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671.
高层建筑防烟楼梯间正压值与门洞风速试验及分析 总被引:3,自引:0,他引:3
对一座 32层综合性高层建筑的楼梯间与前室的机械加压送风系统进行现场试验 ,测定了几种不同工况下楼梯间、前室的正压值、门洞风速、送风机风量、加压送风口风速、系统的阻力损失等参数。笔者着重分析了正压值和门洞风速的试验结果 ,试验暴露了加压送风系统设计、验收、防排烟产品质量等存在许多问题 ,亟待解决。同时也发现了《高规》条文中存在某些不完善之处。试验表明 ,高层建筑防烟楼梯间及前室的加压送风系统如果设计不当 ,火灾时 ,不仅不能起到保证人员安全逃生的作用 ,甚至可能成为严重的安全隐患 相似文献
672.
在实验室条件下研究了西维因对罗非鱼的急性毒性以及在不同暴露浓度下的西维因(0.064,0.8和5mg·L-1)对雄性罗非鱼性腺系数、血清雌二醇、睾酮含量的影响以及对卵黄蛋白原的诱导效应,以期对其环境雌激素效应研究有所贡献。结果表明:西维因对罗非鱼的24、48、72和96h的LC50分别为30.21、25.16、19.76和17.86mg·L-1。长期暴露于低剂量的西维因中,会使雄性罗非鱼精巢系数降低;对其血清雌二醇的合成具有诱导作用,当浓度为0.8mg·L-1时,诱导作用最强,此时血清雌二醇的含量为218.83pg·mL-1;卵黄蛋白原的含量随着西维因浓度的升高,逐渐增多,当处理浓度为5mg·L-1时,达到最大为393.01μg·L-1;随着西维因浓度的升高,睾酮含量逐渐降低,西维因的浓度为5mg·L-1时,睾酮含量达到10.58mol·L-1,差异极显著(p<0.01),这可能是由于西维因对雄性罗非鱼具有雌激素效应。 相似文献
673.
Wenzhen LI Yu DING Qian SUI Shuguang LU Zhaofu QIU Kuangfei LIN 《Frontiers of Environmental Science & Engineering》2012,6(4):445-454
The aim of this study was to identify the intermediates in clofibric acid degradation under various advanced oxidation processes, namely ultraviolet (UV), UV/H2O2, vacuum ultraviolet (VUV), VUV/H2O2, and solar/TiO2 processes, as well as to assess the toxicity of these intermediates. Eleven intermediates have been detected by gas chromatography-mass spectrometer, most of which were reported for the first time to our best knowledge. Combining the evolution of the dissolved organic carbon, Cl- and specific ultraviolet absorption at 254 nm, it could be deduced that cleavage of aromatic ring followed by dechlorination was the mechanism in solar/TiO2 process, while dechlorination happened first and accumulation of aromatic intermediates occurred in the other processes. Different transformation pathways were proposed for UV-, VUV-assisted and solar/TiO2 processes, respectively. The acute toxicity was evaluated by means of Photobacterium phosphoreum T3 spp. bioassay. It was believed that aromatic intermediates increased the toxicity and the ring-opening pathway in solar/TiO2 process could relieve the toxicity. 相似文献
674.
A Lagrangian module has been developed and coupled with the 3D circulation model Symphonie to study the influence of hydrodynamic processes on zooplankton transport and distributions in the North Western Mediterranean (NWM). Individuals are released every 3 days from March to August 2001 in two initial areas: around the DYFAMED sampling station in the central Ligurian Sea and in the Rhône river plume. Then the individuals are tracked for 40 days either as passive particles or with a simple diel vertical migration (DVM) pattern. The simulations suggest strong seasonal patterns in the distributions of the individuals released around the DYFAMED sampling station. Individuals spread all over the NWM basin after 40 days but different patterns occur depending on the season, the initial depths of release and the capacity of DVM. Offshore-shelf transport only occurs in April and May with particles ending up in the Gulf of Lions (GoL) in low concentrations. In other months, the Northern Current (NC) can be considered as a barrier for particles entering the GoL from the offshore sea. A quarter to a half of passive individuals released in the Rhône river plume remain in the GoL. The rest is transported by the NC towards the Catalan Sea. Applying a simple DVM scheme does not increase the retention of particles on the shelf. 相似文献
675.
