In its second big U.S. Gulf Coast deal in as many months, the Canadian petrochemical maker Nova Chemicals has agreed to buy Williams Partners’ Geismar, La., ethylene cracker and related assets for $2.1 billion. Nova will get Williams’s 88% interest in the Geismar cracker, which in 2015 was expanded by 40% to a capacity of 900,000 metric tons per year. Saudi Basic Industries Corp. owns the other 12%. Also included in the deal is Williams’s interest in an ethylene trading hub in Mont Belvieu, Texas, and more than 200 hectares of undeveloped adjacent land that Nova says “represents a significant opportunity for future growth.” Last month, Nova formed a partnership with its European sister company, Borealis, and the French firm Total to build a $1.7 billion ethylene cracker near Total’s refinery in Port Arthur, Texas, and a polyethylene plant in Bayport, Texas. Nova makes ethylene and polyethylene in Joffre, Alberta,