From the earliest life forms to life on earth as we know it today, water has been the one essential constant . Covering roughly seventy percent of the earth’s surface, only a mere fraction is available as freshwater and of that, an even smaller proportion is available for human use and we are only just beginning to truly understand the nature of this most precious and limited resource. In addition to its life sustaining role, water is also one of the most destructive forces on earth, carving breath taking gorges and valleys, yet disasters related to water are responsible for large scale loss of life as well. In its different forms water supports ocean life, retains precious atmospheric samples dating back thousands of years, is a muse for writers, artists, and sculptors, as it tenuously supports a human population of six billion and growing.
The Kunene River (also Cunene River) is a river is southwestern Africa, 1050 kilometers long, with its watershed primarily within the nation of Angola but also drawing...
Nenjiang River grasslandLast Updated on 2014-03-18 16:57:33Nenjiang River grassland is an expansive low lying grassland drained by the Nenjiang and Songhua Rivers of China. The Nenjiang River originates among low hills that define China’s northeastern border with the Russian Far East. After winding through a series of valleys, the Nenjiang River flows down onto the Songhua-Nenjiang plain where flooded grasslands have historically provided important summer breeding habitat for a variety of migratory birds including six of the world’s fifteen crane species. The Red-crowned Crane, White-naped Crane, Siberian Crane and Demoiselle crane breed in this ecoregion, while the Common Crane and Hooded Crane stage here prior to migrating to their breeding habitat. Overfishing and agricultural development threaten the bird populations of this species-rich ecoregion.
Nenjiang River grassland is an expansive low lying grassland drained by... More »
Human population explosionLast Updated on 2014-02-26 17:23:15
Approximately 7.2 billion humans inhabited the Earth in year 2013. By comparison, there might be 500,000 elephants of different kinds, 200,000 chimpanzees, 100,000 gorillas, 20,000 polar bears, 3,000 tigers, 2,000 giant pandas and 200 California condors. Notably, the human population has grown about ten-fold over the past 300 years and nearly four-fold in just the last century. This monumental historical development has profoundly changed the relationship of our species to its natural support systems and has greatly intensified our environmental impact, particularly regarding species extinctions. Equally amazing are the signs that, in our generation, the human population explosion is abating (Figure 1; note that, here and below, many of the values given are estimates and, after the year 2005, projections). Our numbers are expected to rise by another 50%... More »
RespirationLast Updated on 2014-01-31 16:43:42Respiration is the gas exchange effected by living organisms for the purpose of sustaining vital metabolic processes. In the case of most animals, oxygen is taken into the organism, and carbon dioxide is expelled. In the case of plants, the inverse process occurs of consuming carbon dioxide and expelling oxygen as a waste gas.
Respiration may also be viewed at a cellular level, examining gas exchange at the cell wall; for very simple organisms, such as unicellular lifeforms, the process of gas exchange with the environment is simplified, so that cellular wall gas exchange is the totality of respiration for such an organism.
In the case of some bacteria and archaea, respiration sometimes occurs without any oxygen, and alternative molecular gases such as hydrogen sulfide or methane may participate in respiration and subsequent cellular metabolic reactions. Often such organisms are... More »
Aquifer depletionLast Updated on 2013-11-21 23:14:56Scores of countries are overpumping aquifers as they struggle to satisfy their growing water needs, including each of the big three grain producers—China, India, and the United States. These three, along with a number of other countries where water tables are falling, are home to more than half the world’s people. (See Table at end of article.)
There are two types of aquifers: replenishable and nonreplenishable (or fossil) aquifers. Most of the aquifers in India and the shallow aquifer under the North China Plain are replenishable. When these are depleted, the maximum rate of pumping is automatically reduced to the rate of recharge.
For fossil aquifers—such as the vast U.S. Ogallala aquifer, the deep aquifer under the North China Plain, or the Saudi aquifer—depletion brings pumping to an end. Farmers who lose their irrigation water have the option of returning... More »
Lower Kinabatangan-Segama Wetlands, MalaysiaLast Updated on 2013-11-01 10:38:26
This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion.
The Lower Kinabatangan-Segama Wetlands was added to the Ramsar List of Wetlands of Internation Importance on October 28, 2008 (Ramsar Site # 1849). The Lower Kinagatangan-Segama Wetlands are one of six Wetlands of International Importance in Malaysia. These wetlands are threatened by the expansion of oil palm plantations, especially in the upriver portion of the wetlands and tributary catchmentCatchment is the entire area of a hydrological drainage basin..
This 78.803 ha site is situated in Sabah (05°38’N 118°35’E) in Sarawak, East Malaysia on the island of Borneo.
This reserve contains coastal... More »
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