It is not necessary to mild or grind your samples prior to any digestion procedure. you just analyse those samples that passed through a 2 mm sieve.

I'm talking about reference materials or standard certificate soil samples. Beyond that, I'm interested in partition studies, not in total amount (concentration per mass) analysis. So, the soil samples wouldn't be digested, but subjected to determined physico-chemical variations to understand the biogeochemical behaviour of certain radionuclides.

There are many such standard reference materials.

The U.S. National Institute of Standards and Technology (NIST) has at least three currently offered: San Joaquin Soil (2709a), Montana Soil I (2710a), and Montana Soil II (2711a), among others. There are numerous additional soil SRMs previously offered through NIST and the United States Geological Survey (USGS).

You might consider searching GeoRem (http://georem.mpch-mainz.gwdg.de/) to examine the chemical criteria of these, and to see if they will meet your needs. You should also be able to use GeoRem to identify soil SRMs offered through other institutions -- I am certain there are numerous others available.

Dear Matthew, Thank you very much for your answer. The GeoRem website isn't much friendly but could find the data about a few NIST SRM's. Unfortunately the NIST and the USGS websites are unavailable due to the government shutdown. I think that the NISTSRM610 is a good candidate. I'm looking for reference soils for Cs-137. Both the IAEA-444 and IAEA-375 are out of stock. Do you know if there is any publication discussing the suitability of reference materials for biogeochemical partitioning? Usually those reference materials are used for total content analysis, which doesn't gives much information if someone is trying to understand the dynamics of certain element in soils systems.

Guilherme:

I know virtually nothing about biogeochemical partitioning, but NIST 610 is a solid glass disc used (typically) in LA-ICP-MS analysis. I am not sure that would be the best analogue for soils analysis. But, again, I don't know much about what you are doing.

GeoRem allows you to "Search By Chemical Criteria", and you can use 137Cs as a variable in that search. Doing so returns a list of 29 different SRMs with certified 137Cs concentrations. 18 of these are soils or marine/lacustrine sediment. Excepting IAEA-375 and -444, the rest are as follows. I've added links to GeoRem's certified and literature values so you can evaluate each of them.

NRCCRM GBW-08304 River sediment (http://tinyurl.com/mbyfzba)

IAEA-135 Sea sediment (http://tinyurl.com/mxyvglt)

IAEA-300 Sea sediment (http://tinyurl.com/q9k3q4w)

IAEA-327 Soil (http://tinyurl.com/oe2j3tt)

IAEA-367 Sediment (http://tinyurl.com/ounlp6n)

IAEA-368 Sediment (http://tinyurl.com/m4eh4gb)

IAEA-384 Sediment (http://tinyurl.com/oswh43c)

IAEA-385 Sea sediment http://tinyurl.com/nbkfew5

IAEA-401 Soil http://tinyurl.com/pj7pfvu

IAEA-SD-N-2 Marine sediment http://tinyurl.com/nc2v2c6

IAEA-SL-2 Lake sediment http://tinyurl.com/pqbvsvw

IAEA-SOIL-6 Soil http://tinyurl.com/mth7z8j

NIST 4350b River sediment http://tinyurl.com/mwtlx3d

NIST 4354 Lake sediment http://tinyurl.com/ludw3c9

NIST 4355 Sediment http://tinyurl.com/kk49la4

NIST 4357 Marine sediment http://tinyurl.com/o3zc72m

Wow! thank you so much, Matthew. You are totally right. that would not be an analogue for soil at all. I am studying the behavior of Cs-137 within tropical soils. Unfortunately these IAEA soils have very little Cs-137 activity (

If you need further assistance contact Prof. Ian Croudace (Director of Geosciences Advisory Unit (GAU) in Ocean and Earth Science at the University of Southampton). He is an expert on 137Cs and geochemistry (email [email protected]).

Thanks, Bernardo. I'll contact him as soon as possible.

more standard reference matierials including 3-4 soil matrices are produced and sold by The Institute for Reference Materials and Measurements (IRMM) is one of the seven institutes of the Joint Research Centre (JRC), a Directorate-General of the European Commission (EC). they sell them directly or through Sigma

the url of the site is the following:

http://irmm.jrc.ec.europa.eu/reference_materials_catalogue/catalogue/Pages/index.aspx

Guilherme,

You can also contact people from Brasil. In Piracicaba you have the Centro de Energia Nuclear na Agricultura - CENA/USP, with people who worked on cesium-137 and lead-210, studying soils of Brasil. Some of the most experienced people (Prof. Osny Bacchi, ...) were recently retired but there is a good laboratory for environmental radioisotopes studies.

For geochemistry of other elements (mass elements, not radioactivity) you can found several geochemical standards with certified data for leaching tests, from the Canadian CCRMP.

