Bio UA - Ch 2 Updated Cycles of Matter PowerPoint PDF

Chapter 2: Cycles of Matter  Cycles of Matter The Hydrologic (Water) Cycle There is a limited amount of water in the biosphere, but all of the water is naturally recycled. More than 97% of the water in the biosphere is salt water stored in the oceans. The remaining 3% is fre...

Chapter 2: Cycles of Matter  Cycles of Matter The Hydrologic (Water) Cycle There is a limited amount of water in the biosphere, but all of the water is naturally recycled. More than 97% of the water in the biosphere is salt water stored in the oceans. The remaining 3% is freshwater stored in rivers, lakes, glaciers, ice, snow, the atmosphere and living organisms. Cycling of Water in the Biosphere  How does water cycle? How does it exist in all 3 states? Evaporation: the phase change of water from liquid to gas. Transpiration: evaporation of water from plants. Evapotranspiration: the combined transpiration and evaporation from a terrestrial area. Condensation: phase change of water from gas to liquid.  Precipitation: includes rain, snow, hail, etc. Infiltration: water seeping into the ground. Run-off: water from rain or snowmelt flowing over the land surface. Metabolic water: the water that is produced as a byproduct of cellular respiration.  Ground water: water stored beneath the Earth’s surface. Aquifer: a large underground water storage site. Spring: where water flows from an aquifer to the surface of the Earth. Trees and forests are called watersheds because they catch rain and snow and gradually release the precipitation, preventing  Water is… AMAZING! Amazing at carrying dissolved minerals! Amazing at transferring thermal energy around our biosphere! Amazing at helping other cycles of matter (that we will talk about) And lots of fun to drink, wash with, play Check out in…. this cool All living things need it to survive! Evian Wate  POLAR! Polarity is due to unequal sharing of electrons Polarity causes water molecules to form hydrogen bonds with one another H-bonds enable water to dissolve a wide range of substances – hence water is called the “universal solvent” Since many things can dissolve in water, it plays an important role in other cycles of matter!  A large amount of energy is needed to break the many H-bonds in a volume of water This is why liquid water has a relatively high boiling point and solid water (ice) has a relatively high melting point  When water freezes it expands because hydrogen bonds hold the water molecules in an open crystal structure. Water is most dense at 4°C and decreases in density above and below this temperature. Water’s density characteristics have key consequences for life and the cycling of nutrients. Allows ice to float on top of lakes and rivers during the winter – aquatic organisms can survive on dissolved O2  As the water sinks and rises with temperature changes, nutrients and dissolved oxygen are cycled with it. ➔ Hydrogen bonding causes cohesion – the attraction of water molecules to each other ◆ This causes water to have a high surface tension. ➔ Adhesion is the attraction of water molecules to molecules of other substances. This is also caused by hydrogen bonding!  Cohesion and adhesion explain capillary action and transpiration in plants!  Water has a high specific heat capacity – it absorbs and releases a large amount of energy for a given change in temperature. This property enables organisms to maintain a fairly constant internal temperature. Large bodies of water have a moderating effect on the air temperatures of nearby land. Water can absorb large amounts of thermal energy, then release it slowly  Water aids in the distribution of heat globally, through convection currents in oceans  Water vapour is the largest greenhouse gas. Other GH gases include: CO2, CH4 (methane), N2O (nitrous oxide) Without the natural greenhouse effect the average temperature on Earth would be -18°C rather than CBS News: Oceans Give, Oceans Tak e - about Their Role+15°C. in Climate Change (7 What is causing the enhanced greenhouse effect?? Increased global temps may result in more evaporation, less precipitation. This could jeopardize water supplies, ocean levels, agriculture, biodiversity Burning fossil fuels also adds nitrogen and sulfur compounds to atmosphere – react with water vapour – form acid precipitation  Water… Essential to Life! By mass, water comprises more than 50% of all plant and animal tissue! All living cells require water for transport of nutrients and biochemical reactions 95% water!  Photoautotrophs need water for photosynthesis. Organisms must consume water to replace water lost through evaporation, sweating, breathing, urine and feces  Water quality is another issue that affects the amount of water that is available for drinking, washing, and other uses. Water is considered to be a renewable resource, however water that cannot be cleaned of toxic chemicals and pathogens is no longer useful.  