The Research Of Nutrient Dynamic In The China Pioneer Area Of The Northeast Pacific Ocean

As an important part of Natural Variability of Baseline Study (NaVaBa), baseline study was done in the China Pioneer Area of Eastern Pacific Ocean every or every other year from the year 1996. The China Pioneer Area of Eastern Pacific Ocean is to the north of the equatorial high nutrients area, across the the boundary of the North Equatorial Current and North Equatorial Countercurrent. So it's a good place for studying nutrient dynamics. The study area could be divided to two areas, the Eastern and the Western areas. The Eastern area is bounded by the longitude 144°W and 147°W, and by latitude 7°N and 10°N. The Western area is bounded by the longitude 151°W and 155°W, and by latitude 8°N and 11.5°N.The thesis analyzed the nutrient dynamics in the upper water, deep water and bottom water of the China Pioneer Area of the Eastern Pacific Ocean, based on the data of Natural Variability of Baseline Study (NaVaBa) from 1997 to 2003. We have studied the processes of nutrient uptake by phytoplankton, nutrient regeneration, horizontal and vertical advection in the study area, and found that horizontal advection is the main cause of the variation of nutrient concentrations in the upper layer of the Eastern Pacific.Our study area is to the north of the Equator, across the boundary of the North Equatorial Current and North Equatorial Countercurrent. As nutrient in this region could be supplied by the North Equatorial Current from the high nutrient area of the East Equatrorial Pacific, nutrient concentrations were high compared to other poor nutrient areas, and the nutrient concentrations in the eastern area were higher than in the western area. The concentration of nutrient was affected by the ENSO event.In La Nina year (1999), the concentrations of nitrate and phosphorus were lower, the nitrate depletion layer is deeper, but in El Nino years(1997-1998) the condition was just the opposite. There was a dome of nitrate concentration in the boundary between North Equatorial Current and North Equatorial Countercurrent in La nina years, but the dome disappeared in El Nino years. The ratio of N/P/Si also varied temporally and spatially, and largely departed from the Redfield Ratio. The results of nutrient stoichiometric and nutrient enrichment experiments indicate that nitrogen was the predominant limiting nutrient.The nutrient concentrations in the deep and bottom waters have also showed some response to the ENSO events, but the response was opposite to the upper water. These results indicate that although the ocean is deeper than 5000 meters in our study area, as the main constituent of the global surface system, it is also affected by the global ocean-sea event in annual time scale, and it may has some actions to the event.