Simultaneous aggregation and retention of nanoparticles can occur during their transport in porous media. In this work, the concurrent aggregation and transport of GO in saturated porous media were investigated under the conditions of different combinations of temperature, cation type (valence), and electrolyte concentration. Increasing temperature (6–24 °C) at a relatively high electrolyte concentration (i.e., 50 mM for Na⁺, 1 mM for Ca²⁺, 1.75 mM for Mg²⁺, and 0.03 and 0.05 mM for Al³⁺) resulted in enhanced GO retention in the porous media. For instance, when the temperature increased from 6 to 24 °C, GO recovery rate decreased from 31.08% to 6.53% for 0.03 mM Al³⁺ and from 27.11% to 0 for 0.05 mM Al³⁺. At the same temperature, increasing cation valence and electrolyte concentration also promoted GO retention. Although GO aggregation occurred in the electrolytes during the transport, the deposition mechanisms of GO retention in the media depended on cation type (valence). For 50 mM Na⁺, surface deposition via secondary minima was the dominant GO retention mechanism. For multivalent cation electrolytes, GO aggregation was rapid and thus other mechanisms such as physical straining and sedimentation also played important roles in controlling GO retention in the media. After passing through the columns, the GO particles in the effluents showed better stability with lower initial aggregation rates. This was probably because less stable GO particles with lower surface charge densities in the porewater were filtered by the porous media, resulting in more stable GO particle with higher surface charge densities in the effluents. An advection–dispersion-reaction model was applied to simulate GO breakthrough curves and the simulations matched all the experimental data well.

Cadmium (Cd) uptake and accumulation in crop plants, especially in wheat (Triticum aestivum) and rice (Oryza sativa) is one of the main concerns for food security worldwide. A field experiment was done to investigate the effects of limestone, lignite, and biochar on growth, physiology and Cd uptake in wheat and rice under rotation irrigated with raw effluents. Initially, each treatment was applied alone at 0.1% and combined at 0.05% each and wheat was grown in the field and then, after wheat harvesting, rice was grown in the same field without additional application of amendments. Results showed that the amendments applied increased the grain and straw yields as well as gas exchange attributes compared to the control. In both crops, highest Cd concentrations in straw and grains and total uptake were observed in control treatments while lowest Cd concentrations was observed in limestone + biochar treatment. No Cd concentrations were detected in wheat grains with the application of amendments except limestone (0.1%). The lowest Cd harvest index was observed in limestone + biochar and lignite + biochar treatments for wheat and rice respectively. Application of amendments decreased the AB-DTPA extractable Cd in the soil while increasing the Cd immobilization index after each crop harvest. The benefit-cost ratio and Cd contents in plants revealed that limestone + biochar treatment might be an effective amendment for increasing plant growth with lower Cd concentrations.

A main challenge in ecological risk assessment is to account for the impact of multiple stressors. Nuclear facilities can release both radiological and chemical stressors in the environment. This study is the first to apply species sensitivity distribution (SSD) combined with mixture models (concentration addition (CA) and independent action (IA)) to derive an integrated proxy of the ecological impact of combined radiological and chemical stressors: msPAF (multisubstance potentially affected fraction of species). The approach was tested on the routine liquid effluents from nuclear power plants that contain both radioactive and stable chemicals. The SSD of ionising radiation was significantly flatter than the SSD of 8 stable chemicals (namely Cr, Cu, Ni, Pb, Zn, B, chlorides and sulphates). This difference in shape had strong implications for the selection of the appropriate mixture model: contrarily to the general expectations the IA model gave more conservative (higher msPAF) results than the CA model. The msPAF approach was further used to rank the relative potential impact of radiological versus chemical stressors.