When water is scarce, plants respond by closing their stomata to limit transpiration – this also prevents photosynthetic activity because gas exchange is limited. This results in loss of plant life and decreased absorption of atmospheric CO2. Video – Water – Liquid A wesome (11min) Amoeba Sisters: Carbon a nd Nitrogen Cycles (8 min) 2.2 Biogeochemical Cycles  Introdu The recycling of matter through the biotic ction and abiotic components of the ecosystem allows all organisms to obtain essential nutrients. At each step in a biogeochemical cycle, substances are temporarily stored in nutrient reservoirs, such as organisms, air, soil and water.  The rapid cycling of nutrients is when substances can cycle between nutrient reservoirs relatively quickly (e.g. the movement of carbon from producer, to consumer, to decomposer.) The slow cycling of nutrients is when substances accumulate and are unavailable to organisms for a long period of time (e.g. fossil fuels and rocks). Rapi Slow d Cycli Cycli ng ng Peat is formed from dead plants and animals in wetlands – the anoxic environment slows decomposition –  Elements such as oxygen, carbon, nitrogen and sulfur form compounds that easily dissolve in water – hence they can be transported around the world! Iron and Phosphorus are mostly found in soil and water on the earth, not in the atmosphere  Carbon & Oxygen Cycles How do you think the 2  The carbon and oxygen cycles are closely linked through the processes of photosynthesis and cellular respiration. Carbon SINKS = reservoirs that absorb more carbon than they emit Largest carbon sink = ocean. It absorbs CO2 in the water and producers use CO2 to make organic matter that is returned to the ocean floor as sediment when organisms die. Plants are able to “fix” carbon (convert atmospheric carbon into organic compounds) by using CO2 during photosynthesis to make an organic molecule called… Plants consume more carbon (thanks to PS) than living things release during CR.  Why Carbon Sinks Matter It if weren’t for the oceans, would be over 500 ppm Total soils and plants CO2 concentrations Human Ocean CO2 Sink Emissions Absorpti Land since on Sink 1750 Absorpti CO2 on Concentra tion CO2 Conc before pp 1750 pp m m CO2 CO2 Pre-1750 2009 CO2 CO2 Concentration Concentrati on  Deforestation results in increased atmospheric CO2 levels. Why? Carbon SOURCES emit (release) carbon into the atmosphere. Burning fossil fuels releases carbon from the ground into the atmosphere. Cellular respiration in living organisms releases CO2 into the atmosphere.  Rising ocean temperatures result in significant amounts of carbon dioxide being returned to the atmosphere (cold water dissolves more CO2) Forest fires and volcanoes are natural carbon sources (what kind of reaction is this?)  Limestone plays a role in the carbon cycle. It is formed from calcium carbonate (CaCO3) from shells of aquatic organisms and may precipitate from dissolved calcium carbonate in water. As limestone weathers over time, small amounts of carbon are released back into the soil, air, and water. Limestone buffers acids in soil and water. Rapid cycling of carbon involves… ❏Photosynthesis ❏Cellular respiration ❏Decomposition ❏Combustion Slow cycling of carbon involves… ❏formation of fossil fuels ❏formation of rocks ❏formation of sediments in the deep ocean  Atmospheric CO2 Photosynthesis Combustion Respiration Organic Carbon Fossil Decomposition Fuel Human activities have significantly affected the carbon cycle in the last 150 years. Increased fossil fuel use has increased the amount of CO2 in the atmosphere…. Leading to the More CO2 causes an atmosphere to trap and retain more heat. This affects Carbon Cycle & Acid Deposition … a side issue (but a big issue!) In addition to carbon, fossil fuel deposits also contain sulfur and nitrogen When fuels are burned, these are released as sulfur dioxide and nitrogen dioxide SO2 + water vapor + oxygen = sulfuric acid H2SO4(aq)  Burning fossil fuels also cause atmospheric nitrogen to react with oxygen and water to produce nitric acid and nitrous acid. These reactions result in acid Natural deposition that can damage plants, Sourceslakes, acidify of and leach nutrients from NO2 and SO2 the soil. are volcanoes and forest fires – BUT Video - Hydrologic Cycle an d Carbon Cycle  Nitrogen Cycle (N) Nitrogen gas (N2(g)) makes up 78.1% of the Earth’s atmosphere. We are 3% nitrogen – not much, but it’s an essential component of ATP, proteins, and DNA found in cells. Most organisms CANNOT use atmospheric nitrogen (N2(g)) because of the stability of the triple bond. Nitrogen? Nitrogen Fixation: process by which some bacteria convert nitrogen gas from atmosphere (N2(g)) into ammonium ions (NH4+). Some nitrogen-fixing bacteria live in the nodules on the roots of legume plants (e.g. beans, lentils, peas, peanuts) and form a mutually symbiotic relationship with the plant. Plant benefits! Can access and use nitrogen bacteria are “fixing” Bacteria benefits! Can get glucose (food source) from the plant Crop rotation is a farming method in which legumes are grown one season and crops are grown the next to add ammonium ions (NH4+) to the soil  Nitrogen Ammonification: process by which decomposers break down organic matter into ammonium ions (NH4+) Nitrification: process by which nitrifying soil bacteria convert the ammonium What