Effects of Copper Oxide Nanoparticles on Paddy Soil Properties and Components

Abstract

The wide use of metal-based nanoparticles (MNPs) will inevitably lead to their release into soil, and consequently affect the quality and ecological functions of soil environments. In this study, two paddy soils with different properties were exposed to CuO NPs to evaluate the transformation of CuO NPs and their effects on soil properties and components. The results of single chemical extraction and X-ray absorption fine structure analysis showed that CuO NPs could release Cu ions once being applied into the flooding paddy soil and then progress toward the more stable forms (Cu2S and Cu(OH)2). CuO NPs could change the soil properties by increasing the pH and Eh of the lower organic matter-soil rather than those of the higher organic matter-soil. Furthermore, we found that the 1000 mg/kg CuO NPs could accelerate the degradation or mineralization of the organic matter, as well as the Fe reduction process, by increasing the Fe(II) content by 293% after flooding for 60 days in the lower organic matter soil. The microbial biomass in both soils was severely inhibited by CuO NPs and the organic matter could partly mitigate the negative effects of CuO NPs.

Effect of Metal Oxide Nanoparticles on the Chemical Speciation of Heavy Metals and Micronutrient Bioavailability in Paddy Soil

“…As shown in Figure 1a, the addition of ZnO-NPs and CuO-NPs caused significant (p < 0.05) increases in the values of soil pH after the 90-d flooding-drying process. Shi et al (2018) found that CuO nanoparticles could significantly increase the soil pH values, which was consistent with our results [25]. Take CuO NPs as an example, after entering the soil, the following chemical reactions will occur:…”

“…CaCl 2 -extractable is considered "readily available" to plants, and DTPA-extractable is considered "potentially available" fraction. In this study, the bioavailability of the micronutrients in the soil was extracted with calcium chloride solution (CaCl 2 , 0.01 M) and (DTPA) [25]. Solutions was filtered with a Millipore filter (0.45 µm), and the concentrations of the elements in the solution were determined by inductively coupled plasma mass spectrometry (Agilent 7700x ICP-MS, Agilent Technologies, Santa Clara, CA, USA).…”

Influence of Zinc Oxide Nanoparticles on Soil Physicochemical Properties and Arachis hypogea Rhizosphere Microbial Community

“…ENPs can also indirectly affect soil properties through the effect on soil microbial activities. For instance, copper oxide nanoparticles increased iron (II) oxide (Fe 2+ ) in paddy soils exposed to CuO nanoparticles [8]. Increased Fe 2+ was attributed to the nanoparticles exerting a stimulatory effect on iron reducing bacterial community in the soil.…”

“…The effect on soil properties can vary, for example, the soil pH is influenced by the accumulation of different types of nanoparticles [6]. Several studies [7,8,9,10] have reported increased pH of soils on exposure to different nanoparticles. Soil pH determines the function of a soil and is closely related to presence of, and absorption of nutrients, microbial activity and plant growth [8].…”

“…Several studies [7,8,9,10] have reported increased pH of soils on exposure to different nanoparticles. Soil pH determines the function of a soil and is closely related to presence of, and absorption of nutrients, microbial activity and plant growth [8]. The ability of the soil to maintain the presence of positively charged ions (cation exchange capacity) is an important soil property that reflects on the structure, nutrient utilization and pH of soil [11].…”