Ecosystems

gas, which contributes to smog. Another intermediary is the nitrous oxide (N2O) gas. This is considered a greenhouse gas, contributing to global warming. The goal is to make all N2 gas, which ultimately happens. It starts the process all over again.

As you have probably surmised, man has contributed directly to greenhouse gases. The use of synthetic nitrogen fertilizers from chemically fixed nitrogen and the burning of fossil fuels has led to a lot of fixed nitrogen in the environment that hasn’t been there before. In addition, the groundwater has a lot of nitrogen in it. Drinking this groundwater with NO2 and NO3 in it (nitrite and nitrate, respectively) increases the cancer risk in humans. It has also led to the coastal fish-kill events from algae blooms in polluted ocean water.

This has also led to an increase in NO gas, which is a component of smog and an increase in N2O gas, which is a greenhouse gas. This is where acid rain comes from, which leads to forest death and the decline in forests in parts of the US and Europe.

ECOSYSTEMS

All of the different bacteria, animals, plants, and other organisms do not live in isolation. They live together in an ecosystem. An ecosystem, briefly, can be all the organisms living together in a small pond or tide pool; it can also be the entirety of the rainforest or grassland. An ecosystem is the combination of the organisms plus the physical environment. There are many populations or communities within an ecosystem that interact with the environment.

The ecosystem is different from the community in that it involves the physical environment itself. A community is the living or “biotic” aspect of the totality of the ecosystem, making the ecosystem a combination of abiotic (environmental) and biotic factors. Ecosystems can be quite small or very large, depending on the circumstances.

Ecosystems can be freshwater, marine-based, or terrestrial. The most common ecosystems are ocean ecosystems because oceans cover 75 percent of the earth’s surface. Freshwater ecosystems are the least common, comprising just 1.8 percent of the Earth’s surface. The rest are terrestrial.

The terrestrial ecosystems can be divided into different “biomes” based on the climate of the area. There are several different biomes, such as savannas, tropical rain forests, deserts, coniferous forests, tundra, and deciduous forests. There is diversity within the biomes such that different deserts and different forests of the world are structurally different.

Ecosystems have food webs, which are networks of organisms that ultimately feed on one another. They also have their own ways of participating in different biogeochemical cycles, which include the carbon cycle and the nitrogen cycle. Energy and matter are always conserved so that things like nitrogen get transferred from one state to another by organisms in the ecosystem.

It’s important to know that matter simply gets recycled through the Earth’s ecosystems. It can stay within a given ecosystem but just as easily can leave one ecosystem, such as a forest, to go to another ecosystem, such as a river during rain runoff situations. The same atoms on earth get recycled by getting assembled into different chemical forms in order to be used by different types of organisms

As for carbon, you can easily see that it is recycled like nitrogen. It’s in the atmosphere in the form of CO2 and gets fixed through photosynthesis. It then goes into making plants that get eaten and used in cellular respiration. The end result is CO2 formation through cellular respiration and the sending of CO2 back into the atmosphere. Waste products from animals also get excreted and used by bacteria and fungi as decomposers, leaving behind simple molecules that can be taken up by other organisms.

Energy, on the other hand, cannot be recycled. It is a one-way street in an ecosystem— going from light into heat. Energy enters the ecosystems as sunlight, getting captured by plants through photosynthesis. This energy gets stored into molecules that get turned into heat and ATP in order to drive chemical reactions. When these things die, the energy is lost. Energy doesn’t get destroyed, what isn’t used gets given off as heat energy. The sun is required to drive energetic processes at all times.

Ecosystems are highly dynamic with a continual recycling of phosphorus, nitrogen, and carbon. An ecosystem would die if it weren’t dynamic. Populations in ecosystems are always dying and being born or created, so that there are changes in the relative