Heavy Metal and Trace Metal Analysis in Soil by Sequential Extraction: A Review of Procedures

Abstract

Quantification of heavy and trace metal contamination in soil can be arduous, requiring the use of lengthy and intricate extraction procedures which may or may not give reliable results. Of the many procedures in publication, some are designed to operate within specific parameters while others are designed for more broad application. Most procedures have been modified since their inception which creates ambiguity as to which procedure is most acceptable in a given situation. For this study, the Tessier, Community Bureau of Reference (BCR), Short, Galán, and Geological Society of Canada (GCS) procedures were examined to clarify benefits and limitations of each. Modifications of the Tessier, BCR, and GCS procedures were also examined. The efficacy of these procedures is addressed by looking at the soils used in each procedure, the limitations, applications, and future of sequential extraction.

Partitioning Of Some Trace Metals in Floodplain Soil in Onitsha, Anambra State, Nigeria.

“…Metals in this fraction exist as cement between soil particles. They are excellent scavengers for trace metals and are thermodynamically unstable under anoxic conditions [10,11,15]. In this study, zinc had the highest occurrence (52.73%) while manganese did not occur (0%).…”

“…Low level of cadmium in this fraction has been reported [23]. The high distribution of iron and zinc in bound to organic matter is expected due to the strong complexes these metals tend to form with humic material [15]. The appreciable % values of iron in oxidizable (23.94) and residual (23.68) fractions were in line with the values obtained for the same metal in the same fractions which were put at 28.27-44.39% and 26.01-42.64% respectively in accordance with the findings of Adaikpoh [21].…”

“…The % occurrence of zinc in this fraction fell within the values obtained in a similar study (7.90-10.02%) by Adaikpoh [21], while manganese in this fraction was detected to be 5.13% which is lower than the value obtained by the same author. Metals in this form are susceptible to pH changes and are also soluble and easily release into the environment [10,11,15]. Figure 3 depicted the % occurrence of metals bound to Fe-Mn oxides.…”

“…The use of sequential extraction furnishes detailed information about the origin, mode of occurrence, biological and phytochemical availability, mobilization and transport of trace metals [11]. Apart from Horowitz et al used in this study, other notable speciation techniques have been documented [2,11,15].…”

Analytical Relevance of Trace Metal Speciation in Environmental and Biophysicochemical Systems

“…The theory involved in the latter is that the most mobile metals are leached in the first fraction and continue in order of decreasing of mobility. Common examples of the sequential extraction techniques are the Tessier Procedure, the Community Bureau of Reference (BCR) Procedure, the Maiz Short Extraction Procedure, the Galán Procedure, and the Geological Society of Canada Procedure [24,[65][66][67]. These sequential extraction procedures promote fractionation.…”