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891.
Geological emission of methane from the Yakela condensed oil/gas field in
Talimu Basin, Xinjiang, China 总被引:1,自引:0,他引:1
A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p... 相似文献
892.
893.
湖南省雷电特征及闪电数据分析 总被引:1,自引:0,他引:1
湖南是雷暴多发区,雷暴分布是南多北少,西多东少。近35年地面雷暴观测数据显示,全省年平均雷暴数呈下降趋势。湖南闪电以负地闪为主,占总地闪的94.59%,平均闪电强度随着海拔高度的增加而加大,长沙、韶山为闪电强度低值中心。一天中13~20时是闪电高发期,正地闪的平均能量要大于负地闪。 相似文献
894.
This study aims to implement the empirical analysis of the effects of the adaptive measures on the income of herdsmen in the context of the climate change with the positive mathematical programming(PMP)model.The survey was first implemented in three counties in the Three Headwaters Region.Finally the measures and recommendations suitable for the economic development in the ecologically fragile areas were proposed.The main conclusions are as follows:priority can be given to the measures to prevent the damage from rats and the engineering measures for pasture maintenance in Zeku County,where the geological conditions and grass quality are inferior,while the fiscal subsidy can be prioritized in Tongde County where the grassland area is relatively less.These recommendations can not only provide good reference for the protection of grassland resources,but they also lay a foundation for the implementation of more suitable measures to help the herdsmen in the ecologically fragile areas to adapt to the climate change. 相似文献
895.
Development of Customized Fire Behavior Fuel Models for Boreal Forests of Northeastern China 总被引:3,自引:1,他引:2
Knowledge of forest fuels and their potential fire behavior across a landscape is essential in fire management. Four customized
fire behavior fuel models that differed significantly in fuels characteristics and environmental conditions were identified
using hierarchical cluster analysis based on fuels data collected across a boreal forest landscape in northeastern China.
Fuel model I represented the dense and heavily branched Pinus pumila shrubland which has significant fine live woody fuels. These forests occur mainly at higher mountain elevations. Fuel model
II is applicable to forests dominated by Betula platyphylla and Populus davidiana occurring in native forests on hill slopes or at low mountain elevations. This fuel model was differentiated from other fuel
models by higher herbaceous cover and lower fine live woody loading. The primary coniferous forests dominated by Larix gmelini and Pinus sylvestris L. var. mongolica were classified as fuel model III and fuel model IV. Those fuel models differed from one another in average cover and height
of understory shrub and herbaceous layers as well as in aspect. The potential fire behavior for each fuel model was simulated
with the BehavePlus5.0 fire behavior prediction system. The simulation results indicated that the Pinus pumila shrubland fuels had the most severe fire behavior for the 97th percentile weather condition, and had the least severe fire
behavior under 90th percentile weather condition. Fuel model II presented the least severe fire potential across weather conditions.
Fuel model IV resulted in greater fire severity than Fuel model III across the two weather scenarios that were examined. 相似文献
896.
Huei-Jen Tseng Ren-Chung Cheng Sheng-Hai Wu Sean J. Blamires I-Min Tso 《Behavioral ecology and sociobiology》2011,65(12):2351-2359
Animals may build multiple structures to provide benefits to counter the costs of building. Many orb web spiders add multiple
structures, e.g., barricading barrier webs and silk decorations, to their webs and these structures have been hypothesized
to function to deter predators or attract prey. The heavily armored spiny spiders construct barrier webs around their orb
webs and decorate them with conspicuous silk tufts. Why these organisms, already well protected by a thick cuticle and spines,
make the extra investment of building barrier webs and adding conspicuous silk decorations is not known. We predicted that
these structures function to both attract prey and deter predators. Field experiments were conducted in two consecutive years
using orb webs built by the East Asian spiny spider Thelacantha brevispina. We either (1) concealed the decoration, (2) removed the barrier webs, or (3) left the decorations and barrier webs intact.
We found year and treatment to interactively influence prey interception rates. In 2010, but not in 2009, we found prey interception
with T. brevispina webs to be greater when the decorations were conspicuous than when they were concealed suggesting that the decorations may
lure prey. Prey interception was lower when the barrier webs were present without decorations compared to when they were absent
without decorations. The prey-attracting function of the decorations thus may counter the reduction in prey interception incurred
by adding a barrier web. Predatory wasp interactions were not influenced by any of our treatments, probably because the spiders’
thick cuticle is the primary means of protection from wasps. Bird predation events, while rare, occurred only when decorations
were concealed or the barrier webs were removed. It is therefore plausible that the tuft decorations both lure prey and deter
birds. 相似文献
897.
898.
Tao X Tang C Wu P Han Z Zhang C Zhang Y 《Journal of environmental monitoring : JEM》2011,13(11):3269-3276
Occurrence, variation and behaviour of nonylphenol (NP) and octylphenol (OP) were studied in surface water and groundwater in Guiyang, Guizhou Province, southwestern China. Discharge of wastewater from Guiyang City was the main source of alkylphenols (APs) entering the aquatic environment. The concentrations of NP and OP in river water ranged from 40 to 1582 ng L(-1) and from below the lowest limit of detection (LOD) to 67 ng L(-1), respectively. NP and OP were also detected in groundwater. Both NP and OP exhibited spatial and temporal variations in river water and groundwater. It was found that concentrations of NP and OP in river water was low upstream and dramatically increased downstream, and higher concentration of NP was found in winter compared to that in summer. Proportions of NP and OP were trapped by suspended particulate matter (SPM), which accounted for 7.6-50.0% and 3.4-25.6% of their total concentration in the river water system, respectively. Seasonal changes in water flow were responsible for the temporal variations of APs. To determine the behaviour of APs along the river, a mass balance equation based on chloride was used. The results showed that a mixing process was the predominant factor to determine upstream APs concentrations; while the discharge of wastewater controlled the concentrations of APs downstream. Considering the adverse effect of APs on organisms, combined effect modeling was used to assess the toxicity to fish. It was found that the predicted mixture effect for APs in river water on fish vitellogenin induction was low upstream and medium downstream, respectively. 相似文献
899.
Peng G Wang X Wu Z Wang Z Yang L Zhong L Chen D 《Journal of environmental monitoring : JEM》2011,13(7):1927-1934
Two-year monitoring data (2006 and 2009), collected at the sub-urban site (WQS) and the background site (TH), were used to study the characteristics of Particulate Matter (PM) pollution in the Pearl River Delta region, China. Similar levels of PM(2.5) concentration measured at both sites seem to confirm that the fine particles have emerged as a major regional pollution issue. The seasonal variation of PM(2.5) concentration is associated with the regional monsoon circulations while the diurnal variation is related to land-sea breeze, traffic emissions and boundary layer development. Negative correlation was found in PM(2.5)-wind speed and PM(2.5)-humidity. Analysis of radiation, temperature and ozone suggests the existence of secondary aerosol formation. Transport effect may be another contributing factor to high PM pollution in the region, such as occasional long-distance dust intrusion and trans-boundary effects from upwind areas. 相似文献
900.