1. This kind of contamination from industry (waste water from factories) can be dangerous for people.
    这种工业污染 (工厂排放的废水) 会危及人类。

2. Sewage disposal into the sources themselves, leakage of sewage into distribution systems or contamination with industrial or farm waste.
    污水排入水源，污水渗入给水系统或工农业污水造成污染。

3. Contamination of water supplies is usually due to poor sanitation close to water sources,
    水源的污染通常是由于接近水源的地方卫条件太差而造成的：

4. In addition, Germany and the Czech Republic have signed a treaty to protect the Elbe River from further contamination.
    此外，德国和捷克共和国已签订了一项条约以保护易北河，使之不再进一步被污染。