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This programme is about geochemical analysis. John Wright starts with the problems of sampling by looking at a granite deposit in South West England. He continues with the different problem of whet...her continental and oceanic basalts can be said to originate in the same way if they contain the same minerals. He demonstrates the function of major element and trace element analyses in tackling the problem. In the second part of the programme Richard Thorpe shows how geochemical analysis can track down the factors involved in a cattle disease. The disease examined is fluorosis which causes severe lameness in cattle and the analytical techniques examined are the colourimetric and potentiometric methods for the estimation of fluoride ion.
Metadata describing this Open University video programme
Item code: S2-2; 01; 1973
First transmission date: 22-07-1973
Published: 1973
Rights Statement:
Restrictions on use:
Duration: 00:22:20
Note: Open University course S2-2 Geochemistry
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Producer: David Jackson
Contributors: Richard Thorpe; John Wright
Publisher: BBC Open University
Keyword(s): Cattle disease; Colourimetric and potentiometric methods; Fluoride ion; Fluorosis; Granite deposit; Major and trace element analysis; Oceanic and continental basalts; Rock origins; Sampling
Footage description: John Wright discusses the problems of getting representative samples for geochemical analysis. Shots of rock sample and blown up photograph of a granite landscape. Wright uses maps, photographs and rock samples to aid his discussion. Wright discusses the techniques used to prepare samples for geochemical analysis. Shots of the techniques accompany the commentary. Wright with two samples of basalt rock (one terrestrial the other oceanic) and photographs of the sites where these were taken. Shot of samples under the microscope. They look similar. Wright shows a bar chart on which are shown the major element oxides for the basalt samples above. The mineral content for the samples is very similar. Shot of a diagram of the earth's crust and mantle showing the origin of the two basalt samples. Wright discusses the differences in levels of trace elements for the basalt samples. Shot of samples under the microscope. Shot of a chart showing the range of concentration for 5 trace elements present in the basalt samples. Wright points out the significant differences. Wright introduces Richard Thorpe. Richard Thorpe introduces a sequence which looks at the problem of identifying the causes of fluorosis disease in cattle. These methodological problems are similar to those of geochemical analysis and the student is asked to look for these similarities. Shots of a dairy man being interviewed. He describes the symptoms of fluorosis among his cattle. Shots of diseased cows as he describes the symptoms. More shots of diseased cows. Thorpe's commentary gives brief background of the disease in Britain. Symptons of Fluorosis described again accompanied by shots of diseased cattle and cattle joints (both diseased and healthy). Thorpe with a geological map of England and Wales. Fluorosis disease areas are marked. There does not seem to be any obvious correlation between the disease and geological features. The following sequence looks at one of the diseased areas, The Bedford-Ampthill area, in detail. Shots of the brickworks at Bedford. Commentary explains why the smoke emmissions from the brickworks is high in fluorine content. Shot of a map showing the area of disease in the Bedford-Ampthill area. The location of brickworks is also shown and a definite correlation can beseen. Thorpe introduces the quantitative side of the study of fluorosis causes. He describes the samples which were taken for analysis. Shot of field worker taking samples of grass on which the diseased cattle feed. Commentary describes the sampling method. Shots of grass samples being prepared in the laboratory for analysis. Grass is ground and reduced by chemical digestion. Shots of the chemical analysis for amounts of fluoride. Commentary explains each step of the way. Calorimetric analysis is used here to determine amounts of fluoride ions in the sample. A faster method is potentiometric analysis and this is explained and demonstrated. Thorpe sums up his interpretation of the fluorosis experiment. He asks students to refer to the Broadcast notes. Thorpe discusses some possible solutions to the fluorosis problem such as building taller chimneys, diet supplement etc. Shots of Bedford brickwork chimneys and surrounding countryside.
Master spool number: 6HT/71024
Production number: 00525_1064
Videofinder number: 1644
Available to public: no