An Iranian oil tanker that collided with a Hong Kong bulk freighter in the East China Sea is creating a new problem now that it has sunk. The oil tanker was carrying close to 150,000 tons of condensate, a light oil, when it crashed. It is unclear how much of the oil had burned off or spilled when it sank. Unlike crude oil, which can create chronic environmental problems by sinking to the deep ocean and lingering there for years, hydrocarbon condensate is much lighter, evaporating or dissolving into water. That means short-term toxicity might be a bigger concern with this spill.