Exposure of humic acid-coated goethite colloids to groundwater does not affect their adsorption of metal(loid)s and their impact on Daphnid mobility.

Engineered humic acid-coated goethite (HA-Goe) colloids find increasing application in in situ remediation of metal(loid)-polluted groundwater. Once introduced into the subsurface, the colloids interact with groundwater altering their physicochemical properties. In comparison to freshly synthesized, unreacted HA-Goe colloids, such alterations could reduce the adsorption affinity towards metal(loid)s and also result in altered ecotoxicological effects.

Field-scale demonstration of in situ immobilization of heavy metals by injecting iron oxide nanoparticle adsorption barriers in groundwater.

Remediation of heavy metal-contaminated aquifers is a challenging process because they cannot be degraded by microorganisms. Together with the usually limited effectiveness of technologies applied today for treatment of heavy metal contaminated groundwater, this creates a need for new remediation technologies. We therefore developed a new treatment, in which permeable adsorption barriers are established in situ in aquifers by the injection of colloidal iron oxides.

Earthworm Uptake Routes and Rates of Ionic Zn and ZnO Nanoparticles at Realistic Concentrations, Traced Using Stable Isotope Labeling.

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.

Different routes, same pathways: Molecular mechanisms under silver ion and nanoparticle exposures in the soil sentinel Eisenia fetida.

Use of nanotechnology products is increasing; with silver (Ag) nanoparticles particularly widely used. A key uncertainty surrounding the risk assessment of AgNPs is whether their effects are driven through the same mechanism of action that underlies the toxic effects of Ag ions. We present the first full transcriptome study of the effects of Ag ions and NPs in an ecotoxicological model soil invertebrate, the earthworm Eisenia fetida.

Uptake routes and toxicokinetics of silver nanoparticles and silver ions in the earthworm Lumbricus rubellus.

Current bioavailability models, such as the free ion activity model and biotic ligand model, explicitly consider that metal exposure will be mainly to the dissolved metal in ionic form. With the rise of nanotechnology products and the increasing release of metal-based nanoparticles (NPs) to the environment, such models may increasingly be applied to support risk assessment. It is not immediately clear, however, whether the assumption of metal ion exposure will be relevant for NPs.

Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO₃) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils.

This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed.

Soil pH effects on the interactions between dissolved zinc, non-nano- and nano-ZnO with soil bacterial communities.

Zinc oxide nanoparticles (ZnO NPs) are used in an array of products and processes, ranging from personal care products to antifouling paints, textiles, food additives, antibacterial agents and environmental remediation processes. Soils are an environment likely to be exposed to manmade nanoparticles due to the practice of applying sewage sludge as a fertiliser or as an organic soil improver. However, understanding on the interactions between soil properties, nanoparticles and the organisms that live within soil is lacking, especially with regards to soil bacterial communities.

The effect of pH on the toxicity of zinc oxide nanoparticles to Folsomia candida in amended field soil.

The effect of soil pH on the toxicity of 30 nm ZnO to Folsomia candida was assessed in Dorset field soils with pHCaCl2 adjusted to 4.31, 5.71, and 6.

Soil pH effects on the comparative toxicity of dissolved zinc, non-nano and nano ZnO to the earthworm Eisenia fetida.

To determine how soil properties influence nanoparticle (NP) fate, bioavailability and toxicity, this study compared the toxicity of nano zinc oxide (ZnO NPs), non-nano ZnO and ionic ZnCl2 to the earthworm Eisenia fetida in a natural soil at three pH levels. NP characterisation indicated that reaction with the soil media greatly controls ZnO properties. Three main conclusions were drawn.

Assessing the impact of organic and inorganic amendments on the toxicity and bioavailability of a metal-contaminated soil to the earthworm Eisenia andrei.

Metal-contaminated soil, from the El Arteal mining district (SE Spain), was remediated with organic (6% compost) and inorganic amendments (8% marble sludge) to reduce the mobility of metals and to modify its potential environmental impact. Different measures of metal bioavailability (chemical analysis; survival, growth, reproduction and bioaccumulation in the earthworm Eisenia andrei), were tested in order to evaluate the efficacy of organic and inorganic amendments as immobilizing agents in reducing metal (bio)availability in the contaminated soil. The inorganic amendment reduced water and CaCl2-extractable concentrations of Cd, Pb, and Zn, while the organic amendment increased these concentrations compared to the untreated soil.

