Biogeochemical Cycle PDF

BIOGEOLOGICAL CYCLE Nutrient Cycle Maintains homeostasis (balance) in the environment. Merlita Lopez-Almeria Biology Department MSU, Marawi City  What are biogeochemical cycles? Earth system...

BIOGEOLOGICAL CYCLE Nutrient Cycle Maintains homeostasis (balance) in the environment. Merlita Lopez-Almeria Biology Department MSU, Marawi City  What are biogeochemical cycles? Earth system has specific parts – Atmosphere – Hydrosphere – Lithosphere Biosphere Biogeochemical cycles: The chemical interactions (cycles) that exist between the atmosphere, hydrosphere, lithosphere, and biosphere. Abiotic (physio-chemical) and biotic processes drive these cycles A closed system is a natural physical system that does not allow transfer of matter in or out of the system,  Two Types of Nutrient Cycle 1. Gaseous Cycle - involving atmospheric, hydrologic or water and sediment storage. Ex. Carbon Cycle and nutrient Cycle =include those of nitrogen, oxygen, carbon, and water 2. Sedimentary Cycle - involving sediment and hydrologic or water storage. Ex. Phosphorus Cycle and Sulfur Cycle =include those of iron, calcium, phosphorus, and other more earthbound elements. WATER CYCLE: The cycle of processes by which water circulates between the earth's oceans, atmosphere, and land, involving precipitation as rain and snow, drainage in streams and rivers, and return to the atmosphere by evaporation and transpiration.  Rain/Precipitation If the temperature underneath a cloud stays below freezing all the way to the ground, the ice crystals never melt and snow falls. If the temperature is above freezing below the cloud bottom to the ground, the frozen particles melt into liquid droplets that reach the surface and this is called rain.  Carbon Cycle : Key Aspects Carbon is the skeleton of all life. Carbon dioxide is a critical gas: – Taken up by plants in photosynthesis – Released by plants and animals in respiration – Released during decomposition (and fires) – Greenhouse gas (greenhouse effect )  Cellular Respiration ►the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, as waste products, carbon dioxide and water. ► the process through which cells convert sugars into energy (ATP). ►a metabolic pathway that uses glucose to produce adenosine triphosphate (ATP), an organic compound the body can use for energy. ►The chemical reaction for cellular respiration involves glucose and oxygen as inputs, and produces carbon dioxide, water, and energy (ATP) as outputs. C6H12O6 + 6O2 → 6CO2 + 6H2O + 36ATP Changes in Atmospheric C02 - 1  CO2 vary throughout the day Because photosynthetic activity is the cause of seasonal CO2 swings, regions with more plants will experience larger fluctuations. Photosynthesis also occurs in the oceans, but little of this CO2 actually moves into the atmosphere, which is why only land photosynthesizes drive seasonal cycles. During the day or in spring and summer, plants take up more carbon dioxide through photosynthesis than they release through respiration , and so concentrations of carbon dioxide in the air decrease.  Traffic jams during the day also increases the amount of carbon dioxide emitted into the atmosphere. a decrease in CO2 fixation by primary producers at night time. Typically, carbon dioxide levels rise during the night when people are sleeping, especially if the door and windows are closed. The concentrations then fall during the day if the room is unoccupied CO2 is a gas much heavier that the rest of atmosphere (N, O2, H2O etc..) and consequently it slowly accumulates in the lower level of our environment. During day light-time there is a release of Oxygen due to photosynthesis in vegetal and the mix of O2 is consequently richer. That does not happen at night..  What is a bad carbon dioxide level? The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an 8- hour TWA Threshold Limit Value (TLV) of 5,000 ppm and a Ceiling exposure limit (not to be exceeded) of 30,000 ppm for a 10-minute period. A value of 40,000 is considered immediately dangerous to life and health (IDLH value).  