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871.
Saproxylic (dead-wood-associated) and old-growth species are among the most threatened species in European forest ecosystems, as they are susceptible to intensive forest management. Identifying areas with particular relevant features of biodiversity is of prime concern when developing species conservation and habitat restoration strategies and in optimizing resource investments. We present an approach to identify regional conservation and restoration priorities even if knowledge on species distribution is weak, such as for saproxylic and old-growth species in Switzerland. Habitat suitability maps were modeled for an expert-based selection of 55 focal species, using an ecological niche factor analyses (ENFA). All the maps were then overlaid, in order to identify potential species’ hotspots for different species groups of the 55 focal species (e.g., birds, fungi, red-listed species). We found that hotspots for various species groups did not correspond. Our results indicate that an approach based on “richness hotspots” may fail to conserve specific species groups. We hence recommend defining a biodiversity conservation strategy prior to implementing conservation/restoration efforts in specific regions. The conservation priority setting of the five biogeographical regions in Switzerland, however, did not differ when different hotspot definitions were applied. This observation emphasizes that the chosen method is robust. Since the ENFA needs only presence data, this species prediction method seems to be useful for any situation where the species distribution is poorly known and/or absence data are lacking. In order to identify priorities for either conservation or restoration efforts, we recommend a method based on presence data only, because absence data may reflect factors unrelated to species presence.  相似文献   
872.
作为一项市场创新和政策创新,即将启动的中国全国性碳市场备受国内外关注。为保证其成功建立与平稳发展,相关经验借鉴已刻不容缓,但作为投石问路的7大试点碳市场发展层次不齐,可供参考的模式有限,因此研究全球第一大碳市场——欧盟碳排放交易体系(EU ETS)及其对中国的可参照性尤为迫切;而作为市场是否成熟的风向标,碳价规律性特征的挖掘尤为重要。前期国内外学者分别发现CER价格、原油价格、煤炭价格、天然气价格、欧洲工业指数、联合国气候变化大会、政府政策、极寒天气、暖冬天气、自然灾害、重大事件等多种因素都有可能引起EUA期货价格波动。本研究通过引入MIV-BP神经网络模型,对EU ETS二期和三期的EUA期货价格进行训练和测试,模拟了上述11个因素对EUA价格的影响,弥补了传统计量模型难以同时处理较多变量及不能整合定性与定量变量等缺点。通过对EU ETS二期1 149组和三期775组数据的挖掘,得出了各变量对EUA期货价格的影响程度。其中,二期运行阶段各变量影响程度从大到小排序为:自然灾害COPCER极寒天气Coal重大事件Brent政府政策Stock600Gas暖冬天气;三期运行阶段各变量影响程度从大到小排序为:COPStock600Coal自然灾害极寒天气重大事件政府政策BrentGasCER暖冬天气。最后,本研究对二、三期各变量对碳价影响程度的变化进行了解释,并对中国未来建立全国性碳市场提出了以下四点建议:(1)稳定碳市场参与主体预期;(2)完善核证减排抵消机制,保持政策稳定;(3)配额分配考虑区域差异;(4)建立配额应急机制。  相似文献   
873.
介绍木制品加工过程中的危险、有害因素,分析木工机械引发事故的原因,提出一些预防事故发生的措施.  相似文献   
874.
目的 研究铝合金大气腐蚀受自然环境因素的影响性,探索环境因素对铝合金腐蚀的影响规律。方法 采用多层感知器神经网络分析环境因素对7种铝合金平均腐蚀速率的影响。结果 确定了影响铝合金腐蚀损伤的重要因素为SO2沉积率、Cl沉积率、NOx沉积率;辅要因素为年降雨量、年雾露时数、相对湿度、年日照时数、温度、铝合金成分;次要因素为年累积降水时数、雨水pH值。结论 基于多层感知器神经网络分析有效展现了环境因素对平均腐蚀速率的影响性。  相似文献   
875.
Performance of compacted clay liners commonly used as landfill barrier systems can be subject to decline in terms of hydraulic conductivity if left exposed to atmospheric conditions for an extended period of time prior to placement of overlaying layers. The resulting desiccation cracking can lead to increased hydraulic conductivity. Desiccation crack intensity was studied for three clayey soils commonly used for construction of landfill barrier system in a relatively large scale test setup exposed to real time atmospheric conditions over a complete annual cycle. A white separator geotextile cover was presumed to be capable of reducing the intensity of desiccation cracking through absorbing and maintaining higher amounts of moisture and reducing the temperature of the soil surface in comparison to a directly exposed soil surface. Desiccation cracking was monitored using a digital imaging technique for three compacted clay liners in two sets, one open to air and the second covered with the white geotextile. Crack intensity factor approached a relatively stable phase after certain cycles corresponding to atmospheric dry wet cycles. The results indicated that the white separator geotextile was capable of reducing the crack intensity factor by 37.4–45.9% throughout the experiment including the cyclic phase of desiccation cracking. During the stable phase, the maximum reduction in crack intensity factor of 90.4% as a result of applying geotextile cover was observed for the soil with the lowest plastic index and clay content and therefore the lowest magnitude of crack intensity factor. The other two soils with similar clay content but different plastic index showed 23.6% and 52.2% reductions in crack intensity factor after cyclic phase when covered with geotextile.  相似文献   
876.
