GPHY 103 Lecture Notes - Lecture 5: Biochemical Oxygen Demand, Meromictic Lake, 100-Year Flood
Document Summary
Cool water is denser and remains at the bottom. Oligotrophic: young lakes or those with limited nutrients to support aquatic life. Generally clear water, relatively low productivity (artic lakes, ontario lakes) Mesotrophic: intermediate lakes with more nutrients, some organic material accumulation and greater aquatic productivity. 100 of 1000 of years older than above, Eutrophic: older or high nutrients lakes, abundant organic material and nutrient, high aquatic productivity, often partially or nearly full of organic sediments. High nutrients tends to consume oxygen, inherent productivity (biological oxygen consume oxygen, inherent productivity (biological oxygen demand) Nutrients in lake systems change trophic status, degrading lake quality. Nutrients are not toxic, they encourage growth and aquatic activity, its when there is too much nutrients that becomes problematic. Reverse impact, takes longer: rapid turn around, the retention or turnover time is the how long a lake volume takes to fully be replaced, for large lakes, this may be decades or centuries.