Nitrogen Nitrogen gas makes up 78% of the air we breathe. Most nitrogen enters ecosystems via certain kinds of bacteria in soil and plant roots that convert nitrogen gas into ammonia (NH3). This process is called nitrogen fixation. A very small amount of nitrogen is fixed via lightning interacting with the air.  Why is nitrogen important? Nitrogen is the biological limiting nutrient in marine systems, generally by being the least available for marine plants and algae. It is similar to phosphorus in freshwater in that when there is too much or too little it can change how an ecosystem functions. Nitrogen is also a component of the chlorophyll molecule, which enables the plant to capture sunlight energy by photosynthesis, driving plant growth and grain yield. Nitrogen plays a critical role within the plant to ensure energy is available when and where the plant needs it to optimize yield.  The wellness of plant parts (leaves, roots, trunks e.t.c) depends on the availability of essential nutrients like nitrogen to enhance the plant's biological processes including growth, absorption, transportation, and excretion. In humans it is dangerous, exposure to Nitrogen is dangerous because it can replace Oxygen and lead to suffocation. Forms of Nitrogen (N2) N2 - inert gas, 78% of the atmosphere NO, N20, NO2 - other gases of nitrogen, not directly biologically important. Part of the gases found in smog. NO3- (nitrate) and NH4+ (ammonium) - - ionic forms of nitrogen that are biologically usable. Forms & Sources of biologically available nitrogen (N2) For plants NO3- (nitrate) NH4+ (ammonium) Sources: N-fixation by plants (N2 to NH3 and N2 to NO3), lightening, bacteria decomposition of organic N (amino acids & proteins) For animals Organic forms: amino acids and proteins (from plants or other animals) Losses of nitrogen from system: In bogs, lakes (places of low oxygen), NO3- is converted to N2 by bacteria (get their oxygen from the NO3) Volatilization of NH4+ (urea) to ammonia gas (NH3) - warm, dry conditions. Leaching of NO3- (nitrate) Erosion Fire (combustion) Nitrogen Sources over time  Nitrogen Cycle: Key Points Nitrogen is in the atmosphere as N2 (78%) N2 is an inert gas and cannot be used by plants or animals N2 can be converted to a usable form via – Lightening – N-fixing plants and cyanobacteria – Industrial process (energy intensive) Nitrogen limits plant growth Nitrogen is easily lost from biological systems  Phosphorus is an essential nutrient for animals and plants. It plays a critical role in cell development and is a key component of molecules that store energy, such as ATP (adenosine triphosphate), DNA and lipids (fats and oils). Insufficient phosphorus in the soil can result in a decreased crop yield. Phosphorus is usually considered the “limiting nutrient” in aquatic ecosystems, meaning that the available quantity of this nutrient controls the pace at which algae and aquatic plants are produced. In appropriate quantities, phosphorus can be used by vegetation and soil microbes for normal growth.  Sulfur Cycle The sulfur cycle describes the movement of sulfur through the geosphere and biosphere. Sulfur is released from rocks through weathering, and then assimilated by microbes and plants. It is then passed up the food chain and assimilated by plants and animals, and released when they decompose. The sulfur cycle is the collection of processes by which sulfur moves to and from minerals (including the waterways)[clarification needed] and living systems. What is the importance of sulfur in ecology? Sulfur Cycle is important for life because sulfur is an essential element, being a constituent of many proteins and cofactors. Sulfur is an important element in the metabolism of salt marshes and subtidal, coastal marine sediments because of its role as an electron acceptor, carrier, and donor. Sulfate is the major electron acceptor for respiration in anoxic (greatly oxygen deficient) marine sediments.  Sulfur Cycle Steps of the sulfur cycle are: Mineralization of organic sulfur into inorganic forms, such as hydrogen sulfide (H2S), elemental sulfur, as well as sulfide minerals. Oxidation of hydrogen sulfide, sulfide, and elemental sulfur (S) to sulfate (SO42−). Reduction of sulfate to sulfide. Incorporation of sulfide into organic compounds (including metal-containing derivatives). SULFUR CYCLE