Oasis land-use change and its environmental impact in Jinta Oasis, arid northwestern China

Land use change resulted in land degradation is a focus of research on global environmental changes and plays a significant role in the stability and economic development of oases in arid regions of China. Jinta Oasis, a typical oasis of temperate arid zone in northwestern China, was investigated to assess land-use change dynamics during 1988–2003 with the aid of satellite remote sensing and GIS, and to explore the interaction between these changes and oasis environment. Six land-use types were identified, namely: cropland, forestland, grassland, water, urban or built-up land, and barren land. The results indicate that cropland, urban/built-up land, and barren land increase greatly by 30.03, 13.35, and 15.52 km², respectively; but grassland and forestland areas decrease rapidly by 58.06, and 1.76 km², respectively. These results also show that obvious widespread changes in land-use occur within the whole oasis over the study period and result in severe problems of environmental degradation (i.e. land desertification, decline of groundwater, and vegetation degeneracy).     

Combined effect of adsorption and biodegradation of biological activated carbon on H2S biotrickling filtration

In order to evaluate the combined effect of adsorption and biodegradation of H(2)S on activated carbon surface in biotrickling filtration, four laboratory-scale biofiltration columns were operated simultaneously for 120h to investigate the mechanisms involved in treating synthetic H(2)S streams using biological activated carbon (BAC). The first three columns (A, B, C) contained a mixture of activated carbon and glass beads, with the carbons (BAC or virgin activated carbon (VAC)) and conditions (with or without liquid medium recirculation) differentiated. The last column (D) used 100% glass beads with liquid medium recirculation. Air streams containing 45ppmv H(2)S were passed through the columns at 4s of gas retention time (GRT) and liquid flow rate was set at 0.71mlmin(-1). Column D got its breakthrough in 3min of operation, indicating a negligible contribution of glass beads to the adsorption of H(2)S. The removal efficiency (RE) of Columns B and C using VAC dropped quickly to 30% within the first 8h, and afterwards continued to drop further but slowly. Column A using BAC stayed at 25% of RE throughout the operation time. A thorough investigation of the H(2)S oxidation products, i.e., various S species in both aqueous (recirculation media) and solid phases (BAC and VAC), was conducted using ICP-OES, IC, XRF, and CHNS elemental analyzer. BAC demonstrated a better performance than columns with adsorption only. Water film was found to enhance H(2)S removal. The percentage of sulphate in the total sulphur of the BAC system improved to twice of that of VAC system, indicating sulphate is the main product of H(2)S biofiltration. The observed pH drop in BAC system double confirmed that the presence of biodegradation in the biofilm over carbon surface did profound effect on the oxidation of H(2)S, compare to the systems with adsorption only.     

PM<Subscript>10</Subscript> emissions from industrial coal-fired chain-grate boilers

Industrial coal-fired boiler is an important air pollutant emission source in China. The chain-grate boiler is the most extensively used type of industrial coal-fired boiler. An electrical low-pressure impactor, and a Dekati® Low Pressure Impactor were applied to determine mass and number size distributions of PM₁₀ at the inlet and the outlet of the particulate emission control devices at six coalfired chain-grate boilers. The mass size distribution of PM₁₀ generated from coal-fired chain-grate boilers generally displays a bimodal distribution that contains a submicron mode and a coarse mode. The PM in the submicron mode for burning with raw coal contributes to 33% ± 10 % of PM₁₀ emissions, much higher than those for pulverized boilers. And the PM in the submicron mode for burning with briquette contributes up to 86 % of PM₁₀ emissions. Multiclones and scrubbers are not efficient for controlling PM10 emission. Their average collection efficiencies for sub-micron particle and super-micron particle are 34% and 78%, respectively. Operating conditions of industrial steam boilers have influence on PM generation. Peak of the submicron mode during normal operation period is larger than the start-up period.

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Physiological and molecular responses of the earthworm <Emphasis Type="Italic">Eisenia fetida</Emphasis> to polychlorinated biphenyl contamination in soil

Polychlorinated biphenyls (PCBs) are a class of man-made organic compounds ubiquitously present in the biosphere. In this study, we evaluated the toxic effects of different concentrations of PCBs in two natural soils (i.e. red soil and fluvo-aquic soil) on the earthworm Eisenia fetida. The parameters investigated included anti-oxidative response, genotoxic potential, weight variation and biochemical responses of the earthworm exposed to two different types of soils spiked with PCBs after 7 or 14 days of exposure. Earthworms had significantly lower weights in both soils after PCB exposure. PCBs significantly increased catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) activity in earthworms exposed to either soil type for 7 or 14 days and decreased the malondialdehyde (MDA) content in earthworms exposed to red soil for 14 days. Of the enzymes examined, SOD activity was the most sensitive to PCB stress. In addition, PCB exposure triggered dose-dependent coelomocyte DNA damage, even at the lowest concentration tested. This response was relatively stable between different soils. Three-way analysis of variance (ANOVA) showed that the weight variation, anti-oxidant enzyme activities, and MDA contents were significantly correlated with exposure concentration or exposure duration (P < 0.01). Furthermore, weight variation, CAT activity, and SOD activity were significantly affected by soil type (P < 0.01). Therefore, the soil type and exposure time influence the toxic effects of PCBs, and these factors should be considered when selecting responsive biomarkers.     

