BS EN ISO 21268-4:2019

What is ISO 21268‑4 - pH influence on soil leaching about?

ISO 21268‑4 is the fourth part of the multi-series on soil quality that discusses leaching procedures for soil testing. ISO 21268‑4 specifies a test to obtain information on the short- and long-term leaching behaviour and characteristic properties of materials.

ISO 21268‑4 has been developed to measure the pH-dependent release of inorganic and organic substances from soil and soil-like material as well as to produce eluates for subsequent ecotoxicological testing. ISO 21268‑4 provides a test method for eluates, which can subsequently be characterized by physical, chemical, and ecotoxicological methods in accordance with existing standard methods. The results of eluate analysis are presented as a function of the liquid/solid (L/S) ratio.

Note: ISO 21268‑4 does not address issues related to health and safety. It only determines the leaching properties outlined.

Who is ISO 21268 - pH influence on soil leaching for?

ISO 21268‑4 on pH influence on soil leaching is useful for:

• Ecologists and conservationists
• Soil testing laboratories
• Landowners
• Production units that release waste into waterbodies

Why should you use ISO 21268‑4 - pH influence on soil leaching?

The release of soluble substances upon contact with water is regarded as the main mechanism of release, that results in a potential risk to the environment during the use or disposal of materials. The intent of these tests is to identify the leaching properties of materials. The complexity of the leaching process makes simplifications necessary.

ISO 21268‑3 provides a test that is mainly aimed at being used for routine and control purposes, and it cannot be used alone to describe all leaching properties of soil. Additional leaching tests are needed for that extended goal.

The test procedure described in ISO 21268‑4, method belongs to basic characterization tests. Basic characterization” tests are used to obtain information on the short- and long-term leaching behaviour and characteristic properties of materials. Liquid/solid (L/S) ratios, leachant composition, factors controlling leachability, such as pH, redox potential, complexing capacity, the role of dissolved organic carbon (DOC), ageing of material and physical parameters, are addressed in these tests.

What’s changed since the last update?

BS EN ISO 21268‑4:2019 supersedes ISO/TS 21268-4:2007, which is withdrawn. BS EN ISO 21268‑4:2019 includes some technical changes with respect to ISO/TS 21268-4:2007.

These include:

• The maximum grain size has been changed to <2 mm as usual for soil
• References in Clause 2 and the Bibliography have been updated
• Clause 12 “Performance characteristics” has been technically revised
• A new informative Annex D “Repeatability and reproducibility data” has been added
• A new informative Annex E "Calculation of centrifugation duration depending on centrifugation speed and rotor dimensions" has been added