Biogeochemical Cycles ryan lopano

Water Cycle

Description: The water cycle explains how water evaporates from the surface of the earth, rises into the atmosphere, cools and condenses into rain or snow in the clouds, and falls again. There are four steps to the water cycle known as precipitation, condensation, transpiration, and evaporation. Precipitation is where the condensed water or ice falls from the clouds into the ground. Transpiration is where moisture is carried through the plants roots where it changes to vapor and goes into the atmosphere. Then it evaporates into the atmosphere. Condensation converts the gas back into a liquid and builds up in the clouds.

Impact of human intervention- People take water out of the system to irrigate crops to give us drinking water and carry out industrial processes. People also add harmful substances to the water that evaporates into the air. These substances include fertilizers, herbicides and pesticides.

Chemical reaction involved- 2H2 + 02 -> 2H20 ~ H+ +OH- -> H20

Nitrogen Cycle


Description- The nitrogen cycle is where nitrogen is converted into many chemically different forms. This nitrogen circulates among the atmosphere. It includes 5 steps/processes. They are Nitrogen fixation which is where dinitrogen (N2) is converted into Ammonium (NH4+). Step #2 is called denitrification. In this process, oxidized forms of nitrogen such as nitrate and nitrite are converted into Dinitrogen (N03- +N02 ->N2). Step #3 is called Nitrification. In this process, some ammonium produced by decomposition is converted to Nitrate. (NH4+ -> N03). Step #4 is called nitrogen mineralization. After nitrogen is incorporated into organic matter, its often converted back into inorganic Nitrogen. Step #4 is called nitrogen uptake. The ammonium produced by nitrogen fixing bacteria is quickly taken up by a host plant. (NH4 -> N)

Human intervention- 3 ways people have impacted the carbon cycle are fertilizers, agricultural productivity and the production of irrigation systems.

Carbon Cycle

Description: Carbon is attached to oxygen called CO2 with the help of the sun which is called photosynthesis. CO2 is pushed from the air to make the plant food from Carbon. This creates food chains. The Carbon moves from living things to the atmosphere every time a person or animal exhales. This process is called respiration. 3.3 billion tons of carbon is released every year when you burn fossil fuels.

Human intervention: Humans affect the Carbon cycle in many ways. The main reason is exhaling during respiration. Burning fossil fuels and deforestation are two other reasons.

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Phosphorus Cycle

Description: Phosphorus circulates through water, the earths crust, and living organisms. It will most likely enter the food chain following the slow weathering of rock deposits. Some Some of the released phosphates become dissolved in soil water taken up by plant roots. Phosphorus is the main limiting factor for plant growth in most ecosystems. Animals obtain phosphorus by eating plants or herbivores. Dead organisms and animal wastes return to the soil, streams and eventually to the ocean floor as rock deposits. This cycle does not include a gas phase.

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human intervention: Humans intervene with the water cycle by the use of fertilizers and raising livestock. Farmers have a big impact as well as they have lots of animals which produce lots of waste. The waste is high in phosphorus thus is why its important in the phosphorus cycle.


Created with images by bikeride - "York Lake"

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