Impact of gut passage and mucus secretion by the earthworm Lumbricus terrestris on mobility and speciation of arsenic in contaminated soil

Tom Sizmur, Michael J. Watts, Geoffrey D. Brown, Barbara Palumbo-Roe, Mark E. Hodson

Research output: Contribution to journalArticlepeer-review


Earthworms inhabiting arsenic contaminated soils may accelerate the leaching of As into surface and ground waters. We carried out three experiments to determine the impact of passage of As contaminated soil (1150 mg As kg(-1)) through the gut of the earthworm Lumbricus terrestris on the mobility and speciation of As and the effects of earthworm mucus on As mobility. The concentration of water soluble As in soil increased (from 1.6 to 18 mg kg(-1)) after passage through the earthworm gut. Casts that were aged for 56 days still contained more than nine times greater water soluble As than bulk earthworm inhabited soil. Changes were due to increases in As(V) mobility, with no change in As(III). Dilute mucus extracts reduced As mobility through the formation of As-amino acid-iron oxide ternary complexes. More concentrated mucus extracts increased As mobility. These changes, together with those due to the passage through the gut, were due to increases in pH, phosphate and soluble organic carbon. The mobilisation of As from contaminated soils in the environment by cast production and mucus secretion may allow for accelerated leaching or uptake into biota which is underestimated when bulk soil samples are analysed and the influence of soil biota ignored. (C) 2011 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)169-175
Number of pages7
JournalJournal of hazardous materials
Publication statusPublished - 15 Dec 2011

Cite this