Five Democratic presidential candidates took shots at each other -- and occasionally at the Republicans -- during an environmental debate in Iowa Sunday. This debate was their sixth joint appearance and fourth debate -- the second on environmental issues -- in eight days.

Former Arizona governor Bruce Babbitt said he welcomes the many debates: "I don't have the money to buy that kind of exposure."

Massachusetts Gov. Michael S. Dukakis said he hoped Democratic National Chairman Paul G. Kirk Jr. would step in to help set guidelines for such events, but Kirk indicated he has no such plans: "I don't think we ought to be in the position of stifling debate." He added that he is concerned about the demands being placed on candidates. But Sen. Albert Gore Jr. (Tenn.) said after Sunday's debate, "The question is not what's most convenient for us as candidates. The question is what's in the public interest."

At the debate, sponsored by the Iowa Wildlife Federation and the state chapter of the Sierra Club and aired on Iowa public television, all the candidates said they would be leaders in doing more to protect the environment. Disagreements came over their records and who has the best ideas on public policy. Rep. Richard A. Gephardt (Mo.) criticized Gore for not taking a leadership role on acid rain legislation, while Gore denigrated Gephardt's proposals for dealing with ozone depletion by telling him, "The problem is much more complicated." And indeed it seemed to be as Gore went into a detailed discussion of chlorofluorocarbons.

After Gore's explanation, Jesse L. Jackson said: "Sen. Gore just showed you why he should be our national chemist. I want to be our next president." But Jackson did make clear that he, too, has an understanding of chemistry. "H2O," Jackson explained, "is a glass of water. And H1O is a half a glass of water."