Howells, Anthony, Lewis, Steven, Beard, Dylan and Oliver, I (2018) Water treatment residuals as soil amendments: Examining element extractability, soil porewater concentrations and effects on earthworm behaviour and survival. Ecotoxicology and Environmental Safety. ISSN 0147-6513

[img] Text
Howells_Lewis_Beard_Oliver_2018_GREEN.pdf - Accepted Version
Restricted to Repository staff only until 10 July 2019.
Available under License Creative Commons Attribution Non-commercial No Derivatives.

Download (1MB)

Abstract

Drinking water treatment residuals (WTRs), the by-product of water clarification processes, are
routinely disposed of via landfill however there is a growing body of research that demonstrates
the material has great potential for beneficial use in environmental applications. Application to
agricultural land is one option showing great promise (i.e. a low cost disposal route that provides
organic matter input to soils and other potential benefits), however questions remain as to the
impact such applications may have on earthworm survival and behaviour and also on the potential
effects it may have on soil porewater chemistry. This study examined the leachability of elements
within two types of WTRs (one Al- and one Fe- based) from England via 0.001 M CaCl2 solution,
at varying pH, and via the Community Bureau of Reference (BCR) sequential extraction scheme.
Earthworm avoidance, survival, growth, reproduction and element concentrations were examined
in WTR-amended sandy soils (0%, 5%, 10%, 20% w/w), while soil porewaters were also
recovered from experimental units and examined for element concentrations. The results
revealed leachable element concentrations to be very low in both types of WTRs tested and so
element leaching from these WTRs would be unlikely to pose any threat to ecosystems under
typical agricultural soil conditions. However, when the pH was lowered to 4.4 there was a
substantial release of Al from the Al-WTRs (382 mg/kg). Soil porewater element concentrations
were influenced to some degree by WTR addition, warranting further examination in terms of any
potential implications for nutrient supply or limitation. Earthworm avoidance of WTR-amended soil
was only observed for Al-WTRs and only at the maximum applied rate (20% w/w), while survival
of earthworms was not affected by either WTR type at any application rate. Earthworm growth
and reproduction (cocoon production) were not affected at a statistically significant level but this
needs further examination over a longer period of exposure. Increased assimilation of Al and Fe
into earthworm tissues was observed at some WTR application rates (maximum fresh weight
concentrations of 42 mg/kg for Al and 167 mg/kg for Fe), but these were not at levels likely to
pose environmental concerns.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://doi.org/10.1016/j.ecoenv.2018.06.087. Please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: Earthworms, Eisenia fetida, Water treatment residuals, Soil amendment, BCR
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
Depositing User: Symplectic
Date Deposited: 16 Jul 2018 11:00
Last Modified: 16 Jul 2018 11:00
URI: http://eprints.keele.ac.uk/id/eprint/5118

Actions (login required)

View Item View Item