Influence of Ca and pH on the uptake and effects of Cd in Folsomia candida exposed to simplified soil solutions.

The present study sought to quantify the components of a biotic ligand model (BLM) for the effects of Cd on Folsomia candida (Collembola). Assuming that soil porewater is the main route of exposure and to exclude the effects of soil particles on metal availability, animals were exposed for 7 d to different Cd concentrations between 0.1 mM and 100 mM in simplified soil solutions at different Ca concentrations (0.

Sorption, dissolution and pH determine the long-term equilibration and toxicity of coated and uncoated ZnO nanoparticles in soil.

To assess the effect of long-term dissolution on bioavailability and toxicity, triethoxyoctylsilane coated and uncoated zinc oxide nanoparticles (ZnO-NP), non-nano ZnO and ZnCl2 were equilibrated in natural soil for up to twelve months. Zn concentrations in pore water increased with time for all ZnO forms but peaked at intermediate concentrations of ZnO-NP and non-nano ZnO, while for coated ZnO-NP such a clear peak only was seen after 12 months. Dose-related increases in soil pH may explain decreased soluble Zn levels due to fixation of Zn released from ZnO at higher soil concentrations.

Effect of different spiking procedures on the distribution and toxicity of ZnO nanoparticles in soil.

Due to the difficulty in dispersing some engineered nanomaterials in exposure media, realizing homogeneous distributions of nanoparticles (NP) in soil may pose major challenges. The present study investigated the distribution of zinc oxide (ZnO) NP (30 nm) and non-nano ZnO (200 nm) in natural soil using two different spiking procedures, i.e.

Effect of long-term equilibration on the toxicity of molybdenum to soil organisms.

To determine if long-term equilibration may alleviate molybdenum toxicity, earthworms, enchytraeids, collembolans and four plant species were exposed to three soils freshly spiked with Na(2)MoO(4).2H(2)O and equilibrated for 6 or 11 months in the field with free drainage. Total Mo concentrations in soil decreased by leaching, most (up to 98%) in sandy soil and less (54-62%) in silty and clayey soils.

Chronic toxicity of ZnO nanoparticles, non-nano ZnO and ZnCl2 to Folsomia candida (Collembola) in relation to bioavailability in soil.

The chronic toxicity of zinc oxide nanoparticles (ZnO-NP) to Folsomia candida was determined in natural soil. To unravel the contribution of particle size and free zinc to NP toxicity, non-nano ZnO and ZnCl(2) were also tested. Zinc concentrations in pore water increased with increasing soil concentrations, with Freundlich sorption constants K(f) of 61.

The bioaccumulation of Molybdenum in the earthworm Eisenia andrei: influence of soil properties and ageing.

Mo bioaccumulation in the earthworm Eisenia andrei was determined after 28 d exposure in ten different European field soils (pH 4.4-7.8) and an artificial soil, freshly spiked with Na₂MoO₄ at concentrations between 3.

The influence of soil properties on the toxicity of molybdenum to three species of soil invertebrates.

Mo toxicity to earthworms (Eisenia andrei), Collembola (Folsomia candida) and enchytraeids (Enchytraeus crypticus) was determined in 10 European soils and a standard artificial soil, freshly spiked with Na(2)MoO(4), after 28 days exposure. Mo affected survival only in three low pH sandy soils; in all other soils LC50 was >3200 mg Mo/kg dry soil. EC50 values for the reproduction toxicity of Mo were 129-2378 mg/kg for earthworms, 72->3396 mg/kg for Collembola, and 301->2820 mg/kg for enchytraeids.

Influence of soil properties on molybdenum uptake and elimination kinetics in the earthworm Eisenia andrei.

This study aimed at determining the uptake and elimination kinetics of molybdenum in the earthworm Eisenia andrei, and the influence of soil properties on molybdenum bioaccumulation. Three natural and four artificial soils were spiked at concentrations of 10 and 100 microg Mo g(-1) dry soil. Earthworms were exposed individually to spiked soils and sampled at different time intervals for 21 d.