Occurrence of regulated pollutants in populated Mediterranean basins: Ecotoxicological risk and effects on biological quality

Advancing ecotoxicity assessment: Leveraging pre-trained model for bee toxicity and compound degradability prediction

The prediction of ecological toxicity plays an increasingly important role in modern society. However, the existing models often suffer from poor performance and limited predictive capabilities. In this study, we propose a novel approach for ecological toxicity assessment based on pre-trained models. By leveraging pre-training techniques and graph neural network models, we establish a highperformance predictive model. Furthermore, we incorporate a variational autoencoder to optimize the model, enabling simultaneous discrimination of toxicity to bees and molecular degradability. Additionally, despite the low similarity between the endogenous hormones in bees and the compounds in our dataset, our model confidently predicts that these hormones are non-toxic to bees, which further strengthens the credibility and accuracy of our model. We also discovered the negative correlation between the degradation and bee toxicity of compounds. In summary, this study presents an ecological toxicity assessment model with outstanding performance. The proposed model accurately predicts the toxicity of chemicals to bees and their degradability capabilities, offering valuable technical support to relevant fields.

Proposal for priority emerging pollutants in the Nakdong river, Korea: Application of EU watch list mechanisms

The Nakdong River, the longest in Korea, has received numerous pollutants from heavily industrialized and densely populated areas while being used as a drinking water source. A number of research have reported occurrences of emerging pollutants (EPs) in the river. The results requested efficient monitoring and systematic management strategies such as EU watch list under Water Framework Directive. The aim of this study is to propose a watch list through preliminary monitoring of the river and risk-based prioritization approach. As candidates for monitoring target, 632 substances were selected based on literature and database searches. Among them, 175 substances were subjected to target screening method whereas 457 were evaluated via suspect screening. A risk-based prioritization was applied to substances quantified through target screening based on concentrations, and a scoring-based prioritization was applied to substances tentatively identified through suspect screening. Sampling campaigns (n = 12) were conducted from October 2020 to September 2021, at 8 sampling sites along the river. As a result, 130 target substances were quantified above the LOQ. Among the 21 substances whose priority score was assigned through risk-based prioritization, telmisartan and iprobenfos were identified with very high environmental risk while candesartan, TBEP, imidacloprid, azithromycin and clotrimazole were classified with high or intermediate risk. As result of the scoring system for 39 tentatively identified substances, 6 substances (benzophenone, caprolactam, metolachlor oxanilic acid, heptaethylene glycol, octaethylene glycol and pentaethylene glycol), which were then confirmed with reference standards, showed a potential environmental risk. Those substances prioritized through target and suspect screening followed by scoring systems can be a subset for the watch list and potential targets for nationwide water quality monitoring program in the future.

Identification of point and nonpoint emission sources of neonicotinoid pollution in regional surface water

Neonicotinoid insecticides are widely applied in farmland, with high detection rates in soils and surface waters, posing potential risks to biodiversity and human health. As a nonpoint emission, surface runoff is widely regarded as the major source of neonicotinoid pollution in surface waters, but few studies have determined the point source contribution to rivers that may be primarily from wastewater treatment plants (WWTPs). Here, we collected the surface water from eight river basins in Zhejiang Province of China and quantified residual concentrations of eight widely commercialized neonicotinoids. Four of these were detected in all samples, with concentrations of dinotefuran and nitenpyram of 119 ± 166 and 87.6 ± 25.3 ng/L, respectively, representing more than 90 % of the total (282 ± 174 ng/L). Neonicotinoid residues were higher in tributaries due to nearby farmland and more dilution effects in the mainstream, and the residues were higher in lower reaches which can be explained by the water flow direction. Significant spatial differences in neonicotinoid distribution between surface water and agricultural soils result from environmental factors (e.g., water turbidity, precipitation, temperature) impacting migration and transport processes. Neonicotinoid residues in surface water showed a significant positive correlation with total WWTP emissions after adjusting for environmental factors. Conversely, no significant association was observed with cropland density (a nonpoint emission source), indicating that point emission source (contributing 20.6 %) predominantly influenced neonicotinoid residue spatial variation in river basin-scale surface water.

