On the subject of SNIFFER calculations, has anyone else noticed the discrepancy in the way soil organic matter is used in the calculations of inhalation pathways for organics?

 

In the SNIFFER V1.02 spreadsheet the user is prompted to input SOM (%) in cell G281.

In the next cell (G282) the user is prompted to input mass fraction of organic carbon in soil, foc.  This value is then divided by 167 and the result appears in the blue cell I282 with units of kgOC/kgsoil.

 

The problem is that foc is already in these units.  It is the value of SOM in % that should be divided by 167 to give foc.

 

You can see this if you refer to the printed worksheet in LQ01, on page 144, where the user is prompted to input SOM (%) into box 53 and this is divided by 167 to give box 53.  You can see this in the worked example in the same document.

 

The values in box 53 and cell I282 are used in the calculation of SF.  Cell G281 is not actually used anywhere.

 

My interpretation is that the paper version is correct and the spreadsheet version is not.

 

The result of this is that if you use the spreadsheet and input foc into G282 you will derive an SSAC that is too low, by up to 2 orders of magnitude depending on the contribution from that pathway.   In order to get the correct result, you should enter SOM (%) again into G282.  I have checked this by entering the worked example into the spreadsheet, I get the same SSAC when I enter “2” into this cell, not 0.012.

 

 

 

Regards,

Kevin Privett.

 

Dr Kevin Privett

Principal Geo-Environmental Consultant

 

Hydrock Consultants Ltd

Over Court Barns

Over Lane

Almondsbury

Bristol

BS32 4DF

 

Tel: (01454) 619533

Fax: (01454) 614125

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Cell phone: (07799) 430870

 

Offices in Bristol, Plymouth, Northampton, Stoke-on-Trent.  www.hydrock.com

 

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