Limnology 3 - Lake Nutrients PDF

School of Environment and Geomatics ENVR 150 Review Dimictic Lakes  Zones  Midsummer Stratification  Photic  Epilimnion  Aphotic  Metalimnion (thermocline)  Littoral  Hypolimnion  Pelagic  Fall overturn ...

School of Environment and Geomatics ENVR 150 Review Dimictic Lakes  Zones  Midsummer Stratification  Photic  Epilimnion  Aphotic  Metalimnion (thermocline)  Littoral  Hypolimnion  Pelagic  Fall overturn  Temp  Isothermal  4◦c  Winter Stratification  Fetch  4◦c at bottom 0◦c at top  Early Spring  Isothermal  Early Summer  Lake Chemistry  Chemistry impacted by  Size of watershed  Climate  Geology (karst) Lake Karachay, Russia Dumping spot for nuclear waste Chemistry  Concerns  pH (too acidic or too basic)  Sulfates and Nitrates (SO4-2 & NO3)  Acid Rain (Sulfur dioxide)  Heavy metals eg. Mercury (Hg) Powdered lime  Bioaccumulation in aquatic webs  Oil spills  Salt (NaCl) concentrations  Nutrients(N & P)  Pollutants  Point Source  Non-Point Source  Cumulative Lan County, Sweden Dead Lake from Acid Rain Fundamentals of Environmental Measurements http://www.fondriest.com/environmental-measurements/parameters/water-quality/ph/  Chemical Zonation  Horizontal variations  Concentrations close to shorelines  Algal blooms, plant and animal concentrations  Wave action mixes sediments and erodes shoreline  Overland flow and ground water bring nutrients from  weathering, landslides,fires  fertilizers, land clearing, urbanization  Vertical Variations  Chemocline - A rapid vertical change in water chemistry  Salts – Summit Lake, Kitlope Lake  Annoxic conditions - Sannich Inlet (225 m deep)  Purple sulfur bacteria – need both sunlight and H2S produced by anaerobic bacteria, Mahoney Lake Stratification can cause pH levels within a body of water to differ above and below the cline. Kitlope Lake Green color / salt on the bottom and freshwater layers Laguna Verde and Licancabur Volcano, Bolivia, sediments, containing copper minerals Laguna Colorada Bolivia Shallow salt lake – red sediments and red algae, contrasted with white islands  Exploding lakes  Lake Nyos, Cameroon August 21, 1986 belched carbon dioxide and killed between 1,700 people and 3,500 livestock Surface Area 1.58 km2 Depth 208 m Active Volcanic Crater 500 yrs old Lake Kivu, Cameroon Methane + CO2 (500 million tons of Carbon in the lake ) 2% of humans annual emissions 2 million people living in basin Nutrient supply  “Nutrients” N (nitrogen) P (phosphorous)  A low level of nutrients means that N or P is absent  Limiting factors for growth and production of  Algae  Phytoplankton  Zooplankton  Fish  Nutrient Retention Time  How long a particular nutrient is held in a lake  Often reflects HRT  But nutrients can also be consumed by or changed in form by organisms The Phosphorus Cycle Nitrogen Cycle  Oligo-Eutro classification scheme  Succession of Lakes  oligotrophic > mesotrophic > eutrophic > marsh > land  Oligotrophic Lakes  Poorly supplied with nutrients  Support little plant growth  Biological productivity is low  Waters are clear, blue-green  Secchi disk depth of 15 m<  Large, deep, cold, steep  Lots of DO at deepest layers throughout the year Oligo-Eutro classification scheme  Mesotrophic Lakes  Moderately well supplied with plant nutrients  Support moderate plant growth  Secchi disk depth of 7.5 - 15 m Eutrophic Lakes Richly supplied with nutrients Abundant plant growth Biological productivity high (plankton, algae, macrophytes) Waters are turbid green/yellow Secchi disk depth is < 7. 5 m Small, shallow, warm lakes Reduced DO during stratification Eutrophication  Natural eutrophication  slow and gradual process  occurring over many centuries  production and consumption out of balance  lake slowly becomes over fertilized  Cultural eutrophication  green algae and other microorganisms  human-generated fertilization of water bodies  nitrates and phosphates  treated sewage  runoff from farms and urban areas  eventually lake dies How would you classify Kootenay Lake?