腐蚀管道评价标准ASME B31G-2009和SY/T6151-2009对比

腐蚀是油气管道最常见的失效形式之一,对腐蚀管道进行剩余强度评价是保障管道安全可靠运行的基础工作。ASME B31G-2009和SY/T6151-2009是国内外的两种主流评价标准的最新版本,为了在选取适当的评价标准时有判断依据,比较分析了新版标准评价结果的保守程度,研究了评价流程、计算模型和计算参数取值等方面,并结合爆破试验数据和有限元仿真结果进行了验证。结果表明,两种标准仍具有一定的保守性,且当管道强度等级、腐蚀情况及数据资料完整度等不同时,两种标准有各自的适用范围和优缺点。     

Anaerobic ammonia oxidizing bacteria: ecological distribution,metabolism, and microbial interactions

The unique characteristics of anammox bacteria were reviewed. Ecological distribution and nitrogen loss contributions were well documented. Ecological interactions between anammox bacteria and other organisms were discussed. Anammox (ANaerobic AMMonia OXidation) is a newly discovered pathway in the nitrogen cycle. This discovery has increased our knowledge of the global nitrogen cycle and triggered intense interest for anammox-based applications. Anammox bacteria are almost ubiquitous in the suboxic zones of almost all types of natural ecosystems and contribute significant to the global total nitrogen loss. In this paper, their ecological distributions and contributions to the nitrogen loss in marine, wetland, terrestrial ecosystems, and even extreme environments were reviewed. The unique metabolic mechanism of anammox bacteria was well described, including the particular cellular structures and genome compositions, which indicate the special evolutionary status of anammox bacteria. Finally, the ecological interactions among anammox bacteria and other organisms were discussed based on substrate availability and spatial organizations. This review attempts to summarize the fundamental understanding of anammox, provide an up-to-date summary of the knowledge of the overall anammox status, and propose future prospects for anammox. Based on novel findings, the metagenome has become a powerful tool for the genomic analysis of communities containing anammox bacteria; the metabolic diversity and biogeochemistry in the global nitrogen budget require more comprehensive studies.     

Efficacy of alum and coal combustion by-products in stabilizing manure phosphorus

Animal manures contain large amounts of soluble phosphorus (P), which is prone to runoff losses when manure is surface-applied. Here we report the efficacy of alum and three coal combustion by-products in reducing P solubility when added to dairy, swine, or broiler litter manures in a laboratory incubation study. Compared with unamended controls, alum effectively reduced readily soluble P, determined in water extracts of moist manure samples with 1 h of shaking, for all three manures. The reduction ranged from 80 to 99% at treatment rates of 100 to 250 g alum kg(-1) manure dry matter. The fluidized bed combustion fly ash (FBC) reduced readily soluble P by 50 to 60% at a rate of 400 g kg(-1) for all three manures. Flue gas desulfurization by-product (FGD) reduced readily soluble P by nearly 80% when added to swine manure and broiler litter at 150 and 250 g kg(-1). Another by-product, anthracite refuse fly ash (ANT), was ineffective for all three manures. In all cases, reduction in readily soluble P is primarily associated with inorganic phosphorus (P(i)) with little change in organic phosphorus (P(o)). Sequential extraction results indicate that the by-product treatments shifted manure P from H2O-P into a less vulnerable fraction, NaHCO3 - P, while the alum treatment shifted the P into even more stable forms, mostly NaOH-P. Such shifts in P fractions would have little influence on P availability for crops over the long-term but would retard and reduce potential losses of P following manure applications.     

Phosphorus characteristics of dairy feces affected by diets

Phosphorus (P) surplus on dairy farms, especially confined operations, contributes to P buildup in soils with increased potential for P loss to waters. One approach to reduce P surplus and improve water quality is to optimize P feeding and improve P balance on farms. Here we report how varying P concentrations in lactating cow diets affects the amount as well as the chemical forms and fraction distribution of P in fecal excretion, and the environmental implications of this effect. Analysis of fecal samples collected from three independent feeding trials indicates that increasing dietary P levels through the use of P minerals not only led to a higher concentration of acid digest total phosphorus (TP) in feces, but more importantly increased the amount and proportion of P that is water soluble and thus most susceptible to loss in the environment. For instance, with diets containing 3.4, 5.1, or 6.7 g P kg(-1) feed dry matter (DM), the water-soluble fraction of fecal P was 2.91, 7.13, and 10.46 g kg(-1) fecal DM, respectively, accounting for 56, 77, and 83% of acid digest TP. The other fecal P fractions (those soluble in dilute alkaline and acid extractants) remained small and were unaffected by dietary P concentration. Excess P in the P supplemented diets was excreted in feces as water-soluble forms. A simple measure of inorganic phosphorus (Pi) in a single water extract is highly responsive to changes in diet P concentrations and hence can be indicative of dietary P status. A fecal P indicator concept is proposed and discussed.     

峨眉山风景区酸性降水的研讨

本文对峨眉山——乐山大佛风景名胜区多年来降水酸度、酸雨频率与酸性降水的地域分布以及垂直变化特征进行了研讨,并对该区酸雨与四川省酸性降水特征进行了对比。     

大气二氧化硫污染趋势及其防治对策

乌市大气 SO_2年日均值为0.207mg/m~3,超过国家二级标准39%,冬季含量是国标的2.47倍。SO_2巳上升为冬季大气的主要污染物。乌鲁木齐市年耗煤量510万吨,全年通过燃煤排放的 SO_2达7万吨以上,占全市 SO_2总排放量的80%以上,燃煤排放是 SO 主要的排放源。冬季燃煤排放 SO_24.6万吨,占全市排放量的65%以上。因此从现在开始着眼于乌市大气 SO_2的防治是改善乌市大气环境质量的战略措施。治理的途径一是改变燃料结构,大量推广使用无烟煤型煤,二是在防止二次污染,提高水的重复利用率前提下因地制宜地推广湿式除烟尘、除硫技术。     

光量子分解技术在污水处理站臭气污染治理中的应用

本文通过蒙牛乳业包头有限责任公司污水处理站臭气治理工程的实践,分析污水处理站臭气污染的成因、除臭工艺的原理,完善了除臭工艺设计和参数,从经济性和运行可靠性方面总结了光量子分解臭气装置在实际应用方面的优劣。     

Adsorption of benzene,cyclohexane and hexane on ordered mesoporous carbon

Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal.     

公害的演变与预防

在概述公害的发展与演变的基础上, 简要介绍了地方级应急意识与准备（ＡＰＥＬＬ） 计划的有关内容, 以及我国首家实施该计划的上海市的实施情况。