The District has bought an eight-acre site in the Florida Avenue Market area for $2 million as the first step in the city's plan to help the wholesale food industry and to stimulate development of a light industrial center along the New York Avenue corridor in Northeast Washington, Mayor Marion Barry announced yesterday.

Calling it a "great economic development," Barry said the purchase demonstrated the kind of city government-private sector partnership that is crucial to carrying out a major goal of his administration: retention and expansion of the District's economic base.

Barry said the arrangement will enable the city to lay the groundwork to retain major elements of the wholesale food industry in the District. The Florida Avenue Market, situated on 37 acres radiating from Fifth Street and Florida Avenue NE, is the hub of the city's wholesale food trade.

The deal also rescued the struggling efforts of three small merchants to save the site primarily for food wholesalers.

The agreement, in which the city bought the site from the Consolidated Rail Corp. on March 31, enabled the three businessmen to obtain financing to buy the 45,000-square-foot Union Produce Terminal Building, in which they now lease space and which is also on the site now owned by the city.

The District agreed to lease for 99 years the land that holds the building to the merchants, two food wholesalers and a small paper company. The three businessmen paid about $500,000 for the building, officials said.

"It saved us," said Nicholas Lyddane, owner of Imperial Produce Co., who along with Mitchell Deoudes and Robert Stevens, unsuccessfully tried to arrange financing for the site for about two years before the city interceded.

The city will also develop another building of up to 200,000 square feet that will provide new space for food wholesalers who have complained of the need for more space.

Barry said that more than 20 food wholesalers have already expressed an interest in locating there.

Barry said the $2 million used to buy the site came from funds earmarked for economic development in the city's capital improvement budget for 1982 and 1983.

He said that he has pushed for the use of capital improvement funds for economic development as part of his goal to have the city government play a more activist role in stimulating the local economy. "I want to see in the next four years . . . something actually happening," Barry said.

Barry once again said he is close to finding a new chairman for the D.C. elections board, a nomination he has postponed making several times in the last month.

"I've been turned down by a half-dozen people who ordinarily wouldn't have turned it down," Barry said. "They were afraid they would be treated shabbily" by the City Council, which last month killed the nomination of former city council chairman Sterling Tucker.

The mayor also said the summer youth jobs program would have to rely more on the private sector than in the past because only a "small sum of money" from the recently passed federal jobs bill was available. The city is asking for the first time that churches contribute to the effort, he said.

"I don't have any money stashed away" for more jobs, Barry said. This year there will be about 16,000 jobs available, down from about 19,000 last year, he said.