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Evolution of biochar properties in soil
Published in Johannes Lehmann, Stephen Joseph, Biochar for Environmental Management, 2015
Joseph J. Pignatello, Minori Uchimiya, Samuel Abiven, Michael W. I. Schmidt
Over time, metal ions sorbed by the processes described above may undergo transition to precipitate states and mixed-precipitate states, such as layer double hydroxides (Li et al, 2012). Precipitation occurs due to a favourable entropy change upon removal of hydration-shell water molecules that outweighs the unfavourable ordering effects of crystallization (Wulfsberg, 2000). The increase in soil pH caused by addition of alkaline biochar will precipitate metal ions by hydrolysis. Phosphorus-rich manure biochars can lower the availability of Pb2+ by complexation with surface-bound phosphate (Cao et al, 2011) and by forming the extremely insoluble pyromorphite Pb5(PO4)3Cl (Traina and Laperche, 1999). In addition to phosphate, carbonate induced the precipitation of Pb from aqueous solutions treated with biochars made from anaerobically digested sugar beet and manure (Inyang et al, 2012).
Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Lead has an atomic number of 82, an atomic weight of 207.2, and a density of 11.35 g cm–3. It is a soft, malleable, ductile, and bright bluish-white metal which is a poor conductor of electricity. It has a low melting point (327°C). Galena or lead sulfide (PbS)—also commonly called lead glance—is the most common and abundant primary mineral containing lead, and is the principal commercial source of this metal. There are several other secondary ores of lead, such as anglesite or lead sulfate (PbSO4), formed by oxidation of galena; cerussite (PbCO3), a carbonate of lead and a weathering product of galena; crocoite or lead chromate (PbCrO4)—with a bright red color; wulfenite or lead molybdate (PbMoO4), which is orange-red or orange-yellow in color; and the greenish-hued pyromorphite or lead chlorophosphate [Pb5(PO4)3Cl]. Vanadinite [Pb5(VO4)3Cl] belonging to the apatite group of phosphates is a major ore of vanadium and a minor ore of lead; and mutlockite or matlockite is a rare lead halide (PbFCl), which is light yellow to greenish-yellow in color. Because of its soft and malleable nature and anti-corrosion properties, lead has been used since ancient times for manufacturing metal products. Both metallic lead and its various compounds have numerous industrial uses. Metallic lead is used for making pipes or sheets in chemical and building industries, for cable sheathing, as solder, and in storage batteries. Lead oxides (PbO and Pb3O4) are used in battery plates and accumulators. PbO is also used in rubber manufacture, and Pb3O4 in paints. Lead carbonates, sulfates, and chromates are used to manufacture white, yellow, orange, red, and green pigments. Because of its high density, it is extensively used as a shield against ionizing radiation. Tetraethyl lead was used as an anti-knock compound in gasoline until its use was prohibited in most countries. Lead arsenate was used as an insecticide. Many other lead compounds and lead alloys with antimony, arsenic, tin, and bismuth are used in numerous industrial activities (Encyclopaedia of Occupational Health and Safety 2012).
Lead Resistance Mechanisms in Bacteria and Co-Selection to other Metals and Antibiotics
Published in Edgardo R. Donati, Heavy Metals in the Environment, 2018
Milind Mohan Naik, Lakshangy S. Charya, Pranaya Santosh Fadte
The remediation of Pb(II) through biomineralization is observed to be a promising technique as well as an interesting phenomenon for transforming lead from mobile species into very stable minerals in the environment. Aickin et al. (1979) reported precipitation of Pb+2 on the cell surface of Citrobacter sp. as PbHPO4 which was deduced by electron microscopy and X-ray microanalysis, while Levinson et al. (1996) suggested intracellular bioaccumulation and precipitation of Pb3 (PO4)2 by S. aureus grown in the presence of high concentrations of soluble lead nitrate (Aickin et al., 1979; Levinson et al., 1996). Vibrio harveyi and Providentia alcalifaciens strain 2EA were reported to bioprecipitate soluble Pb+2 as unusual phosphate of lead—i.e., Pb9(PO4)6− (Mire et al., 2004; Naik et al., 2013a). Klebsiella sp. cultured in phosphate-limited medium has been reported to bioprecipitate lead as black colour lead sulfide (PbS) (Aiking et al., 1985). Lead resistant Bacillus iodinium GP13 and Bacillus pumilus S3 were reported to precipitate lead as PbS (De et al., 2008). Biomineralization of Pb(II) into nanosized rod-shaped Ca2.5Pb7.5(OH)2(PO4)6 crystal by Bacillus cereus 12–2 has been reported by Chen et al. (2016). XRD and TEM investigation revealed that the Pb(II) loaded on bacteria could be stepwise transformed into rod-shaped Ca2.5Pb7.5(OH)2(PO4)6nanocrystal. Another report by Liang et al. (2016) revealed phosphatase-mediated bioprecipitation of lead by soil fungi, Aspergillus niger, and Paecilomyces javanicus when grown in 5 mM lead nitrate. The minerals were identified as pyromorphite (Pb5(PO4)3Cl), produced only by P. javanicus and lead oxalate (PbC2O4) produced by A. niger and P. javanicus. Biomineralization of Pb, Cu, Ni, Zn, Co, and Cd, by six metal-resistant bacterial strains was investigated using microcosm experiments. Bacterial isolates produced the enzyme urease which hydrolyzed urea and hence soil pH increased and carbonate was produced. This resulted in biomineralization of the soluble lead, copper, nickel, zinc, cobalt, and cadmium present in soil to carbonates (Li et al., 2013). TEM–EDS analysis of lead resistant Pseudomonas aeruginosa CHL-004 has shown that lead was transported from the exterior environment, complexed with phosphate, and stored as discrete cellular inclusions (Feldhake et al., 2008).
