Complex sentence: The sediment at the mouth of the river near Newark Bay remains contaminated by such pollutants as dioxin which largely was produced at the Diamond Shamrock Chemical Plant in Newark as a waste product resulting from the production of the agent orange defoliation chemical used during the Vietnam War.
Split into simpler sentences: The sediment at the mouth of the river near Newark Bay remains contaminated by such pollutants as dioxin. The dioxin was generated principally by the Diamond Shamrock Chemical Plant in Newark, as a waste product resulting from the production of the agent orange defoliation chemical used during the Vietnam War.