Oceanography

Salt marshes can be defined as wet grasslands that have a tendency to grow along estuarine shores. Salt marshes, as their name describes, contain a high concentration of salts, especially sodium salts. A large variety of plant and animal species do survive in salt marshes for a number of reasons. Halophytes are plants that thrive in salty water or are at least resistant to it. Salt marshes are thus inhabited by a number of halophytic plant species, each with its own particular set of exposure, sediment and water requisites. These plant species are able to thrive in this kind of an environment because they have specific structural and biological adaptations that enable them to do so. For example, Salicornia, or pickleweed, stores excess salt in its fleshy leaves, while Spartina, also known as saltgrass, contains special glands that excrete excess salt. These are plants that are found in the deepest parts of a characteristic salt marsh which tend to be swamped for longer periods of time and thus have the highest concentrations of salt in them. These and other plant species living in salt marshes can act as a direct food source for salt marsh herbivores, birds, fish and wildlife such as bream, whiting, mullet, snails and crabs. On the other hand, when this vegetation dies and decays it enters into the estuarine food chains and food webs as detritus. This detritus is acted upon by microorganisms such as bacteria and phytoplankton, which decompose the plant material further and release organic nutrients and inorganic micro nutrients to be reused by other plants in the estuaries. The bacteria in turn become a source of food for estuarine particle consumers such as mussel and oyster. Thus it is evident that a biological cycle exists which allows a wide variety of species of microorganisms and larger organisms to thrive in estuarine communities.

Wind turbines, or wind generators, are rotary devices, much like fans, that harness the power of wind and utilize it to produce electricity on a large scale for example for a utility grid. Wind turbines modify the kinetic energy of wind into rotational mechanical energy, which is eventually converted into electrical energy, or electricity, by means of a generator. As wind turns the blades of a wind turbine, a shaft connected to the blades rotates, and this shaft in turn activates a generator which turns out electricity. Wind turbines can either rotate in the horizontal plane (horizontal-axis wind turbine) or in the vertical plane (vertical-axis wind turbine). Horizontal-axis wind turbines are the commoner type of wind turbines. Small systems known as small-wind turbines or micro-wind turbines can be used to produce enough electricity for use in a boat or caravan.

Biodegradability, or biodegradation, is the ability of a product or material to have its organic components completely broken down through biochemical activity in a physiological environment into simple substances such as water and carbon dioxide. The term biodegradable is commonly associated with environmentally friendly products. The breakdown, or decomposition, is carried out by microorganisms such as bacteria and fungi. The organic matter can be broken down either in the presence of oxygen, that is aerobically, or in the absence of oxygen, also termed anaerobically. Biodegradable stuff is basically plant and animal matter and other organic substances produced by living organisms, or synthetic substances that are close enough in resemblence to plant and animal matter to be put to use by microorganisms It is common to find products that have non-biodegradable components as well as biodegradable ones being sold as biodegradable.