Niobium (Nb) (Columbium)

WITHDRAWN: Lichens as Biomonitors of Air Pollutants Deposition: Strategically Important Element Pollution 

“…Furthermore, as reported by (URL, 1) human activities releasing strontium into the atmosphere include burning of coal, and land application of phosphate fertilizers resulting in the release into the atmosphere in windblown soil. The main sources of tantalum in the environment are geologic, mostly as a result of the weathering of rocks, but a potential anthropogenic source of it is from the combustion of coal (Divine and Goering, 2004;Goering and Ziegler, 2004…”

Niobium and tantalum

“…The main sources of niobium and tantalum in the environment are geologic, mostly as a result of the weathering of rocks, but a potential anthropogenic source of both is from the combustion of coal (Divine and Goering, 2004;Goering and Ziegler, 2004). Tantalum compounds are less mobile than niobium compounds, which are slightly soluble under both acid and alkaline conditions and in the presence of organic complexing agents (Kabata-Pendias and Mukherjee, 2007).…”

“…The permissible exposure limits in the United States for tantalum metal and oxide dust for an 8-hour work day is 5 milligrams per cubic meter (mg/m 3 ) and is based on lung irritation (Occupational Safety and Health Administration, 2013). Although data are sparse and studies on humans lacking, niobium is likely similar to tantalum in that its retention time in the human body is usually relatively short, and much of it is eliminated unabsorbed (Goering and Ziegler, 2004). Studies have shown, however, that small mammals that ingested niobium compounds in drinking water had a shortened lifespan.…”

“…Studies have shown, however, that small mammals that ingested niobium compounds in drinking water had a shortened lifespan. Niobium has been shown to be associated with tumors, but is not mutagenic (Goering and Ziegler, 2004, and references therein). Niobium is considered hazardous by the Occupational Safety and Health Administration (OSHA), but OSHA has not established a permissible exposure limit for niobium dust (Occupational Safety and Health Administration, 2013).…”

“…Niobium may accumulate in plants and is generally less than 0.4 ppm dry weight in terrestrial plants from background locations and greater than 1 ppm in plants growing near niobium deposits (Goering and Ziegler, 2004). According to one recent study, the toxicity of niobium and tantalum to freshwater amphipods (Hyalella azteca) was relatively low compared with that of other trace elements tested in laboratory experiments; 1-week lethal concentrations of hundreds of ppb niobium and tantalum resulted in significant mortality for amphipods in soft waters, whereas those in hard waters were not affected until concentrations reached thousands of ppb (Borgmann and others, 2005).…”