Textbook $3\mathrm{.}10$

What would be the saturation concentration $($mole$/$L$)$ of Oxygen $(O_2)$ in a river in winter when the air temperature is $0C$ if the Henry's law constant at this temperature is $2\mathrm{.}28{10}^{-3}$mol$\frac{e}{L}-$atm $?$ What would the answer be in units of $m\frac{g}{L}?$