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381.
382.
基于实测光谱的叶绿素a估测模型 总被引:1,自引:0,他引:1
为了有效地监测太湖湖区的富营养化程度,建立一种最佳的估测模型。对太湖水体进行了连续监测,获得了从2004年10月20~29日的实测光谱数据和水质数据。通过实测光谱反射率和叶绿素a浓度的相关分析,得到了叶绿素a反演的最佳波段,并通过比值法、反射峰位置法、峰谷距离法、峰高法和一阶微分法建立了基于实测光谱的叶绿素a浓度的估测模型。通过14个检验点,分别对5种模型进行了对比分析,结果发现,通过比值法建立的估测模型总体误差最小,估测精度最高,其695 nm附近反射峰与677 nm反射谷的比值与叶绿素a浓度之间具有良好的相关性,可决系数R2可达0.7433,可以作为整个湖区叶绿素a浓度的最佳估测模型。最后,应用该模型对该季节湖区的营养化程度做出了总体评价。 相似文献
383.
384.
Poplar plantation has the potential to alter the water balance in semiarid Inner Mongolia 总被引:2,自引:0,他引:2
Burkhard Wilske Nan Lu Long Wei Shiping Chen Tonggang Zha Chenfeng Liu Wenting Xu Asko Noormets Jianhui Huang Yafen Wei Jun Chen Zhiqiang Zhang Jian Ni Ge Sun Kirk Guo Steve McNulty Ranjeet John Xingguo Han Guanghui Lin Jiquan Chen 《Journal of environmental management》2009
Poplar plantation is the most dominant broadleaf forest type in northern China. Since the mid-1990s plantation was intensified to combat desertification along China's northwestern border, i.e., within Inner Mongolia (IM). This evoked much concern regarding the ecological and environmental effects on areas that naturally grow grass or shrub vegetation. To highlight potential consequences of large-scale poplar plantations on the water budget within semiarid IM, we compared the growing season water balance (evapotranspiration (ET) and precipitation (PPT)) of a 3-yr old poplar plantation (Kp3) and a natural shrubland (Ks) in the Kubuqi Desert in western IM, and a 6-yr old poplar plantation (Bp6) growing under sub-humid climate near Beijing. The results showed that, despite 33% lower PPT at Kp3, ET was 2% higher at Kp3 (228 mm) as compared with Ks (223 mm) in May–September 2006. The difference derived mainly from higher ET at the plantation during drier periods of the growing season, which also indicated that the poplars must have partly transpired groundwater. Estimated growing season ET at Bp6 was about 550 mm and more than 100% higher than at Kp3. It is estimated that increases in leaf area index and net radiation at Kp3 provide future potential for the poplars in Kubuqi to exceed the present ET and ET of the natural shrubland by 100–200%. These increases in ET are only possible through the permanent use of groundwater either directly by the trees or through increased irrigation. This may significantly change the water balance in the area (e.g., high ET at the cost of a reduction in the water table), which renders large-scale plantations a questionable tool in sustainable arid-land management. 相似文献
385.
鲤鱼鱼鳃微环境酸碱条件与铜形态分布模拟 总被引:3,自引:0,他引:3
用鱼鳃微环境测定装置和化学平衡计算方法,研究了在人工河水中暴露于铜的鲤鱼鳃部微环境的pH、碱度、粘液含量和铜形态分布.结果发现,鱼鳃pH平衡点为6.92,人工河水pH高于或低于此值时,鱼鳃微环境pH偏低或偏高.变化幅度约达-0.6至0.4 个pH单位.根据实测结果分别建立了计算人工河水和鱼鳃微环境碱度以及鱼鳃粘液分泌量随暴露铜含量和pH变化的定量模型.化学平衡计算结果说明,在pH6至9范围内,人工河水中优势态铜从游离态铜过渡到羟基络合态铜.由于粘液和pH差异的影响,鱼鳃微环境中生物有效态铜含量显著低于人工河水.这样的差别在酸性条件下尤为显著. 相似文献
386.
Edward R. Long 《Environmental monitoring and assessment》2000,64(1):391-407
Acute, laboratory toxicity tests were performed by the National Oceanic and Atmospheric Administration (NOAA) on 1543 surficial sediment samples collected during 1991 through 1997 throughout 25 estuaries and marine bays. Selected areas were sampled along the Atlantic, Gulf of Mexico, and Pacific coasts. The toxicity of each sample was determined with 10-day amphipod survival tests performed with solid-phase (bulk) sediments. Collectively, the 1543 samples tested through 1997 represented a total area of approximately 7300 km2. Toxicity was observed with the amphipod survival tests in samples that represented approximately 6% of the combined area. Using similar tests conducted on samples collected in different, but overlapping, study areas, the U.S. Environmental Protection Agency (EPA) estimated that approximately 7% of the combined estuarine area sampled was toxic. Generally, toxicity was most severe in northeastern and southwestern estuaries and least prevalent in southeastern and northwestern areas. However, considerable portions of the Pacific coast have not been tested with the same methods. In tests of CYP1A enzyme induction (n=464), samples were toxic that represented about 5% of the combined study areas. Toxicity was much more widespread, however, when the results of two sub-lethal tests were analyzed. Significant results occurred in samples that represented approximately 25% and 39% of the study areas in tests of sea urchin fertilization (n=1309) and microbial bioluminescence (n=1215), respectively. 相似文献
387.
