One of President Carter's top legislative priorities, the massive Alaska lands bill, appears to have brighter prospects for passage now than before he was defeated.

However, another Carter environmental goal, the so-called "superfund" to finance cleanup of toxic waste dumps, apparently is dead. Both situations are products of the new Republican strength in the Senate.

The House and Senate each have passed versions of the Alaska bill, assigning varying levels of wilderness protection to more than 100 million acres of pristine mountains and forests filled with wildlife. Carter called the measure "the environmental vote of the century" and pushed hard for the 1979 House version, which wrapped more acreage in tighter protection than the Senate would agree to.

The Senate passed a rewritten approach in August after months of acrimonious debate and a filibuster by Alaska Democrat Mike Gravel. But it proved too lenient on developers for the House to stomach. Led by Rep. Morris K. Udall (D-Ariz.), House conservationists were holding out for position. Now all that may be over.

"There's a lot of feeling that we'd better be realistic and take what we can get," said one key staffer on the House Interior Committee. "We're at the mercy of the Senate."

The House essentially has two options. It can accept the Senate bill and thus avoid any House-Senate conference committee report that would be almost guaranteed to vanish in a Senate filibuster. But there are still several provisions that stick in Udall's craw, and he introduced amendments to take care of them before the election. He would have to drop all hope of those to take this road, but at least there would be an Alaska bill.

Senate Minority Whip Ted Stevens, Alaska's other senator, has urged the House to take this approach. "This bill is the best than can be done," he said. "It gives everyone 80 percent of what they were after."

In the other option, some environmentalists are pressing to let the entire issue die for the year. Most of the lands in question are already under a Carter executive order placing them in very strict protection as national monuments, and even Ronald Reagan, when he becomes president, will not have the power to allow development in a national monument.

"That's a very real possibility," said William Turnage, head of the Wilderness Society, one of the groups in the Alaska Coalition of 52 state and national environmental organizations. "There is also the possibility of having additional monuments designated" by Carter before he leaves office.

The problem with this idea is that Congress can tackle the situation again next year, and environmentalists do not regard the incoming Congress as particularly friendly. The best deal, Turnage said, would be to continue negotiations between Udall and Stevens to try to work something out. "We still feel we have a chance," he said.

The betting is that the House will take the first option and run with what will be a historic piece of legislation, even though well short of what Carter wanted.

The "superfund" bill, on the other hand, is in the Senate's court. A $1.2 billion House-passed package would assess the chemical industry 75 percent and the federal government 25 percent of the funds needed to guarantee the cleanup of any abandoned toxic waste dump. But the Carter administration has been pushing a much broader, $4 billion Senate environment committee version that comes up for markup in the Finance Committee late next week.

Also, the bill's major backer, Sen. John C. Culver (D-Iowa), was defeated Tuesday, and Republican opponents have promised to offer many major amendments in the markup session. Chemical Manufacturers Association president Robert Roland is confident it will be stopped.

"The question is whether the Senate wants to take up something as time-consuming and controversial as this is going to be," he said. "I would say they have more important budget matters to take care of."