Upwelling oceanic

Figure 7. Proposed model of the Phosphoria sea showing the interplay of continental wind currents, upwelling ocean currents, algal blooms, and salinity stratification (modified from Stephens and Carroll 1999).

A further factor affecting k- is the air-sea temperature difference. When the sea is colder than the air above it, the enhanced solubility of the gas in the water (relative to the air temperature) tends to increase kj. This will occur in summer in sub-polar waters and over upwelling regions. The opposite is also found, and much of the ocean equatorward of 45"" latitude is colder than the overlying air for much of the year. However, air-sea temperature differences are generally less than 2-3 "C so that this effect results in a less than 10% modulation of k- on average. 

The quantity of primary production that is exported from the upper ocean is said to be equivalent to new production (18, 19) New primary production is that associated with allocthonous nutrients (i.e., those upwelled or mixed into the euphotic zone or input via rivers and rain). In order for steady state to be maintained, an equivalent flux out of the euphotic zone is required. Earlier studies (19) suggested that sediment-trap measurements of particulate organic carbon (POC) flux were equivalent to new primary production however, recently it has become clear that these measurements probably represent only a... 

Chavez, F. P. and Toggweiler, J. R. (1995). Physical estimates of global new production The upwelling contribution. In "Upwelling in the Ocean Modem Processes and Ancient Records" (C. P. Summer-hayes, K.-C. Emeis, M. V. Angel, R. L. Smith and B. Zeitzschel, eds), pp. 313-320. John Wiley. 

Over much of the ocean (exclusive of upwelling regions, high-latitude areas and specific high-nutrient, low-chlorophyll regions) the vertical distribution of dissolved POt is represented by the shape of the profile displayed in Fig. 14-6, which is similar to the shape observed for the... 

Fig. 14-6 Profiles of potential temperature and phosphate at 21 29 N, 122 15 W in the Pacific Ocean and a schematic representation of the oceanic processes controlling the P distribution. The dominant processes shown are (1) upwelling of nutrient-rich waters, (2) biological productivity and the sinking of biogenic particles, (3) regeneration of P by the decomposition of organic matter within the water column and surface sediments, (4) decomposition of particles below the main thermocline, (5) slow exchange between surface and deep waters, and (6) incorporation of P into the bottom sediments.

The deep ocean (6) is the portion of the water column from 300 m to 3300 m and is the largest ocean reservoir of dissolved P. However, since the deep ocean is devoid of light, this P is not significantly incorporated into ocean biota. Mostly, it is stored in the deep waters until it is eventually transported back into the photic zone via upwelling or eddy diffusive mixing. 

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