Concerns about the water quality in the Seine River led officials to call off the swimming portion of an Olympic triathlon training session for a second straight day. Organizers overseeing the event at the Paris Games are optimistic that triathletes will be able to swim in the city’s famed waterway when the competition starts Tuesday. The sport’s governing body, its medical team and city officials, are banking on sunny weather and higher temperatures to bring the levels of E. coli bacteria below the necessary limits to stage the swim portion of a race that also includes biking and running.