Flow of Matter in Ecosystems

The cycling of matter through living components (organisms) and non-living components (geosphere, hydrosphere, atmosphere) of an ecosystem

§ Geosphere □ Earth’s metal core □ Solid rock □ Molten rock □ Soil □ Sediments § Hydrosphere □ All water in all forms - Ice - Vapour in the atmosphere - Liquid in oceans, rivers, soil, groundwater § Atmosphere □ All the gases surrounding the earth § Biosphere □ The sum of all ecosystems around the earth □ All places where life can be found - In the atmosphere, biosphere and hydrosphere

○ Geosphere - Fossil fuels - Methane in seafloor sediment ○ Hydrosphere - Carbonic acid ○ Atmosphere - Carbon dioxide gas - Methane ○ Biosphere - Glucose in producers - Glucose, proteins, and fats in consumers - Methane in cattle

○ Photosynthesis - Carbon dioxide gas is absorbed from the atmosphere into autotrophs and transformed into high-energy carbon compounds (e.g. glucose) ○ Respiration - Glucose is broken down and carbon dioxide gas is released back into the atmosphere ○ Consumption - When consumers feed on a producer or another consumer, high-energy carbon compounds are ingested and broken down through respiration ○ Death - Dead organisms will be decomposed ○ Decomposition - Decomposers break down complex organic molecules into simpler inorganic forms and return carbon to the soil - Makes nutrients available for living plants - Releases carbon dioxide into the atmosphere ○ Diffusion - Carbon dioxide diffuses in and out of the ocean □ Carbon dioxide is used by producers in the ocean for photosynthesis □ In the ocean carbon dioxide is turned into carbonic acid ○ Combustion - Burning fossil fuels releases carbon back into the atmosphere in the form of carbon dioxide ○ Volcanic eruptions - Carbon is released as carbon dioxide when volcanoes erupt ○ Weathering - Carbon stored in rocks and soil is released when the rock breaks down or dissolves in water

○ Atmosphere - Nitrogen gas - 78% of atmosphere ○ Geosphere - Nitrogen dioxide in soil ○ Biosphere - DNA, RNA, proteins in animals - Ammonium ions in bacteria and plants - Nitrite and nitrate in bacteria

○ The nitrogen cycle is the biochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates through the atmosphere, geosphere, and biosphere ○ Nitrogen needs to change form to be useful

• Nitrogen-fixing • Consumption • Death • Decomposition • Ammonification • Nitrification • Denitrification

§ Nitrogen removed from the atmosphere by □ Lightning (small amount) N2 converted to NO2 □ Nitrogen fixers in soil (bacteria in the soil) - Free-living - absorb nitrogen gas from air spaces in soil and build it into amino acids □ Nitrogen fixers in nodule bacteria - Specialised bacteria invade the fine root hairs of plants causing the formation of nodules - This symbiotic relationship provides the bacteria with carbon, and the bacteria deliver additional nitrogen to the plants

• Animals consume nitrogen in food (plants and animals) □ Plants absorb nitrogen from the nitrogen-fixing stage □ Absorbed nitrogen is converted into nucleic acids and proteins

• Plants and animals die, which produces organic waste

• Decomposers break down dead organisms, urine, and faeces (excretion), returning nitrogen into the soil as ammonium (NH4+)

• Bacteria or fungi within the soil convert the organic matter back to ammonium (NH4+)

• ammonium -> nitrites -> nitrates • Plants struggle to absorb nitrogen • Nitrifying bacteria convert ammonium to nitrites □ Nitrites cannot be absorbed by plants • Other nitrifying bacteria convert □ Nitrates can be absorbed by plants

• Denitrifying bacteria turns nitrate (NO3-) into nitrogen gas (N2) • The nitrogen gas is released back into the atmosphere • Also releases oxygen which can be used by plants growing in waterlogged soils where oxygen is in short supply