Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

Browse

Author: search.filters.author.Wang HSubject: search.filters.subject.05 Environmental Sciences

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Responses of rice (Oryza sativa L.) plant growth, grain yield and quality, and soil properties to the microplastic occurrence in paddy soil
    (Springer, 18/05/2022) Chen S; Feng Y; Han L; Li D; Feng Y; Jeyakumar P; Sun H; Shi W; Wang H
    Purpose: Agricultural soil has been recognized as a major sink of microplastic, an emerging pollutant to environmental biodiversity and ecosystem. However, the impacts of microplastic on soil–plant systems (e.g., crop growth, grain yield and amino acid content, nitrogen uptake capacity, and soil properties) remain largely unknown. Methods: Four typical microplastics, i.e., polythene (PE, 200 μm), polyacrylonitrile (PAN, 200 μm), and polyethylene terephthalate (PET) in diameter of 200 μm and 10 μm (PET200 and PET10), were tested to assess the consequent aforementioned responses under rice (Oryza sativa L.) paddy soil in a mesocosm experiment. Results: Microplastics multiply influenced the soil pH, NH4+-N and NO3−-N contents, which effects were depended on the rice growth stage and plastic type. Overall, microplastics significantly decreased the soil urease activity by 5.0–12.2% (P < 0.05). When exposed to PAN and PET (in both diameter of 200 μm and 10 μm), there were significantly 22.2–30.8% more grain yield produced, compared to the control (P < 0.05), which was attributing to the higher nitrogen uptake capacity of rice grain. Meanwhile, microplastics exhibited nominal influences on rice plant height, tillering number, leaf SPAD, and NDVI. The amino acids were affected by microplastic, depending on the types of plastics and amino acids. Conclusion: This study provides evidence that microplastic can affect the development and final grain yield, amino acid content, nitrogen uptake capacity of rice, and some major soil properties, while these effects vary as a function of plastic type. Our findings highlight the positive impacts that could occur when the presence of microplastics in paddy soil.
  • Thumbnail Image
    Item
    Enhanced removal of arsenic and cadmium from contaminated soils using a soluble humic substance coupled with chemical reductant.
    (1/03/2023) Wei J; Tu C; Xia F; Yang L; Chen Q; Chen Y; Deng S; Yuan G; Wang H; Jeyakumar P; Bhatnagar A
    Soil washing is an efficient, economical, and green remediation technology for removing several heavy metal (loid)s from contaminated industrial sites. The extraction of green and efficient washing agents from low-cost feedback is crucially important. In this study, a soluble humic substance (HS) extracted from leonardite was first tested to wash soils (red soil, fluvo-aquic soil, and black soil) heavily contaminated with arsenic (As) and cadmium (Cd). A D-optimal mixture design was investigated to optimize the washing parameters. The optimum removal efficiencies of As and Cd by single HS washing were found to be 52.58%-60.20% and 58.52%-86.69%, respectively. Furthermore, a two-step sequential washing with chemical reductant NH2OH•HCl coupled with HS (NH2OH•HCl + HS) was performed to improve the removal efficiency of As and Cd. The two-step sequential washing significantly enhanced the removal of As and Cd to 75.25%-81.53% and 64.53%-97.64%, which makes the residual As and Cd in soil below the risk control standards for construction land. The two-step sequential washing also effectively controlled the mobility and bioavailability of residual As and Cd. However, the activities of soil catalase and urease significantly decreased after the NH2OH•HCl + HS washing. Follow-up measures such as soil neutralization could be applied to relieve and restore the soil enzyme activity. In general, the two-step sequential soil washing with NH2OH•HCl + HS is a fast and efficient method for simultaneously removing high content of As and Cd from contaminated soils.