Temporal trends of polycyclic aromatic hydrocarbons in soils amended with sludge, compost, and manure in a Scotland pasture: An 8-year field experiment.

ABSTRACT

To optimize the effective utilization of organic waste in agricultural practices, a comprehensive assessment of associated risks and benefits is crucial. This study investigated the impact of three types of organic wastes (sludge, compost, and manure) on polycyclic aromatic hydrocarbons (PAHs) in contaminated soil in a Scottish pasture. The experimental setup comprised 16 plots with four treatments (compost, manure, sludge, and inorganic fertilizer) and four replicates. After eight years of this study, notable disparities in ΣPAH16 concentrations were observed among the different treatments, with compost-amended soil at 378 µg kg-1, sludge-amended soil at 331 µg kg-1, and manure-amended soil at 223 µg kg-1. The concentrations of ΣPAH16 in soil amended with compost and sludge exhibited a linear increase with extended sampling time. Significant changes in ΣPAH16 concentration were evident in the compost treatment plot, with an increase of 20% in the first year and 82% in the eighth year. Risk assessment suggested a low level of health risk from exposure to PAHs at the measured concentrations in the three organic wastes. In conclusion, this study highlights the importance of considering the effects of organic waste amendments on soil PAH levels to make informed decisions in sustainable agricultural practices. It also underscores the need for ongoing research to fully understand the implications of different organic waste applications on soil health and environmental quality.