ISO 17183:2016 土壌の質—光の減衰によって乳化指数を決定することにより、イソプロパノールで抽出可能な有機化合物について土壌をスクリーニングします | ページ 2

Foreword

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The committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics.

Introduction

Light attenuation due to light scattering/absorption by emulsions can be used to screen for a variety of isopropanol-extractable organic substances such as total petroleum hydrocarbons (TPH). This is one of the main organic contaminants of many contaminated land sites.

Petroleum hydrocarbons do not typically have many functional groups or contain any hetero-atoms that are easily detected in common analytical procedures. When the non-polar nature of organic compounds is targeted, as in this proposed method, turbidity/emulsification is produced by a number of organic compounds including BTEX (benzene, toluene, ethylbenzene and xylenes); PNAs (poly-nuclear aromatics); fuels; oils and greases that frequently are found at contaminated land sites.

This method can be used for screening soil samples to estimate the total amount of recoverable petroleum hydrocarbon contamination in soil including a wide range of fuels, oils, and greases. The emulsification approach in this method is incorporated to rapidly screen soil samples using a system calibrated with the organic substance present on the investigated site. If the contaminant is unknown, commercially available diesel oil can be used for calibration. This makes turbidity/emulsification analysis a very versatile analytical method that can be used on most hydrocarbon/non-polar organic substance spills without prior knowledge of the exact BTEX or PNA content or composition of the contaminant. This method is more sensitive to non-polar heavier organic compounds from jet fuel to oils and greases, but less sensitive to more volatile and lighter hydrocarbon fuels. A turbidity analysis assists the user in recognizing the contamination by non-polar organic compounds at a given site.

This International Standard describes the procedure for on-site soil screening of organic compounds using emulsification and light attenuation due to light scattering/absorption analysis.

1 Scope

This International Standard specifies the procedure to screen highly contaminated soils to detect organic compounds extractable with isopropanol, including a wide range of fuels, oils, and greases. The method is useful for finding hot spots. It is applicable both in laboratories and for site screening in the field. The working range is approximately 0,01 to 0,3 in absorbance units, corresponding to approximately 500 mg/kg to 10 000 mg/kg of isopropanol-extractable organic compounds in soil.

The light attenuation due to light scattering/absorption approach in this method is designed to quickly screen soil samples using calibration with the most appropriate substance(s) likely to be present on a given site to indicate the concentration levels.

This screening technique is applicable for a broad spectrum of organic compounds, mainly hydrocarbons. Organic compounds are a very broadly defined mixture of compounds, which show their own specific emulsification indices (see Annex A) and a gross emulsification index in a mixture sample, defined primarily by their insolubility in water. The more insoluble the compounds (e.g. non-polar compounds), the higher the response. Hydrocarbons are generally less-reactive and have little polarity. Determination of emulsification indexes uses their non-polar nature to detect organic compounds including a wide range of hydrocarbons from about C₈ to about C₃₆.

This method is not applicable for determination of specific organic compounds or groups of compounds that may be part of a larger organic compound mixture. As with other screening techniques, it is advisable to confirm a certain percentage of both positive and negative test results, especially when near or above a regulatory action limit or when the presence of background or when interfering organic compounds such as surface active substances are suspected to be present.

This method does not address the evaporation of any volatile organic compound mixtures (i.e., gasoline) during sampling, preparation and detection. Although the screening method can be used for the quantitative detection of volatile hydrocarbons, it is not intended that the method be used for the quantitative determination of volatile petroleum hydrocarbons unless evaporation during sample handling is addressed; the response factor be appropriately corrected, or the method performance be demonstrated on real samples.

If emulsifiers or surface active substances (e.g. detergents) are present, significantly negatively-biased or false negative results can be obtained. If there is any evidence for the presence of surfactances in the soil, this method cannot be applied.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 11074 and the following apply.

Bibliography