February 12, 1982

When Andrew Young, Atlanta's new black Mayor, talks about his plans for running local government, he generates considerable enthusiasm in the white business establishment that had become disenchanted with Maynard Jackson, his predecessor and the city's first black Mayor. They seem impressed, for example, with Mr. Young's immediate assault on petty misconduct and street crimes in the central business district of this convention-dependent city. The enthusiasm cools, however, when the politically sophisticated Mayor talks of his long-range plans for stimulating the city's economy by turning Atlanta into a center of international trade for developing nations, with City Hall serving as the driving force behind such a move. Work at U.N. Cited It may seem like a natural move for Mr. Young, who accumulated a number of contacts and a wealth of knowledge about the needs of developing nations while a member of Congress and as United States delegate to the United Nations during the Carter Administration.

SEVERAL of the singers and musicians who will be celebrating love musically this Valentine's Day weekend gathered around the reproducing piano at the New Ballroom, 253 West 28th Street (244-3005), the other day to discuss the state of love songs. They were around that particular Knabe concert grand, an unusually subtle variant of the old player piano, because it, like them, will be celebrating love - at brunch from noon to 3 P.M. on Sunday, which is Valentine's Day. The centerpiece of the piano's program will be that compelling aphrodisiac, Ravel's ''Bolero,'' transcribed and played by Morton Gould in 1927 at the tender age of 14. Mr. Gould, who is now 68, will be at the New Ballroom Sunday to hear his piano roll played for the first time in public. The other artists who will celebrate Valentine's Day through the medium of the reproducing piano are Sergei Rachmaninoff, who will play Chopin's ''Maiden's Wish,'' Joseph Lhevinne, who will serenade the audience with Beethoven's ''Moonlight'' Sonata, Rudolf Friml, who will play his ''Firefly,'' Vincent Youmans, who will offer ''Tea for Two'' and other selections from his ''No, No, Nanette,'' and Richard Rodgers, who will play a group of his love songs - ''Without a Song,'' ''Baby's Awake Now,'' ''Yours Sincerely,'' ''You Never Say Yes'' and ''Why Can't I?''

A Police Department study tracking 3,000 felony arrests that were processed by the Manhattan District Attorney found that 51 percent were reduced to misdemeanors and concluded that a third of those reductions were not the result of legal problems. The study said that the reductions had occurred because the District Attorney's office elected not to proceed with felony prosecution for any of three basic reasons: the nature of the crime, a prior relationship between the suspect and the victim or the suspect's limited or nonexistent criminal history, The police orginally decided to monitor Manhattan felony arrests for two months last summer after District Attorney Robert M. Morgenthau complained that poor police work was hampering his prosecutors. Who is responsible for thousands of felony arrests resulting in misdemeanor charges and lesser sentences has been a nettlesome question for criminal justice agencies, which often blame one another. No Quarrel With Study In the report, which was released yesterday, Mr. Morgenthau's office acknowledged that 33.8 percent, or 1,013, of the felony arrests had been reduced to misdemeanor charges for reasons that had nothing to do with police work or the strength or weakness of the arrests.

Businesses reduced inventories by 0.4 percent in December, matching the biggest decline during the 1975 recession, new Commerce Department figures indicated. The drop was interpreted as a sign that companies were trying to break out of the current downturn. The report said sales also fell, by 0.6 percent, leaving the inventoryto-sales ratio unchanged at 1.49. (Page D1.) President Reagan said he would give Congress room to cut his 1983 budget, but that he was not ready to yield on plans to reduce income taxes and increase military spending. G.O.P. Congressional leaders told Mr. Reagan that his proposed budget could not be passed. Paul A. Volcker, Federal Reserve chairman, said that the big projected budget deficits posed a threat to the financial markets. (A1.) The Conference of Mayors joined in growing criticism of the budget proposal, saying it would ''seriously undermine the economic and social health of cities.'' (D15.)

Last Sunday, a San Francisco man told the police, he was set upon by a pit bull when the dog's owner slipped the leash and shouted, ''Kill him, kill him!'' The dog attacked, biting the man on the abdomen, arm, hand and leg and sending him to the hospital. Last week, a 2-year-old boy in suburban Pleasanton was attacked in his yard by a 60-pound pit bull that dragged the youngster along the ground until his grandmother managed to free him. Fifty stitches were required to close gashes on the boy's head and body. These and other attacks by pit bulls, dogs trained to fight other dogs in clandestine matches that draw hundreds of paying spectators and high-stakes gamblers, have caused mounting concern in California as the animals proliferate both as pets and fighters. 'A Lethal Weapon' ''The pit bull has one major characteristic,'' said Richard Avanzino, director of the San Francisco office of the American Society for the Prevention of Cruelty to Animals. ''You might call it a flaw in its personality - it shows its love by serving its master. Some of those masters are vicious, evil, sick people who train the dog to fight and kill, turn it into a lethal weapon. If we are to believe the recent report, the animal had to be trained to attack.''