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排序方式: 共有1183条查询结果,搜索用时 546 毫秒
71.
Zhuoyu Li Guangzhao Xie Hui Chen Bixin Zhan Lin Wang Yujing Mu Abdelwahid Mellouki Jianmin Chen 《环境科学学报(英文版)》2022,34(4):221-232
As a secondary pollutant of photochemical pollution, peroxyacetyl nitrate(PAN) has attracted a close attention. A four-month campaign was conducted at a rural site in North China Plain(NCP) including the measurement of PAN, O3, NOx, PM2.5, oxygenated volatile organic compounds(OVOCs), photolysis rate constants of NO2 and O3 and meteorological parameters to investigate the wintertime characterization of photochemistry from November 2018 to Fe... 相似文献
72.
We examined the influence of several hydrological and meteorological parameters on the migratory movements of ayu Plecoglossus altivelis altivelis in central Japan. When comprehensively evaluating rivers and ayu behaviour on a catchment scale, the subjects of analysis typically include human activities and hydrological and meteorological phenomena. However, limiting analyses to such factors may be too restrictive when human activities are being conducted. Accordingly, we incorporated a biological viewpoint into the evaluation method, analysing hydrological data (river discharge, river water temperature, sea water temperature) to determine watershed characteristics and examining the relationship between these characteristics and the habitat conditions of ayu. Then we constructed a numerical model for ayu migratory runs that incorporated ayu ecology and watershed characteristics. Analyses of ayu movements from a lower estuarine dam demonstrated that downstream displacements were associated with high water flows of more than 200 m3 s−1 at the beginning of summer. We conclude that it is important to consider the effects of environmental parameters on the movements of different fish species to understand the causes of spatial variation in fish distribution in lowland rivers. 相似文献
73.
Cristina Zago Gabriele Capodaglio Carlo Barbante Michele Giani Ivo Moret Giuseppe Scarponi 《Chemistry and Ecology》2013,29(1-2):39-51
In the present study the concentrations of cobalt, copper, iron, manganese, zinc were analysed and the speciation of copper and zinc performed, with a summer and winter sampling, for two areas in the Northern Adriatic Sea and crossing at the farthest zones of the Po river-sea water interface. Results show that when salinity increases the concentrations of all investigated metals (with the exception of cobalt) present some degree of biogeochemical cycling. Copper is the element whose dissolved phase has the highest importance in metal transport across the salinity gradient. Results of speciation analysis demonstrate that the presence of excess amounts (5-8 fold) of unbound ligands confers a buffering capacity for potential inputs of dissolved metals into the Northern Adriatic Sea. The speciation of both copper and zinc in the dissolved phase was dominated by organic complexation. 相似文献
74.
The particulate organic matter distribution and its elemental composition in the northern and central Adriatic Sea during different seasonal periods are shown, highlighting the principal processes and factors influencing their distribution and characteristics. In the low salinity waters the concentrations of particulate carbon, nitrogen and phosphorus were higher and more variable than in the dense waters, mainly due to dilution effects which induce an abundant phytoplankton growth. Generally in summer the particulate organic matter distribution followed the trophic gradient while in winter resuspension events often became more important. Differences between summer and winter were more evident in the diluted waters and were mainly due to the seasonal heat exchanges and to the fresh water inputs. Marked differences in C/P ratios were observed in the POM: high ratios in the northern diluted waters and low in the more saline waters and in the central Adriatic. 相似文献
75.
ABSTRACT: Although evidence of modern recharge in the North African and Arabian sedimentary basin aquifers exists, it is difficult to determine the volume of recharge. Also, from the evidence of regional groundwater gradients, the flow within the aquifers seems to be appreciably greater than one would intuitively expect. A hypotehtical model embodying the characteristics of the aquifers has been used to investigate the likely significance of various possible flow mechanisms. It is shown that while dewatering in the unconfined area can possibly contribute to flows for a considerable period of time, the maintenance of water levels in the unconfined zone must be the result of modern recharge. It is also shown that recharge depths of less than 10 mm per annum are sufficient given suitable aquifer parameters. Results for various combinations of aquifer parameters and configurations are given, including layered aquifers and the effects of restricted oufflows. Comparisons are made using a “bench mark” example. The work indicates that there is little point in carrying out conventional hydrological balance studies in hyper-arid areas and that, instead, more emphasis should be placed upon good groundwater hydrographic data and modeling. 相似文献
76.
