Hi

I do agree. Yes, you can use average shale value as reported by Turekian and Wedepohl, 1961. However, it is always preferred if you have geochemical background for the same element for that particular area.

Hi

I do agree. Yes, you can use average shale value as reported by Turekian and Wedepohl, 1961. However, it is always preferred if you have geochemical background for the same element for that particular area.

Dear Prof. Zakir

many thanks for your valued idea 

Hi

In the mining sector, we use Geochemical Abundance Index (GAI) as a screening for identifying element enrichment relative to average crustal (or other rock type) concentrations. This may be of some use to you.

The Global Acid Rock Drainage (GARD) Guide (www.gardguide.com) and DME 1995 (attached) refer to its use. There is one minor difference between the how the two values interpret the GAI value. The GARD Guide identifies that a GAI value of 3 or greater indicates enrichment, whereas DME (1995) identifies a GAI of greater than 3 as being indicative of enrichment.

For an explanation of procedure see link to the webpage of the GARD Guide:

Hope this helps

http://www.gardguide.com/index.php?title=Elemental_composition_of_mineralized_rocks

many thanks Andrew

what do you mean by the world's average shale?

World average shale is the background metal levels (pre-pollution data in a hypothesis to calculate geoaccumulation ) . The widely used source is Turekian and Wedepohl 1961 - Turekian, K.K. and Wedepohl, K.H. (1961). Distribution of the Elements in some major units of the Earth's crust. Geological Society of America, Bulletin 72: 175-192

Okay got it now, many thanks to you

Can we use as well the upper continental (UC) values or lower continental (LC) values given by Wedepohl (1995) as background values in the calculation of the geoaccumulation index? The World average shale values are different to the ones of the continental crust. For example, the background metal level for Cd in the World average is 0.3, while it is 0.102 and 0.101 in the UCC and LCC, respectively.

Wedepohl, K. H. 1995. The composition of the continental crust. Geochimica et Cosmochimica Acta 59:1217–1232.

Turekian, K.K. and Wedepohl, K.H. (1961). Distribution of the Elements in some major units of the Earth's crust. Geological Society of America, Bulletin 72: 175-192

yes u can use it

where we can find the world geochemical background values. please give the cite of the paper.

the metals which I need are Fe, Zn, Pb, Cr, Cu, Al, Si, Cd, Ni, Mn

Sisira Withanachchi

Hello,

In order to calculate the enrichment factor of marine sediments, I need the current background values. e-mail: [email protected]

Please find the original paper of Turekian KK, Wedepohl DH (1961) Distribution of the element in some major units of the earth’s crust. Bull Geol Soc Am 72:175–192

Local background value from a control area can as well be used

Or Taylor and McL enan, 1985, McLenan. 2001.