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31.
Panagiotis Karanis Ioannis Chronis George Zakas Christina Kourenti Isaia Sotiriadou Chrissanthy Papadopoulou 《洁净——土壤、空气、水》2005,33(4):346-354
The objective of the present survey was to assess the microbiological quality of river waters used mainly to irrigate the large plains of Macedonia and Thessaly in Northern Greece. Five rivers (Aliakmonas, Axios, Loudias, Mavroneri and Pineios) were sampled during a 10‐month period (June 2002 – March 2003) for Total Microbial Flora (TMF) at 22 °C and 37 °C, Total Coliforms (TC), Fecal Coliforms (FC), enterococci, staphylococci, Pseudomonas, fungi, Giardia spp. and Cryptosporidium spp. The results indicate moderate to high microbiological pollution, with the highest levels of microbial pollution found in Mavroneri and Pineios Rivers, and moderate pollution levels in Aliakmonas, Axios and Loudias Rivers. The extent of microbiological pollution is accentuated by the fact that Giardia‐ and/or Cryptosporidium cysts were detected in nine out of eleven samples collected in June 2002 with excessive Giardia counts demonstrated for Pineios River. The microbiological pollution of the surveyed rivers is attributed to various degrees of human interference and to lack of ample pollution monitoring systems, which emphasize the need for implementation of the EU Water Framework Directive. 相似文献
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Wetland economic valuation approaches and prospects in China 总被引:1,自引:0,他引:1
Ecosystem services valuation seeks to increase the social relevance of ecosystem characteristics, the underlying biological mechanisms that support services, by making the contribution of ecosystems to human well-being explicit. Economic valuation can help management by clarifying the full range of benefits and costs of proposed management actions. In the past two decades, economic valuation of wetland ecosystem services has become one of the most significant scientific priorities for wetland protection. In this paper, we provide an overview of ecosystem services, and summarize the main interdisciplinary approaches to measure and value wetland ecosystem services. We identified four main methodological gaps preventing progress on wetland valuation of ecosystem services in China, which are: 1) confusion on terminology like intermediate and final ecosystem services, 2) lack of ecological production functions to link ecosystem characteristics to final ecosystem services, 3) static valuation making it difficult to evaluate the trade-offs and synergies among ecosystem services, and 4) lack of clear guidance on relating ecological compensation programs to conservation targets. Overcoming these gaps is important to inform wetland compensation mechanisms and conservation policies. We propose future research on wetland ecosystem services in China should be focused on: 1) defining final ecosystem services based on beneficiary preferences and underlying biophysical mechanisms, 2) establishing wetland monitoring programs at specific sites to collect data on final ecosystem service indicators and ecosystem characteristic metrics to create ecological production functions for economic valuation and rescaling techniques, and 3) incorporating wetland ecosystem service values into decision-making processes to inform wetland management. 相似文献
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Kun?Wang Christina?Yan?WangEmail author Zhong-Yuan?RenEmail author 《Contributions to Mineralogy and Petrology》2018,173(7):59
The ~?2-km-thick Panzhihua gabbroic-layered intrusion in SW China is unusual because it hosts a giant Fe–Ti oxide deposit in its lower zone. The deposit consists of laterally extensive net-textured and massive Fe–Ti oxide ore layers, the thickest of which is ~?60 m. To examine the magmatic processes that resulted in the Fe enrichment of parental high-Ti basaltic magma and the formation of thick, Fe–Ti oxide ore layers, we carried out a detailed study of melt inclusions in apatite from a ~?500-m-thick profile of apatite-bearing leucogabbro in the middle zone of the intrusion. The apatite-hosted melt inclusions are light to dark brown in color and appear as polygonal, rounded, oval and negative crystal shapes, which range from ~?5 to ~?50 µm in width and from ~?5 to ~?100 µm in length. They have highly variable compositions and show a large and continuous range of SiO2 and FeOt with contrasting end-members; one end-member being Fe-rich and Si-poor (40.2 wt% FeOt and 17.7 wt% SiO2) and the other being Si-rich and Fe-poor (74.0 wt% SiO2 and 1.20 wt% FeOt). This range in composition may be attributed to entrapment of the melt inclusions over a range of temperature and may reflect the presence of µm-scale and immiscible Fe-rich and Si-rich components in different proportions. Simulating results for the motion of Si-rich droplets within a crystal mush indicate that Si-rich droplets would be separated from Fe-rich melt and migrate upward due to density differences in the interstitial liquid when the magma unmixed. Migration of the Si-rich, immiscible liquid component from the interstitial liquid caused the remaining Fe-rich melt in the lower part to react with plagioclase primocrysts (An59–60), as evidenced by fine-grained lamellar intergrowth of An-rich plagioclase (An79–84)?+?clinopyroxene in the oxide gabbro of the lower zone. Therefore, magma unmixing within a crystal mush, combined with gravitationally driven loss of the Si-rich component, resulted in the formation of Fe-rich, melagabbro and major Fe–Ti oxide ores in the lower part and Si-rich, leucogabbro in the upper part of the intrusion. 相似文献
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University faculty partners from the Departments of Geography and Instruction and Teacher Education at a large, public university collaborated with K-12 teachers and the leadership of a rural school district in order to investigate the crosscutting content of science, mathematics, and geography through the integration of web-based GIS technologies. The project explored the critical connections among technology, pedagogy, and content with a particular emphasis on developing technology-enhanced, inquiry-based lessons in which the teachers and their students used GIS technologies to analyze, visualize, and present data in real-world contexts. The findings highlight the importance of well-structured professional development that builds community, integrates diverse content and pedagogical expertise, provides feedback and coaching, and is of sufficient duration to effect change. 相似文献