Read the following passage and answer the questions.
Here are two main sources of water pollution; definite sources and nondefinite sources. Definite source pollution is due to discharges from a single source, such as an industrial site. It includes factories, waste water treatment facilities, septic systems, and other sources that are clearly discharging pollutants into water sources. Non definite-source pollution involves many small sources that combine to cause significant pollution. For instance, the movement of rain or irrigation water over land picks up pollutants such as fertilizers, herbicides and insecticides carries them into rivers, lakes, reservoirs, coastal waters, or groundwater. Non-definite sources are more difficult to identify, as they cannot be traced back to a particular location. Landfills can also be a non-definite source of pollution, if substances leach from the landfill into water supplies.
a) Which sources of water pollution are difficult to identify?
b) What are definite sources of water pollution? Give two examples.
