Phytotoxicity and accumulation of zinc oxide nanoparticles on the aquatic plants Hydrilla verticillata and Phragmites Australis: leaf-type-dependent responses

Abstract

The phytotoxicity and accumulation of zinc oxide nanoparticles (ZnO NPs) on aquatic plant Hydrilla verticillata and Phragmites australis were investigated using mesocosms. The percentage of dissolved Zn in the ZnO NP treatment solutions was measured along with plant shoot growth, antioxidant enzyme activity, chlorophyll content, and Zn content. The dissolution rate of ZnO NPs in Hoagland solution was inversely related to the concentration. The submerged aquatic plant H. verticillata, growth was reduced during the early stages of the experiment when exposed to the highest ZnO NP concentration (1000 mg/L), whereas the emerged aquatic plant P. australis began to show significantly reduced growth after a few weeks. The measurements of chlorophyll content, antioxidant enzyme activity, and Zn accumulation showed that P. australis was adversely affected by NPs and absorbed more Zn than H. verticillata. The results indicated that physiological differences among aquatic plants, such as whether they use leaves or roots for nutrient and water uptake, led to differences in nanoparticle toxicity. Overall, High ZnO NP concentrations caused significant phytotoxicity on aquatic plants, and low concentrations caused unpredictable phytotoxicity. Therefore, the use and disposal of zinc oxide nanoparticles should be carefully monitored.

Stable Zn isotopes reveal the uptake and toxicity of zinc oxide engineered nanomaterials inPhragmites australis

“…Biomass allocation, nutrient uptake and distribution, and fractionation of C isotopes were also altered by ZnO-ENMs ( Supplementary Tables 8-9). Similar effects have been previously described in aquatic macrophytes treated with toxic levels of ZnO-ENMs [4][5][6]8,10,51,52 , Zn 2+ (reviewed by 20 ), and other metals [53][54][55][56] . In our previous research on P. australis, exposure to 2 mM ZnCl 2 (131 mg l -1 Zn in solution) for 40 days caused a height reduction of 25% 44 .…”

“…In our previous research on P. australis, exposure to 2 mM ZnCl 2 (131 mg l -1 Zn in solution) for 40 days caused a height reduction of 25% 44 . Song and coworkers 4 reported a ~50% reduction in height after exposure to 100 mg l -1 ZnO NP50 (only 4.5 mg l -1 Zn in solution) for 35 days 4 . Even though [Zn 2+ ] was lower in the latter study, the effects were more severe and attributed to direct root contact with ZnO-NPs.…”

“…This may cause chronic toxicity in emergent wetland plants (helophytes), which play vital ecological roles 3 . Exposure to ZnO-ENMs decreases photosynthesis, antioxidant activity, and growth in aquatic plants, and increases Zn bioaccumulation and oxidative stress [4][5][6][7][8][9][10] . However, studies on helophytes are few and the uptake and toxicity of ZnO-ENMs, especially after chronic exposure, are poorly characterised in these plants.…”

Single and Repeated Applications of Cerium Oxide Nanoparticles Differently Affect the Growth and Biomass Accumulation of Silene flos-cuculi L. (Caryophyllaceae)

“…While this is justified concerning the potential risks of human exposure to nanomaterials through food consumption, in a broader ecological context, the impacts of ENMs on the whole primary producers should not be underrated in a broader ecological context. From this perspective, more aquatic [ 19 , 20 , 21 ] and wetland species [ 22 , 23 , 24 ] have been studied than terrestrial varieties. Concerning terrestrial ecosystems, to the best of our knowledge, Pinus sylvestris L. and Quercus robur L. are the only non-food terrestrial plant species to have been investigated for the exposure to ENMs [ 25 ].…”

Nanoparticle silver coexposure reduces the accumulation of weathered persistent pesticides by earthworms

“…Similarly, nanomaterials have also been shown to enhance plant growth indirectly, largely through particle size–specific modes of disease/pathogen suppression . As with all things in toxicology, the dose of the exposure is critical; the literature is populated with studies demonstrating overt phytotoxicity (physiological, molecular) after exposure to engineered nanomaterials . In fact, several recent thorough reviews are available on plant–nanomaterial interactions, and the majority of the published literature seems to focus on negative effects in plants exposed to these materials .…”