This is a 3 part question that i have attempted to answer. i'm pretty sure i'm on the right track but i think i made 1 or 2 small mistakes along the way. the question states:(adsbygoogle = window.adsbygoogle || []).push({});

The average depth of the ocean is 3.8km and the ocean surface area is 360x10^12 m^2. The average upwelling rate of deep water into the surface ocean is 4 m/yr.

a) about how long would it take to upwell the entire volume of the ocean?

b)assume that the average nitrogen content of deep water is 40 micro molarity or 40x10^-6 moles per liter. What is the flux of nitrogen to the surface ocean due to upwelling(express your answer as moles N m^-2 yr^-1)?

c) At a C:N molar ratio of 106:16 what is the productivity of the surface ocean(expressed as moles C m^-2 yr^-1) sustained by nitrogen upwelling. Re-calculate this productivity flux as a global(whole ocean) rate of upwelled N-driven primary productivity, expressed in units of gigatons C/yr.

MY ATTEMPT AT AN ANSWER:

a) 3800m/4m/yr=950 yrs

b) 40 x10^-6 moles per liter;

upwelling rate of 4m/yr=400 cm/yr;

therefore 400cm rises 1cm^2/yr;

360x10^12 m^2 x 3.8km=1.368x10^18 m^3;

3.6x10^18 cm^2 x 400 cm= 1,440x10^18cm^3/yr;

1 liter=1,000 cm^3;

1,440x10^15 L/yr x 40x10^-6 moles/L;

=5.76x10^13 moles N/yr

(i think that's right but it needs to be expressed as moles N m^-2 yr^-1. would i just divide 5.76x10^13 by the surface area of 360x10^12m^2?)

c) 5.76x10^13 moles N/yr at a C:N ratio of 106:16=3.82x10^14 moles C/yr;

3.82e14/360e12m^2= 1.061 moles C/m^2/yr?;

1.061 moles C/m^2/yr= 12.73 g C/m^2/yr;

Gigaton= 1e15 g;

1.273e-14 Gt C/m^2/yr x surface area(360e12m^2)= 4.5828 Gt C/yr

Is this correct?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Upwelling rates in the ocean involving carbon and nitrogen

**Physics Forums | Science Articles, Homework Help, Discussion**