PhD thesis defense by Rui You
The PhD student Rui You from the Environmental Pollution in Agriculture group (EPA), will defend his thesis next 22nd January 2021 at 11:00h. The thesis will be broadcasted livestream through Microsoft Teams on this link.
Title: The occurrence of contaminants in crops grown under organic soil amendments and peri-urban soils: phytotoxicity and human health implications
Director: Dr. Sergi Díez
Modern agriculture has been continually searching for effective methods to meet the exponentially increasing food demand. Amending soil with fertilizers has been widely adopted, as it could efficiently and fast supply nutrients to vegetables. Since 2015, the European Commission has proposed a circular economy plan which encourages the soil amendment with biosolids. Nevertheless, the presence of a wide range of contaminants, such as trace elements (TEs), organic pollutants, and emerging pollutants such as antibiotics (ABs) and antibiotic resistance genes (ARGs), has been widely reported in many organic fertilizers. Vegetables can absorb the contaminants from the amended soil, and further threaten human health. For this reason, risk assessment of organic fertilizer applications is necessary.
The most commonly used organic fertilizers are animal-based waste (manure), compost (plant sources or food waste), and urban waste (sewage sludge and household waste). Currently, no study evaluates the plant uptake of TEs and ABs under these three organic fertilizers, nor research evaluates the impact of repeated organic fertilization. Additionally, multiple application of sewage sludge might result in the accumulation of Zn and Cu in amended soil, and their presence would influence uptake of other contaminants.
Therefore, in this doctoral thesis, three aspects related to the contaminants in vegetable under different agriculture activities are addressed: (1) amending soils with different doses of different organic fertilizers, which aims to assess the impact of organic fertilizers on the occurrence of TEs and ABs in vegetables, (2) repeated amending soil with organic fertilizers and monitoring the variation of TEs concentrations in vegetables of different productive cycles, which aims to assess the impact of long-term organic fertilization, and (3) amending soils with sludge and different amounts of Zn and Cu, which aims to assess the effect of Zn and Cu on the accumulation of TEs, ABs, and ARGs in vegetables. Furthermore, in every case the risk to human health associated with the consumption of vegetables was evaluated.
In peri-urban area, the agricultural soil may receive the potential pollution from fertilizer, but also from potential contaminants due to urban activities. Those pollutants would influence the growth and development of vegetables. In this thesis, a simple and rapid method to assess soil pollution was also developed. Here, we use two plant growth indexes (seed germination rate and root elongation at the initial stage) for three vegetable seeds to assess soil chemical contamination on proximity agriculture.