In the absence of ailing Councillor Walter J. Sullivan, the City Council last night temporarily blocked a plan to sell land on Riverside Rd. to make way for a new, ultra-modern supermarket.

Stepping back from its August 7 decision to authorize the sale of the land to Stop and Shop Co. for $1 million, the council voted down a recommendation from City Solicitor Russell B. Higley that would have slightly modified the provisions of the original order--a change he said the sale needed to proceed.

At the August meeting, the council voted 8-0 to allow City Manager Robert W. Healy to go ahead with the sale. But last night, proponents of the sale mustered only four votes for Higley's proposal.

Councillor Alice K. Wolf, who abstained from the August vote, joined Councillor Francis H. Duehay '55 in opposing the recommendation last night. Duehay said he was concerned that supermarket developers had not showed the city their plans.

"I think the community now has said, 'If you don't have any plans, then why give up your vote?'" said Councillor Saundra Graham, who abstained from the vote.

Sullivan, who suffered a mild heart attack last week, did not attend last night's meeting. In August, he voted for the sale, and he generally favors new development. Should the proposal be returned to the council next week, Sullivan is likely to provide the fifth, deciding vote.

The council originally decided to sell the land if Stop and Shop agreed to consult a neighborhood advisory committee and a traffic consultant before beginning construction. In addition, the council allocated part of the money for renovations at the Morse Elementary School.

Higley's proposal would have made those conditions part of the initial purchase and sale agreement, rather than the final transfer of property. He told the council that he could not complete the sale without council action.

But wolf said she was concerned that the technical amendments might make the August 7 conditions difficult to enforce, although Healy said the council's restrictions would be enforced in any case.

"All three of those conditions will be lived up to, and they will be complied with," Healy said.

In responce to questions from Councillor Thomas W. Danehy, Higley told the council that the purchase and sale agreement would be legally binding on the developer, even after the sale is completed.

"If there is any violation of those conditions, I can in fact go into court and enforce those obligations," said Higley.

In other business the council:

.postponed debate on a proposal from Councillor William H. Walsh that would block enforcement of the so-called "removal permit ordinance."

The ordinance, passed in 1979, prohibited tenants in rent-controlled housing from purchasing their apartments. Walsh agreed to postpone the measure pending a legal opinion from Higley.

Councillor David E. Sullivan blocked another Walsh proposal that would have declared a general amnesty for violators of the ordinance.

.received a letter from Mayor Alfred E. Vellucci asking all Cambridge students to organize "a working committee calling for continued policing of the global atmosphere."

.Sang a congratulatory round of "Happy Birthday" to councillor Sheila T. Russell on the occasion of her "annual 39th birthday."

"We all sang to you and that's a sign of peace in this City Council," said Vellucci.