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861.
Cyanobacteria, specifically Microcystis, usually form massive blooms in eutrophic freshwater lakes. Cyanobacterial samples were collected from eight sites of both Lake Taihu and Lake Chaohu in late summer to determine the diversity and distribution pattern of cyanobacteria and Microcystis in large, shallow, entropic lakes with significant spatial heterogeneity and long-term Microcystis bloom. Molecular methods based on denaturing gradient gel electrophoresis and clone library analysis were used. A similar heterogeneous distribution pattern of cyanobacteria in both lakes was observed. Most parts of these two lakes with high trophic level were dominated by Microcystis. However, in the regions with low trophic levels as well as low concentrations of chlorophyll a, Synechococcus occupied a considerable percentage. Different morphospecies and genotypes dominated the bloom-forming Microcystis populations in these two lakes. Microcystis viridis and Microcystis novacekii were dominant in Lake Chaohu, whereas Microcystis flos-aquae was dominant in Lake Taihu. Only 2 of the13 Microcystis operational taxonomic units were shared between these two lakes. Analysis of molecular variance based on 16S to 23S internal transcribed spacer sequences indicated the significant genetic differentiation of Microcystis between these two lakes (Fst = 0.19, p < 0.001). However, only 19.46% of the genetic variability was explained by the population variation between lakes, whereas most (80.54%) of the genetic variability occurred within the lakes. Phylogenetic analysis revealed no phylogeographic structure of Microcystis population in these two lakes, as illustrated by their cosmopolitan nature. Our results revealed that spatial heterogeneity within lakes has more impact on the cyanobacterial diversity than geographical isolation in a local scale. 相似文献
862.
谈地磁观测中的温度效应 总被引:1,自引:0,他引:1
地磁场各要素的绝对数值是通过基线值来确定的,而基线值又与温度相关,是一条大致随温度变化的曲线。本文选取通海、贵阳、邵阳、天水等地磁台的基线值资料,计算各分量基线值与记录室温度的相关系数,判定基线值与温度之间的相关关系,掌握在不同记录室温度条件下,温度变化对地磁基线值以及地磁观测仪器的影响程度。以供其他地磁台站新建、改造观测记录室时借鉴。 相似文献
863.
化工产业是天津滨海新区重要的支柱产业,该行业废水是滨海污染物控制的主要威胁。针对常规单一方法存在的问题,试验选取滨海某化工区实际废水从内电解-Fenton、内电解-混凝、内电解-超声及微波强化氧化-光催化4种耦合去毒预处理工艺进行了研究。试验表明,与传统方法相比,内电解-Fenton法中H2O2的加入增加了污染物的降解途径,提高了对污染物的去除效率;内电解-混凝法对于制药废水的生物毒性有比较好的去除作用,不加PAM或Ca(OH)2的效果更佳;内电解-超声法对制药废水的生物毒性去除率可达92%,其可生化性提高45%;微波强化氧化-光催化法对大多数难降解物质有效,而对酚类物质降解效果不佳。 相似文献
864.
酸雨对广西典型碳酸盐岩地区碳源效应研究 总被引:7,自引:0,他引:7
选取广西两个典型碳酸盐岩地区桂林(代表灰岩地区)与柳州(代表白云岩地区)作为研究区域,研究酸雨与岩石表面反应,并计算出由酸雨对碳酸盐岩的化学风化过程中形成CO2成为碳源的量。利用溶蚀试片溶蚀速率以及GIS技术得到研究区由酸雨产生的CO2源为41.066×108 g/a,其中桂林市区速率为33.349×108 g/a,柳州市区速率为7.717×108 g/a。单位面积源桂林与柳州分别为66.967×105 g/a.km2和42.777×105 g/a.km2,虽然低于两地的单位面积汇分别为273.891×105 g/a.km2与43.660×105 g/a.km2,但已不容忽略。柳州市区CO2源的释放速率比桂林市区慢的原因主要有二:桂林市区碳酸盐岩的代表面积为柳州市区2.77倍;由于柳州酸雨总体强度比桂林低,导致碳酸盐岩的溶蚀速率较低。 相似文献
865.
