Pedogenic Chromium and Nickel Partitioning in Serpentine Soils along a Toposequence

Abstract

To elucidate the properties of pedogenic Cr and Ni in serpentine soils in terms of mobilization, three pedons on the shoulder (Entisol), backslope (Inceptisol). and footslope (Alfisol) along a toposequence in eastern Taiwan were examined for metal partitioning and their geochemical origins. The analysis combined bulk soil analysis by selective sequential extraction (SSE) with mineralogical methods, including x-ray diffraction (XRD) and scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDX) analyses. Experimental results showed that Cr and Ni were mainly concentrated in chromites and silicates, respectively, and were gradually exposed by weathering of the parent materials. The SEM/EDX analysis indicated that chemical modification of the chromites was more prevalent near the soil surface and that the chemical modification increased as available Cr content increased from the shoulder to the footslope. Landscape position was the most important factor in controlling the trends in Ni and Cr fractions. The footslope accumulated more total Cr and Ni than the shoulder and backslope. Additionally the soil on the footslope received more effective precipitation as run-on water from upslope and was potentially more leached than the soils on the other landscape positions. The accumulation of clay and dithionite-citrate-bicarbonate (DCB) extractable Fe (Fej) and the increase of exchangeable Ca/Mg ratio correlated with the increased total labile pools of Cr and Ni in the soil from the shoulder and backslope to the footslope. However, the concentrations of acid soluble, reducible, and oxidizable fractions (total labile pool) of Ni were higher than those of Cr, indicating diat Ni was more available than Cr in all soils tested by the SSE procedures.Abbreviations: BCR.European Community Bureau of Rcferenc; BSE. back-scattered electron; BSP, base saturation percentage; CEC, cation-exchange capacity; DCB, ditbionite-citrate-bicarbonate ; EDX, energy dispersive x-ray spectroscopy; FAAS.flame atomic absorption spectrophotometer; OC. organic carbon; SEM. scanning electron microscopy: SSE. selective sequential extraction: XRD. x-ray diffraction; XRF, x-ray fluorescence.

Current status and challenges in developing nickel phytomining: an agronomic perspective

“…Nickel in ultramafic soils is associated with three main fractions: (i) short-term labile fraction (water-soluble fraction, NH 4 -acetate-exchangeable fraction, exchangeable from Mn-oxides and amorphous Fe-oxides); (ii) long-term labile fraction (bound to crystalline Feoxides and adsorbed to organic matter); and (iii) nonlabile fraction (solid phase residual fraction including Ni-Al layered double hydroxides, Ni-silicates and Ni occluded in Fe and Mn oxides), the latter generally constitutes >50 % of the soil total Ni content (Cheng et al 2011;Hseu 2006;Quantin et al 2002;Tessier et al 1979;Viets 1962;Vithanage et al 2014). Soil Ni availability is mainly controlled by the mineralogy and Nibearing mineral phases Chardot et al 2007;Quantin et al 2001).…”

“…Soil Ni availability is mainly controlled by the mineralogy and Nibearing mineral phases Chardot et al 2007;Quantin et al 2001). In strongly leached ultramafic soils, such as in Ferralsols, generally the Ni phytoavailability is low (Bani et al 2014;Cheng et al 2011;Das et al 1999;Echevarria et al 2006;Massoura et al 2006;Raous et al 2010;Raous et al 2013). However, in clay-mineral rich young soils (Cambisols) and saprolite materials, the Ni phytoavailable fraction is generally high (Raous et al 2010).…”

“…Studies show that there is a positive correlation between the exchangeable Ca:Mg ratio and the labile Ni pools in ultramafic soils (Cheng et al 2011). Calcium supply to high Mg ultramafic soils will be required to maintain the annual Ni uptake in Alyssum species because biomass harvest and removal reduces the pool of phytoavailable Ca in these soils, for example, the annual removal of 1 t of biomass removes 20 kg of Ca (Chaney et al 2007a;Chaney et al 2008).…”

TOF-SIMS and FE-SEM/EDS to verify the heavy metal fractionation in serpentinite quarry soils

“…The soils developed on this rock have unfavourable properties, such as high levels of heavy metals (mainly Ni, Cr, Co, Fe, and Mn), lack of nutrients (N, P, and K), and a high content of Mg, which causes an important Ca/Mg imbalance. All these properties affect vegetation growth favouring plant endemism and can cause important toxicity problems in adjacent ecosystems (Brooks, 1987;Lee et al, 2001;Oze et al, 2004Oze et al, , 2008Cheng et al, 2011).…”

Weathering and transport of chromium and nickel from serpentinite in the Coast Range ophiolite to the Sacramento Valley, California, USA

“…Several studies have focused on the Cr chemistry and mineralogy of serpentinite and serpentine-derived soils (e.g., Becquer et al, 2003;Cheng et al, 2011;Fandeur et al, 2009;Hseu et al, 2007;Hseu and Iizuka, 2013;Kelepertzis and Stathopoulou, 2013;Kierczak et al, 2007;Oze et al, 2004a;. Elevated Cr(VI) concentrations in soil pore water and groundwater adjacent to serpentinite have been reported (Ball and Izbicki, 2004;Fantoni et al, 2002;Izbicki et al, 2008;Robertson, 1975;RoblesCamacho and Armienta, 2000;Wood et al, 2010).…”