The massive ship is anchored in Stokes Bay in the Solent because it is too big to sail into Portsmouth Harbour. We have a look at the world's ten biggest and most powerful aircraft carriers. Above: Nimitz Class aircraft carrier USS Theodore Roosevelt as she departed Naval Station Norfolk, Virginia. Nimitz Class, with a full load displacement of 97,000 tonnes, is the world's largest aircraft carrier. The first carrier in the class was deployed in May 1975, while the tenth and last ship, USS George H.W. Bush (CVN 77), was commissioned in January 2009.
Groundwater pollution differs from surface water contamination in several important respects. Among them, it does not typically flow to a single outlet. It can affect people through wells dug in a contaminated aquifer, as it can flow into streams or lakes.
The boundaries of an aquifer are usually gradational into other aquifers, so that an aquifer can be part of an aquifer system. The top of an unconfined aquifer is the water table. A confined aquifer has at least one aquitard at its top and, if it is stacked with others, an aquitard at its base. figure 1. Click on image for larger view. Figure 1 shows an example of an aquifer system in the lower Portneuf River valley.