Definition. The normal concentration of sodium in the blood plasma is 136-145 mM. Hyponatremia occurs when sodium falls below 130 mM. Plasma sodium levels of 125 mM or less are dangerous and can result in seizures and coma. Description. Sodium is an atom, or ion, that carries a single positive charge.
reef1. 1  a ridge of rocks or sand, often of coral debris, at or near the surface of the water. 2  Mining. a lode or vein.
The fringing reef is by far the most common of the three major types of coral reefs, with numerous examples in all major regions of coral reef development.HAT IS A LAGOON? - A lagoon-as used in the context of coral reef typology-refers to a comparatively wide band of water that lies between the shore and the main area of reef development, and contains at least some deep portions.