Sampling For MMI In Boreal Zones

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WHERE TO SAMPLE
Experience in MMI sampling in Europe and North America demonstrates that the mobile metal ion geochemical technique works best when samples are collected at a constant depth BELOW the interface between leaf and twig litter on surface, and completely decomposed material. The sample should be taken as a continuous plug between 10 to 25 cm below the organic / inorganic interface. This sampling interval below the leaf and twig litter can vary from A to B horizon. Please read the detailed instructions below before collecting the samples



SAMPLING PROCEDURE
To sample for MMI geochemistry in boreal climates, particularly in areas with substrates that contain overlying peat blankets;



Before actually taking the sample, brush sampling equipment to eliminate residue from previous samples and flush it with soil from the new sample site.

• Scrape away any extensive organic horizon (O or Ao) and eliminate loose non-decomposed matter, debris, and any possible cultural contamination.
• Penetrate the leaf litter and organic material that still has structure (i.e. decomposing leaves, bark, twigs and peat).  Once through to a true A-horizon (where the soil resembles a decomposed mass without any obvious leaf or vegetation visible), discard the top 10cm of this A-horizon material and then collect the sample between the 10 to 25 cm below this horizon. The sample should be a continuous plug taken from the 15 cm interval. Using a plastic scoop take a cross section of the material between the 10 to 25 cm depth, put into clean, properly labeled plastic bags. Collect approximately 250 to 300 grams of material.
• Ensure not to mix organic and inorganic soils in the collected sample. For example, if the material within the 10 to 25 cm zone has a mixture of humus and inorganic soil then proceed to the base of this “mixed zone” and collect the sample from the inorganic material.  If the thickness of the humified organic layer exceeds 25 cm then the sample should be collected from the organic layer.Note the soil type in your field description of the site
• Different soil types may be characterized by variable geochemical backgrounds for some or all elements. To avoid mixing MMI data populations based on soil type, interpret data for organic and inorganic soils separately. If significant differences between soil types are not noted in the lower 25th percentile and background calculations of the data set, then the data populations may be combined for interpretation based on response ratios. For further details on calculating response ratios, please contact an SGS or MMI representative or visit the MMI web site at www.mmigeochem.com.
• During sample collection and handling, no jewelry (watches, rings, bracelets, and chains) should be worn, as this can be a major source of contamination.
• Regardless of topographic influences and associated variability in the soil profile the sample should be collected 10 to 25 cm below the interface with the non-decomposed surface leaf / twig matter.
• Clear and concise notes should be kept at each site, paying close attention to the location of the sample with respect to the thickness and nature of the soil horizons. Parameters such as soil moisture, development of a “b-horizon”, organic content, presence or absence of suspended aqueous material within the soil and general characteristics of the overburden in the survey area can be very useful for data interpretation.