Influence of Gliricidia sepium Biochar on Attenuate Perchlorate-Induced Heavy Metal Release in Serpentine Soil
Hindawi
Journal of Chemistry
Volume 2017, Article ID 6180636, 8 pages
https://doi.org/10.1155/2017/6180636
Research Article
Influence of Gliricidia sepium Biochar on Attenuate
Perchlorate-Induced Heavy Metal Release in Serpentine Soil
Prasanna Kumarathilaka and Meththika Vithanage
Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Kandy, Sri Lanka
Correspondence should be addressed to Meththika Vithanage;
Received 10 September 2016; Revised 6 December 2016; Accepted 20 December 2016; Published 14 February 2017
Academic Editor: Ana Moldes
Copyright © 2017 Prasanna Kumarathilaka and Meththika Vithanage. This is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
Perchlorate (ClO4 − ) is a strong oxidizer, capable of accelerating heavy metal release into regolith/soil. Here, we assessed interactions
between ClO4 − and serpentine soil to simulate and understand the fate of Ni and Mn and their immobilization with the presence
of biochar (BC). A soil incubation study (6 months) was performed using serpentine soil in combination with different ClO4 −
concentrations (0.25, 0.5, 0.75, and 1 wt.%) and three different amendment rates (1, 2.5, and 5 wt.%) of Gliricidia sepium BC.
Bioavailable fraction of Ni and Mn was analyzed using CaCl2 extraction method. An increase of ClO4 − concentrations enhanced
bioavailability fraction of Ni and Mn. However, BC amendments reduced the bioavailability of Ni and Mn. In comparison, 5% BC
amendment significantly immobilized the bioavailability of Ni (68–92%) and Mn (76–93%) compared to other BC amendment
rates. Electrostatic attractions and surface diffusion could be postulated for Ni and Mn immobilization by BC. In addition, ClO4 −
may have adsorbed to BC via hydrogen bonding which may reduce the influence of ClO4 − on Ni and Mn mobility. Overall, it is
obvious that BC could be utilized as an effective amendment to immobilize Ni and Mn in heavy metal and ClO4 − contaminated
soil.
1. Introduction
Perchlorate is an inorganic anion and strong oxidizer and can
contaminate water and soil due to the dissolution of solid salts
of ammonium (NH4 + ), potassium (K+ ), magnesium (Mg2+ ),
and sodium (Na+ ) perchlorate and perchloric acid (HClO4 )
in water [1, 2]. A wide variety of anthropogenic activities (i.e.,
fireworks, explosives, stick matches, highway safety flares,
and military operations) lead to contamination of ClO4 − in
soil system [3]. In this sense, the presence of ClO4 − in soil may
aid in accelerated mineral dissolution, therefore, increasing
heavy metal release potential into the soil and groundwater. It
has been experimentally observed that the rate of dissolution
of minerals increases with the addition of perchloric acid
in ulexite which is considered as one of the most common
boron-containing minerals [4]. In addition, Senanayake et al.
[5] examined the dissolution of Ni and Co in the presence
of perchloric acid in laterite. Moreover, Majima et al. [6]
investigated dissolution of Fe in goethite and hematite in
the presence of perchloric acid. Therefore, the interaction
between ClO4 − and heavy metal contaminated sites may tend
to dissolve heavy metals, and, consequently, it could be a
possible pathway for leaching metals to the water bodies and,
eventually, accumulate in living organisms through the food
chain [7].
Heavy metals continue to pose environmental contamination worldwide (i.e., naturally contaminated soils, industrially contaminated urban soils, shooting ranges, and mining
sites) [8–11]. Rajapaksha et al. [8] demonstrated that Ni
and Mn have been released from the serpentine soil in
Ussangoda in Sri Lanka at rates of 1.55 × 10−13 and 7.89 ×
10−14 mol m−2 s−1 , respectively, with the presence of inorganic
(sulfuric, nitric, and hydrochloric) and organic (citric, acetic,
and oxalic) acids. In addition, Vithanage et al. [12] examined
four serpentinite bodies in Sri Lanka in order to assess the
bioavailability fraction and the results revealed that bioavailability fraction of Ni and Mn was ranged between 33 to
323 mg kg−1 and 11 to 76 mg kg−1 , respectively. Different kinds
of techniques (i.e., subsurface barriers, chemical treatment,
phytoremediation, and soil washing) have been introduced
2
and proposed to remediate heavy metal contaminated soils
and they could change the chemistry of the soil media which
may reduce the mobility and bioavailability of heavy metals.
In this context, BC is recognized to be an effective adsorbent
for heavy metals [13].
Biochar is produced through the thermochemical process
of biomass under oxygen limited conditions [14, 15]. Different
types of biomass such as forestry and agricultural crop
residues, invasive plant species, wood waste, animal manures,
and organic portion of municipal solid waste have been used
as feedstock for producing BC [16–19]. However, pyrolysis
conditions, together with feedstock characteristics, mainly
govern the physical and chemical properties of the resulting
BC [13]. Furthermore, application of BC to soil system has
shown a significant importance possibly due to its ability to
improve soil nutrient content and water holding capacity as
well as carbon sequestration, therefore minimizing greenhouse gas emissions [20–22].
Biochar amendments onto contaminated soils would
greatly reduce the total metal concentration and bioavailability fraction [23–26]. For instance, Ahmad et al. [27]
found that soybean stover-derived BC more efficiently immobilized Pb (88%) and Cu (87%) in shooting range soil in
Cheorwon-gun in Gangwon-do, Korea. In another study, the
sequential extraction results in a long-term (three years) field
experiment reported that BC amendment (0.5–2%) increased
the residue fractions of Ni(II) (from 51% to 61–66%) and
Zn(II) (from 7% to 27–35%) [28]. Possibly due to the high
porous microstructure, pH, active functional groups, surface
area, and cation exchange capacity, BC may immobilize
heavy metals through different processes (i.e., adsorption, ion
exchange, precipitation, and surface complexation) [29, 30].
Hence, we hypothesized that BC may be a possible material
to be used in the attenuation of heavy metals in ClO4 −
contaminated soil. In this study, the serpentine soil was used
as a model soil due to the high heavy metal concentrations
and bioavailability [12, 31]. Although it has been observed that
the ClO4 − addition may increase the heavy metal release and
enhance leaching, no studies have focused their attention on
immobilizing the metals released due to ClO4 − . Therefore,
this study assessed the effectiveness of BCs derived from
Gliricidia sepium biomass on the Ni and Mn immobilization
in a serpentine soil with the presence of ClO4 − .
2. Experimental Section
2.1. Soil Collection and Characterization. Serpentine soil,
obtained from Yudhaganawa (...truncated)