Stephen P. Mumme 《Environmental management》1995,19(6):827-835
United States-Mexican transboundary water resources management is presently experiencing significant reform resulting from
long-term demographic processes in the border region and greater economic integration. The recently concluded North American
Free Trade Agreement and supplementary environmental accord modify existing agreements and provide old institution with new
mandates. Particularly affected is the International Boundary and Water Commission (IBWC), long the lead agency in binational
water management. This essay reviews the development of the new water management regime against the two preceding phases of
management reform and considers its implications for improved water management in the border region. 相似文献
77.
Monitoring of eutrophication and nutrient limitation in the Izmir Bay (Turkey) before and after Wastewater Treatment Plant 总被引:3,自引:0,他引:3
The distribution of inorganic nutrients and phytoplankton chlorophyll-a was investigated and N/P ratios were determined in Izmir Bay during 1996-2001. The average concentrations showed ranges of 0.01-0.19 and 0.01-10 microM for phosphate-phosphorus; 0.11-1.8 and 0.13-27 microM for (nitrate+nitrite)-nitrogen, 0.30-4.1 and 0.50-39 microM for silicate and 0.02-4.3 and 0.10-26 microg l(-1) for chlorophyll-a in the outer and middle-inner bays, respectively. The results are compared with the values obtained from the relatively unpolluted waters of the Aegean Sea. The N/P ratio is significantly lower than the assimilatory optimal (N/P=15:1) in conformity with Redfield's ratio N/P=16:1. Nitrogen is the limiting element in the Izmir Bay. Phosphate, which originates from detergents, is an important source for eutrophication in the bay, especially in the inner bay. In early 2000, a Wastewater Treatment Plant (WTP) began to treat domestic and industrial wastes. This plant treats the wastes about 60% capacity between 2000 and 2001. The sampling periods cover before and after treatment plant. Although the capacity of wastewater plant is sufficient for removal of nitrogen from the wastes, it is inadequate for removal of phosphate. This is also in accordance with the decreasing N/P ratios observed during 2000-2001 (after WTP) in the middle-inner bays. 相似文献
78.
Dong Yuxiang 《中国减灾(英文版)》2002,(3)
TheNorthTibetanPlateau ,ortheQiangtangPlateau ,asthemainbodyoftheQing hai TibetanPlateauwhichisoneofthethreemajordistributionareasofdesertificationinChi na ,hasawell preservednaturalecosystemcharacterizedbyhigh altitudegrassland ,isanim portantareaforstudyi… 相似文献
79.
Huntington HP Brown-Schwalenberg PK Frost KJ Fernandez-Gimenez M Norton DW Rosenberg DH 《Environmental management》2002,30(6):0778-0792
Traditional ecological knowledge (TEK) and the information and insights it offers to natural resource research and management
have been given much attention in recent years. On the practical question of how TEK is accessed and used together with scientific
knowledge, most work to date has examined documentation and methods of recording and disseminating information. Relatively
little has been done regarding exchanges between scientific and traditional knowledge. This paper examines three workshop
settings in which such exchanges were intended outcomes. The Barrow Symposium on Sea Ice, the Exxon Valdez Oil Spill Restoration Program Synthesis/Information Workshops, and the Alaska Beluga Whale Committee illuminate certain features
of the preparation, format, and context of workshops or series of workshops and their eventual outcomes and influence. The
examples show the importance of long-term relationships among participants and thorough preparation before the actual workshop.
Further research should look more systematically at the factors that influence the success of a given workshop and the various
ways in which participants perceive success. 相似文献