Related topics: water · pollution

Radiation damage spreads among close neighbors

A single X-ray can unravel an enormous molecule, physicists report in the March 17 issue of Physical Review Letters. Their findings could lead to safer medical imaging and a more nuanced understanding of the electronics of ...

Beyond the brim, Sombrero Galaxy's halo suggests turbulent past

Surprising new data from NASA's Hubble Space Telescope suggests the smooth, settled "brim" of the Sombrero galaxy's disk may be concealing a turbulent past. Hubble's sharpness and sensitivity resolves tens of thousands of ...

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Heavy metal (chemistry)

A 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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