Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil’s particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot’s surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.     

火灾条件下弹药仓库储存安全性研究

在分析火灾对弹药及仓库危害的基础上,结合我军弹药仓库的实际情况与运行规律,研究了弹药仓库火灾产生和发展的影响因素,选取典型弹药或元件进行了模拟火灾条件下弹药燃爆时限测试,得出了火灾条件下弹药仓库控火与灭火的安全时限.     

川西亚高山森林土壤有机层碳、氮、磷储量特征

同步研究了川西亚高山云杉林、冷杉林和白桦林生态系统土壤有机层(OL)和矿质层(MS)的有机碳、全氮及全磷储量特征.所有土壤剖面上的有机碳和易氧化有机碳含量均随土壤深度增加而降低,即未分解层<半分解层<完全分解层<腐殖质层<淀积层<母质层.云杉林、冷杉林和白桦林土壤有机层的有机碳储量分别为29.38(±1.28)thm-2、22.70(±1.20)thm-2和8.63(±0.95)thm-2,矿质土壤中分别为17.84(±1.92)thm-2、19.74(±1.76)thm-2和14.92(±1.64)thm-2.冷杉林和白桦林土壤剖面上的全氮和全磷含量大小顺序为半分解层<完全分解层<腐殖质层,但腐殖质层>淀积层>母质层.云杉林、冷杉林、白桦林土壤有机层的全氮储量分别为0.85(±0.11)thm-2、0.68(±0.06)thm-2和(0.36±0.03)thm-2,全磷储量分别为0.29(±0.03)thm-2、0.22(±0.03)thm-2和0.06(±0.02)thm-2.图2表2参22     

Organic carbon stock in topsoil of Jiangsu Province, China, and the recent trend of carbon sequestration

Data collection of soil organic carbon(SOC) of 154 soil series of Jiangsu, China from the second provincial soil survey and of recent changes in SOC from a number of field pilot experiments across the province were collected. Statistical analysis of SOC contents and soil properties related to organic carbon storage were performed. The provincial total topsoil SOC stock was estimated to be O. 1 Pg with an extended pool of 0.4 Pg taking soil depth of 1 m, being relatively small compared to its total land area of lOl?00 km^2. One quarter of this topsoil stock was found in the soils of the Taihu Lake region that occupied 1/6 of the provincial arable area. Paddy soils accounted for over 50% of this stock in terms of SOC distribution among the soil types in the province. Experimental data from experimental farms widely distributed in the province showed that SOC storage increased consistently over the last 20 years despite a previously reported decreasing tendency during the period between 1950--1970. The evidence indicated that agricultural management practices such as irrigation, straw return and rotation of upland crops with rice or wheat crops contributed significantly to the increase in SOC storage. The annual carbon sequestration rate in the soils was in the range of 0.3-3.5 tC/(hm^2. a), depending on cropping systems and other agricultural practices. Thus, the agricultural production in the province, despite the high input, could serve as one of the practical methods to mitigate the increasing air CO2.     

跌落条件下箱装弹药安全性的数值评估

把箱装弹药简化为二自由度系统,将包装箱及弹体等效为线弹性材料,基于Matlab数学软件,运用四阶龙格-库塔法对系统进行数值分析,分别讨论了频率比、包装箱阻尼、质量、弹性系数、保险簧弹性系数以及跌落高度对保险元件冲击响应的影响。所得结论对弹药科学储运具有指导意义。     

国外弹药贮存寿命试验与评价技术概述

简述了国外弹药贮存寿命试验所用的自然环境长期贮存试验监测法和加速寿命试验方法的现状,对国外弹药寿命评价与预测所用的活化能法、凝胶含量法、傅里叶红外光谱分析法、动态粘弹分析法进行了分析,论述了弹药贮存寿命试验与评价技术的发展趋势。     

浅谈我国上市公司资本结构特点及优化措施

我国上市公司资本结构的主要特点是偏好股权投资、流动负债比率偏高、债券比重小。要改变我国上市公司资本结构中呈现的重股轻债的状况,需采取优化股权结构、发展和完善债券市场、规范股市行为等措施,使我国上市公司的资本结构日趋合理。     

加速寿命试验技术在弹药贮存可靠性工程中的应用

阐述了加速寿命试验的基本理论;以典型的恒定应力加速寿命试验和步进应力加速寿命试验应用案例,回顾了加速寿命试验技术在弹药贮存可靠性工程中的应用状况;指出失效机理研究、数据统计分析和实验结果验证是工程应用中待优化解决的3个突出问题,展望了加速寿命试验技术在工程应用中的发展趋势。     

普鲁兰多糖基恶臭气体阻隔喷膜的制备及性能

针对存余垃圾在开挖、运输过程中释放的恶臭气体,研发一种具有阻隔功能的环保型喷膜配方。选取水溶性的高分子普鲁兰多糖作为成膜基质材料制备成喷膜溶液后,通过改变成膜基质的质量分数,添加表面活性剂、纳米功能性材料等途径进行成膜配方优化,使其在应用中快速成膜发挥阻隔作用。结果表明,质量分数为1%普鲁兰多糖、0.1%吐温80所制成的喷膜溶液,最短可在5 min内形成致密的薄膜,并且对质量浓度70 mg∙m⁻³的硫化氢 (H₂S) 和氨气 (NH₃) 的气体截留率分别达到84.73%和86.43%。在此基础上添加质量浓度0.2 mg∙L⁻¹的纳米零价铁 (nanoscale zero-valent iron, nZVI) ,喷膜溶液对相同质量浓度的H₂S气体截留率提高至91.74 %,NH₃气体截留率提高至99.08%。以上研究结果可为存余垃圾资源化利用,尤其是中途转运过程中的恶臭气体阻隔提供参考。     

Modelling the potential impacts of land use/cover change on terrestrial carbon stocks in north-west Morocco

Terrestrial ecosystems store more carbon (C) than the atmosphere and provide ecosystem services (ES) such as global climate regulation, by sequestering carbon within biomass and soil. Land use land cover (LULC) change is considered a key factor, playing an important role in the dynamic variations of carbon storage. The aim of this paper is to assess the effects that LULC has had on carbon stocks and consequently on climate change regulation in north-western Morocco over 21 years. To achieve this aim, the Integrated Valuation of ES and Trade-offs (InVEST) model is used to assess status and variation in the net amount of carbon stored by the different types of LULC, and the economic value of the carbon sequestered in the remaining stock. The results show that the total carbon stock increased from 4.81TgC in 1996 to 4.98TgC in 2017. Over the 21 years, the LULC changes had the greatest effect on carbon storage - an increase of 6.87% with 0.17TgC of carbon sequestered, since the majority of unused land was changed to forest and cultivated land. Based on the global costs of atmospheric carbon, we estimate the economic value of carbon storage services to be between US$1,800,000 and US$3,570,000 for the whole period, with an average yearly increment of between US$86,000 and US$170,000. The results show that the ecosystem management has had a substantial climate mitigation effect. Also, the possibility of paying for ES could inform policy on the adoption of LULC to support livelihood and management choices.