IB Environmental systems and societies 4.3E Productivity, Thermal Stratification, Nutrient Mixing, and Loading Key Definitions

Nutrient loading refers to the addition of nutrients (natural or human-induced) into a water body, affecting productivity.

Nutrient mixing refers to the vertical movement of water that redistributes dissolved nutrients (like nitrates and phosphates) throughout the water column.

The photic zone is the upper layer of a body of water that receives enough sunlight to support photosynthesis.

Primary productivity is the rate of production of biomass using an external energy source and inorganic sources of carbon and other elements.

A thermocline is a layer in a body of water where temperature decreases sharply with depth, restricting vertical movement and mixing.

Turbidity measures water transparency based on suspended particles (sediments, plankton, pollutants).

Upwelling refers to the vertical movement of deep, cold, nutrient-rich water to the surface due to the displacement of surface waters by wind.