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ZHANG Xi XIE Ping CHEN Fei-zhou LI Yan-ling LI Si-xin GUO Ni-chun QIN Jian-hui 《环境科学学报(英文版)》2005,17(3):389-394
Phytoplankton assemblages in the subtrophical oligotrophic Lake Fuxian, the second deepest lake in China, were investigated monthly from September 2002 to August 2003. A total of 113 species belonging to seven phyla were identified, among them, a filamentous green alga, Mougeotia sp., dominated almost throughout the study period and comprised most of the total phytoplankton biomass.Mougeotia sp. has made a substantial development during the past decades: it was absent in 1957, only occasionally present in 1983,increased substantially in 1993, and became predominant in 2002--2003. It is likely that natural invasion of the Taihu Lake noodlefish (Neosalanx taihuensis) has led to a change of dominant herbivorous zooplankton from small to large calanoid, which has increased grazing pressure on small edible algae, and thus has indirectly favored the development of the inedible filamentous Mougeotia sp. 相似文献
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利用云贵高原159个常规气象站1961~2007年汛期(5~10月)逐日降水量,用百分位法定义站点强降水和极端降水阈值,对强降水和极端降水事件进行了分析研究。结果表明:云贵高原汛期强降水和极端降水阈值地理分布差异较大,与汛期降水量关系不大,而与站点海拔高度显著负相关;1961~2007年汛期降水量变化趋势不明显,但降水日数显著减少,降水有集中的趋势;强降水量和极端降水量具有与汛期降水量相似的年际波动特征,极端降水与汛期降水的相关高于强降水;以强降水量和极端降水量与汛期降水量的比重表征事件的强度,两者均呈显著增加的变化趋势,并在1990年代初期发生了显著增加的突变;强降水和极端降水与夏季季风强弱变化显著负相关。 相似文献
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<正>南宁铁路局所辖铁路所经地区地质复杂,地形险峻,沿线溶岩、断层、坍塌、滑坡、泥石流、膨胀土遍布,80%以上线路地处山区。南昆铁路是我国继成昆铁路之后典型的山区铁路,它从海拔78米的南宁盆地,爬上2000多米的云 相似文献
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为探究云贵高原区域城市PM2.5中水溶性离子的污染特征及来源,该文选取贵阳市和遵义市作为典型城市进行PM2.5样品采集,分析样品中8种水溶性无机离子(WSIIs)的污染特征,并采用主成分-多元线性回归法(PCA-MLR)解析其来源。结果表明,研究期间贵阳市和遵义市WSIIs浓度均值分别为22.64、14.44μg/m3,呈夏季最低、冬季最高的季节变化特征。2个站点氮氧化率(NOR)平均值分别为0.15、0.12,说明NO3-二次转化不明显,且夏季NOR的值远小于0.1,表明研究区域夏季NO3-来自于一次源。硫氧化率(SOR)平均值分别为0.44、0.35,表明SO42-主要由二次反应形成。阴阳离子平衡分析表明,贵阳市春、夏、秋3个季节的PM2.5呈碱性,冬季PM2.5呈弱酸性,而遵义市全年PM2.5呈碱性,主要由SO... 相似文献
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Arsenic fractionation and contamination assessment in sediments of thirteen lakes from the East Plain and Yungui Plateau Ecoregions, China 总被引:2,自引:0,他引:2
Fengyu Zan Shouliang Huo Jingtian Zhang Li Zhang Beidou Xi Lieyu Zhang 《环境科学学报(英文版)》2014,26(10):1977-1984
Arsenic(As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecoregions, followed by reducible As and soluble or oxidizable As. The total As is correlated to oxidizable As and residual As in sediment samples from both lake ecoregions. As distribution in sediment samples of lakes of the East Plain Ecoregion appears to be affected by human activity, while the As origin mainly comes from natural sources in sediment samples of lakes in the Yungui Plateau Ecoregion. The potential ecological risk index and geoaccumulation index values suggest "low to moderate" risk degree and "unpolluted to moderately polluted" for As in the studied lake sediments. 相似文献
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贵州地处祖国西南,位于云贵高原的东部,以典型的喀斯特地貌风光著称于世.而随处可见的直插云霄的奇峰、峥嵘诡谲的岩石、飞珠溅玉的山泉、云蒸霞蔚的飞瀑、烟波浩淼的湖泊池沼、高古幽深的溶洞峡谷,又让贵州素有"公园省"之美称.在接受本刊记者采访的时候,贵州省环保局局长李康民坦言,在为贵州的秀美风光自豪的同时,也深感作为一名环保人的责任之重大. 相似文献
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