Biogeochemical Cycles The cycling of nutrients within ecosystems Energy Flow in Ecosystems April 24, 2017

Biogeochemical Cycles Life on Earth depends on recycling essential chemical elements. Biogeochemical cycles move elements between the atmosphere, hydrosphere, lithosphere, and biosphere. Carbon is a necessary building block for most biomolecules Phosphorus is necessary for DNA, RNA and the energy molecule ATP Nitrogen is a key component in proteins, DNA, RNA and many enzymes Water is necessary for most chemical functions Energy Flow in Ecosystems April 24, 2017

General Nutrient cycle model Nutrients cycle between abiotic and biotic components of the ecosystem Energy Flow in Ecosystems April 24, 2017

1. The water cycle Water is essential to all living things Typically found in oceans, lakes, rivers, ice caps, groundwater (small amount in atmosphere) Cycles via sublimation, precipitation, evaporation, condensation, consumption, transpiration Energy Flow in Ecosystems April 24, 2017

The Water cycle Water is necessary for most chemical processes in living organisms. The water cycle includes both biotic and abiotic processes. Water in oceans, rivers etc. evaporates into the atmosphere. Energy Flow in Ecosystems April 24, 2017

Clouds form when water vapour condenses and water falls back to the ground in the form of precipitation. Water returns to the ocean etc. through runoff or returns to aquifers through seepage. Plants take up water and return unused water to the atmosphere through transpiration. Animals take up water and return it through perspiration, breathing, and elimination

The Water cycle Net movement of water vapor by wind (36) Solar heat Water vapor over the land Water vapour over the sea Precipitation over the land (95) Evaporation and transpiration (59) Precipitation over the sea (283) Evaporation from the sea (319) Surface water and groundwater Flow of water from land to sea (36) Oceans Energy Flow in Ecosystems April 24, 2017

2. The Carbon cycle Carbon is essential to building organic molecules Can be found in the atmosphere (CO2), plants, animals, fossil fuels, soils, sediments Cycles via photosynthesis, respiration, combustion, consumption Energy Flow in Ecosystems April 24, 2017

The Carbon Cycle CO 2 in the atmosphere diffuses into the water. Both land and aquatic plants take in CO 2 and produce carbohydrates and other biomolecules through photosynthesis.

2. Carbon Cycle Producers: Plants take in CO2 and make sugar by photosynthesis. Consumers: Animals eat plants to get energy (respiration) from sugar and make proteins from the carbon. Breath out CO2 as a waste product of respiration. Animals die and dentritus (decomposers) break down the carbon and other elements back into the soil and air for plants to use again. Human activities such as burning fossil fuels, and cutting and burning forests puts carbon back into the atmosphere. Energy Flow in Ecosystems April 24, 2017

Higher-level consumers The Carbon cycle CO2 in atmosphere Burning Wood and fossil fuels Cellular respiration Higher-level consumers Decomposition Detritivores Photosynthesis Producers Primary consumers Detritus Energy Flow in Ecosystems April 24, 2017

3.The Nitrogen cycle Found in the atmosphere (it is 80% N2), soils, sediments, water, organisms Nitrogen is part of important biological molecules and limits plant growth Nitrogen in nitrate forms are used by plants for production of amino acids and nucleic acids for protein synthesis and DNA Animals get amino acids by eating plants or animals that have eaten plants. N2 in the atmosphere is FIXED into ammonia (NH3) by nitrogen fixing bacteria in the soil. a small amount is fixed during chemical reaction that occur during lightening storms. Energy Flow in Ecosystems April 24, 2017

Nitrogen Fixation by bacteria Plants need nitrogen but cannot take it in from the air. Bacteria in the soil on the roots of plants take in nitrogen (N2) and make ammonia (NH4) which plants can then use to get nitrogen. Ammonification is the breakdown of nitrogen products in waste and decomposing tissue to return it to the cycle. Denitrification is the conversion of ammonia in the soil to free nitrogen by denitrifying bacteria. Energy Flow in Ecosystems April 24, 2017

Nitrogen (N2) in atmosphere The Nitrogen cycle Denitrifying bacteria Assimilation by plants Nitrogen (N2) in atmosphere Amino acids and proteins in plants and animals Detritus Detritivores Nitrogen-fixing bacteria in root nodules of legumes Decomposition Nitrogen fixation Nitrogen-fixing bacteria in soil Ammonium (NH4+ ) Nitrifying bacteria Nitrates (NO3– ) Energy Flow in Ecosystems April 24, 2017

5. The Phosphorous cycle Important component of many biological molecules (nucleic acids, ATP) Found in rocks in great amount, some in soils and water Cycles through weathering, taken up by organisms, sedimentation Energy Flow in Ecosystems April 24, 2017

The Phosphorus Cycle Phosphorus in the rocks leaches into the soil where it is taken up by plants. Producers make nucleic acids and when they are eaten pass the phosphorus through the food chain to consumers. Phosphorus reenters the soil through decomposition and waste.

Precipitated (solid) phosphates Phosphates in solution The Phosphorous cycle Uplifting of rock Phosphates in rock Weathering of rock Phosphates in organic compounds Consumers Producers Detritus Rock Phosphates in soil (inorganic) Precipitated (solid) phosphates Phosphates in solution Detritivores in soil Energy Flow in Ecosystems April 24, 2017