The concentration profile of algae across a large body of water measured as a function of distance, \(x\), is given as:

\[C(x)=4 x^{2}+x\]

With \(C(x)\) in units of \(\mathrm{kg} / \mathrm{m}^{3}\). If the flux is given as \(1.27 \times 10^{-9} \mathrm{~kg} /\left(\mathrm{m}^{2} \mathrm{~s}\right)\) at a distance of \(x=10\), and the system obeys Fick's law, find the diffusivity of the algae.