Risk ranking of macrolide antibiotics - Release levels, resistance formation potential and ecological risk

Antibiotic resistance (AR) development in natural water bodies is a significant source of concern. Macrolide antibiotics in particular have been identified as pollutants of concern for AR development throughout the literature, as well as by state and international authorities. This study utilises a probabilistic model to examine the risk of AR development arising from human-use macrolide residues, utilising administration rates from Ireland as a case study. Stages modelled included level of administration, excretion, degradation in wastewater, removal in wastewater treatment, assuming conventional activated sludge (CAS) treatment, and dilution. Release estimates per day, as well as risk quotient values for antibiotic resistance development and ecological impact, are generated for erythromycin, clarithromycin, and azithromycin. In the modelled scenario in which conventional activated sludge treatment is utilised in wastewater treatment, this model ranks risk of resistance development for each antibiotic in the order clarithromycin > azithromycin > erythromycin, with mean risk quotient values of 0.50, 0.34 and 0.12, respectively. A membrane bioreactor scenario was also modelled, which reduced risk quotient values for all three macrolides by at least 50 %. Risk of ecological impact for each antibiotic was also examined, by comparing environmental concentrations predicted to safety limits based on toxicity data for cyanobacteria and other organisms from the literature, with azithromycin being identified as the macrolide of highest risk. This study compares and quantifies the risk of resistance development and ecological impact for a high-risk antibiotic group in the Irish context, and demonstrates the potential for risk reduction achieved by adoption of alternative (e.g. membrane bioreactor) technology.

Environmental risk assessment of neonicotinoids in surface water

Neonicotinoids (NNIs) are active substances used as insecticides mainly in plant protection products (PPPs) but also in veterinary applications. The increasing evidence of affecting non-targeted organisms led the European Commission to severely restrict or even ban outdoor uses. To evaluate their current use and their influence in the ecological status of freshwater ecosystem, a total of 19 river water samples were collected to determine the presence of 5 NNIs (acetamiprid, clothianidin, imidacloprid, thiamethoxam and thiacloprid) in the Tagus basin. At least one target analyte was quantified by HPLC-MS/MS analysis in 17 of the 19 water samples, with ∑NNIs ranging from <MDL to 16.8 ng/L. Imidacloprid (2.75 ng/L; mean) and acetamiprid (0.47 ng/L) were quantified in most of the samples. Source identification evidences imidacloprid agricultural use. Risk assessment for different trophic levels was conducted with the data obtained calculating Risk Characterization Ratios (RCR) by two approaches, predicted non effect concentrations (PEC/PNEC) and Toxic Units (TU). RCRs were derived for each NNI and for the mixture of all (RCRmix). Results showed risk for imidacloprid in freshwater organism (RCRfw>1) and for the mix of NNIs (RCRmix (PEC/PNEC) > 1). RCRmix(PEC/PNEC) and the sum of toxic units (STU) showed a risky situation for some locations with different organisms related to agriculture practices. This data arouses concern about NNis (legal or forbidden) use in Tagus basin, and manifest the need of monitoring their presence and effect on the aquatic ecosystem.

Aquatic concentration and risk assessment of pharmaceutically active compounds in the environment

Pharmaceutically active compounds are increasingly detected in raw and treated wastewater, surface water, and drinking water worldwide. These compounds can cause adverse effects to the ecosystem even at low concentrations and, to assess these impacts, toxicity tests are essential. However, the toxicity data are scarce for many PhACs, and when available, they are dispersed in the literature. The values of pharmaceuticals concentration in the environment and toxicity data are essential for measuring their environmental and human health risks. Thus this review verified the concentrations of pharmaceuticals in the aquatic environment and the toxicity related to them. The risk assessment was also carried out. Diclofenac, naproxen, erythromycin, roxithromycin, and 17β-estradiol presented a high environment risk and 17α-ethinylestradiol presented a high human health risk. This shows the potential of these pharmaceuticals to cause adverse effects to the ecosystem and humans and establishes the necessity of their removal through advanced technologies.

Occurrence and risk assessment of pesticides in a Mediterranean Basin with strong agricultural pressure (Guadiana Basin: Southern of Portugal)

The study aimed to assess the occurrence and the environmental risk of a group of 51 selected pesticides in the Guadiana Basin (a biodiversity hotspot, in the Mediterranean). The most abundant pesticides were bentazone and 2,4-D, while terbuthylazine together with terbutryn constituted the most ubiquitous pesticides. Eighteen out of the 38 pesticides detected are no longer approved in Europe, and 5 of them are included in the list of priority substances. The risk assessment showed that azinphos ethyl, diflufenican, irganol, imidacloprid, and oxadiazon occurred occasionally, but always in concentrations above their respective ecotoxicological threshold value. Contrary, bentazone, terbuthylazine, and terbutryn presented a high risk in most of the sampled locations and periods. The site-specific risk assessment showed a spatial and temporal pattern, with a higher risk occurring mainly in intermittent streams, in the drought period. The presence of pesticides banned from the EU market since 2009 showed the importance of improving the monitoring process, to identify the main sources of pollution and the fate of these emerging compounds. The results showed the need of implementing actions to improve the sustainable use of pesticides in agricultural areas, working with farmers and management entities to reduce the contamination of aquatic ecosystems. Transboundary water governance is also required to solve potential transboundary contamination problems.