69 research outputs found
Ecotoxicological assessment of ZnO nanoparticles to Folsomia candida
Straalen, N.M. van [Promotor]Gestel, C.A.M. van [Copromotor
Effect of soil organic matter content and pH on the toxicity of ZnO nanoparticles to Folsomia candida
Effect of soil organic matter content and pH on the toxicity of ZnO nanoparticles to Folsomia candida
Organic matter (OM) and pH may influence nanoparticle fate and effects in soil. This study investigated the influence of soil organic matter content and pH on the toxicity of ZnO–NP and ZnCl2 to Folsomia candida in four natural soils, having between 2.37% and 14.7% OM and pHCaCl2pHCaCl2 levels between 5.0 and 6.8. Porewater Zn concentrations were much lower in ZnO–NP than in ZnCl2 spiked soils, resulting in higher Freundlich sorption constants for ZnO–NP. For ZnCl2 the porewater Zn concentrations were significantly higher in less organic soils, while for ZnO–NP the highest soluble Zn level (23 mg Zn/l) was measured in the most organic soil, which had the lowest pH. Free Zn2+ ion concentrations were higher for ZnCl2 than for ZnO–NP and were greatly dependent on pH (pHpw) and dissolved organic carbon content of the pore water. The 28-d EC50 values for the effect of ZnCl2 on the reproduction of F. candida increased with increasing OM content from 356 to 1592 mg Zn/kg d.w. For ZnO–NP no correlation between EC50 values and OM content was found and EC50 values ranged from 1695 in the most organic soil to 4446 mg Zn/kg d.w. in the higher pH soil. When based on porewater and free Zn2+ concentrations, EC50 values were higher for ZnCl2 than for ZnO–NP, and consistently decreased with increasing pHpw. This study shows that ZnO–NP toxicity is dependent on soil properties, but is mainly driven by soil pH
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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. We studied the effects of nanoparticulate, non-nanoparticulate and ionic zinc (in the form of zinc chloride) on the composition of bacterial communities in soil with a modified pH range (from pH 4.5 to pH 7.2). We observed strong pH dependent effects on the interaction between bacterial communities and all forms of zinc, with the largest changes in bacterial community composition occurring in soils with low and medium pH levels (pH 4.8 and 5.9). The high pH soil (pH 7.2) was less susceptible to the effects of zinc exposure. At the highest doses of zinc (2500 mg/kg dw soil) both nano and non-nano particulate zinc applications elicited a similar response in the soil bacterial community, and this differed significantly to the ionic zinc salt treatment. The results highlight the importance of considering soil pH in nanotoxicology studies, although further work is needed to determine the exact mechanisms controlling the toxicity and fate and interactions of nanoparticles with soil microbial communities
Characterisation of exposure and effects of silver nanoparticles to the earthworm Lumbricus rubellus
Uptake routes and toxicokinetics of silver nanoparticles and silver ions in the earthworm Lumbricus rubellus
Nanoparticles within WWTP sludges have minimal impact on leachate quality and soil microbial community structure and function
One of the main pathways by which engineered nanoparticles (ENPs) enter the environment is through land application of waste water treatment plant (WWTP) sewage sludges. WWTP sludges, enriched with Ag and ZnO ENPs or their corresponding soluble metal salts during anaerobic digestion and subsequently mixed with soil (targeting a final concentration of 1400 and 140 mg/kg for Zn and Ag, respectively), were subjected to 6 months of ageing and leaching in lysimeter columns outdoors. Amounts of Zn and Ag leached were very low, accounting for <0.3% and <1.4% of the total Zn and Ag, respectively. No differences in total leaching rates were observed between treatments of Zn or Ag originally input to WWTP as ENP or salt forms. Phospholipid fatty acid profiling indicated a reduction in the fungal component of the soil microbial community upon metal exposure. However, overall, the leachate composition and response of the soil microbial community following addition of sewage sludge enriched either with ENPs or metal salts was very similar
Effect of different spiking procedures on the distribution and toxicity of ZnO nanoparticles in soil
Tools and rules for modelling uptake and bioaccumulation of nanomaterials in invertebrate organisms
Quantification of the uptake and elimination of nanomaterials (NMs) by organisms is key in assessing the environmental risks of NMs.</p
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. as dry powder and as suspension in soil
extract. Both spiking procedures showed a good recovery
([85 %) of zinc and based on total zinc concentrations no
difference was found between the two spiking methods.
Both spiking procedures resulted in a fairly homogeneous
distribution of the ZnO particles in soil, as evidenced
by the low variation in total zinc concentration between
replicate samples (\12 % in most cases). Survival of
Folsomia candida in soil spiked at concentrations up to
6,400 mg Zn kg-1 d.w. was not affected for both compounds.
Reproduction was reduced in a concentrationdependent
manner with EC50 values of 3,159 and
2,914 mg Zn kg-1 d.w. for 30 and 200 nm ZnO spiked as
dry powder and 3,593 and 5,633 mg Zn kg-1 d.w. introduced
as suspension. Toxicity of ZnO at 30 and 200 nm did
not differ. We conclude that the ZnO particle toxicity is not
size related and that the spiking of the soil with ZnO as dry
powder or as a suspension in soil extract does not affect its
toxicity to F. candid
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