most plants ion (NH 4 + ) into nitrite  Connecting N2- fixation, Ammonification & Nitrification  Cycle Lightning can also convert atmospheric nitrogen into nitrate ions. Denitrification: process by which denitrifying bacteria (anaerobic) convert nitrate (NO3-) or nitrite (NO2-) back into nitrogen gas (N2(g)). Combustion of fossil fuels causes atmospheric nitrogen to combine with Ammonification by Nitrificatio  Insect Eating Plants - Nitrogen Poor Soil? Nature Always Finds A Way! Nepenthes Venus Flytrap attenboroughii – a Rat eating plant! As Hank Says… You owe bacteria a solid – smart enough to make an enzyme that can bust open the triple bonds of nitrogen gas! You owe plants a solid for wrestling nitrogen into their bodies so that can just eat a carrot and not have to think about it! Nitrogen is awesome and Crash Course: Nitrogen and everywhere Phosphorus Cycles and, yet, also elusive  Phosphorus Cycle We are 1% Phosphorus – again, not much, but an important part of DNA, ATP, teeth & bones, cell membranes Phosphorus does NOT cycle through the atmosphere! It is found in soil and water. Producers can only use Phosphorus if it is in the form of a phosphate ion (PO43-), which dissolves in water.  Phosphorus is often in limited quantities in the environment, hence it is an abiotic limiting factor for plants Its scarcity keeps the growth of producers in balance, which is a good thing!  The RAPID cycling of Phosphorus involves: consumption of plants and animals decomposition leaching chemical precipitation. The SLOW cycling of Phosphorus involves: formation of sediment Short Term Cycle Long Term Cycle Remember! Phosphorus does not cycle through atmosphere!  thing… Eutrophication = the buildup of excess nutrients (e.g. Phosphorus, nitrogen) in a body of water Can result in an algal bloom – the overgrowth of algae due to the presence of large amounts of Phosphorus. Algal bloom can prevent the penetration of sunlight  The overgrowth of algae produces a large amount of organic matter (which will eventually die) Decomposers use up oxygen breaking down excess dead organic matter, resulting in the death of fish and other aquatic life. Eutrophication is often caused by fertilizer runoff and sewage entering the water – thanks to humans. Sigh…  Matter & Energy Exchange Productivity is the rate at which an ecosystem’s producers capture and store energy within organic compounds (i.e. glucose) over a certain length of time. It is the rate at which organisms produce new biomass. Productivity In general… the depends on: amount of solar radiation limits 1. number of producers productivity, whether it’s too little 2. amount of light and (low PS rates) or too much (inhibits PS, heat available harms cells) 3. time of year 4. available nutrients 5. amount of rainfall or water available  What factors might impact the productivity of these different ecosystems? The Biosphere in Balance Living things must maintain a level of “balance” or homeostasis - that is, to maintain internal conditions that are relatively constant in spite of changing external conditions So, too, must ecosystems Gaia Hypothesis Homeostasis on a global level! Proposed by James Lovelock in 1979 Biosphere acts like an organism that regulates itself, maintaining environmental conditions within certain limits The biosphere needs a constant input of energy and the cycling of nutrients  In the ancient past, the atmosphere was anoxic and dead microorganisms formed sedimentary rocks called stromatolites Some stromatolites show bands of iron oxides, which formed when iron ions combined with dissolved oxygen in the oceans. evidence for atmospheric change over time…  Iron bands estimated to be about 2.5 billion years old or more, suggesting that oxygen levels in the ocean began to rise at this time Stromatolites that are less than 1.8 billion years old do not have these black bands of iron oxide because most of the iron in the ocean had been used up - hence couldn’t bond with oxygen So, oxygen produced by aquatic organisms doing PS began to build up in oceans Eventually, oxygen escaped into atmosphere, creating new opportunism for other living things! Balance Dead zones are regions of lakes or oceans in which aquatic life has suffocated due to algal blooms. Algal blooms can be caused by various types of pollution such as: Nutrients in the soil exposed by deforestation washed into rivers by rain. Sewage discharged into bodies of water.  Wetlands (where soil is permanently saturated with water e.g. bog, swamps, marsh) act as water filters and are home to many species of wildlife …but they are being drained to make room for agriculture or urban growth.  Human activities contribute to rising atmospheric CO2 levels, disrupting the balance of  An indicator species is sensitive to small changes in their environment and can provide early warning that ecosystem is out of homeostasis Examples: Amphibians –exposed to both aquatic and terrestrial ecosystems. Coral Reef – ocean CO2 (hence acidity) levels) Lichen – sensitive to heavy metals, acid in precipitation – indicate air pollution River otters – can indicate a healthy system Video – Biosph ere 2