soil has decreased the nanoparticle toxicity. The ecotoxicology of ZnO‐NPs on soil microbes was illustrated [65] based on parameters such as ammonification, breathing, dehydrogenase, and fluorescent diacetate hydrolase activity. In acidic and neutral soils, the adverse effects of ZnO‐NPs on microcosmic soil microbes have been found to have a more significant impact.
Alkaline soil, on the other hand, was very damaging. The toxicity of TiO2 NPs was also determined mainly to be influenced by soil and organic matter pH [66]. This substantially reduced carbon in high pH and organic soils. These findings show that nanoparticles show acute toxicity to soil microbial substances in the soil environment to define important soil parameters such as form, organic soil matter, and soil humidity. Significantly, intimate description of the possible effect of different soil properties on the toxicity of the nanomaterials helps to reduce the fuel toxicity of nanoparticles produced throughout the soil environment.
Nanoparticles' plant phytotoxicity is yet another concern because of the leaves, and root system plants' complete surface area has enough opportunity to interact with nanoparticles. Moreover, because their minuscule size can translocate effectively inside the host plant, the risk of nanoparticles becoming toxic is higher in plants. Nanoparticles in the plant body are assumed to enter by surface adsorption or pass through small plant openings [67, 68]. NPs depend on their size and concentration primarily on plant toxicity. Furthermore, thanks to plants' easy absorption and their subsequent translocation within the system, small nanoparticles can cause phytotoxic toxicity at even lower levels [56]. Most commonly used metal nanoparticles, i.e. AgNPs, are thought to play a crucial role in their phytotoxic behaviour, the scale of nanoparticles [69].
Asli and Neumann [70] also noted TiO2 NPs' mechanical treatment concentration mode for hydraulic leakage and Z transpiratory rate. The hydroponic solution is cultivated in mays. In contrast, Yang et al. [71] noticed the stimulating impact of TiO2‐NPs (2.5 g/l) application on fresh and dry weight of Spinacia oleracea and also elevated response was seen in case of chlorophyll, protein and total nitrogen content in leaves. Also in cultivations of cultivated media with a low concentration of 0.5 g/l supplements of TiO2‐NPs, Song et al. [72] have documented a positive effect on duckweed (Lemna minor); the also increased a concentration caused significant crop harm.
Table 2.1 Nanomaterials and their impacts on plants and soil microbiota.
| Soil characteristics | Nanoparticles | Impacts | References |
|---|---|---|---|
| Soil type | |||
| Silt and clay soil | Titanium oxide | Substantially limited mineralization of carbon | [66] |
| Loam sandy | Titanium oxide | Affects soil microbiota | [66] |
| Zinc oxide | No Cucumis sativus toxicity with soil pH 5.5 at a concentration of 2000 mg/kg | [57] | |
| Cupric oxide, zinc oxide | The toxic effect on Triticum aestivum | [82] | |
| Silver | Reduced microbial biomass | [83] | |
| Silver | Significantly lower soil enzymatic activities and respiration caused by the substrate | [84] | |
| Cerium oxide, tin oxide, zinc oxide | Microbial biomass C and N no effect | [85] | |
| Titanium oxide | Reduced bacterial diversity | [86] | |
| Titanium oxide | Reduced bacterial taxa | [61] | |
| Amine‐modified polystyrene nanospheres and TiO2 nanoparticles | Decreases in rhizosphere bacterial counts and plant root and stem growth | [87] | |
| Sulfate‐modified polystyrene nanospheres | Increased rhizosphere bacterial counts | [87] | |
| Clay and loamy | Zinc oxide | Toxic impact on Triticum aestivum | [58] |
| pH | |||
| Acidic | Silver, zinc oxide | Increased toxicity to Eisenia fetida | [65] |
| Alkaline | Titanium oxide | The decrease in the microbial population in soil | [66] |
| Silver | Declined toxicity | [88] | |
| Organic part | |||
| High | Silver | Toxicity reduction for biofilm‐forming populations | [89] |
| Titanium oxide | Effect on C mineralization | [66] | |
| Zinc oxide | Significant effect of adding alginate at a concentration of 400–800 mg/kg/kg on Zea mays | [59] | |
| Low | Cupric oxide, zinc oxide | Improved toxicity to microbes | [64] |
| Cation exchange capacity | |||
| High | Silver | Decreased toxic impact on Pseudomonas chlororaphis | [90] |
| Zinc oxide | No effect on Lepidium sativum | [81] | |
| Low | Silver | Improved toxicity to soil microbes | [90] |
ZnO‐NPs are by far the most widely used material oxide nitrogen NPs, and elevated Vigna radiata and Cicer arietinum have been documented to increase growth, comparatively, in the vegetal agar media [73]. The similar dose‐based effect responses had been observed for Cu‐NPs, where wheat (Triticum aestivum) and mung bean (Phaseolus radiatus) have significantly inhibited growth [74–78]. The critical route that plants are predominantly exposed to the released nanoparticles is the soil. It should be noted that many investigators have also begun to take this approach into account by avoiding the hydroponic system, which offers more appropriate toxicity data and straightforward understanding. Zhu et al. [79] also interpreted the soil system's nanofilling potential