Zinc Oxide Nanoparticles Alleviated the Bioavailability of Cadmium and Lead and Changed the Uptake of Iron in Hydroponically Grown Lettuce (Lactuca sativa L. var. Longifolia)

Abstract

Leafy vegetables are a rich source of iron and fibers for the human diet, which may become hazardous if exposed to heavy metal contamination. Cadmium (Cd) and lead (Pb) are two highly toxic metals even at trace concentrations. Engineered nanoparticles (ENPs) can alter the uptake of heavy metals and localization of essential minerals such as iron (Fe) through different mechanisms. The goal of this study was to understand the mutual effects of zinc oxide nanoparticles (ZnONPs) and coexisting heavy metals Pb 2+ and Cd 2+ on their uptake and accumulation as well as their effects on Fe concentrations in romaine lettuce (Lactuca sativa L. var. Longifolia) in a hydroponic system. At termination, shoots were gently separated from the roots, and the concentrations of Pb, Cd, Fe, and Zn in all plant tissues were quantified by inductively coupled plasma-mass spectrometry (ICP-MS). In addition, microbial density analysis in the growth media was performed for each treatment. The results indicated active interactions between ZnONPs and coexisting divalent heavy metals. ZnONPs significantly reduced the accumulation of Cd and Pb in roots by 49% and 81%, respectively. In shoots, Cd was reduced by 30%, and Pb elevated by 44%. Fe concentration in shoots was strongly affected by ZnONPs, and the total Zn in shoots was negatively correspond with the microbial population in the growth media. Exposure to ZnONPs alone increased the total Fe in shoots by 80% compared to controls, and the copresence of ZnONPs and heavy metals increased Fe concentration by about 77%. The results revealed the role of ENPs in governing the uptake and translocation of some essential elements and toxic heavy metals in plants.

Graphitic Carbon Nitride (C3N4) Reduces Cadmium and Arsenic Phytotoxicity and Accumulation in Rice (Oryza sativa L.)

“…Metal-based NPs have also been shown to decrease the bioavailability of heavy metals to crop species. Sharifan et al (2019) demonstrated that ZnO NPs’ exposure reduced the Cd contents in lettuce roots and shoots by 49% and 30%, respectively [ 59 ]. Similarly, both bulk- and nano-sized TiO 2 NPs reduced the Pb accumulation in rice [ 60 ].…”

Zinc Oxide Nanoparticles Alleviate Chilling Stress in Rice (Oryza Sativa L.) by Regulating Antioxidative System and Chilling Response Transcription Factors

“…Also, ZnO NPs alleviated cadmium (Cd) toxicity in wheat by enhancing wheat growth and Zn concentrations, while reducing the Cd concentration in plants [ 27 ]. ZnO NPs alleviated the bioavailability of cadmium and lead and changed the uptake of iron in hydroponically grown lettuce ( Lactuca sativa L.) [ 31 ]. However, no related research has reported the effects of ZnO NPs on rice seedlings under chilling stress.…”

Bioaccumulation and phytotoxicity of ZnO nanoparticles in soil-grown Brassica chinensis and potential risks

“…Soil is considered as a major sink of ZnO NPs compared to atmospheric and aqueous ecosystems (Liu et al 2020, Rajput et al 2018. In recent years, ZnO NPs have been employed as a novel macronutrient nanofertilizer in the Zn de cient soil (Song &Kim 2020, Sun et al 2020, Yuse -Tanha et al 2020, as an antibacterial agent for plant protection (Singh et al 2018), as well as an effective agent for reducing metal uptake by plants (Rizwan et al 2019, Sharifan et al 2019a. ZnO NPs may enter the soil medium by direct (agricultural products) or indirect (biosolids) pathways, and then can be absorbed and accumulated by plants, causing an effect on plant growth (Zeb et al 2021).…”