16. Great Smog of 1952- London More than 4000 people died
17.
18.
19. Phytoplankton Zooplankton Rainbow smelt Lake trout Herring Gull Fish Fry Polychlorinated biphenyls (PCBs) undetectable in water Biomagnification In food chain X 1 X 49.2 X 416 X 1932 X 49,600 ?????