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- 2. Definition of Heavy Metal "Heavy metals" are chemical elements with a specific gravity at least 5
- 3. Definition of Heavy Metal 2. In the fundamental review paper written by Duffus (2002), 13 different
- 4. Definition of Heavy Metal Thus, “heavy metal” remains an obscure term in the life sciences. It
- 5. Definition of Heavy Metal Some define a heavy metal as a metal with an atomic mass
- 6. Definition of Heavy Metal The term heavy metals (or trace metals ) is applied to the
- 7. Definition of Heavy Metal Despite the fact that the term heavy metals has no sound terminological
- 9. Role in biochemical processes and At their natural concentrations, many metals play an essential role in
- 12. Figure. Typical dose–response curves for a) essential trace metals, and b) non-essential trace metals (modified from
- 13. Bioaccumulation and biomagnification virtually all heavy metals are toxic – especially to animals and humans –
- 14. Metals can transform and accumulate in the body (AMAP)
- 15. Toxicity of metals Metals generally produce their toxicity by forming complexes with organic compounds (ligands). The
- 17. Figure: Possible biochemical and molecular mechanisms of heavy metal-mediated ROS induction and damage to the development
- 18. HM in the Environment most heavy metals are present as cations, though some semi-metals may occur
- 19. Heavy metals (Ag, As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn) can be present in
- 20. The principal geochemical processes controlling the retention of heavy metals in soil and water are adsorption
- 21. Under oxidised conditions, the major process controlling the speciation of heavy metals is adsorption to the
- 22. Nevertheless, the amount of adsorbed metals decreases with decreasing pH . Another reason why the pH
- 23. Some metals (e.g. copper and lead ) also tend to form complexes with dissolved and sediment
- 24. Under reduced conditions, the mobility of most metals is further decreased due to the formation of
- 25. Sources of pollution Heavy metals are emitted to the atmosphere from both natural and anthropogenic sources.
- 26. Changes in total global emissions to the atmosphere of heavy metals from major anthropogenic sources based
- 27. Sources
- 30. Time trend in European atmospheric emissions of cadmium, lead, and zinc.
- 31. Past and present metal mines in the Arctic that still have a significant effect on the
- 32. Winter air concentrations of heavy metals at remote Arctic sites and European emissions of arsenic, lead,
- 34. Mercury concentrations in Arctic freshwater fish.
- 35. Natural sources The principal natural source of heavy metals in the environment is from crustal material
- 36. Numbers under columns : range of estimates (103 t/y). Figure 7·1. Global emissions of trace metals
- 37. Numbers under columns : range of estimates (10 t/y). Figure 7·2. Global emissions of trace metals
- 38. Figure 7·3. Comparison of global emissions of trace metals to the atmosphere from natural and anthropogenic
- 40. Natural sources in the Arctic An accurate inventory of heavy metal sources and emissions to the
- 41. Biogenic sources can account, on average, for over 50% of the Se, Hg, and Mo, and
- 42. The natural sources of heavy metals which influence the freshwater, terrestrial, and marine environment are even
- 43. Figure. Metals emitted from anthropogenic sources based on 1995 inventories (Pacyna and Pacyna, 2001).
- 44. Figure Worldwide emission estimates of anthropogenic heavy metals by continent (Pacyna and Pacyna, 2001).
- 45. Figure. Estimated global anthropogenic emissions of heavy metals in the mid-1990s (Pacyna and Pacyna, 2001) compared
- 46. Figure. Atmospheric emission profiles for the three most impor- tant forms of mercury emitted from anthropogenic
- 47. There is very long range transport within air masses of soil particles from deserts in Asia
- 48. Figure. Global emissions in 1995 from anthropogenic sources of total mercury (Pacyna and Pacyna, 2002).
- 49. Anthropogenic sources There are a multitude of anthropogenic emissions in the environment. The major source of
- 50. Enhanced environmental concentrations of heavy metals are often associated with mining and smelting. These activities cause
- 51. Computers, televisions, and other electronic equipment contain an array of trace materials, including lead, mercury ,
- 52. Major Industries Employing and Releasing Heavy Metals
- 54. In the lead industry, Pb–Cu–Zn–Cd are released in substantial quantities; during Cu and Ni smelting, Co–Zn–Pb–Mn
- 55. Much of the demand for Cr was due to steel and iron manufacturing and the use
- 56. Other important sources of metals to the atmosphere include fossil-fuel combustion (primarily coal), municipal waste incineration,
- 57. Source and Pathways The two main pathways for heavy metals to become incorporated into air–soil–sediment– water
- 58. Relatively pure metals are incorporated into a multitude of technological products which, when discarded, produce a
- 59. Except for Pb in the terrestrial environment and Cd in the marine environment, metal transport to
- 60. Background levels in soil, lakes, rivers, and oceans generally fall within the global ranges. Cadmium levels
- 61. Emission inventories for sources within and outside the Arctic During winter, about two-thirds of the heavy
- 62. The highest concentrations of atmospheric heavy metals in Arctic air occur in the vicinity of smelter
- 63. Heavy metal concentrations in air in the High Arctic are one order of magnitude lower than
- 64. MECHANISMS OF METAL IONS CONTAMINATION The mechanisms of the distribution and contamination of the environment by
- 65. Geological weathering is also responsible for groundwater contamination. The exposure of pyrite (FeS2) and of other
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