聚乙烯生产生命周期评价的研究

生命周期评价是一种对产品、生产工艺以及活动对环境的压力进行评价的客观过程。文章以我国东北某大型石化企业为案例,运用生命周期评价方法对聚乙烯生产生命周期中的环境协调性进行了研究,并对其污染物产生的环境影响潜值进行量化估算。评价结果表明:生产1t聚乙烯能源消耗为32.3×106kJ,环境影响负荷为701.9标准人当量。其中,轻烃、石脑油裂解及裂解气分离工序是释放污染物的最主要工序,光化学烟雾是最大的环境潜在影响,有必要采取措施降低聚乙烯生产过程中的环境负荷。     

基于融合权集对云的煤矿安全评价及应用*

为合理评价煤矿安全状态,针对煤矿安全影响因素多、指标体系关联度复杂等问题,提出融合权与集对云的安全评价模型。运用云理论特征值修饰集对分析联系度,兼顾系统的模糊性与不确定性,并引入融和后的各指标最优权重,得出系统综合云联系度;绘制等级云图判定系统安全状态及偏向趋势;结合煤矿实例进行验证。结果表明:案例煤矿所处安全状态为较安全,有偏向一般安全状态微势。分析结果与实际相符,且充分考虑煤矿安全评价体系的随机性,该模型可为煤矿安全评价提供理论指导。     

不同添加剂对聚氨酯泡沫材料阻燃性能的影响

为研究不同添加剂对聚氨酯泡沫材料阻燃性能的影响,对磷酸、硼酸、杨梅单宁阻燃剂3种添加剂处理后的聚氨酯泡沫材料与标准样分别测定氧指数、热值、烟密度等级和热稳定性,并以层次分析法评价阻燃性能优劣。结果表明:4种材料PUF STD、PUF PA、PUF BA、PUF FR的OI、CV依次分别为34.71%、38.59%、35.88%、37.86%,17.4023、16.7037、15.3197、15.0397kJ/g,燃烧时均少烟,热稳定性排序为:TS PA>TS STD>TS FR>TS BA;采用层次分析法分析3种添加剂对聚氨酯泡沫材料阻燃性能的影响顺序由优到劣为:PUF PA>PUF FR>PUF BA>PUF STD。该结论可为聚氨酯材料阻燃添加剂的选择提供参考方向。     

混凝土箱梁水化热温度损伤安全评价模型研究

目前混凝土箱梁0#块在施工过程中出现水化热温度冲击和裂缝现象,严重影响混凝土箱梁结构早期强度的形成以及结构的安全性能.综合考虑混凝土水化热温度荷载和弹模的时变效应,给出时域损伤函数;根据变权分析原理,确定敏感损伤和累积损伤,建立混凝土水化热温度损伤安全评价模型;对混凝土箱梁0#块水化热温度损伤进行三维数值仿真,总结水化热温度损伤时变效应规律,对早期含水化热温度损伤参数的混凝土箱梁结构安全性能进行分析评价.结果表明:混凝土水化热反应速率、水化热温差峰值与损伤速率敏感度、累积损伤敏感度同步.温差峰值过大、水化热反应速率过快,敏感损伤度和累积损伤度增大,安全指标降低,易形成温冲,产生裂缝,导致整体破坏.通过时域损伤函数和安全评价模型可及时分析计算混凝土箱梁0#块的安全指标,指导混凝土箱梁0#块安全施工.     

Role of the reduction site in the fluorinated or sulfated TiO2 photocatalytic process

In this article,the effects of TiO_2 surface fluorination and sulfation,on the active oxygen species formed at the reduction site in the photocatalytic process,namely O_2~(?) and H_2O_2,were investigated from a new perspective.The superoxide radical,(O_2~(?)),was determined by colorimetry of nitroblue tetrazolium,a prominent O_2~(?) scavenger.Hydrogen peroxide (H_2O_2) was estimated by using the iodide-starch method.In the naked TiO_2 photocatalysis,O_2~(?) though less reactive,was a very important intermediate.When the TiO_2 surface was fluorinated,more O_2~(?) and H_2O_2 were produced,which indicated that the surface modification could greatly reduce the recombination of photogenerated electrons and holes,thus enhancing the photocatalytic rate.In the sulfated system,photocatalysis proceeded with a more complicated mechanism.These results added support to the view of fluoride-induced enhancement and sulfide's nonappreciable inhibition effect.     

