Robert Martin marked Earth Day by resigning yesterday from his position as ombudsperson for the U.S. EPA. Martin, who has held the post since 1992, was well-regarded by environmentalists for his handling of complaints about cleanups conducted under the EPA’s Superfund program, but less beloved by higher-ups at the agency. In November, EPA Administrator Christie Whitman announced plans to transfer Martin to the Office of Inspector General, a move she said would grant him greater independence. Martin begged to differ; he chalked up his resignation to the “untenable situation” with Whitman, but could return to his job if his legal maneuverings to block the transfer are successful.