Adding to the inter-state opposition to St. Lawrence Cement’s plans to build a cement plant in Hudson, the majority leader of Maine’s Senate, Sharon Anglin Treat, has expressed ’’profound concerns’’ in a letter to New York Gov. George Pataki.  After meeting with the Poughkeepsie-based environmental group Scenic Hudson, she wrote Pataki March 5 with concerns about how the plant would affect air quality in the Northeast.  St. Lawrence Cement wants to close a 1960s-era cement plant in Catskill, Greene County, and build a $320m plant with three times its capacity across the Hudson River in the City of Hudson and Town of Greenport.  Dan Odescalchi, plant spokesman, said Treat never sought information from the company. He said the new plant will reduce overall harmful emissions and meet the strictest requirements of the Clean Air Act.