In 2007, 296 million metric tons of iron ore were pulled from the mine. The mine is estimated to contain about 18 billion tons of iron ore, plus gold, manganese, copper, and nickel. The Carajas CarajÃ¡s mine sits in The carajas carajÃ¡s (Mountain range Serra) dos carajas CarajÃ¡s. in northeastern brazil
First, it think the phrase should be the net effect. Mixing up affect and effect  is a common error for both learners and native speakers of English. the net effect = the result in light of an important variable.
The observer effect is the effect whereby the observation of a physical phenomenon necessarily affects that phenomenon. In the context of quantum mechanics, the observer effect implies that a measurement of a physical observable of a system forces that system to randomly pick a particular value of that observable from many possible values.