| environ. |
chlorine A very reactive and highly toxic green, gaseous element, belonging to the halogen family of substances. It is one of the most widespread elements, as it occurs naturally in sea-water, salt lakes and underground deposits, but usually occurs in a safe form as common salt (NaCl). Commercially it is used in large quantities by the chemical industry both as an element to produce chlorinated organic solvents, like polychlorinated biphenyls (PCBs), and for the manufacture of polyvinyl chloride plastics, thermoplastic and hypochlorite bleaches. Chlorine was the basis for the organochlorine pesticides, like DDT and other agricultural chemicals that have killed wildlife. The reactivity of chlorine has proved disastrous for the ozone layer and has been the cause of the creation of the ozone hole, which was first detected in the Southern Hemisphere over Antarctica and then over the Northern Hemisphere (一种很活泼、有毒、绿色的气体元素，属于卤族。是最普遍的元素，以自然形态在海水、盐湖水和地下矿藏中存在，但是它通常以一种稳定形态存在例如普通的盐(NaCl)。商业上，它被用大量用于化学工业，即作为一种元素来生产绿色的有机溶剂，如多氯化联(二)苯(略作PCB)，也用于聚氯乙烯塑料、热塑性塑料、次氯酸盐漂白剂的生产。氯是有机氯农药的基本元素，例如DDT和其他可以杀死野生生物的农业化学药品。活性氯已证明可对臭氧层造成灾难，已经成为臭氧空洞的起因。臭氧空洞首次在南半球的南极上空出现，随后在北极上空也出现了臭氧空洞。) |
