地下车库防排烟和通风系统设计

本文介绍了地下汽车库的通风与排烟系统设计,探讨了地下车库通风与排烟系统的形式,并提出了地下汽车库通风与排烟系统合一的可行性.分析了传统通风方式的利弊,对无风管诱导通风系统在地下车库中的应用作了介绍.指出车库诱导通风系统和传统防排烟与通风系统相结合的优越性.     

Baseflow nitrate in relation to stream order and agricultural land use

Management of agricultural nonpoint-source pollution continues to be a challenge because of spatial and temporal variability. Using stream order as an index, we explored the distribution of nitrate concentration and load along the stream network of a large agricultural watershed in Pennsylvania-the East Mahantango Creek Watershed and two of its sub-watersheds. To understand nitrate concentration variation in the stream water contributed from ground water, this study focused on baseflow. Impacts of agricultural land use area on baseflow nitrate in the stream network were investigated. Nitrate concentration showed a general decreasing trend with increasing stream order based on stream order averaged values; however, considerable spatial and temporal variability existed within each snapshot sampling. Nitrate loads increased with stream order in a power function because of the dominant effect of stream flow rate over the nitrate concentration. Within delineated sub-watersheds based on stream orders, positive linear functions were found between agricultural land use area percentage and the baseflow nitrate concentration and between agricultural drainage area and the nitrate load. The slope of the positive linear regression between the baseflow nitrate concentration and percent agricultural land area seems to be a valuable indicator of a watershed's water quality as influenced by agricultural practices, watershed size, and specific physiographic setting. Stream order seems to integrate, to a certain degree, the source and transport aspects of nonpoint-source pollution on a yearly averaged basis and thus might provide a quick estimate of the overall trend in baseflow nitrate concentration and load distribution along complex stream networks in agricultural watersheds.     

云南省主体功能区综合交通运输网络建设对区域可达性影响

云南省地处我国西南边疆,随着经济的发展,交通可达性正逐渐成为该省经济发展的“瓶颈”。从可达性的概念入手,分析了目前云南省交通运输网络建设的空间格局及各类主体功区内存在的主要问题,针对各类功能区内交通运输结构中存在的问题给出了合理化建议,以期提高云南省交通的可达性。     

Cement paste column for simultaneous removal of fluoride, phosphate, and nitrate in acidic wastewater

Cement paste, a cured mixture of cement and water, was reported to have considerable capacity for fluoride removal. In this study, heavily mixed fluoric acid wastewater from a semiconductor fabrication plant was applied to a column packed with cement paste granules to evaluate its capacity for the removal of fluoride and three other contaminants, phosphate, nitrate, and sulfate, as well as to investigate the interactions between these contaminants and cement components. The column reduced fluoride to remarkably low levels since fluorite was formed at highly elevated concentrations of calcium and the residual fluoride was further sorbed into the amorphous calcium phosphate that precipitated the entire amount of phosphate until breakthrough. The simultaneous removal of sulfate in the earlier stage was followed by significant removal of nitrate in exchange with the gradual release of sulfate. This behavior was explained by the co-precipitation of sulfate with calcium phosphate or calcium aluminate solids and the subsequent substitution of nitrate for the interlayer sulfate of monosulfate. However, the overall removal capacity of cement paste was reduced due to the high effluent loss of calcium and competition for calcium between fluoride and phosphate.     

Stressor identification and health assessment of fish exposed to wastewater effluents in Miho Stream, South Korea

This study evaluated the effects of an industrial wastewater treatment plant (IWTP) and a municipal wastewater treatment plant (MWTP) effluents on a variety of bioindicators ranging from biochemical, organism, and population-level responses in pale chub (Zacco platypus) and fish community structure. The Index of Biotic Integrity (IBI) indicated that the site upstream of these wastewater treatment plant discharges is in fair–good condition and downstream of the plant is in poor condition. The EROD (ethoxyresorufin-O-deethylase) activity, condition factor, and liver somatic index were significantly increased at the downstream site compared to those of the upstream site. The most significant change observed in pale chub population in the downstream site of the Miho Stream, relative to the upstream population, was the total absence of an younger age group. Stressors impacting the downstream site were identified as mostly organic or nutrient enrichment and habitat degradation associated with wastewater treatment plants. The results of causal analysis suggest that the primary causes affecting fish population in the downstream site are through both size-selective mortality caused by ammonia toxicity and recruitment failure caused by habitat degradation and reproduction problem due to an IWTP and MWTP effluents.     

