Nitrogen (N) is an essential macronutrient the non-availability of which in suitable form or concentration often limits biological production both in the terrestrial and marine environments. It is a polyvalent element that occurs in oxidation states ranging from –3 to +5. Molecular nitrogen (N2), the dominant constituent of our atmosphere, is the most abundant form of nitrogen on Earth.
The global dust budget refers to an accounting of the emission, atmospheric loading, and deposition of the mineral dust aerosol on a global scale. The topic covers the location and strength of sources, transport paths, atmospheric distribution, and deposition of mineral dust aerosol.
A food web is a graphical description of feeding relationships among species in an ecological community, that is, of who eats whom (Fig. 1). It is also a means of showing how energy and materials (e.g., carbon) flow through a community of species as a result of these feeding relationships.
The growth and subsistence of coral depends on a number of requirements: temperature, irradiance, calcium carbonate saturation, turbidity, sedimentation, salinity, pH and nutrients. The level of these variables influences the physiological processes of photosynthesis and calcification, and also survival.
The earth is a constant recipient of an enormous flux of solar radiation as well as considerable infall of the cosmic debris that also arrives periodically in huge, catastrophe-inducing encounters with other space bodies, particularly with massive comets and asteroids.
Energy transitions are the changes from one state to another in the energy system; a given state of the system is defined by specific patterns of both energy supply and demand quantities and qualities. Energy transitions can be described in terms of three major interdependent characteristics…
Fusion powers the sun and stars as hydrogen atoms fuse together to form helium, and matter is converted into energy. Hydrogen, heated to very high temperatures, changes from a gas to a plasma in which the negatively charged electrons are separated from the positively charged atomic nuclei (ions).
