷素固持材料是有效减少土壤磷流失的措施之一,本文对比分析了室内条件下几类磷素固持材料(黏土矿物类、铁铝类、钙镁类和其他类)对磷酸盐的吸附量和吸附机制,总结了设施土壤中添加磷素固持材料对土壤有效磷含量、磷形态和磷素淋洗量的影响。基于材料的易获取性、安全性、价格以及被固持磷素的再利用性,提出了不同土壤中适宜施用的磷素固持材料。结果表明,添加磷素固持材料能通过物理、化学等作用吸附土壤磷,降低磷移动性。一般而言,铁铝类、钙镁类材料的磷素吸附量和吸附键能高于黏土矿物类,而改性生物炭材料的磷吸附量和强度常取决于改性物质。施入土壤后,铁铝类、钙镁类材料能快速降低土壤磷活性,进而减少磷的移动和流失,然而过量施用铁铝类材料可能影响作物正常生长及其对磷的吸收,适宜钙镁比的材料不仅能固持土壤磷,而且不影响作物对磷素的吸收利用。因此,在磷含量极高的设施石灰性土壤上,推荐适量施用铁铝类材料;在酸性土壤上,建议施用适宜钙镁比的材料,固持土壤磷并保持磷的有效性;黏土类材料则在磷含量适中的土壤上较为适用。此外,利用废弃物作为磷素固持材料,可在减少土壤磷流失的同时实现废弃物资源化利用,具有较好的应用前景。

钴酸锂电池低温特性和针刺安全性能研究

以低温下工作的钴酸锂(LCO)电池为研究对象,通过实验研究其在低温下的特性和热失控温度变化情况。首先,通过不同温度下的容量测试,对比了-30℃时三元锂离子电池与LCO电池的容量保持率,结果表明,LCO电池在-30℃低温放电容量保持率几乎达到三元锂离子电池的2倍;其次,利用混合功率脉冲特性测试得到了不同温度下电池的内阻;接着,对低温下LCO电池电化学阻抗进行测试,结果表明,-10,-20,-30℃时的电荷转移阻抗较0℃时分别增加了180%,702%,2 400%;最后,对LCO进行针刺热失控实验,结果表明,钢针刺破电池背面后,电池表面最高温度不超过530℃,伴有少量火星,很快产生大量烟雾,并没有发生着火的现象。

亚热带树种在未成林造林地的凋落物量和周转与叶片性状的关系

【目的】测定亚热带树种的叶片功能性状、凋落叶质量、凋落物量和周转期,揭示叶片性状对凋落物量和周转的影响,为杉木采伐后如何选择造林树种以改善土壤肥力提供科学依据。【方法】选取在二代杉木林采伐迹地营造的17种亚热带树种,测定其在3年生未成林造林地的凋落物量和周转期,同时测定各树种的叶片功能性状(比叶面积、干物质含量、氮含量等)和凋落叶质量(碳氮比、单宁含量、可溶性糖含量等),建立叶片性状与凋落物量和周转期的回归关系。【结果】17种树种中,米老排凋落物量最高(6.67 t·hm^(-2)a^(-1)),杉木凋落物量最低(0 t·hm^(-2)a^(-1));江南桤木凋落叶周转期最短(0.09年);深山含笑凋落叶周转期最长(1.09年)。凋落物量随比叶面积增加而增加,随叶氮含量增加而降低;凋落叶周转期随凋落叶碳氮比和单宁含量增加而增加,随凋落叶最大持水率增加而降低。【结论】在亚热带未成林造林地中,凋落物量受比叶面积和叶氮含量的影响,凋落叶周转期受凋落叶碳氮比、单宁含量和最大持水率的影响;杉木在未成林造林地阶段的凋落物归还量极少。经营亚热带人工林时,要考虑种植比叶面积和凋落叶最大持水能力较高、凋落叶单宁含量和碳氮比较低的树种,以提高林地凋落物归还量和周转速率,改善退化人工林的土壤肥力。

河北省某钼尾矿土壤化改良及种植实验研究

以河北省某钼尾矿为研究对象,采用低成本添加剂与机械混合方法对钼尾矿进行土壤化改良。针对钼尾矿的保水性、酸碱性及阳离子交换能力,开展了单因素改良实验及复合改良实验。结果表明,利用农家肥、蒙脱土、聚丙烯酰胺及柠檬酸复合改良剂对钼尾矿进行改良,钼尾矿的饱和吸水率提高至61.1%,水分挥发速率和渗滤速率明显降低;阳离子交换能力达到了10.15 cmol/kg,pH值降低至8.08,达到了适宜种植的水平。此外,通过盆栽实验验证了复合改良后钼尾矿的植物生长效应,与原始钼尾矿相比,复合改良后钼尾矿中的小白菜生长状态良好,植株的高度和质量分别提高了77.4%和98.1%。经过15 d的小白菜种植后,改良钼尾矿的保水性、pH值及阳离子交换能力达到了正常土壤的水平,实现了钼尾矿向可种植土壤的转化。

抗冻剂与浸渍冷冻协同处理对调理牛排冻藏期品质的影响

为阐明抗冻剂与浸渍冷冻协同处理对调理牛排冻藏品质的影响,以牛肉为原料,添加调味料或辅料,经加工制成调理牛排。调理牛排样品采用空气冻结、抗冻剂、浸渍冻结和抗冻剂与浸渍冻结联合处理进行冷冻处理。将牛排置于-30℃冰柜冻藏90 d,分别在0、30、60、90 d测定解冻损失率、汁液损失率、蒸煮损失率、质构特性、剪切力、色泽和硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARS)值及观察牛排微观结构。结果表明:与其他处理组相比,抗冻剂与浸渍冻结联合处理组的调理牛排解冻损失率、汁液损失率、蒸煮损失率均明显降低,且TBARS值也明显低于其他处理组;此外,该处理组调理牛排的亮度值和红度值较高,组织结构中肌纤维排列整齐、最紧密。综上,采用抗冻剂与浸渍冻结联合处理调理牛排不仅能促使其组织结构紧密以保持较好的保水性,而且可保持其肉色稳定。

聚丙烯酸钠/桑黄菌段复合高吸水树脂的制备及溶胀性能研究

采用微波辐射加热引发合成聚丙烯酸钠/桑黄菌段复合高吸水树脂(PISSR)。采用单因素试验研究变量配比方案,优化制备工艺,通过傅里叶变换红外光谱、热重分析仪、扫描电子显微镜及能谱对材料进行表征。结果表明,在桑黄菌段、引发剂、交联剂用量分别为丙烯酸的20%、0.60%、0.15%,丙烯酸中和度为85%、微波功率为500 W时,PISSR吸液倍率最大,在蒸馏水中为652.6 g/g,0.9%NaCl溶液中为61.1 g/g;离子类型和电解质浓度是影响PISSR吸液性能的重要因素;PISSR表面粗糙多孔,富含Na、K、Ca元素,同时具有良好的保水性能以及再溶胀性能。