title: Earthworm Uptake Routes and Rates of Ionic Zn and ZnO Nanoparticles at Realistic Concentrations, Traced Using Stable Isotope Labeling.
abstract: The environmental behavior of ZnO nanoparticles (NPs), their availability to, uptake pathways by, and biokinetics in the earthworm Lumbricus rubellus were investigated using stable isotope labeling. Zinc isotopically enriched to 99.5% in (68)Zn ((68)Zn-E) was used to prepare (68)ZnO NPs and a dissolved phase of (68)Zn for comparison. These materials enabled tracing of environmentally relevant (below background) NP additions to soil of only 5 mg (68)Zn-E kg(-1). Uptake routes were isolated by introducing earthworms with sealed and unsealed mouthparts into test soils for up to 72 h. The Zn isotope compositions of the soils, pore waters and earthworms were then determined using multiple collector inductively coupled plasma mass spectrometry. Detection and quantification of (68)Zn-E in earthworm tissue was possible after only 4 h of dermal exposure, when the uptake of (68)Zn-E had increased the total Zn tissue concentration by 0.03‰. The results demonstrate that at these realistic exposure concentrations there is no distinguishable difference between the uptake of the two forms of Zn by the earthworm L. rubellus, with the dietary pathway accounting for ∼95% of total uptake. This stands in contrast to comparable studies where high dosing levels were used and dermal uptake is dominant.
authors.affiliation: Department of Earth Science & Engineering, Imperial College London , London SW7 2AZ, England.|Earth Sciences, Natural History Museum , Cromwell Road, London SW7 5BD, England.
authors.forename: Adam
authors.initials: A
authors.lastname: Laycock
authors.affiliation: Centre for Ecology and Hydrology , Wallingford, Oxfordshire OX10 8BB, England.|Leitat Technology Centre , C/de la Innovació 2, 08225 Terrassa, Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Diez-Ortiz
authors.affiliation: Department of Earth Science & Engineering, Imperial College London , London SW7 2AZ, England.|Department of Earth Sciences, University of Oxford , South Parks Road, Oxford OX1 3AN, England.
authors.forename: Fiona
authors.initials: F
authors.lastname: Larner
authors.affiliation: Earth Sciences, Natural History Museum , Cromwell Road, London SW7 5BD, England.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Dybowska
authors.affiliation: Centre for Ecology and Hydrology , Wallingford, Oxfordshire OX10 8BB, England.
authors.forename: David
authors.initials: D
authors.lastname: Spurgeon
authors.affiliation: Earth Sciences, Natural History Museum , Cromwell Road, London SW7 5BD, England.|School of Geography, Earth and Environmental Sciences, University of Birmingham , Edgbaston, Birmingham, B15 2TT, England.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Valsami-Jones
authors.affiliation: Department of Earth Science & Engineering, Imperial College London , London SW7 2AZ, England.|Earth Sciences, Natural History Museum , Cromwell Road, London SW7 5BD, England.
authors.forename: Mark
authors.initials: M
authors.lastname: Rehkämper
authors.affiliation: Centre for Ecology and Hydrology , Wallingford, Oxfordshire OX10 8BB, England.
authors.forename: Claus
authors.initials: C
authors.lastname: Svendsen
mesh_terms: D000818:Animals; D007553:Isotope Labeling / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009835:Oligochaeta / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D015032:Zinc / Q000737:chemistry / Q000493:pharmacokinetics; D015033:Zinc Isotopes / Q000737:chemistry / Q000493:pharmacokinetics; D015034:Zinc Oxide / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D012987:Soil; D015033:Zinc Isotopes; D015032:Zinc; D015034:Zinc Oxide