Question

why is monitoring water quality important near mining sites?
to detect contaminants that could harm ecosystems
to ensure the growth of aquatic plants
to check for increased soil fertility in surrounding areas

Explanation:

Mining activities often release toxic contaminants like heavy metals and chemicals into nearby water sources. Monitoring water quality here primarily aims to identify these harmful substances before they damage local aquatic and terrestrial ecosystems. The other options are not the core purpose: ensuring aquatic plant growth is a secondary outcome, and checking soil fertility is unrelated to water quality monitoring.

Answer:

to detect contaminants that could harm ecosystems