Question

ecologist describe Earth's Global bio geochemical Cycles as close what does this mean

Answer 1

The Earth is a closed system for matter, except for small amounts of cosmic debris that enter the Earth’s atmosphere. This means that all the elements needed for the structure and chemical processes of life come from the elements that were present in the Earth’s crust when it was formed billions of years ago. This matter, the building blocks of life, continually cycle through Earth’s systems, the atmosphere, hydrosphere, biosphere, and lithosphere, on time scales that range from a few days to millions of years. These cycles are called biogeochemical cycles, because they include a variety of biological, geological, and chemical processes.

Each of the chemical, biological, and geological processes varies in their rates of cycling. Some molecules may cycle very quickly depending on the pathway.

The biogeochemical cycles transport and store these important elements so that they can be used by living organisms.

Some molecules may cycle very quickly depending on the pathway. Carbon atoms in deep ocean sediments may take hundreds to millions of years to cycle completely through the system. An average water molecule resides in the atmosphere for about ten days, although it may be transported many miles before it falls back to the Earth as rain.

Biogeochemical cycles are subject to disturbance by human activities. Humans accelerate natural biogeochemical cycles when elements are extracted from their reservoirs, or sources, and deposited back into the environment (sinks).