Best of luck

Thanks, Sumia. Unfortunately, my interest in this kind of sample is not for total activity analysis, but I'm rather interested in understand the behaviour of some radionuclides due to certain phisico-chemical conditions within the soil system. But it would be interesting to know some features of this sample as granulometry, minimum representative sample size and Cs-137 activity per gram.

In the Netherlands, Wageningen University organizes now for over 50 years several proficiency testing schemes (totals as extractions) on soils and sediments.

Check out a result book on their web site www.wepal.nl

This is from their website:

Wepal is a world-leading organiser of proficiency testing (PT) programs in the fields plants, soil, sediments and organic waste. We are organising this for over 50 years and currently have over 500 participants in these PT schemes in countries all over the world. A wide variety of samples from the PT programs are also available as reference material.

e.eg. NIST2709 (soil from California San Joaquin Valley) is certified for elements total concentration and concentration of some elements in acid leachable fraction, more: www.nist.gov/srm/upload/SP260-172.pdf‎

Hello,

Since several years, I have used the CRM 483 (sewage amended soil) with certified values for acetic acid and ETDA extractions and indicative values for the BCR sequential extraction scheme. This CRM is provided by NIST and I think that other CRM with certified values are now available.

Have a good day.

Try: http://crustal.usgs.gov/geochemical_reference_standards/

Dear Juan, I'm afraid that there are no soil samples available at USGS :|

Dear Guilherme, BCR 701 is meant for sequential extractions (BCR 3 stages). Although it is a sediment, it is well used for soil purposes.

Dear Professor Daniel, thanks for your comment. It's a pleasure to have an answer from you. I have enjoyed pretty much your contribution to the book "Química e Mineralogia do Solo" (SBCS, 2009) ^^. Here is a doubt about the suitability of BCR 701 for the experiments I'm performing, once I'm studying Cs+ geochemistry within tropical soils. It seems that this certificate sample would be a manner to control the quality of data, but how could I use this sample to deepen the understanding about Cs+ behavior within the soil systems I'm studying since both matrices and elements at issue have quite different properties? Thanks in advance.

Dear Guilherme, as a matter of fact, you are searching a way of accreditation of yours results. Since we do not have any certificate material for sequential extraction for Cs in soil, there are 2 approaches you can use:a) for the accreditation of Cs, you can use the Cs total recovery by a pseudo-total extraction (aqua regia in the case of BCR protocol) and compare to the sum of the fractions of the sequential extraction; b) in the case of applying the BCR 3 stages protocol, you can also perform an accreditation "by analogy", considering the certified elements Cd,Cr,Cu,Ni,Pb, Zn.

Canada has several geochemical reference materials. http://www.nrcan.gc.ca/minerals-metals/technology/certified-reference-materials/3075 which in the documentation on the materials will indicate how the material was analyzed as well as different extraction values for some standards. there are other materials for mine acid drainage references that might be useful. Contacting the CCRMP Coordinator could help to explain what you are seeking and if the standards are not CCRMP they may be able to refer you to one of the other standard companies. There are private reference material providers in the USA and Australia as well as several geological survey standards. There is an international publication that describes standards and the latest materials being released with values etc. I think that you would find that CCRMP would try to be very helpful to you. The website has fallen under the Government guidelines of look and feel ( now it looks and feels like a useless government website) but the people are still very knowledgeable and helpful. http://www.nrcan.gc.ca/sites/www.nrcan.gc.ca.minerals-metals/files/pdf/mms-smm/tect-tech/ccrmp/cer-cer/stsd-1-eng.pdf is an example of stream sediment samples as a summary of how samples were selected prepared and values for partial and total analysis. http://www.comar.bam.de/en/ provides a searchable database for reference materials

A large private supplier is http://www.brammerstandard.com/introduction.html

I would suggest looking at NIST standards-they ahve a range of standards that are appropriate for most types of soil analysis:total concentration etc.

In the CCRMP series of standards, the Till Series standards have been analysed by both an aqua regia digestion and a weak acid digestion as well as by EPA methods 3050 and 3051. This data along with the total data were released in a Geostandards Newsletter publication (Vol 20 No. 2, ) as part of the certification of these standards by John Lynch who collected prepared and certified the standards with CCRMP.

ftp://ftp.nrcan.gc.ca/ess/geochem/files/publications/pub_00857/geostds_v20no2.pdf

Guilherme, You can use istope Cs 134 as a marker for Cs 137. It is useful if you want to be sure that no loss happens due to adsorption on filters, glass,... The sum of Cs 134 at the end of extraction should be same like at the beggining.

However, you should not expect that the fractionation of Cs 134 and Cs 137 is same. The difference is a result of different period during which the contaminant (Cs 137) and marker (Cs 134) are in the soil. Moreover, adsorption of Cs in clay soil is quite fast, therefore, 1 month should be enough for soil incubation. On the other hand, the Cs fractionation in peat is far complex and for incubation you will need far more time.