Identification of barley genotypes with low grain Cd accumulation and its interaction with four microelements

The variation in grain cadmium (Cd) concentrations was evaluated among 600 barley genotypes grown in the same field condition to select low Cd accumulating genotypes. The results showed that there is considerable genotypic variation in grain Cd concentrations in barley grain samples, with the mean concentration of 0.16 mg kg(-1) DW and the variation of 0 (not detected) to 1.21 mg kg(-1) DW, and 47.2% of the grain samples exceeded the maximum permissible concentration (MPC) for Cd in cereal grains. In addition, differences between genotypes over the two years were fairly consistent, and Beitalys and Shang 98-128 showed the lowest grain Cd concentration, being 97.5% lower than that in the two highest Cd accumulators E-barley 6 and Zhenong 8 in the second harvest year. The great genotypic differences in Cd concentrations indicated that it is possible to lower Cd content of barley through cultivar selection and breeding for use at sites where Cd concentration in grain exceeds the MPC. Significant genotypic difference was also found in microelement concentrations. Correlation analysis showed that only Mn accumulation is synergetic with Cd accumulation, despite slightly positive relationship between Cd and Zn, Cu, or Fe in accumulation in barley grains.     

Excess copper induced physiological and proteomic changes in germinating rice seeds

Copper is an essential micronutrient for plants. Present at a high concentration in soil, copper is also regarded as a major toxicant to plant cells due to its potential inhibitory effects against many physiological and biochemical processes. The interference of germination-related proteins by heavy metals has not been well documented at the proteomic level. In the current study, physiological, biochemical and proteomic changes of germinating rice seeds were investigated under copper stress. Germination rate, shoot elongation, plant biomass, and water content were decreased, whereas accumulation of copper and TBARS content in seeds were increased significantly with increasing copper concentrations from 0.2mM to 1.5mM followed by germination. The SDS-PAGE showed the preliminary changes in the polypeptides patterns under copper stress. Protein profiles analyzed by two-dimensional electrophoresis (2-DE) revealed that 25 protein spots were differentially expressed in copper-treated samples. Among them, 18 protein spots were up-regulated and 7 protein spots were down-regulated. These differentially displayed proteins were identified by MALDI-TOF mass spectrometry. The up-regulation of some antioxidant and stress-related proteins such as glyoxalase I, peroxiredoxin, aldose reductase, and some regulatory proteins such as DnaK-type molecular chaperone, UlpI protease, and receptor-like kinase clearly indicated that excess copper generates oxidative stress that might be disruptive to other important metabolic processes. Moreover, down-regulation of key metabolic enzymes like alpha-amylase or enolase revealed that the inhibition of seed germinations after exposure to excess copper not only affects starvation in water uptake by seeds but also results in failure in the reserve mobilization processes. These results indicate a good correlation between the physiological and biochemical changes in germinating rice seeds exposed to excess copper.     

Removal of Prussian blue from contaminated soil in the rhizosphere of cyanogenic plants

The fate of radiolabeled cyanide in soil was investigated during exposure to cyanogenic plant species, sorghum (Sorghum bicolor var. P721) and flax (Linum usitassimum var. Omega-Gold), in fully-contained growth chambers. Labeled cyanide was subject to microbial transformation, assimilation by plant roots, incorporation and biodegradation in plant tissue. For this study, (14)C-labeled cyanide was added to soil, and distribution of (14)C activity was assessed before plant establishment and after harvest. After 3 months of plant growth, 7% of the (14)C-labeled cyanide was converted to (14)CO(2) with sorghum and 6% with flax, compared with only 2% conversion in unplanted soil. A small amount of unaltered cyanide was shown to be accumulated by the plants (approximately 140 mg cyanide/kg plant or <0.1% of the total). Results from this experiment demonstrate the potential of cyanogenic plants for use in phytoremediation of cyanide-contaminated soil.     

N1923络合萃取丙酸的研究

分别以模拟和实际丙酸发酵废水体系为研究对象,采用络合萃取法回收稀溶液中的丙酸,结果表明,对含2%丙酸的水溶液,以45%(体积比)的N1923为萃取剂,以煤油和正辛醇为稀释剂进行萃取,在油水相比1∶4的情况下,单级萃取率可达97%.对实际发酵废水中丙酸的萃取,在二级错流萃取的情况下,也能达到同样的分离效果.有机溶剂循环使用实验表明,经过10次重复利用后其萃取能力基本不变.     

Enhanced biohydrogen generation from organic wastewater containing NH 4+ by phototrophic bacteria Rhodobacter sphaeroides AR-3

NH₄⁺ is typically an inhibitor to hydrogen production from organic wastewater by photo-bacteria. In this experiment, biohydrogen generation with wild-type anoxygenic phototrophic bacterium Rhodobacter sphaeroideswas found to be sensitive to NH₄⁺ due to the significant inhibition of NH₄⁺ to its nitrogenase. In order to avoid the inhibition of NH₄⁺ to biohydrogen generation by R. sphaeroides, a glutamine auxotrophic mutant R. sphaeroides AR-3 was obtained by mutagenizing with ethyl methane sulfonate. The AR-3 mutant could generate biohydrogen efficiently in the hydrogen production medium with a higher NH₄⁺ concentration, because the inhibition of NH₄⁺ to nitrogenase of AR-3 was released. Under suitable conditions, AR-3 effectively produced biohydrogen from tofu wastewater, which normally contains 50–60 mg/L NH₄⁺, with an average generation rate of 14.2 mL/L·h. This generation rate was increased by more than 100% compared with that from wild-type R. sphaeroides.