低DO紊动床内有机物对硝化过程的影响

利用生物紊动床在低溶解氧（DO）和有机物存在的条件下研究了氨氮的亚硝化、硝化和有机物氧化的规律，分析了异养菌与自养菌竞争的特点。试验结果表明，DO为2－3mg/L、有机物浓度（TOC）为200mg/L、C／N＝1：1．5时对硝化作用影响不大；DO为0.5-1mg/L、TOC≥mg/L、C／N＝1：3时硝化系统即受到破坏。     

神州西来第一山崆峒山

崆峒山位于平凉市崆峒区,主峰海拔2123米,游览区面积89.8平方公里.它背靠笄头山,东望泾河川,南与关山相对峙,北和马头山相接壤.泾河、胭脂河南北环抱,古迹胜景遍布于层峦叠翠之间.自古就有"西镇奇观"、"神州西来第一山"之美誉,从宗教渊源关系上讲又被誉为"天下道教第一山".     

非饱和黄土的强度特征

以初始基质吸力为条件，根据大量的试验测定和分析，得到了非饱和黄土的粘聚力与基质吸力的相关关系；阐述了非饱和黄土的抗剪强度随基质吸力的变化特征；给出了临界基质吸力的计算式。为进一步采用控制吸力试验，揭示非饱和黄土抗剪强度的基本规律作了初步探索     

Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan

The consumption of contaminated seafood has been reported as an important route of human exposure to metals in Taiwan. We consider the concentrations of TBT, Cu, Zn, Cd, As, and the consumption of oysters of Taiwanese to be the important information related to public health in Taiwan. Therefore, the aim of this study was to evaluate the public health risks associated with TBT, Cu, Zn, Cd and As from shellfish for the general population and fishermen of Taiwan. In general, TBT concentrations in various oysters ranging from 0.32 to 1.51 microg/g dry wt. varied with sampling locations. The highest TBT, Cu, and Zn geometric mean (GM) concentrations in oysters of 1.51, 1180 and 1567 microg/g dry wt. were obtained from the Hsiangshan coastal area. The values of oyster consumption for fishermen were 94.1 and 250 g/day for typically and maximally exposed individuals, respectively. In particular, the highest intake (250 g/day) from fishermen was almost two times greater than that of the general population (139 g/day). The THQ (target hazard quotient) values of Hsiangshan's fishermen are 3.87 and 20.50 for TBT and Cu for maximally exposed individuals are higher than other oyster culture areas. It is interesting that those consuming oysters from Hsiangshan, Lukang, Taishi caused abnormally high THQs of TBT and other metals (100% over 1.0), and TBT was attributed to only 3-21% of the total THQs in different fishermen of Taiwan. Our results suggest that current environmental levels of TBT and other metals are associated with a significant potential threat to human health for fishermen resident in coastal areas of Taiwan.     

Characterization of nitrogen-fixing cyanobacteria in the Brazilian Amazon floodplain

The diversity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the Solimões and Amazon Rivers and some of their tributaries (Japurá, Negro and Madeira) was investigated. Five cyanobacterial genera were morphologically identified, four of which (Nostoc, Calothrix, Cylindrospermum and Fischerella) have not previously been isolated from the Brazilian Amazon floodplain. Nostoc strains were the most commonly found heterocyst-forming cyanobacteria. Five strains (N. muscorum CENA18 and CENA61, N. piscinale CENA21, Cylindrospermum sp. CENA33 and Fischerella sp. CENA19) were selected for growth measurement, ability to fix N₂ and phylogenetic analysis, based on their widespread distribution and morphological distinction. Molecular analyses employing 16S rRNA sequences indicated that some of the isolates may represent novel cyanobacterial species. Dinitrogen fixed by these strains was measured indirectly as acetylene reduction activity and ranged from 11.5 to 22.2 nmol C₂H₄ μg Chl a⁻¹ h⁻¹. These results provide evidence of widespread and importance of nitrogen-fixing cyanobacteria as a source of N inputs in the Amazonian ecosystem.     

沉管夯扩灌注桩的施工监理

以某高校教学楼沉管夯扩灌注桩基础工程监理为背景 ,介绍了沉管夯扩灌注桩在施工中的质量控制要点和桩基检测的内容 ,并对检测结果进行了分析     

高雄捷運紅橘線交會大港埔圓形站體連續壁施工

高雄捷迎紅橘綜交會大港埔圓形站體為高雄捷迎路網通車之要徑工程。因此,為維持正常交通服務水準、有限工期、施工條件及安全等,連續壁施工選用水平多軸回轉式切削機以維持品質、控制挖掘精度及施工速度,另為避免造成連續壁之偏壓作用而損壞,站體之開挖順序安排亦為設计及施工人員重視之課題。     

工程量清单计价模式下施工企业的成本管理

分析了新旧两种工程造价管理模式的区别所在 ,结合对新的造价管理模式内涵的理解 ,从概念分析 ,企业成本管理的变化及思路等方面 ,提出了顺利完成企业成本管理模式转变的措施     

用于混凝土保护涂层的有机硅改性丙烯酸乳液的研制

采用化学改性的方法将丙烯酸树脂用有机硅改性,合成了一种新型的混凝土保护材料,并就合成过程当中的一些问题进行了分析讨论。     

Chromate reduction by waste iron from electroplating wastewater using plug flow reactor

Waste iron was used to treat high concentration chromate (534 mg/L as Cr) from electroplating wastewater by plug flow reactor (PFR) due to the following reasons: (1) two wastes are treated simultaneously, (2) low pH of the electroplating wastewater ( approximately 2) benefits the reaction between these two wastes, (3) effluent pH is elevated in the PFR, reducing the base requirement to meet the pH discharge standard for wastewater (pH 6-9). Complete chromate reductions were achieved at pH 1.7 for hydraulic retention time (HRT) of 98 min, pH 1.5 for HRT of 40 min and pH 1.3 for HRT of 20 min. Consequently, optimum HRT for complete chromate reduction was obtained for different pHs. Although more acids were used to lower influent pH to reduce HRT, effluent pH was higher due to more hydrogen ion reacting with chromate. Eventually, fewer bases are required to fulfill the discharge pH requirement of wastewater. Effluent pH 3-5 was observed with high turbidity, indicating the precipitations of chromium oxide and hydroxide were enhanced by the dissolved iron coagulation. X-ray diffraction was conducted to examine the remaining species. Other than chromium oxide and hydroxide species, an iron-chromium complex (Cr2FeO4) was also observed.