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91.
中国东部主要河流河水腐殖酸的起源、含量及地域分异规律 总被引:7,自引:6,他引:7
测定了中国东部地区主要河流河水、悬浮物和沉积物中腐殖酸含量,研究了该地区河水腐殖酸含量的地域分异规律,并探讨了河水腐殖酸的可能来源。结果表明,所研究河流河水腐殖酸含量在0.9—14.4mg/L范围内,中值为4.16mg/L,并有北高南低的一般趋势。黑龙江上游及松花江北部支流的河水腐殖酸含量在8.5mg/L以上,滦河以北其它地区在3.9—6.4mg/L范围内,黄河以南区域则在0.9—3.3mg/L之间,所研究地区河水中的腐殖酸为混合起源的,它既来自河流悬浮物和沉积物中腐殖酸的释放,又来自流域表土中腐殖酸的淋溶。 相似文献
92.
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
93.
A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada 总被引:2,自引:0,他引:2
Xiaolu Zhou Changhui Peng Qing-Lai Dang Jiaxin Chen Sue Parton 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):525-543
Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability
in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems.
As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and
monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level
using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and
carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal
forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha−1 yr−1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central
Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground
biomass was 125.3, 111.8, and 106.5 tC ha−1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested
land was estimated at 154.4 tC ha−1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the
LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s. 相似文献
94.
In angiosperms, archesporial cells in the anther primordium undergo meiosis to form haploid pollen, the sole occupants of anther sacs. Anther sacs are held together by a matrix of parenchyma cells, the connective tissue. Cells of the connective tissue are not known to differentiate. We report the differentiation of parenchyma cells in the connective tissue of two Gordonia species into pollen-like structures (described as pseudopollen), which migrate into the anther sacs before dehiscence. Pollen and pseudopollen were distinguishable by morphology and staining. Pollen were tricolpate to spherical while pseudopollen were less rigid and transparent with a ribbed surface. Both types were different in size, shape, staining and surface architecture. The ratio of the number of pseudopollen to pollen was 1:3. During ontogeny in the connective tissue, neither cell division nor tetrad formation was observed and hence pseudopollen were presumed to be diploid. Only normal pollen germinated on a germination medium. Fixed preparations in time seemed to indicate that pseudopollen migrate from the connective tissue into the anther sac. 相似文献
95.
96.
强化混凝去除黄浦江水有机物的试验研究 总被引:11,自引:0,他引:11
强化混凝去除有机物的效果与水源的分子量分布特性有着密切的关系.由于黄浦江水中低分子量的溶解性有机物占多数,因此,强化混凝处理有机物效果有限.对于<1k分子量区间的有机物.增加混凝剂投量可有效去除紫外吸光值(UV254),但去除溶解性有机碳(DOC)的效果很差.尽管增加混凝剂投量和降低pH都能有效地去除有机物,但决定强化混凝效果的主要因素是pH,去除黄浦江水有机物的最佳pH范围为6~5. 相似文献
97.
超深厌氧塘的技术特性 总被引:8,自引:0,他引:8
超深厌氧塘是一种稳定塘新工艺。与常规厌氧塘相比,具有BOD5容积负荷大、占地面积小,受温度影响小的优点。探讨了它的工作机理,本研究确定了负荷、水深和去除率之间的定量关系以供实际应用。 相似文献
98.
99.
100.
膜分离技术处理电镀废水的实验研究 总被引:1,自引:0,他引:1
采用纳滤+反渗透2级处理系统浓缩回收电镀铜漂洗废水。实验结果显示:在△P=1.5MPa条件下进行浓缩.纳滤膜可以使料液浓缩近10倍。纳滤膜对Cu^2+的截留率在96%以上,对COD的截留率在57%以上。在△P=3.0MPa条件下进行浓缩,反渗透膜可以使料液浓缩近10倍。反渗透膜对Cu^2+的截留率在98%以上,对COD的截留率在67%以上。随着料液浓度的增加,纳滤膜和反渗透膜的截留率会降低。 相似文献