1.VCE Environmental ScienceUnit 4: Area of Study 1: Pollution

2. Fluoride compounds are all relatedby containing fluorine. Fluorine is anaturally occurring element in theearth. It is usually found in the formof the mineral fluorspar, CaF2.Fluorine is a yellow-green gas witha strong, sharp odour (like poolchlorine). It combines withhydrogen to make hydrogenfluoride, a colourless gas with astrong irritating odour. 3. Hydrogen fluoride dissolves inwater to make hydrofluoricacid. Hydrogen fluoride willcorrode most substancesexcept lead, wax,polyethylene, and platinum. Hydrogen fluoride is used tomanufacture other fluorine-based chemicals includingSodium fluoride, which is awhite powder, althoughsometimes it is dyed blue foridentification purposes. 4. Hydrogen fluoride is used: In Aluminium production In Chlorofluorocarbon (CFCs) production In the production of aluminium fluoride, sodiumfluoride and other fluoride salts. Petroleum, chemical, and plastics industries. To separate uranium isotopes. To clean metals, bricks, or remove sand frommetal castings. To etch glass and enamel, polish glass andgalvanize iron. Brewing and to cloud light bulbs. 5. The primary sources of fluoride emissions are the industries that manufacture it or use it in production: Aluminium industry, Oil drilling and refining, Chemical and plastics industries, Agricultural and pesticide chemical manufacturers, Dye manufacturers, Manufacturers of metal parts.These are emissions to the air unless there is a spill. 6. Other possible emitters of fluoride are metalcleaning operations, glass and enamelmanufacturing and glazing, toothpaste, andfluoride enhanced water. These emissions may beto the soil, water, or air. Fluorine is a naturally occurring element in theearth, but elemental fluorine is too reactive to befound in nature. Fluorine is found in nature as partof the mineral fluorspar. Water in rivers or streamsthat flow over rocks rich in fluorine-containingminerals such as fluorspar may naturally containdissolved fluoride. 7. Toothpaste, pesticides, ceramic and glass polishing etching and frosting materials, special dyes, drinking water in some areas may be naturally or artificially enriched in fluoride.Australian DrinkingWater Guidelines(NHMRC and ARMCANZ, 1996):Maximum of 1.5 mg/L (i.e. 0.0015 g/L). 8. Fluorine was produced for the first time by Henri Moissan in1886, for which he received the Nobel Prize in chemistry in1906. The unique properties of fluorine have led to thedevelopment of fluorine chemistry and numerous syntheticfluorinated compounds have been prepared and tested fordifferent applications. The commercial use of organofluorinecompounds has grown significantly during recent years,mainly because of increased uses in industrial,pharmaceutical and pest-control applications. It is estimatedthat the world market for fluorochemicals amounts to 11.6billion dollars with an expected growth of 5 percentannually. The USA is the largest fluoroorganics market,followed by China (Baharatbook Market Research, 2004). 9. When fluoride is emitted to theair as a gas or particulate itmay be carried by the wind anddeposited on surroundingvegetation and soil. The gasdissolves in clouds, fog, rain, orsnow. This impacts theenvironment as wet aciddeposition (acid rain). In theenvironment it will react withother chemicals present(ammonia, magnesium,calcium) to form salts,neutralising the acid. 10. Industrial emissions of fluoridecompounds can produceelevated concentrations in theatmosphere. Hydrogen fluoridewill exist as a particle, which maydissolve in clouds, fog, rain, dew,or snow. In clouds and moist air itwill travel along the air currentsuntil it is deposited as wet aciddeposition (acid rain, acid fog,etc). In waterways it readilymixes with the water. 11. The substitution of HCFCs and other chemicals forhydrofluorocarbons and the increased growth influorinated refrigerants and coatings will boost thedemand for fluorochemicals in the coming years. Muchof the usefulness of organofluorine compounds rests intheir chemical stability and recalcitrance to biologicaldegradation. Of all types of bonds in organic chemistry,the carbon-fluorine bond is the most inert and resistantto cleavage (Hiyama, 2000). Given the chemicalinertness of fluorinated organics, their bioactivitypersistence, it is important to understand theirenvironmental fate and the mechanisms by which theycan be degraded. 12. Workers in the industries that use orproduce fluoride compounds are atgreatest risk of exposure.Consumers are most likely to beexposed to fluoride compounds whenusing consumer products containingfluoride compounds; especiallytoothpaste or fluoride enhanced water.Residents in close proximity toproduction and processing facilitiesusing fluoride compounds may alsoreceive very low levels of fluorideexposure. 13. Fluoridesare everywherethroughout the environment,but at very low levels that arenot believed to be harmful. Small amounts of sodiumfluoride help prevent toothdecay, but high levels mayharm your health. In children whose teeth areforming, excessive fluoridelevels may cause dentalfluorosis with visible changesin the teeth. 