Arsenic-containing soil from geogenic source in Hong Kong: Leaching characteristics and stabilization/solidification

Jiang Shan Li, Jingzi Beiyuan, Chiu Wa Tsang, Lei Wang, Chi Sun Poon, Xiangdong Li, Scott Fendorf

Research output: Journal article publicationJournal articleAcademic researchpeer-review

81 Citations (Scopus)

Abstract

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 bioaccessibility. 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.
Original languageEnglish
Pages (from-to)31-39
Number of pages9
JournalChemosphere
Volume182
DOIs
Publication statusPublished - 1 Jan 2017

Keywords

  • Bioaccessibility
  • Distribution profile
  • Geogenic arsenic
  • Leaching tests
  • Soil remediation
  • Stabilization/solidification

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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