导电滑环热真空试验污染物抑制方法试验研究

针对目前航天器导电滑环热真空试验时可凝挥发物VCM抑制的控制需求,根据低温吸附原理,在传统热真空设备温度控制系统基础上,加装独立控温功能的低温冷屏,并开展VCM吸附能力验证试验,对比分析改造前后微量可凝挥发物总量,改造后真空容器内的VCM量减少约1_～2个数量级,说明冷屏对污染物有良好的抑制效果。     

A spatially explicit empirical model of structural development processes in natural forests based on climate and topography

Stand structure develops with stand age. Old-growth forests with well-developed stand structure support many species. However, development rates of stand structure likely vary with climate and topography. We modeled structural development of 4 key stand variables and a composite old-growth index as functions of climatic and topographic covariates. We used a hierarchical Bayesian method for analysis of extensive snap-shot National Forest Inventory (NFI) data in Japan (n = 9244) to account for differences in stand age. Development rates of structural variables and the old-growth index exhibited curvilinear responses to environmental covariates. Flat sites were characterized by high rates of structural development. Approximately 150 years were generally required to attain high values (approximately 0.8) of the old-growth index. However, the predicted age to achieve specific values varied depending on environmental conditions. Spatial predictions highlighted regional variation in potential structural development rates. For example, sometimes there were differences of >100 years among sites, even in the same catchment, in attainment of a medium index value (0.5) after timber harvesting. The NFI data suggested that natural forests, especially old natural forests (>150 years), remain generally on unproductive ridges, steep slopes, or areas with low temperature and deep snow, where many structural variables show slow development rates. We suggest that maintenance and restoration of old natural forests on flat sites should be prioritized for conservation due to the likely rapid development of stand structure, although remaining natural forests on low-productivity sites are still important and should be protected.     

膨润土强化畜禽粪便厌氧消化生产甲烷的探究

为探究膨润土(Be)对畜禽粪便厌氧消化性能的影响,(30±1)℃下进行Be强化畜禽粪便厌氧消化生产甲烷实验,并分析微生物结构。结果表明:(1)适量的Be能提高畜禽粪便产甲烷效率;提高溶解性有机碳(DOC),为后续酸化、产甲烷提供充足的基质;促进挥发性脂肪酸含量升高,为产甲烷古菌提供底料。当Be为3.0%(质量分数)时,甲烷日产量最高至268.5mL/d,第40天单位质量挥发性悬浮固体(VSS)的甲烷累积产量为(289.3±9.2)mL/g,DOC最大值为(5 985±142)mg/L,溶解性蛋白质为(3 015±118)mg/L,多糖最大值为(1 061±56)mg/L,乙酸在前10天急剧升高至(385±10)mg/L,戊酸最大值为(124±9)mg/L,VSS减量率为31.2%±1.3%。(2)Be的存在有利于提高厚壁菌门(Firmicutes)相对丰度,当Be为3.0%时,厚壁菌门相对丰度为61.2%。     

燃用蔗髓锅炉的硫平衡及二氧化硫排放分析

通过现场监测和调研数据,分析燃用蔗髓锅炉的硫平衡及SO 2排放情况。结果显示,烟气排放的SO 2主要来源于鲜蔗和回用洗布水中含有的硫。8个锅炉硫排放在线监测均值与手工监测均值相对偏差为3.76%~14.9%,表明结果一致性较好。蔗髓硫质量分数为0.01%~0.04%,蔗髓含硫折算后的SO 2值和在线监测SO 2值分别为22.1 mg/m 3~49.9 mg/m 3和43.9 mg/m 3~114.5 mg/m 3,说明鲜蔗和制糖工艺流程的共同影响使得燃用蔗髓锅炉排放烟气SO 2值偏高。     

基于局部强度阶梯折减法的边坡渐进破坏研究∗

通过强度折减法获取边坡的潜在滑裂带是目前数值计算广泛使用的方法,研究边坡滑裂带形成的渐进过程及坡体内部土体的应力状态具有重要的理论意义和工程价值。基于边坡破坏的渐进性思想,针对均质边坡提出了一种局部强度阶梯折减的方法。该方法以屈服接近度(YAI)作为判别土体是否存在破损区的评价标准,将局部破损区按不同破损次序分配予不同的折减系数,利用通用软件ABAQUS对局部坡体进行强度折减计算,研究边坡渐进变形过程,直至边坡发生整体破坏。计算结果表明,坡体内部初始破损区参与了潜在滑裂面的形成过程,对边坡后期渐进变形具有贡献;有效解决了传统强度折减法潜在滑裂面上折减区和非折减区边界处的塑性应变值的跳跃性问题,合理地演化了边坡的渐进失稳进程。     

“十四五”时期危险废物污染防治思路探讨

"十三五"时期,我国环境质量改善和生态文明建设取得显著进展,"十四五"时期生态环境保护面临的形势和任务仍然严峻艰巨,亟须正确识别当前的环境形势以及未来的重大环境问题,制定针对性的规划。本文概述了"十三五"期间我国危险废物污染防治取得的进展和成效,并分析了当前危险废物环境风险防控面临的废物产生量大且持续增加、环境风险高、利用处置短板凸显、综合利用风险防控不足等突出问题,从制度优化、科学管理和技术支撑等重点任务、重大工程方面,提出"十四五"环境保护危险废物污染防治规划思路,为编制"十四五"危险废物污染防治规划提供参考。     

土壤对三氯乙烯的吸附行为及其影响因素

基于静态吸附实验对土壤吸附三氯乙烯的影响因素进行研究,通过利用有机质含量为0.96%的土样及经375℃、600℃、次氯酸钠和联合氧化方法(600℃+次氯酸钠)处理后的土样为吸附剂,考察了各种土样吸附TCE的吸附动力学和吸附热力学,以及土壤中有机质含量、软碳、硬碳、矿物质、TCE初始浓度和钙离子强度对吸附作用的影响.结果表明,土壤对TCE的吸附分为快速吸附、慢速吸附和平衡3个阶段,并在30 h左右达到吸附平衡,且吸附过程符合准二级动力学方程(R~298%);Freundlich模型能较好地拟合TCE在土壤中的吸附等温曲线(R~293%);土壤对TCE的吸附以物理吸附为主,其中吸附贡献主要为硬碳(60%);TCE浓度的升高可以增加矿物质的吸附贡献率;离子强度的增加显著降低了土壤各组分对TCE的吸附.