基于灰色理论的铁路水害危险度计算模型

在分析铁路这一特殊承灾体成灾机理和致灾因子的基础上 ,应用灰色理论和数理统计 ,对铁路环境水害危险度计算模型进行了探讨和构建。分析中 ,以新亚欧大陆桥新疆段 (以下简称为‘陆桥新疆段’) 39年 (195 9～ 1997年 )的水害资料为统计分析数据 ,以水害频次、水害密度和断道时间为铁路环境水害危险度计算和危险性评估指标 ,根据灰色关联分析原理 ,确定出危险性评估中水害密度、断道时间和水害频次的权重依次为 5 ,3,2。然后 ,基于水害密度、水害频次和断道时间 3个指标的内在联系 ,以及权重的大小 ,以沿线 3级车站之间的区段为对比分析单元 ,构建出铁路环境水害危险度计算模型为 :Pfd=dPfHec/ (dPf Hec)。最后 ,应用这一模型对陆桥新疆段水害进行了计算和对比分析 ,发现所得结果与水害实际分布情况符合得较好。     

CuZnAl形状记忆合金在井下火灾防预系统上的应用初探

应用ＣｕＺｎＡｌ形状记忆合金的感温——驱动原理,制作井下火灾防预系统装置,具有较大的实用性。探讨该系统的设计原理及方法,研究复合细化、热处理工艺对形状记忆合金的影响     

测定生产力中"叶绿泰a"的方法探讨

对测定生产力中"叶绿素a"的方法进行了探讨与改进,并进行了方法的验证.本方法的精密度范围为6.1%～8,4%,实验证明,本方法具有简单、快速、准确等特点.     

适用于低氨污水的高效氨氧化菌的分离筛选及其氨氧化特性

文章从生活污水中富集得到了一种培养物,其中的唯一自养氨氧化菌被命名为Nitrosomonas europaea SH-3。研究了亚硝氮浓度、盐度、温度和pH对其生长的影响,并探究了其在低氨污水中的脱氨效果及最大比增长速率。结果表明,该培养物的半数抑制亚硝氮浓度<500 mg/L,半数抑制盐度为0.5%～1%(以NaCl计);最适生长温度为32.2℃,最适pH为7.7。该培养物在低氨污水中的氨氮去除率能达到92.64%～100%,最大比增长速率为(2.34±0.35) d~(-1),最短代时为(7.28±1.07) h。该培养物生长迅速,对氨的亲和力高,在低氨污水中具有较高的应用价值。     

Significant coal combustion contribution to water-soluble brown carbon during winter in Xingtai, China: Optical properties and sources

To understand the characteristics of atmospheric brown carbon (BrC), daily PM_2.5 samples in Xingtai, a small city in North China Plain (NCP), during the four seasons of 2018-2019, were collected and analyzed for optical properties and chemical compositions. The light absorption at 365 nm (abs_{λ=365 nm}) displayed a strong seasonal variation with the highest value in winter (29.0±14.3 M/m), which was 3.2∼5.4-fold of that in other seasons. A strong correlation of abs_{λ=365 nm} with benzo(b)fluoranthene (BbF) was only observed in winter, indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic heating. The mass absorbing efficiency of BrC also exhibited a similar seasonal pattern, and was found to correlate linearly with the aerosol pH, suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the city. Positive matrix factorization (PMF) analysis further showed that on a yearly basis the major source for BrC was biomass burning, which accounted for 34% of the total BrC, followed by secondary formation (26.7%), coal combustion (21.3%) and fugitive dust (18%). However, the contribution from coal combustion was remarkably enhanced in winter, accounting for ∼40% of the total. Our work revealed that more efforts of “shifting coal to clean energy” are necessary in rural areas and small cities in NCP in order to further mitigate PM_2.5 pollution in China.     

海藻酸钠固定化纳米铁还原脱色活性红X3B

采用海藻酸钠固定纳米铁制备海藻酸钠纳米铁小球,研究了海藻酸钠浓度、纳米铁含量、活性红X3B浓度、反应温度、pH值等对海藻酸钠固定化纳米铁小球还原活性红X3B的影响.采用高效液相色谱（HPLC）、紫外可见分光光度计（UV-Vis）、扫描电镜（SEM）、透射电镜（TEM）等方法分析污染物的还原脱色过程.结果表明,X3B的还原脱色获得了较好的效果,当温度25.0℃,海藻酸钠浓度2.0%,纳米铁含量2.0g/L,转速200r/min,pH值10.9时,反应720min后,25.0mg/L活性红X3B的脱色率达98.9%.海藻酸钠凝胶对活性红X3B没有吸附作用,海藻酸钠固定化纳米铁小球降解活性红X3B的主要机制为纳米零价铁的还原作用.     

Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

• With the same charge, current density had little effect on As(III) removal in ACEC. • ACEC had the lowest energy consumption compared with EC/O₂ or EC/N₂. • There was a trade-off relationship between energy consumption and removal time. • The ·OH concentration in ACEC was 1.5 times of that in the EC/O₂ system. Naturally occurring arsenic enrichment in groundwater poses a huge threat to human health. Air cathode electrocoagulation (ACEC) has recently been proposed to enhance As(III) oxidation and lower energy consumption. In this study, ACEC, EC/O₂ and EC/N₂ were evaluated with different current densities from 1 to 8 mA/cm² to investigate the effect on As(III) removal in different redox environments. Current density had no appreciable effect on arsenic removal efficiency given the same charge in ACEC because the concentration ratio of Fe/H₂O₂ under different current densities remained stable. However, in EC/O₂ and EC/N₂, As(III) removal was inhibited at higher current densities (4–8 mA/cm²), likely because more Fe(II) competed with As(III) for the oxidant, leading to less effective oxidation of As(III). In all EC systems, the ·OH units generated per power consumption reached the highest value at the lowest current density. Compared with other EC systems, the ACEC system showed lower energy consumption at all current densities due to the low energy consumption of the electrode reaction and more free radical generation. A lower current density saved more energy at the expense of time, showing the trade-off relationship between energy consumption and removal time. The operation costs for As(III) removal under optimal conditions were calculated as 0.028 $/m³ for ACEC, 0.030 $/m³ for EC/O₂, and 0.085 $/m³ for EC/N₂     

The implications of planting mode on cadmium uptake and remobilization in rice: Field experiments across growth stages

•Direct seeding (DS) method led to more distributed Cd in aerial parts of rice. •The Cd content was significantly higher in brown rice with planting mode of DS. •Using DS lessened the Fe plaque covering the root surface in all growth stages. •Transplantation mode should be considered as a priority in Cd-contaminated areas. Global rice production practices have gradually changed from a reliance on transplanting to direct seeding. Yet how this shift may alter cadmium (Cd) accumulation in rice is poorly known. Here we conducted field experiments with two rice genotypes cultivars that were planted using three methods: via direct seeding (DS), seedling throwing (ST), and manual transplanting (MT). Rice samples were collected during four growth stages. The formation and distribution of iron plaque were analyzed using DCB (dithionite-citrate-bicarbonate) extractions and observed under micro-XRF (micro X-ray fluorescence). The results revealed that, in each growth stage, DS rice was more apt to harbor Cd distributed in the plant’s aerial parts, and the Cd concentration of brown rice from DS was 21.8%–43.3% significantly higher than those from ST and MT at maturity stage (p<0.05). During the vegetative stages, the Cd uptake percentage was higher in DS than MT rice, and those plants arising from the DS method were capable of absorbing more Cd earlier in their growth and development. Conversely, using DS decreased the amount of iron plaque covering the root surface in every growth stage, especially in the critical period of Cd accumulation, such that the roots’ middle areas were distinguished by a near-complete absence of iron plaque, thus weakening its role as an effective barrier to Cd uptake from soil. Collectively, this study demonstrated that implementing the DS mode of planting will increase Cd’s distribution in the aboveground parts of rice, and heightening the risk of Cd contamination in grain.     

一起换流变阀侧套管升高座重瓦斯动作原因分析

在已经投入运行的换流站中,换流变压器的非电气量保护在换流变压器保护中占有重要地位。通过介绍某±660 kV换流站换流变压器阀侧套管升高座重瓦斯保护动作的经过,利用现场收集的换流变非电量保护及保护暂态故障录波对故障进行分析,同时对一、二次设备进行事故后的检查和试验,得出此次故障的主因是瓦斯继电器行程较小引起的误动,并提出了相应的预防和改善措施。     

Influence of human activity and monsoon dynamics on spatial and temporal hydrochemistry in tropical coastal waters (Sanya Bay,South China Sea)

Human activities and oceanic influences like mixing and/or upwelling define the hydrochemical and biological characteristics of coastal regions. In Sanya Bay, northern South China Sea, the balance between these two influences on spatial and temporal scales is poorly understood. The influence from human activities was due to discharge from Sanya River, whereas the most important marine influence was related to seasonal changes in hydrodynamics. Spatial differences (p<0.05) in total nitrogen (TN) and chlorophyll-a (Chl-a) were observed. Seasonal differences were observed for temperature and nutrients. Human activities are the dominant factor influemcing hydrochemistry in the inner bay. This region exhibited the maximum influence of discharge from Saya River as estimated by higher nutrient levels. Oceanic influences like upwelling and mixing caused by monsoons are the dominant factors influencing hydrochemistry in the central and outer bay. Both human activities and oceanic influences play important roles in coastal ecosystems in Sanya Bay. This study has defined these characteristics so that better management policies can be enacted.