The Henry's law constant of $\mathrm{CO}_{2}$ is $3.4 \times 10^{-2} \mathrm{M}$ per atm in neutral water at $25^{\circ} \mathrm{C}$. The dissolved $\mathrm{CO}_{2}$ (i.e., $\mathrm{CO}_{2} \cdot \mathrm{H}_{2} \mathrm{O}$ ) at equilibrium undergoes the following reactions.
\[
\begin{array}{l}
\mathrm{CO}_{2} \cdot \mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{H}^{+}+\mathrm{HCO}_{3}^{-} \quad\left(\text { Equilibrium constant }=4.3 \times 10^{-7} \mathrm{M}\right. \text { ) } \\
\mathrm{HCO}_{3}^{-} \rightleftharpoons \mathrm{H}^{+}+\mathrm{CO}_{3}^{2-} \quad\left(\text { Equilibrium constant }=4.7 \times 10^{-11} \mathrm{M}\right)
\end{array}
\]
If ambient $\mathrm{CO}_{2}$ concentration is $300 \mathrm{ppm}$, the total dissolved $\mathrm{CO}_{2}$ (in $\mu \mathrm{M}$, rounded off to one decimal place) is ________
