Metal contamination at a wood preservation site: characterisation and experimental studies on remediation

Abstract

The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil. The mean As content of the contaminated surface soils (0-10 cm) was 186 mg kg , where as the mean concentrations of Cu, Cr y1 and Zn in soils from the contaminated area were 26, 29 and 91 mg kg , respectively. The elevated As content in y1 the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions. Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area. The fine fraction of the soil (-0.125 mm) has an average metal content increased by nearly 34% as compared to the -2-mm fraction conventionally used for the analysis and assessment of soil contamination. The -2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (-0.125 mm) constitutes approximately 10%. These facts, taken together, are essential for the choice of remediation measures. Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al-and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species. Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites. With a three-step sequential leaching, up to 98-99% of the metals could be removed. At lower concentrations and higher pH, the leaching decreased to approximately 70%. ᮊ

Composition chimique et activité antifongique des huiles essentielles deThymus algeriensisBoiss. & Reut. etThymus ciliatus(Desf.) Benth. contre les champignons de pourriture du bois

“…Bien qu'ils soient efficaces, ils sont souvent nocifs à l'homme et à l'environnement. Les produits les plus employés étaient, le chromate acide de cuivre (CCA), l'arséniate de cuivre chromé (ACC) et l'arséniate de cuivre et zinc (ACZA), des fongicides dont l'usage est de plus en plus restreint en raison de leur grande toxicité (Lund & Fobian, 1991 ;Andersen et al, 1996 ;Stilwell & Gorny, 1997 ;Deferera et al, 2000 ;Hingston et al, 2001 ;Bhattacharya et al, 2002). Pour faire face à cette problématique, il devient de plus en plus indispensable de remplacer ces produits chimiques par des produits qui respectent l'environnement (Schultz & Nicholas, 2000).…”

Assessing Drinking Water Quality in Punjab, Pakistan

“…The source of arsenic may be the erosion of natural deposits, runoff from orchards, and runoff from industrial and municipal wastes. Anthropogenic activities also intensified the As contamination in water by several means such as processing and combustion of fossil fuels, production and use of arsenical pesticides in agriculture, and incineration and disposal of industrial and municipal wastes [62,63]. From these sources, As releases to the soil -especially in the form of pesticides and solid waste, from which its soluble forms ultimately leach out to the ground water [64].…”

Comparison of Various Single Chemical Extraction Methods for Predicting the Bioavailability of Arsenic in Paddy Soils

“…Elliott and Shastri (1999) reported that the overall extent of metal solubilization increased modestly as the system became more acidic. Other researchers suggested low molecular weight organic acid and phosphate salts were more effective in Log(BCF-1M NH4NO3) = 1.511+1.156Log(Na) 0.62*** <0.000 **(P<0.01), ***(P<0.001) extracting As, attaining more than 40% extraction in the pH range of 6~8 (Alam et al, 2001;Bhattacharya et al, 2002;Stroud et al, 2011). Bioconcentration factors (BCF) of soil to rice according to various single extracting solutions are shown in Table 5.…”