Sequential extraction procedures for the determination of phosphorus forms in sediment

Abstract

This article summarizes the main extraction methods for sedimentary phosphorus (P) determination. With sequential chemical extractions, P is supposed to be selectively removed from different compounds in the sediments. Extraction schemes using strong acids and alkaline solutions have been tested on different sediments and found not to extract well-defined fractions. In addition, several systematic errors in these schemes have been detected. Thus, these schemes have been modified and simplified accordingly. The Standards Measurements and Testing Program of the European Commission (SMT) method is a popular modification of these extraction schemes, as it is simple to handle, allows laboratories to achieve reproducible results and could provide a useful tool for routine use by water managers. The SEDEX (sequential extraction method) method, another popular modification, is widely applied in biogeochemical research as it can separate authigenic carbonate fluorapatite from fluorapatite. Other chemical extractions using chelating compounds have attempted to extract P bound with iron and calcium in sediments without disturbing claybound or organic P, the purpose being to determine the algal-available non-apatite, apatite and organic fractions of sediment P. All extraction procedures still yield operationally defined fractions and cannot be used for identification of discrete P compounds. Future modifications of the extraction scheme should aim to achieve better extraction efficiency and selectivity, simple handling techniques and methods that can prevent the extracted P from being re-adsorbed onto Fe(OOH) and CaCO3. Abstract: This paper summarizes the main extraction methods for sedimentary phosphorus (P) determination. With sequential chemical extractions, P is supposed to be selectively removed from different compounds in the sediments. The extraction schemes using strong acids and alkaline solutions have been tested on different sediments, and found not to extract well defined fractions. In addition, several systematic errors in these schemes have been detected. Then these schemes have been modified and simplified accordingly. The SMT (Standards Measurements and Testing Program of the European Commission) method is a popular modification of these extraction schemes, as it is simple to handle, suitable to allow laboratories to achieve reproducible results and could provide a useful tool for water managers on a routine basis. The SEDEX (sequential extraction method) method, another popular modification, is widely applied in the biogeochemical research as it is capable of separating authigenic carbonate fluorapatite (CFAP) from fluorapatite (FAP). Other chemical extractions using chelating compounds have attempted to extract P bound with iron and calcium in sediments without disturbing clay-bound or organic P, the purpose being to determine the algal-available non-apatite, apatite and organic fractions of sediment P. All extraction procedures still yield operationally defined fractions and cannot be used for ide...

Characteristics of phosphorus components in the sediments of main rivers into the Bohai Sea

“…According to the combination state of P it can be divided into exchangeable P, the fraction associated with Al, Fe, and Mn oxides and hydroxides, and the fraction in Ca-bound compounds often referred to as apatite P. According to its bond character, it can be divided into orthophosphate, phosphonates, pyrophosphate, orthophosphate monoesters, DNA-P, and phospholipid. Accordingly, there are a variety of methods for the research of sediment P (Wang et al, 2013), and the most commonly used is SMT, which is launched by the European Commission through the Standards, Measurements and Testing Program. The fractionations include NaOH-extractable P, HCl-extractable P, organic P, inorganic P and concentrated-HCl-P (Ruban et al, 1999(Ruban et al, , 2001.…”

Geochemistry of phosphorus in sediment cores from Sishili Bay, China

“…Furthermore, no significant difference was found among the sedimentary P forms between Scallop cultivation area (core B, core C, and core D) and background area (core E). These results indicate that shellfish aquaculture did not have significant effect on the depositional environment, at least in case of P. Given a sedimentation rate of 0.78-0.91 cm/year (Wang et al, 2013a(Wang et al, , 2013b, the increase of TP in the upper 20 cm (Fig. 4) is coincident with a time span from mid1980s to the sampling date.…”

“…4) is coincident with a time span from mid1980s to the sampling date. During this period, the quickly-developed human activities around Sishili Bay including fertilizer use, marine dumping and sewage discharge have contributed to the eutrophication (Wang et al, 2013a(Wang et al, , 2013b, which includes enrichment of TP.…”

“…A widely-used technique for understanding element distribution in the solid phase, which is known as fractionation, is based on the application of sequential selective chemical extractions. These methods are based on the rational use of a series of more or less selective reagents chosen to solubilize successively the different mineralogical fractions thought to be responsible for retaining the larger part of the trace elements (Wang et al, 2013a). They are intended to simulate the various possible natural and anthropogenic modifications of environmental conditions.…”

An innovative approach for sequential extraction of phosphorus in sediments: Ferrous iron P as an independent P fraction

“…Even when external P is controlled, P release from sediments sustains water eutrophication for several decades (Søndergaard et al, 2003;Schindler, 2006;Lewis et al, 2007). In some lakes, the quantity of internal P is several orders of magnitude higher than that of external sources (Wang et al, 2013). Thus, it is highly important to scientifically identify P forms in sediments to facilitate management of internal P.…”