Bian S Zhang Y Feng A Chiu L Wu S Hu Z 《Environmental monitoring and assessment》2008,138(1-3):281-287
This paper examines a small tidal system in Wanpingkou, Rizhao of China. The tidal system was originally maintained by a balance
of the natural interaction between tidal currents and waves. But this tidal system was diminishing by reclamation processes
since the 1980s, especially in 2003 when a sailing boat station was built in the study area. To investigate the stability
and development mechanism of the tidal system, its feasibility was evaluated before the sailing boat station was built. The
erosion and deposition in and out of the tidal system was analyzed, forecasted and compared with the data from field monitoring.
The results show that the tidal system would remain relatively stable, although its adjacent shoreline might change somewhat
after the newly built sailing boat station. This change would also affect the coastal water and wetland environment in the
study area. Further field monitoring in the area is still necessary. 相似文献
388.
An internally consistent dataset comprising 103 surficial estuarine sediment samples were collected from Sydney Harbour, Australia and locations south of Sydney. This paper describes the chemical characteristics of the dataset and evaluates its suitability for use in evaluating biological effects-based sediment quality guidelines (SQGs). The sediments contained mixtures of chemicals, the most prevalent chemical classes being metals and polycyclic aromatic hydrocarbons, whereas sediments from coastal lakes/estuaries south of Sydney had low concentrations of contaminants. Maximum concentrations of the prevalent contaminants zinc, lead, copper and pyrene were 11,300, 1,420, 1,060 mg kg(-1) and 23,300 microg kg(-1), respectively. For the majority of samples, concentrations of individual chemicals exceeded most effects-based SQGs that have been adopted for use in Australia, implying occasional or frequent adverse biological effects are expected. Comparing mixtures of contaminants to ranges in numbers of SQGs exceeded and mean SQG quotients showed that most samples (57% to 68%) had contamination characteristics associated with moderate probabilities (30% to 52%) of acute toxicity, based on North American data. A smaller proportion of samples (15% to 17%) had contamination characteristics associated with high probabilities (74% to 85%) of toxicity. The wide range of chemicals and concentrations, associated with low, medium and high probabilities of toxicity, indicated that the dataset was suitable for future use in evaluating predictive abilities of SQGs. This is relevant, given the recent introduction of North American-derived SQGs for Australia. 相似文献
389.
泡沫分离法去除废水中微量钴离子 总被引:1,自引:0,他引:1
采用泡沫分离法对水中微量钻离子的去除进行了研究,考察了表面活性剂种类及浓度、pH、气流量等因素对钴离子去除率的影响。实验结果表明:当水中钴离子初始质量浓度为10mg/L、采用十二烷基硫酸钠(SLS)做表面活性剂且质量浓度为10mg/L、pH为11.0、气流量为300L/h时,钴离子去除率达97.61%。根据泡沫分离过程与化学反应过程在物理行为上的类似性,引入等效的化学反应常数,对泡沫分离法去除水中钴离子进行了宏观动力学研究。结果表明,该泡沫分离过程可等效为一级反应。 相似文献
390.
Julie A. Robinson †† Kamlesh P. Lulla Minoru Kashiwagi † Maggie Suzuki † M. Duane Nellis ‡ Charles E. Bussing § Warren J. Lee Long Len J. McKenzie 《Conservation biology》2001,15(4):876-884
Abstract: National Aeronautics and Space Administration ( NASA) photographs taken by astronauts from low Earth orbit can provide information relevant to conservation biology. This data source is now more accessible because of improvements in digitizing technology, Internet file transfer, and availability of image processing software. We present three examples of conservation-related projects that benefited from the use of astronaut photographs. First, NASA scientists requested that astronauts photograph the area of the controversial Isahaya Bay reclamation project in Japan. Japanese researchers used photographs from before and after the reclamation as a tool for communication with the public about the effects of tidal-flat loss. The newly acquired images and the availability of high-resolution digital images from NASA archives provided timely public information on the observed changes. Second, we digitally classified and analyzed a Space Shuttle photograph of Chobe National Park in Botswana to identify the locations of woodlands affected by elephants. Field validation later confirmed that areas identified on the image showed evidence of elephant damage. Third, we used a summary map from intensive field surveys of seagrasses in Shoalwater Bay, Australia, as reference data for a supervised classification of a digitized photograph taken from orbit. The classification distinguished seagrasses, sediments, and mangroves with accuracy approximating that in studies using other satellite remote-sensing data. Astronaut photographs are in the public domain, and the database of nearly 400,000 photographs from the late 1960s to the present is available at a single searchable location on the Internet ( http://eol.jsc.nasa.gov/sseop ). These photographs can be used by conservation biologists as a source of general information about the landscape and for quantitative mapping. 相似文献