Introduction to the Marine Environment from Physical and Chemical Perspectives

Most of the solar radiation that reaches Earth’s surface is absorbed and redistributed, producing a latitudinal pattern for the long-term average sea surface temperature. Differences in temperature and salinity segregate seawater into vertical layers in a process known as stratification. The drag of winds on the ocean surface creates currents that combine to produce gyres that rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.Ocean primary productivity refers to the production of organic matter by photosynthesis. Phytoplankton fixes inorganic CO₂ into organic carbon, making it available to heterotrophs. By the sinking of organic matter, marine organisms are responsible for the largest carbon sequestration on Earth, a process known as the biological pump. Dissolved inorganic compounds required for phytoplankton growth at high concentrations are considered macronutrients; while micronutrients are needed in quantities that are orders of magnitude smaller. Some micronutrients, such as vitamins, are organic molecules. Ocean acidification is the ongoing decrease in the pH of seawater, caused by the increasing rate of dissolution of atmospheric CO₂ into the oceans. This decrease in pH may have a wide range of impacts upon marine life, especially on calcifying organisms.