Growth and nutritive quality of Poa pratensis as influenced by ozone and competition

Interspecific plant competition has been hypothesized to alter effects of early-season ozone (O3) stress. A phytometer-based approach was utilized to investigate O3 effects on growth and nutritive quality of Poa pratensis grown in monoculture and in mixed cultures with four competitor-plant species (Anthoxanthum odoratum, Achillea millefolium, Rumex acetosa and Veronica chamaedrys). Mesocosms were exposed during April/May 2000-2002 to charcoal-filtered air+25 ppb O3 (control) or non-filtered air+50 ppb O3 (elevated O3). Biomass production was not affected by O3, but foliar injury symptoms were observed in May 2002. Early-season O3 exposure decreased relative food value of P. pratensis by an average of 8%, which is sufficient to have nutritional implications for its utilization by herbivores. However, forage quality response to O3 was not changed by interspecific competition. Lack of injury and nutritive quality response in P. pratensis harvested in September may reflect recovery from early-season O3 exposure.     

Enhanced photocatalysis of pentachlorophenol by metal-modified titanium (IV) oxide

The effects of four metals (Ag, Au, Pt, and Cu) doped on TiO2 on the photocatalysis of pentachlorophenol (PCP) were investigated. The results of this study indicated that all four metals-doped TiO2 catalysts were able to enhance the efficiency of PCP photocatalysis with an optimum metallic content of 0.1 wt%. For the metal-doped TiO2 samples (Au, Pt, and Cu), the patterns of light absorption were significantly extended toward visible light spectra in the wavelengths between 400 and 800 nm. The photocatalysis of PCP was pH dependent with the maximum degradation rate achieved in the solution at pH 3. The formation of chloride ion corresponded with the concentration of PCP degraded which confirmed that dechlorination was the major pathway of PCP photocatalysis. The overall toxicities of PCP samples were reduced with the extension of light exposure using the microtox test. The results of PCP photocatalysis are also discussed based on the characteristics of metal/TiO2 including X-ray differential (XRD) patterns, Brunquer Emmett Teller (BET) specific area analysis, and Ultra Violet (UV)-Vis absorption spectra.     

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.     

Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash

This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.     

基于可靠性理论的区域大气环境质量风险评价模型探讨

为了用可靠性理论进行区域大气环境质量风险评价．从理论上研究了几个需要解决的基本问题。包括：明确区域环境质量风险评价的研究对象．确定区域环境质量可靠性的内涵,提出区域环境系统的“应力-强度-失效”假说．分析环境系统净化环节闻的串、并联关系。因此．从可靠性的视角,对区域环境质量的复杂性和不确定性进行新的探讨．构建环境科学与可靠性理论联系的桥梁。在理论分析的基础上．对福建省泉港区石化工业基地大气环境质量风险评价问题进行研究。从大气环境污染的主要问题出发。研究区域环境系统对大气污染物的净化环节及其串并联关系。在此基础上．构建区域大气环境污染的故障树,并以区域环境质量的可靠性作为评价指标对区域环境风险问题进行具体评价。这是一种以概率为基础的、新的区域环境质量风险评价模型．对于研究污染型工业系统的环境质量风险具有重要意义。     

基于改进灰色模型的管壁蜡沉积厚度预测研究

为对含蜡原油管道中的蜡沉积厚度进行准确预测,在函数cot(x2)变换的基础上,结合平移变换思想,利用cot(x2+c)变换建立新的改进GM(1,1)模型。以现场管道结蜡数据和室内环道结蜡数据为例,对比改进GM(1,1)模型、基于函数cot(x2)变换建立的GM(1,1)模型及传统GM(1,1)模型之间的预测精度,并分析平移量c对改进GM(1,1)模型预测精度的影响。结果表明:改进GM(1,1)模型的预测精度最高,其次是基于函数cot(x2)变换建立的GM(1,1)模型,而传统GM(1,1)模型的预测精度最低;随着平移量的增大,改进GM(1,1)模型的平均相对预测误差呈现出先减小后增大的趋势,因此合理的平移量有助于模型精度的提高。应用改进GM(1,1)模型来预测管道蜡沉积厚度是可行的,该方法可为含蜡原油管道蜡沉积厚度的准确预测提供参考和借鉴。     

隧道内偏置火源顶棚近壁面温度边界层效应研究

基于隧道火灾不同横向火源位置的非对称卷吸影响,通过模拟计算分析了中心火源和偏置火源产生的烟气沿纵向最大温升变化规律,研究了顶棚下方近壁面区域内的不同温度分布,提出偏置火源纵向空间最大顶棚温升公式。结果表明:在壁面黏性作用下,沿纵向蔓延的烟气最高温度在顶棚下方呈现“温度边界层”分布;随着火源位置的偏移,下游出现偏置距离起主导作用影响温度衰减的区域,衰减速度相较于中心火源逐渐降低;火源下游近壁面最高温度位置逐渐远离顶棚后趋于稳定。研究结果对于排烟方式的设计以及空间通风效果的提升有着重要意义。     

变坡度情况下森林地表上坡火行为若干特征的实验研究

应用自行研制的“多坡段固相材料火蔓延实验台”，模拟森林地表火的蔓延过程，对变坡度情况下森林地表上坡火行为规律进行了实验研究。研究发现，上坡火火焰随坡度的变化有三种火焰类型，即小坡度的缓慢燃烧，随坡度增加的火焰的抖动以及大坡度时的贴壁剧烈燃烧。     

全新世青藏高原东部西南季风的演变

本研究报道一组新的西南季风代用指标,即泥炭中单一种属植物———木里苔草残体纤维素和泥炭混合植物残体纤维素的δ13C时间序列,所记录的青藏高原东部全新世气候变化。两记录表明,该区全新世的下限年龄约11200aBP(14C年龄约9900aBP);从约11200aBP起该区迅速进入湿暖的全新世阶段,季风活动迅速增强;在约10800～5500aBP期间,季风总体保持在强盛状态,但其间有4次突然减弱,气候变干冷;约从5500aBP起季风活动在波动中逐渐减弱,其中有4次减弱最明显。所有这8次气候的突然变化都与北大西洋浮冰事件一一对应。这种密切的相关关系表明,西南季风强度的波动可能是对全球变化,特别是对海洋热盐环流引起的地球南北方气候波动的所谓"跷跷板效应"的响应。     

都市农业生态系统中污水资源化利用

文章介绍了都市农业生态系统中的污水处理工艺和资源化利用方案,并对回用过程中的水质状况进行了连续监测与分析,结果表明,主要污染物CODCr、BOD5、浊度、TN的去除率均达到90%以上。再生水完全可以满足系统内农业灌溉的要求,每年可减少50%的地下水开采量,且提供了良好的景观资源。蟹岛生态度假村以生活污水处理为中心的水资源循环利用方式,为污水资源化利用工程作了有益的尝试并取得了良好的效果。