Heavy metal (chemistry)
hideA heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight, and some on chemical properties or toxicity. The term heavy metal has been called "meaningless and misleading" in an IUPAC technical report due to the contradictory definitions and its lack of a "coherent scientific basis". There is an alternative term toxic metal, for which no consensus of exact definition exists either. As discussed below, depending on context, heavy metal can include elements lighter than carbon and can exclude some of the heaviest metals. Heavy metals occur naturally in the ecosystem with large variations in concentration. Nowadays anthropogenic sources of heavy metals, i.e. pollution, have been introduced to the ecosystem. Waste derived fuels are especially prone to contain heavy metals so they should be a central concern in a consideration of their use.
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News tagged with heavy metals
Heavy metal paradox could point toward new therapy for Lou Gehrig's disease
Medicine & Health / Neuroscience
Nov 30, 2009 |
4.5 / 5 (2) |
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New discoveries have been made about how an elevated level of lead, which is a neurotoxic heavy metal, can slow the progression of amyotrophic lateral sclerosis, or Lou Gehrig's disease - findings that could point the way ...
Glowing channels: Microanalysis system for rapid mercury detection
Chemistry / Analytical Chemistry
Dec 22, 2009 |
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(PhysOrg.com) -- Water contaminated with mercury is very dangerous for both people and the environment, as mercury is one of the most toxic heavy metals. Though laboratory analyses do deliver precise quantitative measurements, ...
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BlackBerry e-mail restored for some after outage
16 hours ago |
4 / 5 (1) |
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(AP) -- BlackBerry e-mail service in North America was restored for some users Wednesday morning following its second outage in less than a week.
NREL Evaluates UPS Hybrid-Electric Van Performance
Dec 22, 2009 |
3.3 / 5 (3) |
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(PhysOrg.com) -- The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has collected and analyzed fuel economy, maintenance and other vehicle performance data from UPS’s first generation hybrid diesel ...
Is nicotinamide overload a trigger for type 2 diabetes?
Dec 22, 2009 |
4.7 / 5 (3) |
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Facing the increasing prevalence of type 2 diabetes worldwide in the past few decades, one may ask what is wrong with humans. Geneticists tell us that the human genome has not changed markedly in such a short time. Therefore, ...
Pot and pop: New research finds stronger link between music and marijuana use among teens
Medicine & Health / Psychology & Psychiatry
Dec 22, 2009 |
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1
Teens who frequently listen to music that contains references to marijuana are more likely to use the drug than their counterparts with less exposure to such lyrics, according to a University of Pittsburgh School of Medicine ...
Method makes refineries more efficient
Dec 22, 2009 |
4.5 / 5 (6) |
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(PhysOrg.com) -- Refineries could trim millions of dollars in energy costs annually by using a new method developed at Purdue University to rearrange the distillation sequence needed to separate crude petroleum into products.
Japan mines toxic e-waste for precious materials
Dec 17, 2009 |
4.9 / 5 (7) |
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Seeking to turn an environmental problem into an economic opportunity, high-tech companies in resource-poor Japan are mining mountains of toxic e-waste for precious materials.
Lost water of the Napa Valley vineyards
Space & Earth / Earth Sciences
Dec 16, 2009 |
4.3 / 5 (3) |
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Getting the most out of every drop of water is a high priority for grape growers in the southern Napa Valley, where summers are hot and dry and vines have to be irrigated to make it through the growing season. But Stanford ...
Suzaku spies treasure trove of intergalactic metal
Dec 02, 2009 |
4.7 / 5 (6) |
1
Every cook knows the ingredients for making bread: flour, water, yeast, and time. But what chemical elements are in the recipe of our universe?
Autism treatment: Risky alternative therapies have little basis in science
Nov 24, 2009 |
3.7 / 5 (3) |
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James Coman's son has an unusual skill. The 7-year-old, his father says, can swallow six pills at once. Diagnosed with autism as a toddler, the Chicago boy had been placed on an intense regimen of supplements and medications ...
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