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101.
Flow regulation has reduced the exchange of water, energy, and materials between rivers and floodplains, caused declines in native plant populations, and advanced the spread of nonnative plants. Naturalized flow regimes are regarded as a means to restore degraded riparian areas. We examined the effects of flood regime (short [SIFI] vs. long [LIFI] inter-flood interval) on plant community and soil inorganic nitrogen (N) dynamics in riparian forests dominated by native Populus deltoides var. wislizenii Eckenwalder (Rio Grande cottonwood) and nonnative Tamarix chinensis Lour. (salt cedar) along the regulated middle Rio Grande of New Mexico. The frequency of inundation (every 2-3 years) at SIFI sites better reflected inundation patterns prior to the closure of an upstream dam relative to the frequency of inundation at LIFI sites (> or =10 years). Riparian inundation at SIFI sites varied from 7 to 45 days during the study period (April 2001-July 2004). SIFI vs. LIFI sites had higher soil moisture but greater groundwater table elevation fluctuation in response to flooding and drought. Rates of net N mineralization were consistently higher at LIFI vs. SIFI sites, and soil inorganic N concentrations were greatest at sites with elevated leaf-litter production. Sites with stable depth to ground water (approximately 1.5 m) supported the greatest leaf-litter production. Reduced leaf production at P. deltoides SIFI sites was attributed to drought-induced recession of ground water and prolonged inundation. We recommend that natural resource managers and restoration practitioners (1) utilize naturalized flows that help maintain riparian groundwater elevations between 1 and 3 m in reaches with mature P. deltoides or where P. deltoides revegetation is desired, (2) identify areas that naturally undergo long periods of inundation and consider restoring these areas to seasonal wetlands, and (3) use native xeric-adapted riparian plants to revegetate LIFI and SIFI sites where groundwater elevations commonly drop below 3 m. 相似文献
102.
Huong Ta Thi Shah Izhar Hussain Park Hung-Suck 《Environmental science and pollution research international》2021,28(1):518-529
Environmental Science and Pollution Research - Vietnam has witnessed a rapid increase in national-level CO2 emissions due to rising urbanization, economic expansion, export growth, and industrial... 相似文献
103.
Younis Ijaz Longsheng Cheng Zulfiqar Muhammad Imran Imran Muhammad Shah Syed Ahsan Ali Hussain Mudassar Solangi Yasir Ahmed 《Environmental science and pollution research international》2021,28(30):40355-40370
Environmental Science and Pollution Research - The COVID-19 pandemic needs immediate solution before inflicting more devastation. So far, China has successfully controlled transmission of COVID-19... 相似文献
104.
Khan Nasir Abbas Gao Qijie Abid Muhammad Shah Ashfaq Ahmad 《Environmental science and pollution research international》2021,28(4):4229-4244
Environmental Science and Pollution Research - In developing countries like Pakistan, agriculture constitutes the primary source of support for the majority of rural and the adjacent urban... 相似文献
105.
采用平行因子分析方法,结合紫外吸收光谱、三维荧光光谱以及傅里叶变换红外光谱技术,研究了沉水植物狐尾藻在低、中、高营养底泥腐解过程中胡敏酸(HA)的变化,进一步揭示了不同营养底泥对沉水植物腐解的影响机制.结果表明,底泥营养水平越高,狐尾藻腐解得越快(P<0.05),释放出更多的溶解性有机碳(DOC)、溶解性总氮(DTN)、溶解性总磷(DTP)和腐殖质;底泥营养程度与HA的疏水性、分子复杂性、分子量大小呈正相关(P<0.05);荧光鉴别出不同营养底泥HA都含有1种类蛋白质组分C2和2种类富里酸组分C1、C3,且类富里酸组分和类蛋白质组分在不同腐解条件下具有相似的组分特征;不同营养底泥不同时间提取的HA红外图谱较为相似,表明不同腐解条件不同时间提取的HA含有相似的官能团,狐尾藻腐烂高营养底泥组提取的HA含有更多的芳香性物质和有机磷.采用光谱分析法对狐尾藻腐烂分解HA成分的化学结构特征进行系统的研究,可深入了解不同营养底泥对沉水植物腐解的影响机制,为湖泊水环境生态治理和修复提供理论参考. 相似文献
106.
Jasmin Shah M. Rasul Jan Behisht Ara Farhat-un-Nisa Shehzad 《Environmental monitoring and assessment》2011,178(1-4):111-119
A method for the determination of herbicides residues, triazine (atrazine, metribuzin, ametryn, and terbutryn), in soil samples with high-performance liquid chromatography (HPLC)?CUV detection is described. The proposed method is based on microwave-assisted extraction (MAE) of soil samples for 4 min at 80% of 850-W magnetron outputs in the presence of mixture of solvents (methanol/acetonitrile/ethylacetate). Related important factors influencing the MAE efficiency, such as the solvent type and volume, irradiation energy, and time, were optimized in detail. Calibration curve ranges established using HPLC for metribuzin, atrazine, ametryn, and terbutryn are 1.0?C19.0, 0.9?C18.0, 0.6?C11.0, and 0.7?C11.0 µg mL???1, respectively. The limits of detection of metribuzin, atrazine, ametryn, and terbutryn are 0.30, 0.24, 0.16, and 0.20 µg mL???1 while limits of quantification are 1.0, 0.80, 0.50, and 0.60 µg mL???1, respectively. A Plackett?CBurman factorial design was used as a screening method in order to select the variables that influence MAE extraction. The recoveries of the method at three different spiked levels were assessed by analyzing real soil samples and were found to be in the range of 83.33 ± 0.12?C96.33 ± 0.23 with good precision (<8%). 相似文献
107.
基于向量自回归模型(VAR)的计量分析,对甘肃省旅游业发展与经济增长的关系进行了实证分析.结果显示,甘肃省旅游业发展与经济增长间存在长期均衡的协整关系;经济增长是旅游收入提高的Granger原因,而旅游业发展不是经济增长的Granger原因;甘肃省经济增长对其旅游业发展具有正向影响;同时,旅游业收入的结构冲击对经济增长波动的影响有限. 相似文献
108.
Lifei ZHANG Minghui ZHENG Bing ZHANG Wenbin LIU Lirong GAO Te BA Zhiyuan REN Guijin SU 《环境科学学报(英文版)》2008,20(12):1523-1526
Decomposition of hexachlorobenzene (HCB) was investigated over several metal oxides (i.e., MgO, CaO, BaO, La2O3, CeO2, MnO2, Fe2O3, and Co3O4) supported on Al2O3, which was achieved in closed system at a temperature of 300°C. Catalysts were prepared by incipient wetness impregnation with different metal oxides loading and impregnating solvents. The decomposition efficiency of different catalysts for this reaction depends on the nature of the metal oxide used, and Al2O3 supported La2O3 was found to be the most active one. Pentachlorobenzene (PeCB), and all tetrachlorobenzene (TeCB), trichlorobenzene (TrCB), and dichlorobenzene (DCB) isomers were detected after the decomposition reaction, indicating that the decomposition was mainly a dechlorination process. The detection of all lower chlorinated benzenes suggested the complexity of decomposition and the presence of more than one dechlorination pathway. 相似文献
109.
110.
尽管世界金融风暴放缓了世界节能减排的步伐,但节能减排仍是中央经济工作会议确定的我国2009年重点工作之一。对于新兴资源型工业城市乌海市来说,确保经济平稳快速增长的同时,又要顺利完成“十一五”节能减排目标,必须要有新的节能减排思路。 相似文献