Does ochre have the potential to be a remedial treatment for As-contaminated soils?

Abstract

13Ochre is an iron oxyhydroxide-rich waste that accumulates in water bodies associated with 14 disused mines. Laboratory experiments were conducted to examine the potential of four 15 different ochres to be used as remedial agents for As contaminated soils. The ochres 16 removed As from solution (200 and 500 mg L -1 ) in adsorption experiments at pH 3 and 8 and 17 when added to As contaminated soil (5 % w/w) significantly reduced As release to solution. 18In both these experiments the highest surface area ochres performed best. The impact of 19 ochre amendments on uptake of As from soil by plants and humans and release of As to 20 ground water was assessed in a year-long incubation. Ochres increased soil pH and 21 reduced CaCl 2 extractable As but had no consistent effect on plant growth, plant As uptake 22 or As extraction in physiologically based extraction tests. Ochre may be better used for water 23 treatment than soil remediation. 24 Keywords: arsenic; ochre; contaminated soil; incubation; bioassays 25 2 26 Capsule: Ochre amendments to As-contaminated soil increase pH and reduce CaCl 2 27 extractable As but have no impact on plant growth, As uptake or PBET extractable As. 28 29 Introduction 30High concentrations of As in soils and water bodies occur throughout the world due to 31 anthropogenic activities such as mining, smelting and wood preservative usage (Abrahams 32 and Thornton; Álvarez-Ayuso et al., 2012; Eapaea et al., 2007; Lin et al., 2004; Mench and 33 Bes, 2009; Nriagu et al., 2007; Ritchie et al., 2013;. The main routes of 34 arsenic poisoning from contaminated soils are accidental ingestion or inhalation of 35 contaminated soil or water or consumption of plants grown on As-contaminated soils 36 (Miretzky and Cirelli, 2010). There is a need for affordable remedial solutions that can be 37 applied to As-contaminated soil. It is increasingly recognised that the remedial methods of 38 ,1997;Sun and Doner, 1998; Jain et al., 1999;Garcia-Sanchez et al., 2002; 47 Goldberg, 2002;Ford, 2002; Jackson and Miller, 2000; Grafe et al., 2001;Waltham and Eick, 48 2002;Sun and Doner, 1996; Manning et al., 1998; Goldberg and Johnston, 2001; Livesey 49 and Huang, 1981; Elkhatib et al.,1984a,b; Manning and Suarez, 2000;Smith et al., 2002) 50 and this had led to investigations into using Fe oxides to remediate As-contaminated soil 51 3 (e.g. Boisson et al., 1999;Garcia-Sanchez et al., 1999; Warren and 52 Alloway, 2003; Nielsen et al., 2011; Kumpiene et al., 2008; Lee et al., 2011). Ochre is the 53 name given to Fe(III) oxyhydroxide precipitates that accumulate in the outflows of mine 54 systems. In the United Kingdom the Coal Authority is responsible for over 68 (as of August 55 2014) mine water treatment schemes that remove c. 4000 tonnes of iron per year from water 56 courses resulting in ochre production (UK Government, 2014). Some of this ochre is used in 57 brick production to partially offset the waste management costs (Clean Rivers Trust, 2012). 58Additionally, research has been car...

Microcosm-scale biogeochemical stabilization of Pb, As, Ba and Zn in mine tailings amended with manure and ochre

“…Immobilization of As by ochre in soils polluted with As has already been observed (Doi et al, 2005;Nielsen eat al., 2011;Olimah et al 2015). However, the experiment described here was able to show that ochre can simultaneously decrease Pb and As leachability.…”

“…However, the manure may have introduced some phosphate that contributed to the precipitation of a minor fraction of the mobile As whereas, in our microcosms, Pb immobilization seemed to be mainly linked to the ochre amendment (Fig.6). The addition to soils of iron oxide-hydroxide wastes (ochres) from water treatment facilities is known to induce immobilization of Pb as a result of pH increase (Doi et al, 2005;Nielsen eat al., 2011;Olimah et al 2015). In the experiment, the ochre induced a rise in pH to neutral values in the amended microcosms.…”

“…More recently, Olimah et al (2015) tested four different iron-rich wastes produced in mine water treatment plants for the remediation of As-polluted soils. Their results suggest that this treatment is efficient in decreasing As mobility in water.…”

Effects of biochar, ochre and manure amendments associated with a metallicolous ecotype of Agrostis capillaris on As and Pb stabilization of a former mine technosol

“…Ochre, on the other hand, is not a typical agricultural amendment. Ochre is a by-product found in the outflows of some mining systems (Olimah et al 2015). It is a brown or yellowish-brown product, and rich in Fe(III) oxyhydroxides (Abed et al 2017, Olimah et al 2015.…”

Liberation of selenium from alteration of the Bowland Shale Formation: evidence from the Mam Tor landslide

“…The ready adsorption of As, Cd and Tl has led to the application of ochres and iron oxides to sequester these elements out of groundwaters (Doi et al 2005;Abed et al 2017;Li et al 2017). The As concentration in the Mam Tor ochre is higher than concentrations in some ochres from UK coal mines (Dobbie et al 2005;Olimah et al 2015), but not in others (Sapsford et al 2015) or in ochres elsewhere (e.g. Bowell & Bruce 1995;Cravotta 2008;Valente et al 2011), but is nonetheless above the crustal mean concentration of 5.7 ppm.…”