Section 2HHH. There shall be set up on the books of the commonwealth a separate fund to be known as the Open Space Acquisition Revolving Fund. There shall be credited to the fund all revenues or other financing sources directed to the fund by appropriation, any income derived from the investing of all amounts credited to the fund and the monies from the repayment of loans from the fund. Monies credited to the fund may be expended by the department of conservation and recreation, without further appropriation, for loans to cities and towns for the acquisition of open space under section 3E of chapter 21.