Tolerance of calluna vulgaris and peatland plant communities to sulphuric acid deposition

Critical loads offer a unique way of evaluating impacts of acid deposition by quantifying environmental sensitivity. The critical loads of acidity for UK peat soils have been based upon an arbitrary reduction in pH of 0.2 units. This chemical shift needs to be better related to adverse effects on sensitive biological receptors. It is known that effective precipitation pH equates closely to soil solution pH, and the latter is directly linkable to biotic effects of pH change. On continuation of a long-term experiment assessing impacts of simulated acid rain on peat microcosms in a realistic outdoor environment, Calluna vulgaris continued to flourish at acid deposition loads well above the existing critical load. Calluna plants were harvested and analysed, and acid deposition treatments to the microcosms continued to allow natural vegetation to regenerate. A diverse mixture of moorland plants and bryophytes established at acidity treatments well above the existing critical load, and only a very high acid load resulted in no natural regeneration. A critical effective rain pH value of 3.6 is suggested as a basis for setting critical loads. At this pH, Calluna grows well, and a healthy diverse vegetation community re-establishes when harvested. It is suggested that the peat critical load should be set at the acid load that, at any specific site, would result in a mean effective precipitation pH of 3.6.     

Measurement of respiration amount of white birch(Betula platyphylla) population in the mountainousregion of Beijing

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大直径TA2卷焊坯制备工艺

此文介绍尺寸为φ1547×L900×δ30的大直径TA2卷焊坯的制备工艺。主要包括卷焊坯设计、展开下料的计算、卷圆工艺、焊接工艺等,可供同类材质圆筒件卷圆时参考。     

呼和浩特市不同粒径空气颗粒物中汞的分布规律

采用分级采样装置 ,于冬夏两季采集呼市三个不同功能区不同粒径空气颗粒物中的汞进行分析 ,结果表明 :呼市空气颗粒物中的汞含量冬季明显高于夏季 ;冬季空气颗粒物中的汞含量为居民区 >交通区 >对照区 ,夏季为交通区 >居民区 >对照区 ;空气中汞主要富集在可吸入粒子中。     

南京市城区气溶胶粒度分布特征

以九段串级式撞击采样器对南京市气溶胶进行采样测定。经统计分析发现，气溶胶呈双峰分布，粒度分布规律明显，峰值粒径在0.37μm-0.65μm和4．3μm-5.6μm之间，气溶胶浓度季节变化显著，秋季＞夏秋，秋季颗粒物中细粒子质量百分比较夏季的多，两季质量中位位直径分别为6．5μm,4,4μm，说明与季节变化密切相关。     

Effect of catalyzed diesel particulate filter and its catalyst loading on emission characteristics of a non-road diesel engine

In this study, the effects of a diesel oxidation catalyst (DOC) coupled with a catalyzed diesel particulate filter (CDPF) with different catalyst loadings on the power, fuel consumption, gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption. The reduction effect of the DOC on the CO and hydrocarbon (HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO₂ proportion to 37.9%, and more NO₂ was produced when coupled with the CDPF below 250°C; above 250°C, more NO₂ was consumed. The after-treatment could reduce more than 99% of the particle number (PN) and 98% of the particle mass (PM). Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution (PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter (GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.     

砷对蔬菜生长的影响和临界值的研究

本文研究了紫色土添加砷对蔬菜生长的影响与临界值,并采用灰色系统的关联度分析方法,使它们与土壤性度联系起来,结果表明:三种紫色土砷的临界值一般为:红紫泥> 灰棕紫泥>红棕紫泥.     

事故和安全舰艇指挥员的心理素质对比研究

对有过不同程度操舰事故经历的舰艇指挥员和无事故经历的舰艇指挥员的心理素质测评比较研究 ,为舰艇指挥员心理素质的选拔和培训提供依据。根据研究要求选择了 4 2名被试者 ,并对其进行实验测评研究。结果表明 ,实验组在颜色视觉、立体视觉、注意分配能力、简单反应时间、复杂反应时间、速度预期反应等的能力水平都比控制组低 ,同时在结果的图表中 ,还注意到二组被试者在各个反应时指标中的临界值。对比研究的 6个项目指标 ,在一定程度上可以认为是舰艇指挥员心理品质指标中的重要组成部分 ,其临界值可以为更好地选拔合格舰艇指挥员的心理素质提供科学依据。     

水泥土搅拌桩的桩径分析

针对搅拌桩施工会引起周围土体的位移及产生很高的超静孔隙水压力的工程现象,首先分析了搅拌桩施工中固化剂的注入体积与膨胀压力、成桩直径的关系。结果表明,5%~10%的注入浆液的体积可以对周围土体产生1.8~3.0倍不排水抗剪强度的膨胀压力,成桩直径比搅拌叶片的名义直径大5%~10%。然后量测室内模型桩、现场搅拌桩的成桩直径,分析了注入浆液的体积与成桩直径的关系。结果表明,对于深度不太大的水泥土搅拌桩,有约45%的注入体积会通过上浮隆起的土体损失掉;大约5%的注入体积通过劈裂裂缝渗入到周围土体中;大约50%的注入体积会转化为成桩直径,使桩体膨胀5%~10%,即实测桩径比搅拌叶片的名义直径大5%~10%。     

Review of LCA studies of solid waste management systems – Part II: Methodological guidance for a better practice

Life cycle assessment (LCA) is increasingly used in waste management to identify strategies that prevent or minimise negative impacts on ecosystems, human health or natural resources. However, the quality of the provided support to decision- and policy-makers is strongly dependent on a proper conduct of the LCA. How has LCA been applied until now? Are there any inconsistencies in the past practice? To answer these questions, we draw on a critical review of 222 published LCA studies of solid waste management systems. We analyse the past practice against the ISO standard requirements and the ILCD Handbook guidelines for each major step within the goal definition, scope definition, inventory analysis, impact assessment, and interpretation phases of the methodology. Results show that malpractices exist in several aspects of the LCA with large differences across studies. Examples are a frequent neglect of the goal definition, a frequent lack of transparency and precision in the definition of the scope of the study, e.g. an unclear delimitation of the system boundaries, a truncated impact coverage, difficulties in capturing influential local specificities such as representative waste compositions into the inventory, and a frequent lack of essential sensitivity and uncertainty analyses. Many of these aspects are important for the reliability of the results. For each of them, we therefore provide detailed recommendations to practitioners of waste management LCAs.