石化企业浮顶罐大呼吸损耗核算方法分析

石化企业储罐无组织排放挥发性有机物(VOCs)带来严重的环境问题和油品损耗问题,以浮顶罐的大呼吸损耗为代表。在概述浮顶罐大呼吸损耗机理的基础上,以北京某石化企业的甲苯内浮顶罐为基准案例,对国内外4种核算公式进行了对比分析,考察了影响浮顶罐大呼吸损耗的因素,并提出有效的减耗措施。结果表明:采用我国推荐的公式进行核算更符合我国实际,需建立和完善以我国有机液体理化参数和储罐构造为基准的核算方法和软件;影响浮顶罐大呼吸损耗的主要因素包括油品性质、周转量、罐体直径、罐壁黏附系数等,其中罐壁黏附系数为关键影响因素。     

Habitat use by giant panda in relation to man-made forest in Wanglang Nature Reserve of China

To evaluate the effectiveness of human restoration in species conservation, in this study, we undertook a field survey of giant panda (Ailuropoda melanoleuca) habitat and man-made forest habitat in Wanglang Nature Reserve of China. Our results revealed that giant panda did not use the man-made forest in this area so far, and that there were significant differences between the giant panda habitat and the man-made forest habitat. Compared with giant panda habitat, the man-made forest habitat was characterized by lower shrub coverage, thinner trees and lower bamboo density. To improve the effectiveness of human restoration, the habitat requirement of giant panda should be fully consider in the whole process of habitat restoration.     

气候变化和人类活动对天津海岸带影响综述

21世纪全球海平面上升和区域地面沉降叠加所致的相对海平面上升速率存在加快趋势,将加剧天津沿海地区风暴潮、洪涝灾害和土地淹没的危害,影响沿海地区的城市抗灾功能、建筑物安全及生态资源。为此,本文综合讨论了气候变化导致的海平面上升和地面沉降对天津沿海风暴潮、海岸侵蚀以及港口码头的影响。建议滨海新区建设要高度重视海洋灾害的监测预警,提高沿海地区防潮和防汛工程的设计标准和城市抗灾能力,以有效实现滨海新区经济和社会可持续发展。     

云南极端霜冻气候事件的气候特征及环流背景分析

利用云南124个气象站逐日最低气温和天气现象(霜)资料,计算最低气温低于-5℃的站点数占全省总站数的比例,定义站点比例超出25%的霜冻事件为云南极端霜冻气候事件。分析了云南极端霜冻气候事件的气候特征及环流背景。结果表明,云南极端霜冻事件发生前气温偏低,云量偏多;霜冻发生时夜间晴朗,辐射散热强烈,气温再度下降。这种霜冻属于混合霜冻或称为平流辐射霜冻。极端霜冻气候事件发生的主要原因之一是高空冷平流与底层冷高压控制下夜间晴空辐射冷却降温。发生时空气湿度较发生前小,空气相对干燥。     

热处理对脱水污泥溶解特性及厌氧消化性能的影响

分别对脱水污泥在100、130和170℃条件下进行热处理,研究热处理对脱水污泥溶解特性的影响。此外,在半连续式完全混合反应器中进行厌氧消化实验研究不同热处理污泥的厌氧消化性能。实验结果表明,在100、130和170℃条件下,污泥COD溶解率由处理前的5.23%分别提高至20.08%、22.50%和27.20%,脱水污泥热处理规律和效果与高含水率污泥(总固体含量<5%)基本一致。经130℃2 h和170℃30 min高温热处理后污泥甲烷产率显著提高,较原泥分别提高24.64%和38.61%,沼气中甲烷含量稍有降低。     

Mn/GO复合催化剂催化氧化NO

针对尾气中NO浓度高且传统方法脱除NO代价高的问题,研究了锰固载氧化石墨诱导单过硫酸氢钾(PMS)催化氧化并吸收NO方法。通过浸渍法在氧化石墨上负载了Mn3O4制得Mn/GO催化剂,以此为催化剂催化PMS氧化NO。研究了p H、PMS投加量、催化剂投加量以及温度等因素对NO氧化率的影响。结果表明,该系列Mn/GO催化剂可以有效地诱导PMS氧化NO,热处理时间为7 h时催化效果最佳。同时,对Mn/GO(7 h)的FT-IR、XRD、SEM、EDS以及XPS表征可知,Mn3O4是主要的锰氧化物,并成功负载在GO表面。