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Donner E, Scheckel K, Sekine R, Popelka-Filcoff RS, Bennett JW, Brunetti G, Naidu R, McGrath SP, Lombi E. Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing. Environ Pollut 2015; 205:78-86. [PMID: 26021819 DOI: 10.1016/j.envpol.2015.05.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/06/2015] [Accepted: 05/07/2015] [Indexed: 06/04/2023]
Abstract
Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with (110 m)Ag showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 μg/kg (0.002-3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability.
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Affiliation(s)
- E Donner
- Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus, South Australia 5095, Australia; CRC CARE, PO Box 486, Salisbury, South Australia 5106, Australia.
| | - K Scheckel
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA
| | - R Sekine
- Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus, South Australia 5095, Australia
| | - R S Popelka-Filcoff
- School of Chemical and Physical Sciences, Flinders University, Adelaide, South Australia 5001, Australia
| | - J W Bennett
- Neutron Activation Group, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - G Brunetti
- Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus, South Australia 5095, Australia
| | - R Naidu
- Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus, South Australia 5095, Australia; CRC CARE, PO Box 486, Salisbury, South Australia 5106, Australia
| | - S P McGrath
- Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom
| | - E Lombi
- Centre for Environmental Risk Assessment and Remediation, University of South Australia, Building X, Mawson Lakes Campus, South Australia 5095, Australia; CRC CARE, PO Box 486, Salisbury, South Australia 5106, Australia
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Nazif W, Marzouk ER, Perveen S, Crout NMJ, Young SD. Zinc solubility and fractionation in cultivated calcareous soils irrigated with wastewater. Sci Total Environ 2015; 518-519:310-9. [PMID: 25770943 DOI: 10.1016/j.scitotenv.2015.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 03/02/2015] [Accepted: 03/04/2015] [Indexed: 05/03/2023]
Abstract
The solubility, lability and fractionation of zinc in a range of calcareous soils from Peshawar, Pakistan were studied (18 topsoils and 18 subsoils). The lability (E-value) of Zn was assessed as the fraction isotopically exchangeable with (70)Zn(2+); comparative extractions included 0.005 M DTPA, 0.43 M HNO3 and a Tessier-style sequential extraction procedure (SEP). Because of the extremely low concentration of labile Zn the E-value was determined in soils suspended in 0.0001 M Na2-EDTA which provided reliable analytical conditions in which approximately 20% of the labile Zn was dissolved. On average, only 2.4% of soil Zn was isotopically exchangeable. This corresponded closely to Zn solubilised by extraction with 0.005 DTPA and by the carbonate extraction step (F1+F2) of the Tessier-style SEP. Crucially, although the majority of the soil CaCO3 was dissolved in F2 of the SEP, the DTPA dissolved only a very small proportion of the soil CaCO3. This suggests a superficial carbonate-bound form of labile Zn, accessible to extraction with DTPA and to isotopic exchange. Zinc solubility from soil suspended in 0.01 M Ca(NO3)2 (PCO2 controlled at 0.03) was measured over three days. Following solution speciation using WHAM(VII) two simple solubility models were parameterised: a pH dependent 'adsorption' model based on the labile (isotopically exchangeable) Zn distribution coefficient (Kd) and an apparent solubility product (Ks) for ZnCO3. The distribution coefficient showed no pH-dependence and the solubility model provided the best fit to the free ion activity (Zn(2+)) data, although the apparent value of log10 Ks (5.1) was 2.8 log units lower than that of the mineral smithsonite (ZnCO3).
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Affiliation(s)
- W Nazif
- Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK
| | - E R Marzouk
- Division of Soil and Water Sciences, Faculty of Environmental Agricultural Sciences, Suez Canal University, North Sinai 45516, Egypt
| | - S Perveen
- Department of Soil and Environmental Sciences, Khyber Pakhtunkhwa Agricultural University, Peshawar, Pakistan
| | - N M J Crout
- Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK
| | - S D Young
- Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK.
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