The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes
much to it. A Sino-German cooperation program has been carried out to improve the understanding of the ecosystem by observations
and modelling. A three-dimensional ecosystem model, coupled with a physical transport model, is adopted in this study. The
simulation for the year 1982 is validated by the data collected in 1982/1983. The simulated annual mean nutrient concentrations
are in good agreement with observations. The nutrient concentrations in the bohai Sea, which are crucial to the algal growth,
are high in winter and low in summer. There are depletion from spring to summer and elevation from autumn to winter for nutrients.
The nutrients’ depletion is a response to the consumption of the phytoplankton bloom in spring. Internal recycle and external
compensation affect the nutrient cycle. Their contributions to the nutrient budgets are discussed based on the simulated results.
Production and respiration are the most important sink and source of nutrients. The process of photosynthesis consumes 152
kilotons-P and 831.1 kilotons-N while respiration releases 94.5 kilotons-P and 516.6 kilotons-N in the same period. The remineralization
of the detritus pool is an important source of nutrient regeneration, It can compensate 23 percent of the nutrient consumed
by the production process. The inputs of phosphates and nitrogen from rivers are 0.55 and 52.7 kilotons respectively. The
net nutrient budget is −3.05 kilotons-P and 31.6 kilotons-N. 相似文献
Aerosol samples of PM10 (particulate matter with aerodynamic diameters less than 10μm) and TSP (total suspended particles) were simultaneously collected from April 2001 to March 2002 at the top of Mount Baguan on the downtown campus of Ocean University of China, Qingdao, China. The concentrations of Al, Fe, Mn, Cu, Pb and Zn were determined by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The monthly variability of the mass concentrations of aerosol particles and the concentrations of trace metals are presented and discussed. The distribution pattern of these metals in PM10 and TSP is also discussed. During the observation period, the mass concentration of PM10 at this site ranged from 13.80 to 306.42μgm-3 , while that of TSP ranged from 31.02 to 568.82μgm-3. Both PM10 and TSP reached their highest concentrations in springtime, while the lowest values occurred in summertime. The concentrations of crustal metals followed the same variation pattern, while those of anthropo 相似文献
Synthetic methods of thin section petrography, scanning electron microscope, electron microprobe, energy spectrum analysis, cathodoluminescence, isotopic analysis and temperature measuring for fluid inclusions were used in analyzing sandstone samples collected from the Zhiluo Formation in order to fully understand the diagenesis evolution and the mineralizing response as well as the genesis of the uranium-bearing sandstone in Dongsheng area. The result shows that (1) the sandstone include lithic silicarenite, feldspathic litharenite and litharenite; (2) the authigenic minerals include clay minerals, carbonate minerals, siliceous and ferric minerals; (3) the physical property of sandstone is obviously controlled by diagenesis; and (4) the sandstone with favorable physical property is propitious to migration and storage of ore-forming fluid, and finally, forming the ore deposit. The sandstone of the Zhiluo Formation had undergone the early diagenetic stage (periods A and B) and the epidiagenetic stage. The evolution of diagenetic environment is in the order of acidic oxidation, alkalescent deoxidization, acidity to transitional environment of oxidation-deoxidization and acidity-alkalescence. The uranium exists in forms of pre-enrichment uranyl ion, active uranyl ion, dispersive adsorptive uranium and uranium mineral, respectively. In addition, the authors also hold that the formation of the sandstone-type uranium is not only related to the oxidation-deoxidization environment, but also closely related to the acidic-alkaline transitional environment, which are propitious to uranium mineralization in sandstone.