Effect of various metal ions on gypsum precipitation
Published in Indian Chemical Engineer, 2021
Moreover, during the production of boric and phosphoric acid, other minerals can be foundalongside the main mineral, which originate from the ore including scholzite (CaZn2(PO4)2.2H2O), pyromorphite (Pb5(PO4)3Cl), eosphorite (MnAl(PO4)(OH)2.H2O), elbaite (Na(Li1.5Al1.5)Al6Si6O18(BO3)3(OH)4), terujit Ca4MgAs2B12O28.20H2O, and seamanit Mn3(PO4)B(OH)6. Further, the excess sulfuric acid used in these processes causes corrosion, and metal ions such as Ca2+, Pb2+, Mn2+, Al3+, Mg2+, Cr3+, Fe2+, and Zn2+ leach into the reaction media.
The limits of lead (Pb) phytoextraction and possibilities of phytostabilization in contaminated soil: a critical review
Published in International Journal of Phytoremediation, 2020
Sara Perl Egendorf, Peter Groffman, Gerry Moore, Zhongqi Cheng
Pb exists in a variety of forms (Table 2). The majority of Pb found in the Earth’s crust (52%) is the stable isotope 208Pb, the radioactive decay product of 232Th. Other isotopes include 206Pb (24%), which derives from 238U, and 207Pb (23%), which derives from 235U. 204Pb is the only primary isotope, not a decay product, and accounts for only 1% of the Earth’s total Pb. While these isotopes do not necessarily influence processes like plant uptake, they have been used to fingerprint and trace the sources of the element in various environmental media (Komárek et al.2008; Duzgoren-Aydn and Weiss 2008; Del Rio-Salas et al.2012). These isotopes of Pb exist in a variety of mineral forms, such as galena (PbS), anglesite (PbSO4), cerussite (PbCO3), minium (Pb3O4), pyromorphite (Pb5(PO4)3Cl), and mimetesite (Pb5(AsO4)3Cl). When these mineral forms undergo weathering, they release a variety of ionic forms, such as Pb2+, Pb4+, PbCl+, PbOH+, Pb4(OH4)4+, PbCl3−, and Pb(CO3)22−.
Lead contamination in Chinese surface soils: Source identification, spatial-temporal distribution and associated health risks
Published in Critical Reviews in Environmental Science and Technology, 2019
Yunhui Zhang, Deyi Hou, David O’Connor, Zhengtao Shen, Peili Shi, Yong Sik Ok, Daniel C. W. Tsang, Yang Wen, Mina Luo
Pb is a natural constituent of the Earth's crust, and may occur naturally and heterogeneously in soils by the natural weathering and erosion of crustal materials or via deposition of Pb emitted into the Earth’s atmosphere by volcanic activities, totally accounting for 80% of natural sources (Callender, 2003; Hou, O’Connor, et al., 2017). Forest fires and biogenic sources also contribute to soil Pb, accounting for 10% each. Pb from natural sources can be separated as atmospheric soil dust (allochthonous) or detritic source (autochthonous) (Bao, Shen, Wang, & Tserenpil, 2016). Naturally derived lead in soil is commonly in the form of gelena (PbS, logKsp = −27.5) and in smaller quantities in cerussite (PbCO3), anglesite (PbSO4), pyromorphite (Pb5(PO4)3Cl), crocoite (PbCrO4), litharge (PbO) and Massicot (PbO) (Ruby, Davis, & Nicholson, 1994; Mulligan, Yong, & Gibbs, 2001; Laperche, Traina, Gaddam, & Logan,1996). Pb usually coexists with copper, zinc and silver, and the metallic form of Pb in nature is rare (Cheng & Hu, 2010).