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
Hidden Risks Of Modular Classrooms
Nov 18, 2009 |
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Every school day, more than 5 million students in the United States attend lessons held in modular classrooms. With new carpeting and paint, metal roofs and noisy ventilation systems, they can be a health ...
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Braking news: Particles from car brakes harm lung cells
Nov 20, 2009 |
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Real-life particles released by car brake pads can harm lung cells in vitro. Researchers writing in BioMed Central's open access journal Particle and Fibre Toxicology found that heavy braking, as in an emergency stop, caused ...
Alcohol helps lower heart disease risk for men: study
Nov 19, 2009 |
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Men who drink alcohol every day see a nearly one-third average reduction in the risk of coronary heart disease, according to a long-term study among Spanish men published on Thursday.
The developing child: Rating aggressive and delinquent behavior in pre-adolescence
Medicine & Health / Psychology & Psychiatry
Nov 19, 2009 |
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In a study published in an upcoming issue of The Journal of Child Psychology and Psychiatry researchers show that over reactive parenting, such as heavy criticism or yelling as a response to a child's negative behavior, can pr ...
Liquid battery big enough for the electric grid?
Nov 19, 2009 |
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(PhysOrg.com) -- There's one major drawback to most proposed renewable-energy sources: their variability. The sun doesn't shine at night, the wind doesn’t always blow, and tides, waves and currents fluctuate. ...
Tiny bubbles clean oil from water
Nov 16, 2009 |
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Small amounts of oil leave a fluorescent sheen on polluted water. Oil sheen is hard to remove, even when the water is aerated with ozone or filtered through sand. Now, a University of Utah engineer has developed ...
The benefits of stress ... in plants
Nov 19, 2009 |
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Chronic stress in humans has been implicated in heart disease, weight gain, and diabetes, among a host of other health problems. Extreme environments, a source of chronic stress, present a challenge even for the hardiest ...
Rich Ore Deposits Linked to Ancient Atmosphere
Space & Earth / Earth Sciences
Nov 19, 2009 |
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(PhysOrg.com) -- Much of our planet's mineral wealth was deposited billions of years ago when Earth's chemical cycles were different from today's. Using geochemical clues from rocks nearly 3 billion years old, a group of ...
Researcher: Faint writing seen on Shroud of Turin (Update)
Other Sciences / Archaeology & Fossils
Nov 20, 2009 |
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(AP) -- A Vatican researcher has rekindled the age-old debate over the Shroud of Turin, saying that faint writing on the linen proves it was the burial cloth of Jesus. Experts say the historian may be reading ...
Battery Research Aims To Store Renewable Energy
Nov 19, 2009 |
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The biggest chemical battery in the United States is located near Interstate 90 in the small town of Luverne, Minn. The 80 ton device -- the size of two tractor-trailers stacked on top of each other -- stores ...
Don't Blame Tryptophan for Thanksgiving Snooze
Nov 20, 2009 |
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(PhysOrg.com) -- Blame it on the heavy meal, the alcohol, or simply the opportunity afforded by a free afternoon on a traditional holiday. Just don't blame it on the tryptophan, say experts at the University ...
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