May 4: ORONO, Karen Merritt, Ph.D. student at the Department of Civil and Environmental Engineering at UMaine, will speak about her research into mercury cycling in sulfide-rich sediments in the Penobscot River Estuary at noon at UMO Norman Smith Hall. Free 581-3196

May 7: BATH, Peter Kent will speak at 3 p.m. at the Chocolate Church Arts Center, 798 Washington St. $5/$8 442-8455

May 7: LEWISTON, investment consultant William Arata will speak about tactics for managing cash flow that promote an optimum return on long-range investments, at 7 p.m. at Bates College Pettengill Hall, Andrews Road. Free 786-6232

May 7: RANGELEY, Drexler and Tom Sullivan will speak about their experiences in aviation at 4 p.m. at Rangeley Public Library. 864-5529

May 11: BRYANT POND, Ed Howe will speak about his most recent trip to Alaska at 10 a.m. at Whitman Memorial Library. 674-2143