The Washingtonian has won two 1985 National Magazine Awards, one for Public Service and the other for Service to the Individual. The 10 winners of 12 awards were announced yesterday in New York.

American Heritage and The Washingtonian each took two editorial awards. Playboy, Forbes, Life and a new magazine -- Manhattan, inc. -- were among the other winners of the magazine industry's most coveted honor.

"It's a wonderful day for Washingtonian," said John A. Limpert, editor of the 135,000-circulation monthly.

The Washingtonian and writers Nick Kotz, Nancy B. Nathan and Cathryn Donohoe won the Public Service award for "Where Have All the Warriors Gone?", a story about the decline in leadership values in the military services. Kotz led a team of 14 students, including Donohoe, who were in a graduate course in investigative reporting he taught at American University. Nathan is a former Federal Elections Commission lawyer who turned to journalism. The magazine financed trips to the war colleges and several military bases, Kotz said, allowing the team to interview 200 current and former career officers.

The 12,000-word article has been reprinted for the Army War College and the National Defense College. According to the citation, it "stirred attention and debate in the . . . Congress and the military itself."

Staff writer John Pekkanen, who won a National Magazine Award three years ago for "The Saving of the President," led a team of three other staff writers and editors for "How to Save your Life," a survey of emergency and trauma care in the Washington area. Pekkanen, Gail Friedman, Marilyn Dickey and William O'Sullivan spent five months examining the services and flaws in local hospital emergency rooms. A result of the article, Pekkanen said, was the replacement of the emergency-room staff at one hospital. The citation singled out "fine research, extraordinary writing and dramatic visual presentation."

"We've put a lot of energy and resources into improving the editorial product in the last few years," said Washingtonian owner Philip Merrill. "It's nice to have your efforts recognized by your peers. It's really a tribute to Jack Limpert."

Playboy won the fiction award for printing stories by Gabriel Garcia Marquez, Andre Dubus III and John Gardner. Boston magazine won for essays and criticism for pieces by Howard Carr on the city's changing political scene, and Life won the photography award.

"Manhattan, inc." won the general excellence award for a magazine with less than 100,000 circulation. The magazine, "in less than a year, has done an extraordinary job of establishing an identity and an audience," said the judges. "This new magazine, which humanizes the role of business in the New York community, gives a fresh and provocative perspective on life in the world of industry and commerce." The magazine's editor is Jane Amsterdam, a former editor at The Washington Post. "It's a real honor after four issues -- all that qualified for 1984," said Amsterdam yesterday. "So we're incredibly proud."

Other winners in the general excellence category were American Health, American Heritage, and Time. Winning the award for reporting was Texas Monthly.

The awards, established in 1966 by the American Society of Magazine Editors, are administered by the Columbia University Graduate School of Journalism. The 36 judges included former Columbia journalism school head Elie Abel, current dean Osborn Elliott, former Newsweek editor in chief William Broyles Jr., journalism professor Ben Bagdikian, writer Lucinda Franks, photographer Gordon Parks and former Redbook editor Sey Chassler. The awards were presented at a lunch at the Waldorf Astoria Hotel in New York.