Looking into the effects of co-contamination by micro(nano)plastics in the presence of other pollutants on irrigated edible plants.

To address water shortage challenges, treated wastewater is used to meet the demand for irrigation water in several countries worldwide. Considering the presence of pollutants in treated wastewater, its use for land irrigation might have an impact in the environment. This review article focuses on the combined effects (or potential joint toxicity) of microplastics (MPs)/nanoplastics (NPs) and other environmental contaminants present in treated wastewater on edible plants after irrigation. Initially, the concentrations of MPs/NPs in wastewater treatment plant effluents and surface waters are summarized, indicating the presence of MPs/NPs in both water matrices (i.e., wastewater after receiving treatment and lakes/rivers). Then, the results of 19 studies related to joint toxicity of MPs/NPs and co-contaminants (e.g., heavy metals and pharmaceuticals) on edible plants, are reviewed and discussed. This concurrent presence may result in several combined effects on edible plants, e.g., rapid root growth, increase in antioxidant enzymes, decrease in photosynthetic rate and increased production of ROS. These effects, as discussed in the various studies on which this review is based, can generate antagonistic or even neutral impact on plants, depending on the size of MPs/NPs and their mixing ratio with the co-contaminants. However, a combined exposure of edible plants to MPs/NPs and co-contaminants can also lead to hormetic adaptive responses. The data reviewed and discussed herein may relieve overlooked environmental impacts of treated wastewater reuse and may be useful to address challenges related to the combined effects of MPs/NPs and co-contaminants on edible plants after irrigation. The conclusions drawn in this review article are relevant to both direct (i.e., treated wastewater irrigation) and indirect (i.e., discharging treated wastewater in surface waters used for irrigation purposes) reuse, and may contribute to the implementation of the European Regulation 2020/741 on the minimum requirements for water reuse.

Investigation of the effect of microplastics on the UV inactivation of antibiotic-resistant bacteria in water.

This study investigated the effect of polyethylene and polyvinyl chloride microplastics on the UV fluence response curve for the inactivation of multidrug-resistant E. coli and enterococci in ultrapure water at pH 6.0 ± 0.1. In the absence of microplastics, the UV inactivation of the studied bacteria exhibited an initial resistance followed by a faster inactivation of free (dispersed) bacteria, while in the presence of microplastics, these 2 regimes were followed by an additional regime of slower or no inactivation related to microplastic-associated bacteria (i.e., bacteria aggregated with microplastics resulting in shielding bacteria from UV indicated by tailing at higher UV fluences). The magnitude of the negative effect of microplastics varied with different microplastics (type/particle size) and bacteria (Gram-negative and Gram-positive). Results showed that when the UV transmittance of the microplastic-containing water was not taken into account in calculating UV fluences, the effect of microplastics as protectors of bacteria was overestimated. A UV fluence-based double-exponential microbial inactivation model accounting for both free and microplastic-associated bacteria could describe well the disinfection data. The present study elucidated the effect of microplastics on the performance of UV disinfection, and the approach used herein to prove this concept may guide future research on the investigation of the possible effect of other particles including nanoplastics with different characteristics on the exposure response curve for the inactivation of various microorganisms by physical and chemical disinfection processes in different water and wastewater matrices.

New Evidence on the Distribution of the Highly Endangered Natrix natrix cypriaca and Implications for Its Conservation.

The critically endangered Cyprus grass snake (Natrix natrix cypriaca) has been studied for the past 25 years. Although the need for a complete survey on the distribution of its population, outside the strict boundaries of the known mountainous localities, had been stressed, such an effort has not been conducted to date. In this study, we used a rapid survey approach to investigate possible sightings of the species upstream of the known distribution in the Troodos Mountains. We are presenting evidence from 13 sightings of the species that expand the previously known distribution in Cyprus by nearly 70%. This is the first time that new localities for the critically endangered N. n. cypriaca have been reported since the rediscovery of the species in 1992 and the extensive work that followed. Almost all new localities were discovered outside of the currently known species distribution, while individuals were found, for the first time, within the Natura 2000 site of Dasos Machaira (CY2000004) with indications of healthy populations in the area. New localities were recorded within watersheds of the Pediaios and Gialias Rivers, the first sightings outside of Serrachis watershed, indicating an even broader distribution of the species in the Troodos region. The importance of sparse springs within systems of ephemeral streams is highlighted as an exceptional niche for the population in the region. We are discussing the importance of our findings for the conservation of the species and propose targeted conservation actions that will highly improve connectivity of the populations in the region. We underline the necessity of expanding the research on this critically endangered subspecies, based on current findings, so as to fully comprehend its ecology and distribution range in the region.