I have a task where I'm supposed to calculate the "mean annual solid load" in $Mt*yr^{-1}$. I am given the following equation and a table with data. There is one example, but the numbers don't add up when I try to calculate the mean annual solid load.
Solid load = river flow x concentration (suspended solids)
Example data for Danube river:
- Mean river flow: $6430m^3*s^{-1}$
- Suspended solids concentration: $340mg*L^{-1}$
The suspended solids concentration is $340mg/L=0.34 kg/m^3$. So, the mean annual solid load should be $6,430m^3/s*0.34kg/m^3=2,186.2kg/s$ which is approx. $68.99 Mt/year$ (megatons per year). But the example data says that the mean annual solid load is $76 Mt/year$.
Why did I calculate a "wrong" value? Where did I make an error? Thank you!