Q2. What is the effect of Cu on plants?
In general, exposure to Cu compounds resulted in alteration of metabolite profiles, inducing anti-oxidant response, potential defense mechanisms (e.g. down-regulation of citric acid in root exudate tominimize Cu dissolution, up-regulation of chelators and other metabolites that serve to protect the plants), reduced photosynthetic rates and increased transpiration rates in some species.
Q3. What is the way to minimize exposure to Cu NPs?
Given that inhalation of Cu NPs may result in pulmonary inflammation and a strong immune system response, even at low concentrations, occupational exposure to paints and pesticides containing Cu NPs must be minimized by using appropriate personal protective equipment, particularly when handling dry powders of Cu NPs (e.g. during formulation) or aerosolized pesticide formulations.
Q4. What is the rate of dissolution of Cu NPs in water?
Surface water renewal and immobilization of NPs on a substrate can lead to accelerated dissolution, even for these relatively insoluble NPs.
Q5. What is the effect of Cu NPs on plants?
The slow release of Cu from Cu NPs in paints and pesticides serves to minimize short-term impacts, but the increasing accumulation of Cu in sediments and soils may eventually reach and surpass the lowest observable effect concentrations.
Q6. What are the main processes that initiate the aggregation of Cu in the environment?
Homoand hetero-aggregation, coating with natural organic matter, sedimentation, dissolution, oxidation in oxic environments, reduction or sulfidation in anoxic waters all initiate from the moment the dry ENM powder is placed in an aqueous medium.
Q7. What is the effect of nCu(OH)2 on the lettuce roots?
ascorbate peroxidase activity in lettuce roots increased in all treatments except μCuO, and it also increased in alfalfa roots in all treatments except the two nCu(OH)2 nanopesticides.
Q8. What is the common way to accumulate Cu NPs in soil?
Agricultural soils receiving WWTP biosolids would accumulate Cu (dissolved and Cu NPs hetero-aggregated with soil particles) at concentrations ranging from 1 to 10 μg/kg above the background Cu concentrations (Garner et al., 2017).
Q9. How do the authors know the concentration of Cu NPs in the water column?
Assuming a continuous input of Cu NPs, and the dissolution and transformation of the NPs once released, the concentrations of dissolved Cu2+ in the freshwater would increase by< 0.1 μg/L relative to background, and the concentrations of small aggregates of Cu NPs in the water column would be< 1 ng/L (Garner et al., 2017).
Q10. How many NPs are released in a day?
A recent study showed that the release from paints is ~3 to 27 μg/cm2·day, or in other terms, around 0.2 to 1.8% of the Cu NPs present in the paint were released in 180 days (Adeleye et al., 2016).
Q11. What is the common use of Cu NPs in the environment?
Although Cu NPs can enter the environment via several applications, at present the majority of the releases are attributed to their use in marine antifouling paints (Adeleye et al., 2016) (which includes freshwater uses) and agriculture (Gardea-Torresdey et al., 2014), since there is a direct application of the product containing the nanomaterial to the receiving environmental medium.
Q12. What is the likely source of Cu NPs?
While it is likely that Cu is internalized as Cu2+ or in organic complexes, in some cases Cu NPs are ingested or taken up from soil into the organisms, where they likely dissolve.
Q13. How did the nCuO effect the plant biomass?
In addition, μCuO at 20 mg/kg reduced the relative chlorophyll content, and at 80 mg/kg significantly (p < 0.05) plant biomass (Zuverza-Mena et al., 2015).
Q14. What was the median lethal concentration in sediment?
For a coastal marine benthic amphipod, Leptocheirus plumulosus, exposed for 10 days to nCuO the median lethal concentration in sediment (LC50) was 868 ± 89 μg Cu/g dry weight (DW) (Hanna et al., 2013).
Q15. What is the common type of Cu NPs in the environment?
Most of the Cu (dissolved and Cu NPs heteroaggregated with sediment particles) would be accumulated in the sediment beds of freshwater and marine environments.
Q16. What is the effect of Cu NPs on the environment?
Future studies should address questions regarding the effect of Cu NP coatings, the nature of the released Cu species from paints and coatings, and the potential accumulation of Cu and Cu NPs in agricultural applications where application rates will likely be continuous and at higher concentrations than other releases.