A House of Delegates committee, responding to strong pressure from the House speaker, approved legislation today that would cut about $1.8 million from a state environmental trust fund, an action that environmental activists said could stymie research into such problems as acid rain.

The House Environmental Matters Committee, which earlier today had refused to make the reduction, reversed itself this afternoon under pressure from Speaker Benjamin L. Cardin and committee Chairman Larry Young, both Baltimore Democrats.

The bill, which now goes to the full House, would cap at $1,000 per month the amount the state's largest industrial users of electricity pay into the trust fund that oversees a $5 million power plant siting and research program. It would also limit the so-called environmental surcharge paid by ordinary consumers. Approval of the amended version of the bill by the full legislature would save the average residential consumer 3 cents a month on utility bills.

The measure, sponsored by Senate President Melvin A. Steinberg (D-Baltimore County), was originally intended to cut the surcharge paid by large industries that consume large amounts of electricity. In amending the bill today, the House committee voted to reduce the maximum surcharge even further, which environmental lobbyists and state government officials said could seriously crimp the research aspects of the program.

Funds from the electricity surcharge are used to monitor and conduct research into the effects of power plants on the state's environment, including the Chesapeake Bay. Current research projects include studies of radioactive discharges from the Calvert Cliffs nuclear plant and the effects of acid rain on the bay's fisheries.

"There are games being played with this bill," asserted Sierra Club lobbyist Jim Clarke. "I don't have any idea as to what the agenda is. It will probably cut acid rain research."

John Griffin, the state's deputy secretary of natural resources, predicted that the cuts mandated by the legislation would force his department to spend the remaining funds on studies relating to electric plant expansion and monitoring of pollutants rather than "topical research."

Cardin, who directed his committee chairman to try to reverse this morning's vote rejecting the funding cut, said "there is more money in the program than they need" and argued that the environmental studies should be funded from the state's general budget rather than from the utility surcharge.

Under pressure from Cardin and Young, five committee members switched their votes this afternoon. One of the five, Del. W. Timothy Finan (D-Western Maryland), explained his change of heart by saying that Cardin's "opinion was sufficiently strong to overcome the feeling on the committee that the surcharge is a good idea."

Another member who switched his vote, Del. Lawrence LaMotte (D-Baltimore County), said he was swayed by Young's assurances that Natural Resources Secretary Torrey C. Brown had agreed to the amendment. Griffin, Brown's deputy, said the department had never changed its position opposing the reduction.