(NBBJ) - Industrial real estate in southern Napa County is enjoying a resurgence of business activity in wine-related businesses, and retail real estate activity is picking up with major properties under construction or being considered for repositioning or redevelopment. Of about 10.5 million square feet of industrial space in the southern Napa County business parks, 1.06 million square feet or 10.2 percent, was available for lease at the end of last year, according to estimates by Steve Crocker of commercial real estate brokerage Colliers International. That’s up from 9.89 percent the third quarter, but the vacancy rate came down from 11.7 percent at the end of 2010