$6.)$ A farmer applies $1605kg$ of a fertilizer that contains $10\mathrm{.}0\%$ nitrogen to his feilds each year. fifteen percent $(15\%)$ of the fertilizer washes into the river.

If the river flows at an average rate of $0\mathrm{.}250$ cubic feet per second, what is the additional concentration of nitrogen lexpressed in milligrams of nitrogen per liter