Derivation of ecological standards for risk assessment of molybdate in soil
Date
2016
Authors
Oorts, K.
Smolders, E.
McGrath, S.
Van Gestel, C.
McLaughlin, M.
Carey, S.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Environmental Chemistry, 2016; 13(1):168-180
Statement of Responsibility
Koen Oorts, Erik Smolders, Steve P. McGrath, Cornelis A.M. van Gestel, Michael J. McLaughlin and Sandra Carey
Conference Name
DOI
Abstract
An extensive testing programme on the toxicity of sodium molybdate dihydrate in soil was initiated to comply with the European REACH Regulation. The molybdate toxicity was assayed with 11 different bioassays, 10 different soils, soil chemical studies on aging reactions, and toxicity tests before and after 1-year equilibration in field conditions. Differences in molybdate toxicity among soils were best explained by soil pH and clay content. A correction factor of 2.0 was selected to account for the difference in molybdate toxicity between laboratory and field conditions due to leaching and aging processes. Toxicity thresholds were determined as the HC₅−₅₀ (median hazardous concentration for 5 % of the species, i.e. median 95 % protection level) derived from the species sensitivity distribution of ecotoxicity data after bioavailability corrections. Uncertainty analysis illustrated that the HC₅−₅₀ provides a robust and ecologically relevant predicted no-effect concentration (PNEC) for risk characterisation. The 10th and 90th percentiles for site-specific PNEC values in European agricultural soil are 10.7 and 168 mg Mo kg⁻¹ dry weight respectively based on a large survey of metal concentrations and soil properties in arable land soils. Total soil Mo concentrations in these soils are below corresponding PNEC values at most locations, suggesting no regional risks of molybdate to soil organisms at this scale. The information presented can be used in the EU risk-assessment framework as well as for national and international regulatory purposes for the setting of soil quality criteria based on total molybdenum concentrations, soil pH and clay content.
School/Discipline
Dissertation Note
Provenance
Description
Access Status
Rights
Journal compilation © CSIRO 2016 Open Access