针对水污染防治领域开展了技术预见研究。通过德尔菲调查法所获数据及其结果分析,确定出排名最高的10项技术课题,作为未来水污染防治领域的关键技术课题,其中共涉及6个领域:城镇污水处理与回用,饮用水净化与安全,工业废水处理与回用,农村、农业污水处理与回用,地下水体污染控制以及微量有毒物质的防控。分析表明,10项关键技术课题的预期实现时间集中在2014年-2018年;领先国家或地区主要是美国、日本和欧盟;发展路径选择最多的是集成创新的方式;技术本身可行性、市场需求、政策支持是最主要的3个制约其发展的因素;目前所处的阶段主要是实际应用阶段。 相似文献
866.
Abstract Climate change will alter the capacity of carbon sequestration, and the risk assessment of carbon sequestration for terrestrial ecosystems will be helpful to the decision-making for climate change countermeasures and international climate negotiations. Based on the net ecosystem productivity of terrestrial ecosystems simulated by Atmosphere Vegetation Integrated Model, each grid of the risk criterion was set by time series trend analysis. Then the risks of carbon sequestration of terrestrial ecosystems were investigated. The results show that, in the IPCCSRES-B2 climate scenario, climate change will bring risks of carbon sequestration, and the high-risk level will dominate terrestrial ecosystems. The risk would expand with the increase of warming degree. By the end of the long-term of this century, about 60% of the whole country will face the risk; Northwest China, mountainous areas in Northeast China, middle and lower reaches plain of Yangtze River areas, Southwest China and Southeast China tend to be extremely vulnerable. Risk levels in most regions are likely to grow with the increase of warming degree, and this increase will mainly occur during the near-term to mid-term. Northwest China will become an area of high risks, and deciduous coniferous forests, temperate mixed forests and desert grassland tend to be extremely vulnerable. 相似文献
867.
The Appellate Body report in January 2012 had supported the decision of Panel in the “China-measures related to the exportation of various raw materials” case (WT/DS394,395,398) and affirmed that China’s restrictions (such as tariffs and quota measures) on the exportation of raw materials violated rules put forth by the WTO, which were required to be modified. In this case China’s right to invoke Article 20 of GATT1994 (“general exception”) to justify its exemption from the guidelines in Article 11.3 of the WTO Accession Protocol was denied by the Panel and the Appellate Body. This was due to the fact that the phrasing in Article 11.3 of Protocol failed to mention “GATT.” This was the consequence of the two interpretation approaches the Dispute Settlement Body (DSB) adopted – a narrow textual interpretation and a subjective presumption of “legislative silence.” The inappropriate use of the two methods of interpretation lead to an imbalance between the right and obligation of China under the additional obligations that were imposed upon China by the WTO, which create a negative impact on China’s rare earth case and the protection of domestic natural resources. 相似文献
868.
Rong Cheng Yingying Zhang Tao Zhang Feng Hou Xiaoxin Cao Lei Shi Peiwen Jiang Xiang Zheng Jianlong Wang 《Frontiers of Environmental Science & Engineering》2022,16(8):108
869.
Liu Xiaoran Shi Jiaming Bai Xuefeng Wu Wei 《Environmental science and pollution research international》2022,29(32):48558-48572
Environmental Science and Pollution Research - N-Ethylcarbazole (NEC), as a promising liquid organic hydrogen carrier (LOHC), can store and release hydrogen through a reversible catalytic... 相似文献
870.
Deng Yan-Ling Yang Pan Wang Yi-Xin Liu Chong Luo Qiong Shi Tian Zeng Jia-Yue Lu Ting-Ting Chen Pan-Pan Miao Yu Zhang Min Cui Fei-Peng Lu Wen-Qing Zeng Qiang 《Environmental science and pollution research international》2022,29(54):81749-81759
Environmental Science and Pollution Research - Previous studies have reported that exposure to phthalates and polycyclic aromatic hydrocarbons (PAHs) is individually associated with altered semen... 相似文献