Presdient Reagan expressed "deep concern over the continuing wave of death and disappearances" of black children in Atlanta, and Vice President Bush in Washington announced formation of a federal task force to aid the city's investigation.

While Reagan spent another sunny day in seclusion at this mountaintop ranch 30 miles northwest of here, an administration spokesman also announced the nomination of former Colorado legislator Ann M. Gousuch as administrator of the Environmental Protection Agency and New Mexico engineer John W. Hernandex as her deputy. Both appointments, which require Senate confirmation, were anticipated.

Reagan has not been seen since he and wife Nancy flew by helicopter from Point Mugu to their ranch Thursday afternoon. White House deputy press secretary Larry Speakes said the president spent another day riding and chopping wood but that he also talked by telephone with Bush, White House adviser Michael K. Deaver and Rep. James Jones (D-Okla.), chairman of the House Budget Committee.

After the conversations with Deaver and Jones, the president expressed optimism once again that Congress would move speedily to approve a significant number of the federal budget cuts he proposed in a nationally televised speech Wednesday night.

Announcement of the federal task force to assis Atlanta Mayor Maynard Jackson in investigating the killings was made here and by the vice president's office in Washington.

"President Reagan and I believe that is is essential that federal, state and local officials do everything possible, not only to provide a end to this nightmare of slayings and disappearances, but also to provide the necessary health, mental health and community services for the children and parents of the area," Bush said.

The task force will be headed by Charles Rinkevich of the Law Enforcement Assistance Administration and will include representatives of the departments of Justice, Health and Human Services, and Education.

During the last year and a half, 18 black children between ages of 7 and 15 have been found dead in Atlanta and two others have disappeared. Local officials have sought federal help, but the FBI has been limited in the formal aid it can provide because there is no evidence any killer or killers crossed state lines.

In Atlanta today, police were investigating the apparent suicide death of a young man to determine whether he was the same person sought for questioning in the children's deaths, Jackson said. He said no link to the child cases had been established, although police were considering the possibility.

Except for a few appointments, formation of the task force was about the only new annoncement so far on Reagan's brief vacation, which ends Sunday with a return flight to Andrews Air Force Base.

But speakes did have a reply of sorts for reporters who asked about a report in the Philadelphia Bulletin quoting Reagan, at a breakfast meeting with editors in Washington last week, that he had been "wondering" if Social Security could not be made voluntary.

"He has wondered that over the years," Speakes said, adding the president had vowed to "protect the integrity of the Social Security system" and has no plans to propose conversion to a voluntary system.

Reagan's periodic reflections on whether the system could work with voluntary participation have plagued him in all his presidential campaigns. His opponents usually characterize such statements as demonstrating opposition to Social Security, putting Reagan on the defensive and requiring him to issue statements, as Speakes did today, pledging his undying support for the Social Security system as it exists.

Speakes also commented on another newspaper report, in the Los Angeles Times, which said the Federal Reserve System had decided to tighten significantly the growth of money and credit in 1981.

The report said Federal Reserve Chairman Paul Al. Volcker would make the announcement in testimony Wednesday before the Senate Banking Committee.

If such an announcement is made, Speakes said, the president would regard it as demonstrating the Federal Reserve and the administration are "in harness" working toward the same goals of restricting inflation.

The board is an independent entity. But there have been discussions between representatives of the administration and the Fed, including a meeting between Reagan and Volcker, aimed at coordinating monetary policy. Administration officials consider that a more consistent money restriction policy is needed to control inflation, even if the short-term result is to keep interest rates high.