1. Because water vapor molecules are lighter than nitrogen or oxygen molecules, a. Hot air rises
b. Air pressure is low at high altitudes
c. Humid air is lighter than an equal volume of dry air at the same temperature
d. Clouds form in cold fronts

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.