| 1 | Estimation of internal nutrient release in large shallow Lake Taihu, China显示文摘Based on field investigation of wave, sediment suspension and the changes in nutrient concentration of the water column in Lake Taihu, China, we proposed two release models to quantify nutrient release under static and dynamic conditions, respectively. Under static conditions, nutrient release from sediments to the overlying water mainly depends on chemical diffusion induced by concentration gradient, in which the nutrient release is controlled by the temperature, dissolved oxygen concentration in the sediment-water interface, oxidation-reduction potential and the concentration difference between porewater and overlying water. Under dynamic condition (or disturbed condition),both dissolved and particulate nutrients in sediments are released into the water column because of wind-induced sediment suspension. The amount of nutrient release under dynamic conditions is larger than that under the static condition. The release of dissolved nutrients, however, does not increase because the wind induced turbulence made oxidation of metallic elements such as Fe (ferric iron), Mn which are capable of precipitating soluble reactive phosphate (SRP). Under dynamic conditions, therefore, the release of total phosphorus (TP) increases dramatically but the release of SRP is close to those under static conditions. In sediments of Lake Taihu, high Fe content leads to a high ratio of Fe to P contents in sediments (Fe:P ratio). Under dynamic conditions, therefore, nutrient release is controlled by the intensity of disturbance, sediment consolidation and nutrient content in sediments.As for dissolved nutrients, especially SRP, the release is also controlled by the intensity of dynamic re-oxidation, Fe content in sediments and nutrient concentration gradient between porewater and overlying water. Based on these two release modes, the release flux in Lake Taihu has been estimated. In the static condition (i.e. laboratory experimental condition), total release of NH4+-N for whole lake is ca. 10,000 ton/a, and PO43--P is ca. 900 ton/a. In the dynamic condition, nutrient release following sediment suspension was estimated according to three different intensities of wind forcing which were defined as 'calm' (wind speed is less than 2 m/s), 'gentle' (wind speed is greater than 2 m/s and less than 6 m/s) and 'gust' (wind speed is greater than 6 m/s). The release rate in the condition of 'calm' was estimated in terms of the nutrient release in the laboratory experimental static condition; whereas the release rate in conditions of 'gentle' and 'gust' was estimated in terms of measurement during sediment resuspension conducted in flume experiments. With the observation of wind velocity and frequency in 2001, each type of wind forcing took the frequency of 12%, 82% and 6% for 'calm', 'gentle' and 'gust', respectively. The yearly release of nitrogen was 81,000 ton and phosphorus was 21,000 ton, which is about 2-6 folds of annual external loading, respectively. | QIN Boqiang, ZHU Guangwei, ZHANG Lu, LUO Liancong, GAO Guang & GU Binhe Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China Everglades Department, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, FL 33406, USA | 2006 | Science China Earth Sciences2006，49，z1： | 37 |
| 2 | 国际天然气定价新趋势显示文摘目前全球存在四个相互独立的天然气定价体系。北美与英国实行不同气源之间的竞争定价;欧洲大陆实行与油价挂钩的定价;东北亚采用与日本进口原油加权平均价格(JCC)挂钩的定价;前苏联地区采用双边垄断(出口垄断和进口垄断)的定价。全球经济衰退、北美页岩气的大规模开发、天然气液化能力的大幅提高等因素缓解了此前LNG资源的短缺状况,新的全球天然气价格互动体系正在形成。中国迫切需要建立一个国产气和进口气之间、天然气与其他能源之间可以互相关联、有序联动的定价体系。理顺天然气价格与其他可替代能源的比价关系,引导天然气资源合理配置,推动天然气与其他能源的合理竞争,是我国能源产业发展的重要方向。净回值价格体系将天然气价格与竞争性能源联系起来,避免单纯与油价挂钩而造成的价格虚高,可保证天然气在能源市场的竞争力。在目前油价高企、实现净回值价格体系尚有一定难度的LNG市场,可通过对JCC油价指数挂钩公式的调整来降低LNG的采购成本。 | Beijing Energy Club | 2011 | 国际石油经济2011，19，3： | 5 |
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