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431.
研究了卵圆卡盾藻(Chattonella ovata)在不同环境因子下的溶血活性特征。根据卵圆卡盾藻的生长曲线,分别收集对数生长期、稳定期、衰亡期的藻细胞进行溶血毒性的测定。采用不同温度、盐度和营养元素结构的培养基对卵圆卡盾藻进行培养,对不同培养条件下的藻细胞进行溶血活性的测定。结果表明,卵圆卡盾藻衰亡期藻细胞的溶血活性最强,达到29.5×10-7HU/cell(HU,Hemolytic Unit,溶血单位),其次为对数生长期(21.9×10-7HU/cell)。在10~25℃培养条件下,温度对藻细胞溶血活性无显著影响;在盐度15~25 psu范围内,藻细胞溶血活性变化不明显,而高盐度(33 psu)能够刺激溶血毒素的产生。在Fe限制时,藻细胞溶血活性最强(37.4×10-7HU/cell),为正常培养条件下(f/2培养基)溶血活性值(18.8×10-7HU/cell)的2.0倍;其次为P限制,藻细胞的溶血活性值为24.1×10-7HU/cell;N、Mn限制条件下藻细胞溶血活性与正常培养条件无显著性差异。 相似文献
432.
Selecting Sites for Converting Farmlands to Wetlands in the Sanjiang Plain, Northeast China, Based on Remote Sensing and GIS 总被引:4,自引:0,他引:4
Wetlands in the Sanjiang Plain are rich in biodiversity and natural resources in the northeast of China. However, this wetland
area has decreased in size and deteriorated in quality owing to expanded agricultural activities since the 1950s. Converting
farmlands to wetlands is necessary to improve these conditions. Using Remote Sensing (RS) and Geographic Information Systems
(GIS) technologies, we derived farmland productivity data and hydrology data for the Sanjiang Plain. The farmland productivity
data were derived from land use and net primary productivity (NPP) data of the MODIS products. We obtained three productivity
farmland classes (low, medium, and high) through the NPP anomaly percentage method. We were only concerned with the low-productivity
farmland. Hydrology data were modeled with a wetness index, which was derived from Digital Elevation Model (DEM) data. Based
on these two data layers, we identified and prioritized sites for the conversion of farmlands to wetlands. The areas with
low farmland productivity and medium or high wetness values have potential to support the conversion of farmlands to wetlands.
Potential sites were prioritized in terms of patch size and proximity to natural wetlands and water bodies. We obtained three
priority classes, among which the high-priority class would be used as the areas for the recent conversion of farmlands to
wetlands. The area of this class was 75,888 ha and accounted for 1.3% of the total farmland area. 相似文献
433.
为了解西安城市不同功能区的环境现状,通过采集西安城市不同功能区街道灰尘的样品,进行系统的环境磁学实验分析并结合扫描电子显微镜研究表明,街道灰尘中磁性矿物含量相对较高,多畴和假单畴的低矫顽力软磁性矿物为主要的载磁矿物,还含有赤铁矿等高矫顽力的硬磁性矿物.磁化率、饱和等温剩磁、低矫顽力软磁性矿物和非磁滞剩磁磁化率与饱和等温剩磁比值等磁性参数揭示出街道灰尘的磁学特征在西安城市不同功能区的差异以及污染的主要来源,根据污染程度划分为重度污染区、中度污染区和轻度污染区并对应西安市7个城市功能区:浐灞生态区(F区)为重度污染区,磁性物质含量较高,表明环境污染相对较重,污染的主要来源为"工业+交通";高新技术产业开发区(A区)和中心商务区(B区)磁性物质含量相对较高,粗颗粒物质相对较少,是中度污染的区域,其污染源分别为"工业"和"交通";经济技术开发区(C区)、科教商业区(D区)、科教文化产业区(E区)和教育科技产业区(G区)城市主要功能具有相似性,是轻度污染的区域,污染源主要为"交通". 相似文献
434.
435.
Liu Zhuang Liu Dunyu Jin Jing Feng Liang Ni Mingguo Zhao Bingtao Wu Xiaojiang 《Environmental science and pollution research international》2021,28(34):46130-46146
Environmental Science and Pollution Research - Coal-based mercury pollution from power plants has received increasing attention. In a previous study, high iron and calcium coal ash (HICCA) was... 相似文献
436.
Han Jingwen Hu Lin He Leqing Ji Kang Liu Yaqing Chen Can Luo Xiaomei Tan Ni 《Environmental science and pollution research international》2020,27(30):37313-37323
Environmental Science and Pollution Research - The preparation, characterization, and uranium (VI) adsorption properties of tri-amidoxime modified marine fungus material (ZZF51-GPTS-EDA-AM/ZGEA)... 相似文献
437.
438.
439.
A sensitivity study was performed to investigate the responses of potential natural vegetation distribution in China to the
separate and combined effects of temperature, precipitation and [CO2], using the process-based equilibrium terrestrial biosphere model BIOME4. The model shows a generally good agreement with
a map of the potential natural vegetation distribution based on a numerical comparison using the ΔV statistic (ΔV = 0.25). Mean temperature of each month was increased uniformly by 0–5 K, in 0.5- or 1-K intervals. Mean precipitation of
each month was increased and decreased uniformly by 0–30%, in 10% intervals. The analyses were run at fixed CO2 concentrations of 360 and 720 ppm. Temperature increases shifted most forest boundaries northward and westward, expanded
the distribution of xeric biomes, and confined the tundra to progressively higher elevations. Precipitation increases led
to a greater area occupied by mesic biomes at the expense of xeric biomes. Most vegetation types in the temperate regions,
and on the Tibetan Plateau, expanded westward into the dry continental interior with increasing precipitation. Precipitation
decreases had opposite effects. The modelled effect of CO2 doubling was to partially compensate for the negative effect of drought on the mesic biomes and to increase potential ecosystem
carbon storage by about 40%. Warming tended to counteract this effect, by reducing soil carbon storage. Forest biomes showed
substantial resilience to climate change, especially when the effects of increasing [CO2] were taken into account. Savannas, dry woodland and tundra biomes proved sensitive to temperature increases. The transition
region of grassland and forest, and the Tibetan plateau, was the most vulnerable region. 相似文献
440.
Impacts of climate change on Chinese ecosystems: key vulnerable regions and potential thresholds 总被引:1,自引:0,他引:1
Jian Ni 《Regional Environmental Change》2011,11(1):49-64
China is a key vulnerable region of climate change in the world. Climate warming and general increase in precipitation with strong temporal and spatial variations have happened in China during the past century. Such changes in climate associated with the human disturbances have influenced natural ecosystems of China, leading to the advanced plant phenology in spring, lengthened growing season of vegetation, modified composition and geographical pattern of vegetation, especially in ecotone and tree-lines, and the increases in vegetation cover, vegetation activity and net primary productivity. Increases in temperature, changes in precipitation regime and CO2 concentration enrichment will happen in the future in China according to climate model simulations. The projected climate scenarios (associated with land use changes again) will significantly influence Chinese ecosystems, resulting in a northward shift of all forests, disappearance of boreal forest from northeastern China, new tropical forests and woodlands move into the tropics, an eastward shift of grasslands (expansion) and deserts (shrinkage), a reduction in alpine vegetation and an increase in net primary productivity of most vegetation types. Ecosystems in northern and western parts of China are more vulnerable to climate changes than those in eastern China, while ecosystems in the east are more vulnerable to land use changes other than climate changes. Such assessment could be helpful to address the ultimate objective of the United Nations Framework Convention on Climate Change (UNFCCC Article 2). 相似文献