This study aims to investigate the impact of eco-friendly technology on environmental degradation indicated using the load capacity factor (LCF) with the framework of the Load Capacity Curve (LCC) hypothesis. In this regard, an environmental degradation function is formed and analyzed using the Augmented Autoregressive Distributed Lag (AARDL) approach during the period spanning from 1975 to 2021 for India. The outcome indicates that eco-friendly technology reduces the LCF, thereby fostering environmental degradation in the long run, but the relationship is not significant in the short run. Further, an N-shaped LCC hypothesis has been observed in both long and short runs. Besides, energy consumption exhibits a LCF reducing or environmental degradation boosting role in the short run and long run. These findings are consistent with other models that are used to check the robustness of AARDL-based results. Thus, the study recommends policies for promoting eco-friendly technology, judicious economic growth, and cautious energy consumption to attain sustainable development by increasing the LCF in India.  相似文献   
877.
To study the emission characteristics of typical construction machinery in Chengdu, 12 construction machinery (excavators, bulldozers, loaders, and forklifts) under idling mode, moving mode, and working mode, were tested using a portable emission measurement system (PEMS). Under three operating modes, the typical construction machinery in the working mode was higher in the fuel-based average emission factors of PM2.5 and NOx, while the fuel-based average emission factors of HC and CO were higher in idling mode. Integrated the results of investigation on ownership and activity levels of construction machinery, an exhaust emission inventory of typical construction machinery of Chengdu in 2018 was established according to the recommendation method. The annual emission of PM2.5, NOx, HC, and CO were 1.67 × 106, 1.61 × 108, 3.83 × 106, and 1.26 × 107 kg, respectively, and the excavator contributed the maximum emissions, accounting for an average proportion of 43.95%. The emission of construction machinery in Chengdu exhibited a clear monthly trend, with the highest from April to October and the lowest from November to March. In addition, the exhaust emissions presented an obvious spot-like characteristics, and the high-value areas were mainly concentrated in the surrounding suburban counties such as Shuangliu Wenjiang etc. To reduce pollution from construction machinery and improve the quality of the atmospheric environment, more effective measures on housing construction and municipal construction should be taken in those districts in Chengdu.  相似文献   
878.
通过危险度评价法与蒙德法评分项目的比较分析,得出危险度评价法中的压力、温度和操作参数,反映在蒙德法中,表现为特殊工艺危险性的评分项,这表明利用简单、直观的危险度评价法,在一定程度上,可以表征复杂单元的危险性大小,且与蒙德法的评价相一致.以焦化装置为例子,首先只针对压力、温度和操作三个参数,运用两种评价法分别进行评价,得出的结论相一致,验证了上述结论;然后分别用两种方法对焦化装置进行评价,分析对比结果,危险度评价法在参数选取和运行中,更加简单直观,可以为蒙德法提供装置各单元危险性高低的依据并缩小评价的范围.蒙德法是危险度评价的拓展与延伸,它将危险度评价法得出的危险性高的单元,更深入的找出导致危险性高的原因与参数.  相似文献   
879.
Abstract

Bioaccumulation kinetics and bioconcentration factor (BCF) of chlorinated pesticides like Aldrin, Dieldrin, Benzene hexachloride (BHC), and Dichloro-diphenyl-dichloro-ethane (DDT) in fish tissues of Puntius ticto was studied in detail in a continuous fed system. The bioconcentration process is summarized by using a first order uptake model and the steady-state BCF is calculated based on the 30 days exposure. Rate of bioaccumulation of DDT was maximum of 4.6432 µg g?1 wet weight per day in liver tissue whereas it was minimum of 0.0002 µg g?1 wet weight per day in case of Dieldrin in the muscle tissue among the pesticides. It was observed that DDT showed maximum BCF of 89,010 in case of liver tissue of the fish exposed to 30 days. The regression coefficient (r 2) between pesticide concentration and exposure time varied between 0.6212 and 0.9817 indicating high correlation. Based on actual calculated BCF values, the octanol–water partition coefficient (K ow) values were predicted. In order to prove the hydrophobic property of chlorinated compounds and its affinity towards lipid, the K ow is predicted. Results showed that pesticide burden differ from tissue to tissue and can be correlated to the lipid content, size, exposure time, and species.  相似文献   
880.
韦丽萍  冯建舫 《环境化学》1998,17(5):457-461
本文测定了甲黄隆,氯黄隆,苄嘧黄隆及其主要降解产物取代磺胺和取代氮杂环化合物的辛醇-水分配系数,研究了反相高效液相色谱容量因子、分子连接性指数、Leo碎片常数与分配系数间的相关关系,从而建立了估算磺酰类除草剂及其降解产物的疏水性方程。  相似文献   
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