Arsenic uptake and transport of Pteris vittata L. as influenced by phosphate and inorganic arsenic species under sand cu｜ture

In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator, uptake and transport of arsenate (As(Ⅴ)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As(Ⅲ) more than As(Ⅴ), while the reverse was observed at high concentrations of phosphate (≥ 1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposure to As(Ⅴ); but the suppression of phosphate to As transport in the root or rhizome may be insignificant when P. vittata when exposure to As(Ⅲ) under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata.     

Phenotypic diversity in populations of the common blue butterfly <Emphasis Type="Italic">Polyommatus icarus</Emphasis> Rott. As a trend in the ecocenotic strategy of the species

Phenotypic diversity in populations of Polyommatus icarus Rott. (Lepidoptera, Lycaenidae) is regarded as a component of the ecocenotic strategy of the species, trends in which may serve as markers characterizing the state of natural populations.     

湘江株潭长段江水(枯水期）和沉积物中汞的分布和形态

湘江株潭长段江水中(枯水期)的总汞含量为(1.881 ±1.854)μg·L-1,以颗粒态汞为主.总汞和溶解态汞最大值都出现在霞湾,霞湾-湘潭段衰减快,此后缓慢衰减一直到洞庭湖.沉积物中总汞平均含量为0.846 mg·kg-1,处于高的污染水平,沉积物总汞的最大值也出现在霞湾,达到3.268 mg·kg-1.远远超过国...     

Forest soil CO2 fluxes as a function of understory removal and N-fixing species addition

We report on the effects of forest management practices of understory removal and N-fixing species (Cassia alata) addition on soil CO2 fluxes in an Eucalyptus urophylla plantation (EUp), Acacia crassicarpa plantation (ACp), 10-species-mixed plantation (Tp), and 30-species-mixed plantation (THp) using the static chamber method in southern China. Four forest management treatments, including (1) understory removal (UR); (2) C. alata addition (CA); (3) understory removal and replacement with C. alata (UR+CA); and (4) control without any disturbances (CK), were applied in the above four forest plantations with three replications for each treatment. The results showed that soil CO2 fluxes rates remained at a high level during the rainy season (from April to September), followed by a rapid decrease after October reaching a minimum in February. Soil CO2 fluxes were significantly higher (P < 0.01) in EUp (132.6 mg/(m2·hr)) and ACp (139.8 mg/(m2·hr)) than in Tp (94.0 mg/(m2·hr)) and THp (102.9 mg/(m2·hr)). Soil CO2 fluxes in UR and CA were significantly higher (P < 0.01) among the four treatments, with values of 105.7, 120.4, 133.6 and 112.2 mg/(m2·hr) for UR+CA, UR, CA and CK, respectively. Soil CO2 fluxes were positively correlated with soil temperature (P < 0.01), soil moisture (P < 0.01), NO3?-N (P < 0.05), and litterfall (P < 0.01), indicating that all these factors might be important controlling variables for soil CO2 fluxes. This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.     

综合权重-静态水量区域水质评价方法研究

建立了水质与静态水量、动态水资源量、社会经济和生态环境相结合的区域水环境质量综合权重评价新方法,即用动态水量权重、社会经济权重和生态环境权重之和作为综合权重,根据各个监测断面水质和该断面所代表的用综合权重加权后的静态量,以某类别水质的各监测断面代表的加权后的静态量之和占评价区域各类断面代表的加权后的静态水量总量分比来表...