# Detection of polycyclic aromatic hydrocarbons, microplastic presence and characterization of microbial communities in the soil of touristic zones at Alqueva’s edges (Alentejo, Portugal)

## TL;DR

This study analyzed soil pollution and microbial communities near tourist areas at Alqueva's edges in Portugal, finding low levels of pollutants and potential plastic-degrading bacteria.

## Contribution

The study provides new insights into the presence of pollutants and plastic-degrading bacteria in soils near a water reservoir in a touristic region.

## Key findings

- Low concentrations of polycyclic aromatic hydrocarbons (PAHs) were detected, but potentially carcinogenic PAHs were present.
- Microplastics including polyamide, polyester, and polystyrene were identified in the soil samples.
- Bacterial genera like Bacillus and Pseudomonas, known for plastic degradation, were found in the soil microbiome.

## Abstract

Environmental pollution is a growing concern. Here, we assessed the occurrence of two groups of persistent organic pollutants (POPs—polycyclic aromatic hydrocarbons (PAHs) and microplastics (MPs)) and bacterial populations in the topsoil of three tourist spots located at the Alqueva’s edges during 1 year, once per season. Soil chemical analysis revealed low content of total organic carbon, pH close to neutrality, and nitrogen and phosphorus levels consistent with acquisition of these nutrients only by atmospheric deposition. PAH’s concentrations were in the range of ng/kg, being significantly below the “reference values” for contaminated soils. Nevertheless, potentially carcinogenic PAHs, detected at all locations, raise ecotoxicological concerns. Polyamide, polyester, polystyrene, and styrene acrylonitrile resin MPs were found. Six bacterial phyla constitute the core microbiome in the three locations and include genera of bacteria reported as plastic degraders, such as Bacillus, Exiguobacterium, Paenibacillus, and Pseudomonas. The presence of POPs, even at low levels, in the soil at the edges of a water reservoir should be monitored. The identification of bacteria reported as plastic degraders in the soil, and previously in the water, is promising, and their ability to spontaneously ensure the detoxification of the ecosystem should be further investigated.

The online version contains supplementary material available at 10.1007/s11356-026-37415-6.