• Mercury Featured Article Mercury Mercury

    Mercury is a chemical element that occurs naturally in the environment and exists in several forms.  Previous Element: Gold Next Element:... More »

  • Calcium Featured Article Calcium Calcium

    Calcium is the chemical element with atomic number 20; it has an atomic mass of 40.078 atomic mass units (amu). The chemical symbol for calcium is Ca. Calcium is a soft gray... More »

  • Sulfur Featured Article Sulfur Sulfur

    Sulfur (alternatively spelled sulphur) is the chemical element with  atomic number 16. The chemical symbol S is used in formulae and abbreviations. Sulfur has high abundance... More »

  • Acid sulfate soils Featured Article Acid sulfate soils Acid sulfate soils

    Main source: K.Ljung, F.Maley, A.Cook & P.Weinstein. Acid sulfate soils and human health. A Millennium Ecosystem Assessment. Environment International 35 (8), 1234-1242.... More »

  • Arctic Mercury Cycling and Ice Cover Featured Article Arctic Mercury Cycling and Ice Cover Arctic Mercury Cycling and Ice Cover

    Eggs Show Arctic Mercury Cycling May Be Linked to Ice Cover An international research team working with National Institute of Standards and Technology (NIST) scientists at the... More »

  • Krebs cycle Featured Article Krebs cycle Krebs cycle

    The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is one of the most important reaction sequences in biochemistry. Not only is this series of... More »

  • Health effects of nickel Featured Article Health effects of nickel Health effects of nickel

      Pure nickel is a hard, silvery-white metal, which has properties that make it very desirable for combining with other metals to form mixtures called alloys. Some... More »

  • Extremophile Featured Article Extremophile Extremophile

    An extremophile is an organism adapted to unusual limits of one or more abiotic factors in the environment. Some of the extreme conditions are temperature, pH, high salinity,... More »

  • Zinc Featured Article Zinc Zinc

    Previous Element: Copper Next Element: Gallium ... More »

Recently Updated
Ecosystem Last Updated on 2014-09-24 22:46:28 An ecosystem is a community of organisms interacting with each other and with their environment such that energy is exchanged and system-level processes, such as the cycling of elements, emerge. The ecosystem is a core concept in Biology and Ecology, serving as the level of biological organization in which organisms interact simultaneously with each other and with their environment. As such, ecosystems are a level above that of the ecological community (organisms of different species interacting with each other) but are at a level below, or equal to, biomes and the biosphere. Essentially, biomes are regional ecosystems, and the biosphere is the largest of all possible ecosystems. Ecosystems include living organisms, the dead organic matter produced by them, the abiotic environment within which the organisms live and exchange elements (soils, water, atmosphere), and the interactions... More »
Concentration expressions and notations Last Updated on 2014-06-18 18:21:06 In chemistry and other sciences, engineering and in fairly common usage, concentration is the measure of how much of a given substance there is in a given mixture of substances. There are many different notations and quantitative expressions of concentration.[1] The most commonly used expressions are discussed below: The mole fraction is a measure of the concentration of a component substance in a mixture of substances. It is defined as the number of moles of a component substance in a mixture divided by the total number of moles of the mixture.[2][3] The mole percent  (also referred to as the molar percent) is usually denoted by mole % and is equal to 100 times the mole fraction. The mass fraction is also a measure of the concentration of a component substance in a mixture of substances. It is defined as the mass of a component substance in a mixture divided by the total... More »
Climate change in relation to carbon uptake and carbon storage in the Arctic Last Updated on 2014-06-11 17:04:43 This is Section 14.10 of the Arctic Climate Impact Assessment. Lead Author: Glenn P. Juday; Contributing Authors: Valerie Barber, Paul Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Authors: Edward Berg, Rosanne D’Arrigo, Olafur Eggertsson,V.V. Furyaev, Edward H. Hogg, Satu Huttunen, Gordon Jacoby, V.Ya. Kaplunov, Seppo Kellomaki, A.V. Kirdyanov, Carol E. Lewis, Sune Linder, M.M. Naurzbaev, F.I. Pleshikov, Ulf T. Runesson,Yu.V. Savva, O.V. Sidorova,V.D. Stakanov, N.M.Tchebakova, E.N.Valendik, E.F.Vedrova, Martin Wilmking. Within the terrestrial biosphere, forests cover 43% of the land area but are potentially responsible for 72% of the annual net primary productivity[1]. The boreal forest covers roughly 1.37 billion hectares (ha) and by itself (not including high-latitude tundra) contains approximately 20% of global reactive soil... More »
Araya and Paria xeric scrub Last Updated on 2014-05-15 14:07:26 WWF Terrestrial Ecoregions Collection Included in the large coastal area of the Caribbean, the Araya-Paria xeric scrub ecoregion occupies the arid zones of Araya-Paria peninsula, with the exception of the montane areas of the Paria side. The montane areas of Paria are included in the Cordillera de la Costa ecoregion. Aria-Paria also includes the island of Margarita (all except the mangroves), and extends south on to the mainland to Cumaná. The Araya-Paria xeric scrub ecoregion is characterized by very dry environments, and constitutes one of the last refuges for a number of rare and restricted-range animal species. Oriented from east to west, the island of Margarita is located at 38 kilometers (km) north of Araya peninsula and has a total area of 934 square kilometers (km2). The island is made up of two regions joined by an isthmus.... More »
Serra do Mar coastal forests Last Updated on 2014-05-14 16:26:42 WWF Terrestrial Ecoregions Collection This tropical moist forest ecoregion along the southern coast of Brazil has a subtropical climate with high levels of annual rainfall. The Serra do Mar mountain range defines this ecoregion with montane forests of Bromeliaceae, Myrtaceae, Melastomataceae, and Lauraceae species. This region contains outstanding biodiversity in endemism and species richness of flora, mammal, bird, and herpetofauna. More than half of the original forest has been altered; urban development and tourism constitute the main threats to this ecoregion. The Serra do Mar coastal forests cover a 100-kilometers(km) wide strip along the Atlantic Coast of Southeast and South Brazil. The climate is subtropical with an annual rainfall ranging from 1,400 to 4,000 millimeters (mm) without a dry period. This area of Brazil is occupied by... More »