Plant Communities,Soil Carbon,and Soil Nitrogen Properties in a Successional Gradient of Sub-Alpine Meadows on the Eastern Tibetan Plateau of China

To assess the recovery trajectory and self-maintenance of restored ecosystems, a successional gradient (1, 3, 5, 15, and 30 years after abandonment) was established in a sub-alpine meadow of the eastern Tibetan Plateau in China. Plant communities and soil carbon and nitrogen properties were investigated and analyzed. Regression analyses were used to assess the models (linear or quadratic) relating measures of species richness, soil carbon and nitrogen properties to fallow time. We found that species richness (S) increased over the first 20 years but decreased thereafter, and aboveground biomass showed a linear increase along the fallow time gradient. The richness of different functional groups (forb, grass and legume) changed little along the fallow time gradient, but their corresponding above ground biomass showed the U-shaped, humped or linear pattern. Soil microbial carbon (MBC) and nitrogen (MBN) in the upper 20 cm showed a U-shaped pattern along the fallow time gradient. However, soil organic carbon (C_org) and total nitrogen (TN) in the soil at depth greater than 20 cm showed significant patterns of linear decline along the fallow time gradient. The threshold models of species richness reflected best the recovery over the 15 year fallow period. These results indicated that fallow time had a greater influence on development of the plant community than soil processes in abandoned fields in sub-alpine meadow ecosystem. These results also suggested that although the succession process did not significantly increase soil C, an increase in microbial biomass at the latter stage of succession could promote the decomposability of plant litter. Therefore, abandoned fields in sub-alpine meadow ecosystem may have a high resilience and strong rehabilitating capability under natural recovery condition.     

四种砷化合物对藻类生长及光合作用的影响——以三角褐指藻为例

为了给砷对生态系统的影响研究提供参考,利用调制叶绿素荧光技术探讨了自然环境中常见的4种形态的砷对三角褐指藻生长和光合作用的影响.结果表明,在36 h内,亚砷酸盐对藻类生物量的增长和光合活性都有明显的抑制作用;砷酸盐在抑制藻类生长的同时却因为干扰代谢而使藻类表现出光合活性的增强;一甲基砷酸盐和二甲基砷酸盐对藻类在这些方面的影响相对较弱.但对藻类光能利用效率、非光化学淬灭系数等还是产生了较明显的影响.因此,除亚砷酸盐毒性较强之外,其余几种砷化合物在宏观层次上都观测不到明显的生长抑制效应,但是在微观层次上已表现出对光合效应的不同影响.     

定型机油烟废气监测分析方法初探

定型机废气污染是当前环境投诉的热点之一,油烟污染是定型机废气的主要问题,我国尚无定型机废气监测分析的标准方法。本文参照《餐饮业油烟排放标准》（试行）（GB 18483-2001）中的方法,比较了餐饮业油烟废气和定型机油烟废气在成分、排放方式等方面的相同点和不同点,从采样方法、采样时间等对定型机油烟废气的监测分析进行了初探,确定了定型机油烟废气竣工验收参考的采样方法和时间等要素。     

全氟辛烷磺酸(PFOS)对人骨髓间充质干细胞PPARs亚型及分化潜能的影响

过氧化物酶体增殖物激活受体(peroxisome proliferators-activated receptors,PPARs)是全氟辛烷磺酸(perflurooctane sulfon-ate,PFOS)的首要分子靶标,但PPARs各亚型在PFOS毒性效应中可能产生不同调控作用,相关机理并不清楚.本研究采用人骨髓间...     

多效唑对水仙观赏效果的影响

水仙对多效唑比较敏感,无论浸泡法或叶面喷施法都具有明显的矮化效应,但当浓度≥200mg·l-1时又会产生药害,也有碍观赏;叶面喷施法对水仙矮化效应不如浸泡法,开花期亦迟10·15d;浸泡法的最佳处理浓度是50 mg·l-1;叶面喷施法以浓100-200mg·l-1效应最好,但此法费工费时,操作不便,生产上最好不采用。     

Performance and efficiency of old newspaper deinking by combining cellulase/hemicellulase with laccase-violuric acid system

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H₂O₂, enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.     

Influence of liquid- and solid-state coupling anaerobic digestion process on methane production of cow manure and rice straw

Journal of Material Cycles and Waste Management - Based on the different characteristics of cow manure and rice straw, liquid- and solid-state coupling anaerobic digestion (L-SS-AD) is designed in...     

城市级危险废物转移安全监管系统设计研究

通过对我国危险废物运输安全现状的分析,以及危险废物转移运输管理中存在的问题,借鉴国内外先进经验,提出构建低成本城市级危险废物转移监控系统的设想,为城市危险废物管理提供辅助工具。以广州市为例,将自建监控中心与基于商业平台监管危险废物转移的设计方案作对比,发现两者构建技术大致相同,但基于商业平台的监管方案节省系统的建设和运行费用50%以上,其不仅可实现政府部门通过内网进行正常业务管理,还可实现政府和危险废物运输企业通过外网对危险废物运输车辆进行实时安全监控,能有效地提高政企对危险废物运输的两级安全监管效能,为突发污染事件提供查询和应急辅助决策,同时为我国各城市危险废物运输的安全监管提供借鉴意义。     

GEO-SLOPE软件在某滑坡稳定性计算中的应用

以某滑坡为例,在充分分析其成因机制基础上,运用GEO-SLOPE软件对该滑坡的整体稳定性进行计算分析。结合室内试验、工程地质类比及参数反演确定稳定性计算参数,考虑到未来水库蓄水,在不同工况下对滑坡的稳定性进行计算,计算结果表明该滑坡的整体稳定性较好,只是在考虑地震作用的时候滑坡的整体稳定性迅速下降,甚至处于临稳状态。     

女性旅游者行为特征分析及其动机研究——以西递、宏村为例

利用SPSS社科统计软件对2005年西递、宏村调查数据进行交互分析和主成分分析，得出女性旅游者客源地结构特征、人口统计学特征、决策行为模式、出游动机等一般规律，最后比较分析了我国与美国高学历女性出游动机的异同，试图为国内外女性旅游市场开发和营销人员提供有价值的参考。