14. High levels of fluorine or hydrogen fluoride gascan cause muscle spasms, harm the lungs andheart and cause death. At low levels they canirritate the eyes, skin and lungs.Contact with hydrofluoric acid (even diluted)can burn the eyes (causing blindness) and skin,causing severe burns deep beneath the skindamaging internal tissues. This can occur hoursafter contact, even if no pain is initially felt. Contact with hydrofluoric acid happens mainly inthe workplace. Long-term exposures maydamage the kidneys and liver. 15. In adults, high fluorideover a long time maylead to skeletal fluorosiswith denser bones, jointpain, and limited jointmovement. This is rarein developed countries,but many people in Indiaand Africa may beaffected. 16. Hydrogen fluoride will exist as a particle in the air if releasedto the atmosphere. It dissolves when mixed with water.Insufficient data are available to predict the short-term orlong term effects of hydrogen fluoride to aquatic life, plants,birds or land animals. Concentrated hydrogen fluoride isvery corrosive and would badly burn any plants, birds orland animals exposed to it. The concentrations of hydrogenfluoride found in close proximity to sources may adverselyaffect some species of plants. Small quantities of hydrogenfluoride will be neutralised by the natural alkalinity in aquaticsystems. Larger quantities may lower the pH for extendedperiods of time. Fluorides are not expected to bio-accumulate. 17. Both Point Henry and PortlandAluminium smelters continue tofocus on minimising andsustaining fluoride emissionswithin internal (Alcoa) targets,which is reflected in the long-termhistorical trends (see graph).Alcoas internal targets are morestringent than those set by theVictorian Environmental ProtectionAuthority.http://www.alcoa.com/australia/en/info_page/environ_air.asp 18. Portland Aluminium continues toprogress a long-termmanagement program for fluorideemissions, to further understandand manage the effects of lowlevel fluoride emissions on localfauna inhabiting the landsurrounding the smelter. Fluorideemissions were sustained ataround 0.3kg/tonne of aluminiumproduced in 2009, makingPortland Aluminium one of thelowest fluoride-emitting smeltersin the world. 19. The Portland Aluminium smelter is situatedon 600 hectares of land, 500 of which formSmelter in the Park, a once-barren area thathas been revegetated with a large variety ofindigenous plants. This area forms a bufferzone, that protects surrounding residentsfrom the full impact of gaseous emissionsfrom the smelter. There are five monitoringstations at different locations around thesmelter that provide data on fluoride andsulfur emissions on a regular basis. PortlandAluminium also routinely test their workers,using urine and blood tests, as well asexposure badges, which monitor the levels offluoride that staff have been subjected to. 20. Environmental scientists also dowater testing and take tail-bonesamples of the local kangaroos andteeth, bone and horn samples of thebeef cattle , to test for long-termfluoride exposure. An internationalbotany expert visits annually tocheck for signs that toxic emissionsmay be affecting local vegetation.Signs of fluoride exposure includeyellowing and curling of leaves andtissue death. 21. Inthe potrooms, the major point source of fluoride emissions, Portland Aluminium have laser air monitoring of gaseous fluoride, with a traffic light system green, amber and red. Between 045ppb and 600ppb, the lights are green; between 600ppb and 800ppb the lights are amber and above 800ppb the lights are red, which indicates an error in the process too many hoods open at the same time. 22. Portland Aluminium use several methods to preventexcessive fluoride emissions, including the A398 fluoriderecovery system, in which fluoride emissions are capturedfrom the hooded aluminium pots and forced through aconveyor of alumina, to form reacted or fluoride-enrichedalumina. This is then added to the pots, which reduces thetemperature (and therefor the energy required) to obtain thepure aluminium. The particulate and gaseous emissions arefiltered through huge canvas bags, also coated withalumina, which traps 98% of fluoride.When the laser monitoring systems indicate excess fluoridelevels, staff will be evacuated to prevent critical exposure. 23. Research-Cottrell is the exclusive worldwide licensee for Alcoas A-398and A-446 fluidized bed dry scrubbing technologies. The technologiesprovide emission control and fluoride recovery from both primaryaluminum potline and bake oven applications. A-398 systems are currently installed on more than 20 smelters (56potlines) worldwide, treating over 20 million cfm of potroom gases fromboth prebake and reduction cells. The A-398 and A-446 technologies routinely achieve greater than99.9% fluoride removal efficiencies. In addition to controlling fluoridesand particulate, the A-446 scrubbing process significantly reduceshydrocarbons (Tars, POM, B(a)P) and SO2 emissions from bakeovenfurnaces, without a separate spray cooling chamber. The systems combine fluid bed scrubbers with air pollution controlssuch as fabric filters, electrostatic precipitators, wet and dry scrubbersand VOC-removal technologies, to reduce emissions. http://www.tms.org/Meetings/Annual-98/Exhibitors/ResearchCott.html 24. Bacterial Degradation of FluorinatedCompoundshttp://dissertations.ub.rug.nl/faculties/science/2007/m.i.m.ferreira/?pLanguage=en&pFullItemRecord=ON Portland Aluminium EIPhttp://www.alcoa.com/australia/en/info_page/environ_air.asp