Introduction

Introduction
    • The flow of energy through the ecosystem drives the movement of nutrients within the ecosystem. Inorganic nutrients are chemical elements and compounds necessary to living organisms. Although an ecosystem needs a constant source of energy from outside, the nutrients upon which life depends can be recycled indefinitely.

    • The pathways in which the chemical nutrients move through the biotic and abiotic components of the ecosystem are called biogeochemical cycles or nutrient cycles. Major biogeochemical cycles include the water cycle, carbon cycle, oxygen cycle, nitrogen cycle, phosphorous cycle, sulfur cycle and calcium cycle. Decomposers play a key role in many of these cycles, returning nutrients to the soil, water, or air, where they can again be used by the biotic constituents of the ecosystem.

    • An important aspect of biogeochemistry is the fact that elements can occur in various molecular forms that can be transformed among each other, often as a result of biological reactions. Such transformations are an especially important consideration for nutrients, i.e., those chemicals that are required for the healthy functioning of organisms. As a result of biogeochemical cycling, nutrients can be used repeatedly, nutrients contained in dead biomass can be recycled through inorganic forms, back into living organisms, and so on.

    • Biogeochemistry is also relevant to the movements and transformations of potentially toxic chemicals in ecosystems, such as metals, pesticides, and certain gases. The important nutrient cycles considered here are the carbon cycle, the nitrogen cycle, and the phosphorus cycle. Carbon, nitrogen, and phosphorus are considered to be among the macronutrients essential to life apart from hydrogen, oxygen, potassium, calcium, magnesium, and sulfur. The many micronutrients, required only in very small quantities, include iron, manganese, copper, zinc, and sodium. Biogeochemical cycles are broadly classified into two i.e.,
    1. Sedimentary cycle (Phosphorous and Sulphur)
    2. Gaseous cycle (Oxygen, Nitrogen, Carbon).

Last modified: Tuesday, 28 February 2012, 10:00 PM