Article

Digestion Methods for Total Heavy Metals in Sediments and Soils

Water Air and Soil Pollution (Impact Factor: 1.55). 11/2002; 141(1):189-205. DOI: 10.1023/A:1021302405128

ABSTRACT

The objectives of this study were to analyze the total contents of Cd, Cr, Cu, Ni, Pb, and Zn in the freshwater sediments
and the arable and non-arable soils of Taiwan, and to compare the different digestion methods for their determination. Two
hundred and thirty-nine freshwater sediments were collected from the Fei-Tsui Reservoir Watershed (FTRW) in northern Taiwan.
Forty-two surface (0–15 cm) and subsurface (15–30 cm) soil samples were likewise collected from 21 representative arable soils
derived from various parent materials and with varying weathered degrees in different regions of Taiwan. In addition, one
hundred and ninety-four non-arable soils were collected from the different forest regions, industrial parks, resident areas,
and commercial areas. Several digestion methods including the aquaregia and different combinations of concentrated acids (HClO4, HNO3, H2SO4, or HF) were compared. All samples were digested both by the aqua regia method and the Baker and Amacher method for Cd, Cr, Cu, Ni, Pb, and Zn. The Reisenauer method was used for Cr and the Burau
method for Pb further. The results indicate that the best digestion methods to analyze the total contents of heavy metals
in the sediments and soils were recommended as follows: the Baker and Amacher method for Cd, Cr,Cu, Ni, and Zn; the Reisenauer
method for Cr, but for simplicity the Baker and Amacher method is also recommended as the flexible method for the total analysis
of Cr; the aqua regia method for Cu, Ni, and Zn; and the Burau method for Pb.

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    • "of homogenized sediment were digested with aqua regia (3:1 v/v, HCl to HNO 3 ) and H 2 O 2 at 100 °C (Hseu et al., 2002). The extracts were centrifuged, diluted to 25 ml with deionized water and stored in polyethylene bottles. "
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    ABSTRACT: Water and sediment samples were collected in the Samborombón Bay, outer Río de la Plata estuary to evaluate the dynamics of trace metals along the fluvial–marine transition. This estuarine environment presented strong salinity (0.11–31.4) and turbidity (21 to 4999 mg L-�1) gradients with a consistent turbidity maximum zone (TMZ:41 g suspended solids L�-1) in the low salinity region. Suspended particulate metals showed different spatial patterns: homogeneous distributions (Fe, Zn) and progressive enrichment from the TMZ to the maritime area (Cu, Ni). The influence of the TMZ is clearly reflected by the enrichment of flocculated clays which in turns control the distribution of sedimentary TOC and trace metals resulting in a prevailing decreasing land–sea gradient. Mn has a particular behavior along the salinity gradient denoting intense dissolved-particulated phase changes both in the water column and bottom sediments. An average 36% drop of particulate Mn observed in parallel with a strong dissolved peak suggests a rapid Mn desorption/dissolution in the water column whereas bottom sediments display an average 72% Mn enrichment in the TMZ relative to the riverine sector reflecting the diffusive escape from anoxic sediments and reprecipitation in oxic surface layers.
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    • "The aim of digestion is to achieve a selective or complete extraction of metals from the samples. Mostly, the digestion procedures are based on the addition of inorganic acids such as, aqua regia, HNO 3 - HF, HFHNO 3 -H 2 SO 4 -HClO 4 , HNO 3 -HClO 4 in a closed vessel, which may be heated on different sources (Scancar, Milacic, & Horvat, 2000;Hseu et al., 2002 ;Jeneper & Hayao, 2005). Atomic Absorption spectroscopy is based on absorption of radiation by atoms. "
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    ABSTRACT: Rapidly increasing human population, urbanization, industrialization, and mining activities have become the serious environmental issue of today’s world. Conventional physico-chemical remediation methods are highly expensive and generate secondary waste. However, bioremediation of contaminated ecosystems using indigenous microbes and plants or amalgamation of both has been recognized as a cost effective and eco-friendly method for remediation as well as restoration of polluted or degraded ecosystems. Further, variety of pollutant attenuation mechanisms possessed by microbes and plants makes them more feasible for remediation of contaminated land and water over physico-chemical methods. Plants and microbes act cooperatively to improve the rates of biodegradation and biostabilization of environmental contaminants. This chapter aims to emphasize on potential application of microbes and plants to attenuate the organic and inorganic pollutants from the contaminated sites as well as eco-restoration of mine degraded and jhum lands by way of biodegradation and phytoremediation technologies.
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    • "This complete dissolution process—termed acid digestion—is required for element determination . The effectiveness of closed (pressure) digestion using a combination of HNO 3 , HClO 4 , and HF has been demonstrated for bulk-certified reference materials of marine sediments, in which both HNO 3 and HClO 4 are oxidizers; the HNO 3 prevents explosive reactions of the organic matter with HClO 4 while HF attacks silicate minerals to form gaseous SiF 4 (Hseu et al., 2002; Begum et al., 2007). The solutions from the extractable and residual fractions were evaporated to dryness, and clear solutions were generated using 10 ml of 1% HNO 3 . "
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    ABSTRACT: We sampled two box-core sediments from the slope of the eastern South Korea Plateau (SKP) in the East Sea (Sea of Japan) at water depths of 1400 and 1700 m. Two chemical fractions of extractable (hydroxylamine/acetic acid) and residual rare earth elements (REEs) together with Al, Ca, Fe, Mg, Mn, P, S, As, Mo, and U were analyzed to assess the post-depositional redistribution of REEs. Extractable Fe and Mn are noticeably abundant in the oxic topmost sediment layer (<3 cm). However, some trace elements (e.g., S, As, Mo, U) are more abundant at depth, where redox conditions are different. Analysis of upper continental crust (UCC)-normalized (La/Gd)UCC, (La/Yb)UCC, and (Ce/Ce*)UCC revealed that the extractable REE is characterized by middle REE (MREE) enrichment and a positive cerium (Ce) anomaly, different from the case of the residual fraction which shows slight enrichment in light REEs (LREEs) with no Ce anomaly. The extractable MREEs seem to have been incorporated into high-Mg calcite during reductive dissolution of Fe oxyhydroxides. In the top sediment layer, the positive Ce anomaly is attributed to Ce oxide, which can be mobilized in deeper oxygen-poor environments and redistributed in the sediment column. In addition, differential concentrations of Ce and other LREEs in pore water appear to result in variable (Ce/Ce*)UCC ratios in the extractable fraction at depth.
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