Water pollution is the contamination of natural water bodies by chemical, physical, radioactive or pathogenic microbial substances. Adverse alteration of water quality presently produces large scale illness and deaths, accounting for approximately 50 million deaths per year worldwide, most of these deaths occurring in Africa and Asia. In China, for example, about 75 percent of the population (or 1.1 billion people) are without access to clean drinking water. Widespread consequences of water pollution upon ecosystems include species mortality, biodiversity reduction and loss of ecosystem services. Some water pollution may occur from natural causes such as sedimentation from severe rainfall events; however, natural causes, including volcanic eruptions and algae blooms from natural causes constitute a minute amount of the instances of worldwide water pollution. The most problematic of water pollutants are microbes that induce disease, since their sources may be construed as natural, but a preponderance of these instances result from human intervention in the environment (such as discharge of raw sewage) or human overpopulation phenomena. One of the chief causes of water pollution is agricultural activity where tillage practices, fertilizer, pesticide and herbicide use create massive amounts of sedimentation and chemical discharge to natural waters. Industrial discharges, by contrast, have been greatly mitigated in Western Countries, but remain a significant issue in developing countries.
[Raul Perianez is the lead author of this article]
Heavy metal distributions in the Gulf of Cadiz are generated chiefly by coastal riverine discharge, and thus...
Deepwater Horizon Oil Spill: The Fate of the OilLast Updated on 2015-02-02 17:02:07Summary
The April 20, 2010, explosion of the Deepwater Horizon offshore drilling rig led to the largest oil spill in U.S. waters. Federal government officials estimated that the deepwater well ultimately released (over 84 days) over 200 million gallons (or 4.9 million barrels) of crude oil. Although decreasing amounts of oil were observed on the ocean surface following the well’s containment on July 15, 2010, oil spill response officials and researchers have found oil in other places. A pressing question that has been raised by many stakeholders is where did the oil go?
On August 4, 2010, the federal government released an estimate of the oil spill budget for the Deepwater Horizon incident. On November 23, 2010, the federal government released a peerreviewed “Technical Document” that further explained how the estimates were derived, and in some cases, modified the... More »
Daugava RiverLast Updated on 2015-01-12 07:37:16The Daugava River drains portions of the countries of Latvia, Belarus and Russia, prior to discharging to the Gulf of Riga. Also known as the West Dvina River, this watercourse is the fourth largest river discharging to the Baltic Sea catchment.
This 1005 kilometer long river has suffered environmental damage from agricultural runoff and from hydroelectric dam construction, with major impacts dealt in the Soviet era of collective farming. In ancient history the Daugava estuary was a locus of prehistoric settlement, and later marked one of the eastern limits of the voyages of the Vikings.
The lower Daugava valley (nearest the Gulf of Riga) was formed in relatively recent times, as glacial meltwater formed incision on the relatively level terrain near the Baltic Sea coast; these events occurred in the early Holocene, approximately 11,000 years before present. The relatively soft upper... More »
OverfishingLast Updated on 2014-12-07 17:22:32Overfishing is the human act of extracting aquatic (that is, marine and freshwater) fauna from natural water bodies at a rate greater than the reproductive and recruitment functions can replace that extraction. While there is some evidence that localized overfishing may have occurred in prehistoric eras, the bulk of overfishing has taken place in the last 150 years as the human population has expanded greatly and fishing technologies have enabled harvesting of many species at rates not imagined in earlier times. For over a century man's role in the depletion of certain regional fisheries has been noted. A functional definition of overfishing is sometimes given as the reduction in catch per unit effort by fishermen. Typically the concept of overfishing is linked to an individual aquatic species, and this issue is most often discussed within a specific marine or lacustrine province... More »
Mississippi RiverLast Updated on 2014-11-29 22:15:22The Mississippi River drains the largest river basin in North America, and is one of the major rivers of the world.
The Mississippi River watershed is the fourth largest in the world, extending from the Allegheny Mountains in the east to the Rocky Mountains in the west. The watershed includes all or parts of 31 states and two Canadian provences. The watershed measures approximately 1.2 million square miles (3.1 million square kilometers), covering about 40% of the lower 48 states. The Mississippi drains most of the United States between the Appalachian Mountains in the east and the Rocky Mountains in the West.
The mainstream of the Mississippi River has headwaters rising at Lake Itasca, Minnesota and flows approximately 2340 miles (3765 km). Though the longest part of the river includes the the Missouri River which flows approximately 2540 miles (4088 km) before joining the... More »
Water pollutionLast Updated on 2014-11-17 12:18:45Water pollution is the contamination of natural water bodies by chemical, physical, radioactive or pathogenic microbial substances. Adverse alteration of water quality presently produces large scale illness and deaths, accounting for approximately 50 million deaths per year worldwide, most of these deaths occurring in Africa and Asia. In China, for example, about 75 percent of the population (or 1.1 billion people) are without access to unpolluted drinking water, according to China's own standards. Widespread consequences of water pollution upon ecosystems include species mortality, biodiversity reduction and loss of ecosystem services. Some consider that water pollution may occur from natural causes such as sedimentation from severe rainfall events; however, natural causes, including volcanic eruptions and algae blooms from natural causes constitute a minute amount of the... More »
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