September 28 Class

This evening we finished up looking at chemistry and the nutrient cycles. Nutrient cycles are how nutrients move through ecosystems. The carbon cycle describes the way carbon atoms move through the environment. Producers pull carbon out of the atmosphere and out of surface water to use in photosynthesis. Primary producers and consumers that eat them use the carbohydrates produced in photosynthesis and release carbon back into the atmosphere and oceans. During the phosphorus cycle, plants absorb phosphorus through their roots when phosphate is dissolve in water. Primary consumers take in phosphorus from water and plants and pass it on to secondary and tertiary consumers. Decomposers break down organisms rich in phosphorus and heir wastes and return phosphates back into the soil. The nitrogen cycle is a bit more difficult. Nitrogen is an inert gas that must be combined with hydrogen to form ammonia. This ammonium can then be taken up by plants. Animals get the nitrogen they need by eating plants or other animals. Decomposers obtain it from dead or decaying plants and animals, and also from animal urine and feces. Once the decomposers process these compounds they release the ammonium ions making them available to nitrifying bacteria to change back to nitrates and nitrites. Denitrification converts nitrates in soil or water into nitrogen gas that is released back into the atmostphere, completing the cycle.