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411.
酸雨对汉白玉的危害研究 总被引:1,自引:0,他引:1
采用模拟的方法研究了酸雨对天然汉白玉危害,研究结果表明,酸雨对汉白玉石材的危害主要是溶解腐蚀。根据数量统计获得了影氧化钙损失的因素和腐蚀速率“b”以及腐蚀的规律。 相似文献
412.
港口油气污染扩散及源强计算方法的探讨 总被引:3,自引:2,他引:3
系统分析了港口油气污染扩散的特点式,对油港油原强及扩散速率计算方法进行了研究和验证,对适用国内油港油气扩散模拟源强公式及计算方法进行了探讨。 相似文献
413.
414.
内凸筋口琴管,是汽车空调的一种新型散热管.具有散热效果好、单位面积小、重.量轻等优点.此文介绍了连续挤压内凸筋口琴管模具的设计方法及其模具芯头的冷挤压加工. 相似文献
415.
416.
以某污水厂的氧化沟污泥和剩余污泥为培养对象,获得了SRB占优的厌氧污泥,分析了活性污泥厌氧驯化过程中微生物的分布规律,考察了不同种类SRB污泥固定化小球处理水中硫酸根、锌及镉的效果.结果表明:pH6.0~7.0,温度35℃,硫酸盐浓度4g/L,时间在24h时,剩余污泥固定化小球处理含Zn(II)400mg/L的废水,去除率达到100%,氧化沟污泥固定化小球Zn(II)的去除率为90%左右;对500mg/L含镉废水,剩余污泥固定化小球8h能去除水中95?(II),氧化沟污泥固定化小球对Cd(II)的去除率为80%.硫酸盐还原菌污泥固定化技术中剩余污泥优于氧化沟污泥. 相似文献
417.
张维平 《防灾技术高等专科学校学报》2006,8(1):11-16,10
频发的突发公共事件造成的危机已经成为社会管理生活中不可避免的重大挑战,危机管理也就成为各国和各级政府都必须认真对待的重要问题,本文归纳了危机管理中应遵循的原则,运用的策略以及处理危机的过程。 相似文献
418.
It is widely acknowledged that a simplified and robust approach to evaluating thecombined effects of chemical mixtures is critical for ecological risk assessment (ERA) of contaminated soil. The earthworm (Eisenia fetida) was used as a model to study the combined effects of polymetallic contamination and the herbicide siduron in field soil using a microcosm experiment. The responses of multiple biomarkers, including the activities of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and acetylcholine esterase (AChE), the concentrations of glycogen, soluble protein (SP), malonaldehyde (MDA), and metallothionein (MT), and the neutral red uptake test (NRU), were investigated. Multivariate analysis, Principal Component Analysis (PCA) and Spearman's Rank Correlations analysis (BVSTEP) revealed that the activities of AChE and CAT and the NRU content were the prognostic biomarkers capturing the minimum data set of all the variables. Internal Cd (tissue Cd) in earthworms was closely related to the health status of worms under combined contamination of heavy metals and siduron. The integrated effect (Emix) calculated based on the activities of AChE and CAT and NRU content using the stress index method had significantly linear regression with internal Cd (p<0.01). Emix(10), Emix(20), and Emix(50) were then calculated, at 1.27, 1.63 and 2.71 mg/kg dry weight, respectively. It could be concluded that a bioassay-based approach incorporating multivariate analysis and internal dose was pragmatic and applicable to evaluating combined effects of chemical mixtures in soils under the guidance of the top-down evaluation concept of combined toxicity. 相似文献
419.
Nini Pang Jian Gao Fei Che Tong M Su Liu Yan Yang Pusheng Zhao Jie Yuan Jiayuan Liu Zhongjun Xu Fahe Chai 《环境科学学报(英文版)》2020,32(9):201-209
To investigate the cause of fine particulate matter (particles with an aerodynamic diameter less than 2.5 µm, PM2.5) pollution in the heating season in the North China Plain (specifically Beijing, Tianjin, and Langfang), water-soluble ions and carbonaceous components in PM2.5 were simultaneously measured by online instruments with 1-hr resolution, from November 15, 2016 to March 15, 2017. The results showed extreme severity of PM2.5 pollution on a regional scale. Secondary inorganic ions (SNA, i.e., NO3?+SO42+ NH4+) dominated the water-soluble ions, accounting for 30%-40% of PM2.5, while the total carbon (TC, i.e., OC + EC) contributed to 26.5%-30.1% of PM2.5 in the three cities. SNA were mainly responsible for the increasing PM2.5 pollution compared with organic matter (OM). NO3? was the most abundant species among water-soluble ions, but SO42- played a much more important role in driving the elevated PM2.5 concentrations. The relative humidity (RH) and its precursor SO2 were the key factors affecting the formation of sulfate. Homogeneous reactions dominated the formation of nitrate which was mainly limited by HNO3 in ammonia-rich conditions. Secondary formation and regional transport from the heavily polluted region promoted the growth of PM2.5 concentrations in the formation stage of PM2.5 pollution in Beijing and Langfang. Regional transport or local emissions, along with secondary formation, made great contributions to the PM2.5 pollution in the evolution stage of PM2.5 pollution in Beijing and Langfang. The favourable meteorological conditions and regional transport from a relatively clean region both favored the diffusion of pollutants in all three cities. 相似文献
420.
底泥内源污染是导致黑臭水体"反弹"的主要因素.为防止水体黑臭现象反复,以低剂量硝酸钙为修复剂,联合低氧曝气技术修复底泥,降低因ρ(NO3--N)剧增而造成的生态风险,并对修复过程中菌群转化规律进行探究.结果表明:①当硝酸钙投加量为底泥质量的1.2%、低氧曝气量为0.05~0.10 m3/h时修复效果最佳,其上覆水中ρ(DO)和ORP分别升至4.08 mg/L和119.9 mV,NH3-N、TOC(总有机氮)去除率平均值分别达42.5%和84.9%.②底泥中NH3-N和AVS(酸挥发性硫化物)去除率平均值分别达76.8%和97.4%,投加低剂量硝酸钙不会造成NO3--N在底泥中长期累积.③高通量测序分析表明,底泥优势菌群在纲水平上由梭菌纲(Clostridia)转变为γ-变形菌纲(Gamma-proteobacteria),其相对丰度达60.0%,且厌氧菌群被有效抑制;在属水平上出现产黄杆菌属(Rhodanobacter)、硫杆菌属(Thiobacillus)和热单胞菌属(Thermomonas)等脱氮菌群.研究显示,低剂量硝酸钙+低氧曝气技术可有效改善底泥-上覆水体系DO条件,加快系统的脱氮速率,抑制AVS的生成,促进底泥优势菌群转化并降低生态风险. 相似文献