Perfluorinated compounds (PFCs) are ubiquitously distributed in the environment mainly as perfluoro-carboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFASs). In this paper, six PFCAs and two PFASs were quantified in surface and tap water samples from 12 sites around Lake Taihu near Shanghai City in East China. Predominant PFCs were perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), of which the concentration ranges were 6.8–206 and 1.2–45 ng·L−1, the geometric means were 35.3 and 9.4 ng·L−1, and the median (quartile range) values were 31.4 (34.4) and 10.4 (10.7) ng·L−1, respectively. Other PFCs were also detected but in much lower concentrations than PFOA. The sources of the PFCs were expected to be direct industrial discharges in the Lake Taihu area, and this area was also a possible source of PFCs contaminations in Shanghai district in the downstream. PFCs distributions were found different in the upstream, downstream and north part of Lake Taihu. Occurrences of PFCs in the tap water in Lake Taihu area indicated their exposure to the local people. A brief estimation of the environmental risks by PFCs implied no acute or immediate risks from PFCs to local human health, but chronic risks from PFOA in the tap water should be considered in the downstream regions. 相似文献
676.
Phosphorus (P) sediment sorption is regarded as the most important buffering process against P increases in overlying water. In this study, two shallow eutrophic sediments (Mei and Hua) with distinct compositions were selected to assess effects of pH (from 6 to 9) and ionic strength (IS) (0, 0.001, 0.01 and 0.1 M KCl) on P sorption. In Mei sediments, the P sorption decreased as pH increased (6.97–9.13), but it increased as IS increased over the pH range in question. These results could be attributed to the negatively charged surface of Mei sediments, as indicated by the salt titration curve, and the high cation exchange capacity (CEC). P sorption in Hua sediments was facilitated by a pH increase (6.12–7.49), but it was hindered by an IS increase. A reasonable explanation for this phenomenon is that calcium phosphate precipitates at high pHs and that Cl? exchanges with P because the surface is weakly charged (small CEC). These results indicate that the sediment P sorption may have trends opposite to one another in relation to the salt change (e.g. drought and rainy season) in the lake water between the two sediments. These data provide additional support to explain P concentration variations in lakes. 相似文献
677.
Yulu Qiu Zhiqiang Ma Weili Lin Weijun Quan Weiwei Pu Yingruo Li Liyan Zhou Qingfeng Shi 《Frontiers of Environmental Science & Engineering》2020,14(4):71
678.
Assessing Critical Source Areas in Watersheds for Conservation Buffer Planning and Riparian Restoration 总被引:2,自引:0,他引:2
Zeyuan Qiu 《Environmental management》2009,44(5):968-980
A science-based geographic information system (GIS) approach is presented to target critical source areas in watersheds for
conservation buffer placement. Critical source areas are the intersection of hydrologically sensitive areas and pollutant
source areas in watersheds. Hydrologically sensitive areas are areas that actively generate runoff in the watershed and are
derived using a modified topographic index approach based on variable source area hydrology. Pollutant source areas are the
areas in watersheds that are actively and intensively used for such activities as agricultural production. The method is applied
to the Neshanic River watershed in Hunterdon County, New Jersey. The capacity of the topographic index in predicting the spatial
pattern of runoff generation and the runoff contribution to stream flow in the watershed is evaluated. A simple cost-effectiveness
assessment is conducted to compare the conservation buffer placement scenario based on this GIS method to conventional riparian
buffer scenarios for placing conservation buffers in agricultural lands in the watershed. The results show that the topographic
index reasonably predicts the runoff generation in the watershed. The GIS-based conservation buffer scenario appears to be
more cost-effective than the conventional riparian buffer scenarios. 相似文献
679.
680.
本文分析了我国绿色包装的发展现状和面临的困境,提出必须从环境保护、循环经济、绿色市场和技术进步等方面推动绿色包装,实现包装业可持续发展。 相似文献