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51.
对京津区域1980-1992年间能源利用状况进行分析,并通过模式计算该区域大气污染物的扩散规律,结果表明,大气污染物随能源利用增加而增加,其增加速率NOx大于OS2,经预测,至2004年京津地区SO2排放量增咖11.40%,NOx增加56.80%,由于气象和地形条件所致,该区域内不利于大气污染物远距离输送,这使箱型区域内物料平衡计算可以简化。 相似文献
52.
Numerous studies support that biodiversity predict most to ecosystem functioning, but whether other factors display a more significant direct impact on ecosystem functioning than biodiversity remains to be studied. We investigated 398 samples of the phytoplankton phosphorus resource use efficiency (RUEP = chlorophyll-a concentration/dissolved phosphate) across two seasons in nine plateau lakes in Yunnan Province, China. We identified the main contributors to phytoplankton RUEP and analyzed their potential influences on RUEP at different lake trophic states. The results showed that total nitrogen (TN) contributed the most to RUEP among the nine lakes, whereas community turnover (measured as community dissimilarity) explained the most to RUEP variation across the two seasons. Moreover, TN also influenced RUEP by affecting biodiversity. Species richness (SR), functional attribute diversity (FAD2), and dendrogram-based functional diversity (FDc) were positively correlated with RUEP in both seasons, while evenness was negatively correlated with RUEP at the end of the rainy season. We also found that the effects of biodiversity and turnover on RUEP depended on the lake trophic states. SR and FAD2 were positively correlated with RUEP in all three trophic states. Evenness showed a negative correlation with RUEP at the eutrophic and oligotrophic levels, but a positive correlation at the mesotrophic level. Turnover had a negative influence on RUEP at the eutrophic level, but a positive influence at the mesotrophic and oligotrophic levels. Overall, our results suggested that multiple factors and nutrient states need to be considered when the ecosystem functioning predictors and the biodiversity-ecosystem functioning relationships are investigated. 相似文献
53.
在世界矿物能源资源日趋减少的今天,再生能源资源引起人们广泛的兴趣,特别是陆地再生能源资源更是如此。本文对我国陆地再生能源资源——太阳能、风能、水能、生物质能——中的前两种能源资源进行了分区及分省计算,并依据全国已有的调查及普查资料,对后两种源能资源进行了分省及分区统计,在此基础上又对全国陆地再生能源资源的数量、分布及特征进行了对比分析,并从宏观上提出了开发利用我国陆地再生能源资源的建议和设想。 相似文献
54.
3种活性污泥法处理工艺的生命周期能耗分析 总被引:7,自引:0,他引:7
运用LCA方法对普通活性污泥法、AB活性污泥法和厌氧水解-活性污泥法3种处理系统从其原材料开采和加工开始直至污水厂施工建设、处理运行以及废弃拆除的LC全过程能耗进行了识别和量化分析,并进行相互比较。研究结果表明,在微孔和穿孔管2种曝气条件下与普通活性污泥法相比,厌氧水解法的LC能耗分别省节14.0%和17.6%,并且比能耗可大幅降低40.5%-43.0%。AB法的LC能耗分别节省9.5%和15.8%,但由于产泥量较大而比能耗仅与普通活性污泥法相当。 相似文献
55.
Rob H.G.Jongman 《环境科学学报(英文版)》2003,15(2):173-181
The paper gives an overview of approaches towards ecological networks throughout Europe.It does not intend to present a complete picture,but to highlight comon developments within countries and regions and show common principles and differences between countries and regions that have to be taken into account when developing a joint European intiative,Countries or regions that have not been included can be active in the same way ,but information was not accessible to be authors for different reasons.This overview shows the comparable trends in decline of landscapes and the diversity in approaches to biodiversity conservation and nature conservation planning.Understanding the differences and common issues are of utmost imprtance to generalise common principles and to understand the way neighbours and other European partners approach problems. 相似文献
56.
The influence of source and timing of nitrogen fertilizers on yield and nitrogen use efficiency of four sweet potato cultivars 总被引:2,自引:0,他引:2
R. O. Ankumah V. Khan K. Mwamba K. Kpomblekou-A 《Agriculture, ecosystems & environment》2003,100(2-3):201
Nitrogen (N) availability is a very important determinant of crop yield. It is also one of the most expensive inputs in crop production. Thus, the efficient management of N by farmers with limited resource is a very important part of successful soil and crop management system. A field study was conducted on a Norfolk sandy loam soil at the George Washington Carver Agricultural Experiment Station, Tuskegee, AL, to evaluate the influence of fertilizer source and timing on the yield of four sweet potato [Ipomoea batatas (L.)] cultivars. Two N sources (urea, CO(NH2)2 and ammonium nitrate, NH4NO3), four sweet potato cultivars (‘Georgia Jet’, GA-Jet; ‘TU-82-155’, TU-155; ‘TU-1892’; and ‘Rojo Blanco’, Rojo-Bl) and three times (zero, single, and split applications) were used in a factorial designed experiment. Plants were harvested after 80 and 120 days and total and marketable yields determined. Nitrogen recovery efficiency, yield efficiency and physiological efficiency were also determined. Total and marketable yields of early maturing cultivars were significantly higher than of late maturing cultivars (P<0.05). The single application of N resulted in significantly higher yield in storage roots than split application (P<0.05). Physiological efficiency values were highly correlated with total marketable yields. Recovery rates increased with time. Late maturing cultivars tended to have higher N recovery and physiological efficiency than early maturing cultivars. These results suggest that cultivar maturity group should play an important part in N fertilization recommendations for sweet potato. 相似文献
57.
陡坡地灌桑垄槽栽培研究结果,免除土壤侵蚀的危害,其50cm、100cm土壤中,比对照区持水量高10.20%~33.67%、8.27%~65.37%,含全氮率为对照的90%,含全磷率高2.9%、26.2%,含全钾率高3.18%、8.01%,而水解氮均为对照的61.5%,速效磷高较对照39.02%、97.72%,速效钾为对照的91.48%、92.54%。公顷产桑叶量和蚕茧量均较对照高5~10倍,经济效益较对照高11.88倍。 相似文献
58.
介绍了放射性废物微波真空干燥处理器的微波漏能现状及所采取的防护措施。监测结果表明,经过防护,有效地减弱了设备的微波漏能,达到了国家防护标准。 相似文献
59.
城市土地利用下的植物物种资源特征分析 总被引:14,自引:0,他引:14
根据对前联邦德国卡尔斯鲁厄市城市自生植被的调查资料,分析了城市植物区系的特征及其与人类活动影响的关系。结论为:①城市植物区系在优势科组成和生态特征方面与其所在地区自然植被明显不同,并在城市之间表现出较大的相似性;②人类活动和城市热岛效应对城市植物区系及其生态特征的作用明显;③城市土地利用和城市绿地管理对许多物种的生存构成威胁 相似文献
60.