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排序方式: 共有497条查询结果,搜索用时 45 毫秒
1.
Eco-Environmental Degradation in the Source Region of the Yellow River, Northeast Qinghai-Xizang Plateau 总被引:4,自引:0,他引:4
The Yellow River is the second longest river in China and the cradle of the Chinese civilization. The source region of the Yellow River is the most important water holding area for the Yellow River, about 49.2% of the whole runoff comes from this region. However, for the special location, it is a region with most fragile eco-environment in China as well. Eco-environmental degradation in the source region of the Yellow River has been a very serious ecological and socially economic problem. According to census data, historical documents and climatic information, during the last half century, especially the last 30 years, great changes have taken place in the eco-environment of this region. Such changes are mainly manifested in the temporal-spatial changes of water environment, deglaciation, permafrost reduction, vegetation degeneracy and desertification extent, which led to land capacity decreasing and river disconnecting. At present, desertification of the region is showing an accelerating tendency. This paper analyzes the present status of eco-environment degradation in this region supported by GIS and RS, as well as field investigation and indoor analysis, based on knowledge, multi-source data is gathered and the classification is worked out, deals with their natural and anthropogenic causes, and points out that in the last half century the desertification and environmental degradation of this region are mainly attributed to human activities under the background of regional climate changes. To halt further degradation of the environment of this region, great efforts should be made to use land resources rationally, develop advantages animal agriculture and protect the natural grassland. 相似文献
2.
对武钢第一炼钢厂100t转炉OG系统设备存在的问题进行了分析、研究,结合生产实际进行了一系列的技术改进和工艺参数调整,提高了OG系统效率。 相似文献
3.
为了应对日趋严苛的废水TN排放标准要求,试验采用溴百里酚蓝(BTB)培养基,从某煤化工废水处理厂反硝化缺氧池活性污泥中,经多次分离、纯化获得了一株高效兼性厌氧反硝化菌株HK13.通过形态观察及16S rRNA基因序列分析,菌株HK13被鉴定为施氏假单胞菌属(Pseudomonas stutzeri).在此基础上,利用含硝酸盐模拟废水,探讨了碳源类型、C/N(碳氮比)、初始pH、溶解氧(以不同摇床转速表征不同浓度的溶解氧)和培养温度对菌株HK13反硝化脱氮能力的影响,确定了该菌株的最优生长条件和最大脱氮效率.结果表明:①菌株HK13最适反硝化脱氮条件为以柠檬酸钠碳源,C/N 8,培养温度35℃,初始pH 8~10,摇床转速100 r/min.②初始ρ(NO3--N)为106.67 mg/L下,反应12 h后菌株HK13对TN的去除率可达92.62%;反应9~12 h时,该菌株的脱氮速率最高,可达20.03 mg/(L·h),其16 h的脱氮率在98%以上,且无亚硝酸盐积累.③菌株HK13适宜生长的温度和pH范围广泛,分别为20~40℃和7~10.研究显示,菌株HK13具有快速高效的脱氮能力及嗜碱特性,拓宽了生物脱氮工艺对环境条件的适用范围,在废水脱氮领域具有广泛的应用前景. 相似文献
5.
Ji Hu Jianmin Wang Shuxia Liu Zhechao Zhang Haifeng Zhang Xiaoxia Cai Jianming Pan Jingjing Liu 《环境科学学报(英文版)》2018,30(4):208-215
TiO_2 nanoparticles(NPs) could adversely impact aquatic ecosystems. However, the aggregation of these NPs could attenuate this effect. In this work, the biological effects of TiO_2 NPs on a marine microalgae Isochrysis galbana were investigated. The aggregation kinetics of TiO_2 NPs under different conditions was also investigated to determine and understand these effects. Results showed that, though TiO_2 NPs had no obvious impact on the size and reproducibility of algal cells under testing conditions, they caused a negative effect on algal chlorophyll, which led to a reduction in photosynthesis. Furthermore, fast aggregation of TiO_2 NPs occurred under all conditions, especially at the pH close to the p Hzpc. Increasing ionic strength and NP concentration also enhanced the aggregation rate.The aggregation and the following sedimentation of TiO_2 NPs reduced their adverse effects on I. galbana. 相似文献
6.
检验环境影响预测准确度统计方法的研究近况 总被引:2,自引:0,他引:2
开展环境影响评价工作近二十年来,国内外对预测结果准确度的检验尚无制定统一标准,而预测结果的准确与否,又直接影响到环境影响报告书的质量。为此,本文将国内外这方面的研究状况作以评论,以供从事环境影响评价和后评估的专业人员参考 相似文献
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8.
Gong Peiyu Li Xiuzhen Wu Kunjun Shu Jianmin Cao Hongfa Institute of Zookogy Academia Sinica Beijing ChinaInstitute of Zookogy Chinese Research Academy of Environmental Science Beijing China 《环境科学学报(英文版)》1990,(4)
This paper deals with effects of airborne fluorine on the army worm, Mythimna separata (Walker), by rearing the larvae on the wheat foliage exposed to HF or fumigating the larvae on the artificial diet with the pollutant. Larval relative growth rate (GR) and index of population trend of the insect reduced by 5% and 11%, respectively, when the larvae were reared on the foliage taken from the wheat plants exposed to 0.87 g·dm-2·day-1 of fluorine compared with those of the control. An extra instar appeared in a majority of the larvae treated. Survival rate and GR of the larvae on the wheat plant being exposure to the same concentration of fluorine in field open-top fumigation device were 40% and 15% lower than that of the control, respectively. Similar experiment with the insect on the artificial diet also showed that direct impact of the pollutant on the army worm was greater than its indirect effect via their host plant. 相似文献
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