Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/76005
Title: Arsenic-containing soil from geogenic source in Hong Kong : leaching characteristics and stabilization/solidification
Authors: Li, JS 
Beiyuan, JZ 
Tsang, DCW 
Wang, L 
Poon, CS 
Li, XD 
Fendorf, S
Keywords: Geogenic arsenic
Distribution profile
Leaching tests
Bioaccessibility
Stabilization/solidification
Soil remediation
Issue Date: 2017
Publisher: Pergamon Press
Source: Chemosphere, 2017, v. 182, p. 31-39 How to cite?
Journal: Chemosphere 
Abstract: Geogenic sources of arsenic (As) have aroused extensive environmental concerns in many countries. This study evaluated the vertical profiles, leaching characteristics, and surface characteristics of As-containing soils in Hong Kong. The results indicated that elevated levels of As (486-1985 mg kg(-1)) were mostly encountered in deeper layer (15-20 m below ground). Despite high concentrations, geogenic As displayed a high degree of chemical stability in the natural geochemical conditions, and there was minimal leaching of As in various leaching tests representing leachability, mobility, phytoavailability, and bio-accessibility. Microscopic/spectroscopic investigations suggested that As in the soils was predominantly present as As(V) in a coordination environment with Fe oxides. Sequential extraction indicated that the majority of As were strongly bound with crystalline Fe/Al oxides and residual phase. Yet, uncertainties may remain with potential As exposure through accidental ingestion and abiotic/biotic transformation due to changes in geochemical conditions. Hence, the effectiveness of stabilization/solidification (S/S) treatment was evaluated. Although the leached concentrations of As from the S/S treated soils increased to varying extent in different batch leaching tests due to the increase in alkalinity, the mobility of As was considered very low based on semi-dynamic leaching test. This suggested that As immobilization in the S/S treated soils was predominantly dependent on physical encapsulation by interlocking framework of hydration products, which could also prevent potential exposure and allow controlled utilization of S/S treated soils as monolithic materials. These results illustrate the importance of holistic assessment and treatment/management of As-containing soils for enabling flexible future land use.
URI: http://hdl.handle.net/10397/76005
ISSN: 0045-6535
EISSN: 1879-1298
DOI: 10.1016/j.chemosphere.2017.05.019
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