Reproducibility of up-flow column percolation tests for contaminated soils

Abstract

Up-flow column percolation tests are used at laboratory scale to assess the leaching behavior of hazardous substance from contaminated soils in a specific condition as a function of time. Monitoring the quality of these test results inter or within laboratory is crucial, especially if used for Environment-related legal policy or for routine testing purposes. We tested three different sandy loam type soils (Soils I, II and III) to determine the reproducibility (variability inter laboratory) of test results and to evaluate the difference in the test results within laboratory. Up-flow column percolation tests were performed following the procedure described in the ISO/TS 21268–3. This procedure consists of percolating solution (calcium chloride 1 mM) from bottom to top at a flow rate of 12 mL/h through softly compacted soil contained in a column of 5 cm diameter and 30 ± 5 cm height. Eluate samples were collected at liquid-to-solid ratio of 0.1, 0.2, 0.5, 1, 2, 5 and 10 L/kg and analyzed for quantification of the target elements (Cu, As, Se, Cl, Ca, F, Mg, DOC and B in this research). For Soil I, 17 institutions in Japan joined this validation test. The up-flow column experiments were conducted in duplicate, after 48 h of equilibration time and at a flow rate of 12 mL/h. Column percolation test results from Soils II and III were used to evaluate the difference in test results from the experiments conducted in duplicate in a single laboratory, after 16 h of equilibration time and at a flow rate of 36 mL/h. Overall results showed good reproducibility (expressed in terms of the coefficient of variation, CV, calculated by dividing the standard deviation by the mean), as the CV was lower than 30% in more than 90% of the test results associated with Soil I. Moreover, low variability (expressed in terms of difference between the two test results divided by the mean) was observed in the test results related to Soils II and III, with a variability lower than 30% in more than 88% of the cases for Soil II and in more than 96% of the cases for Soil III. We also discussed the possible factors that affect the reproducibility and variability in the test results from the up-flow column percolation tests. The low variability inter and within laboratory obtained in this research indicates that the ISO/TS 21268–3 can be successfully upgraded to a fully validated ISO standard.

Automated noninvasive detection of idiopathic scoliosis in children and adolescents: A principle validation study

“…One-way ANOVA was used to compare differences across positions. Repeatability was determined in terms of the coefficient of variation (CV), which is a measure of variability relative to the mean and is calculated by dividing the standard deviations of intrasubject results by the mean and multiplying by 100 to present the result as a percentage 30 . A CV less than 10% was regarded as very good, 10% < CV ≤ 20% as good, 20% < CV ≤ 30% as fair/moderate, and CV > 30% as poor 31 .…”

Evaluation of Long-Term Leaching of Arsenic from Arsenic Contaminated and Stabilized Soil Using the Percolation Column Test

“…The eluates were preserved by the addition of nitric acid and stored in a refrigerator at 4 • C until required for analysis. The percolation column test is usually carried out until a 10 L/S ratio is reached [17,19,23]. However, we also investigated long-term leaching (using a long exposure time) of a 50 L/S ratio.…”

“…The constituent chemicals leached from contaminated soil and/or other solid materials can be evaluated using different leaching tests [17]. Tests include the batch leaching test, toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and single and sequential chemical extractions [8,[18][19][20].…”

“…Recently, studies have tested the release of chemicals using various percolation column tests, such as Nordest (1995), CEN (2004), NEN (2004), OECD (2004), ISO (2007), DIN (2009), and USEPA (2013) [17][18][19].These experiments replicate long-term leaching conditions. To the best of our knowledge, only one study has evaluated the release of constituents from stabilized soil using column tests [21].…”

Speciation and Fractionation of Soil Arsenic from Natural and Anthropogenic Sources: Chemical Extraction, Scanning Electron Microscopy, and Micro-XRF/XAFS Investigation

“…This attests to the fact that the environmental regulation of soil contaminants is commonly assessed by using total concentrations or readily dissolved fraction of target metal(loid)s. Water-soluble metal(loid)s represent the readily mobile and ecotoxicologically relevant fraction in soils, for which batch and column test methods have been developed by the authorized organizations including American Society of Testing and Materials (ASTM) 7 and International Standard Organization (ISO). 8,9 It is unknown however which species of As, for example, dissolve in the extraction process and contribute to the readily extractable fraction. In addition, the total concentration of metal(loid)s in soils is not necessarily related to the labile fraction of metal(loid)s and may be an insufficient indicator for environmental risk assessment.…”