The revenue, less the cost of collection, obtained from the tax levied in subdivision (3) of subsection (a) of Section 40-17-325 shall be paid into the State Treasury to the credit of the Department of Transportation and be used exclusively for the purpose of paying the cost of acquiring, engineering, construction, improvement, and maintenance of existing or proposed airports and other air navigation facilities within the state, for the payment of the salaries of all employees who have been transferred from the Alabama Department of Aeronautics to the Department of Transportation under Article 12 of Chapter 1 of Title 23, and for the payment of administrative expenses incurred by the Department of Transportation in performing aeronautical activities and for the further purpose of creating a sinking fund for the payment of the interest and retirement of the principal of all bonds which may be hereafter lawfully issued, sold, and delivered for funds to be used exclusively for the enumerated purposes.