Seasonal variations in the concentrations of eight ultraviolet (UV) filters and 22 illicit drugs including their metabolites in the Korean aquatic environment were investigated. Seawater samples from three beaches, water samples from two rivers, and influents and effluents from three wastewater treatment plants were analyzed. The UV filter concentrations in the seawater, river water, and effluent samples were 39.4–296, 35.4–117, and 6.84–51.1 ng L-1, respectively. The total UV filter concentrations in the seawater samples were 1.9–4.4 times higher at the peak of the holiday season than outside the peak holiday season. An environmental risk assessment showed that ethylhexyl methoxy cinnamate (EHMC) could cause adverse effects on aquatic organisms in the seawater at the three beaches during the holiday period. Seven of the 22 target illicit drugs including their metabolites were detected in the wastewater influent samples, and the total illicit drug concentrations in the influent samples were 0.08–65.4 ng L-1. The estimated daily consumption rates for cis-tramadol (Cis-TRM), methamphetamine (MTP), meperidine (MEP), and codeine (COD) were 25.7–118.4, 13.8–36.1, 1.36–12.6, and 1.75–8.64 mg d-1 (1000 people)−1, respectively. In popular vacation area, the illicit drug consumption rates (Cis-TRM, MTP and MEP) were 1.6–2.6 times higher at the peak of the summer holiday season than at the beginning of the summer.

Discharge of antimicrobial residues and resistant bacteria in hospital effluents is supposed to have strong impacts on the spread of antibiotic resistant bacteria in the environment. This study aimed to characterize the effluents of the Gabriel Montpied teaching hospital, Clermont-Ferrand, France, by simultaneously measuring the concentration of ciprofloxacin and of biological indicators resistant to this molecule in biofilms formed in the hospital effluent and by comparing these data to ciprofloxacin consumption and resistant bacterial isolates of the hospital. Determination of the measured environmental concentration of ciprofloxacin by spot sampling and polar organic chemical integrative (POCIS) sampling over 2 weeks, and comparison with predicted environmental concentrations produced a hazard quotient >1, indicating a potential ecotoxicological risk. A negative impact was also observed with whole hospital effluent samples using the Tetrahymena pyriformis biological model.During the same period, biofilms were formed within the hospital effluent, and analysis of ciprofloxacin-resistant isolates indicated that Gamma-Proteobacteria were numerous, predominantly Aeromonadaceae (69.56%) and Enterobacteriaceae (22.61%). Among the 115 isolates collected, plasmid-mediated fluoroquinolone-resistant genes were detected, with mostly aac(6′)-lb-cr and qnrS. In addition, 60% of the isolates were resistant to up to six antibiotics, including molecules mostly used in the hospital (aminosides and third-generation cephalosporins).In parallel, 1247 bacteria isolated from hospitalized patients and resistant to at least one of the fluoroquinolones were collected. Only 5 of the 14 species identified in the effluent biofilm were also found in the clinical isolates, but PFGE typing of the Gram-negative isolates found in both compartments showed there was no clonality among the strains.Altogether, these data confirm the role of hospital loads as sources of pollution for wastewater and question the role of environmental biofilms communities as efficient shelters for hospital-released resistance genes.

This study evaluated the occurrence of 36 PPCPs in urban river water samples collected from Beijing, Changzhou and Shenzhen. Twenty-eight compounds were detected. Compounds found with highest median concentrations included: sulfadimethoxine (164 ng/L), sulpiride (77.3 ng/L), atenolol (52.9 ng/L), and indomethacin (50.9 ng/L). Antibiotic was the predominant class detected and contributed about half of the overall PPCPs contamination level. Effluents from wastewater treatment plants (WWTPs) were demonstrated to be the predominant pathways through which PPCPs entering into aquatic environment in all investigated areas. The ratio of persistent PPCPs like sulpiride and carbamazepine was identified to be feasible in tracing their contamination sources in rivers. Concentrations of most detected PPCPs showed significant positive correlations with total nitrogen and total phosphorus. Two groups of representative PPCPs were selected as the chemical indicators for predicting the overall PPCPs contamination, based on the significant correlations between PPCPs.

Complex toxicant mixtures present in estuarine sediments often render contaminant screening unfeasible and compromise determining causation. HepG2 cells were subjected to bioassays with sediment extracts obtained with a series of progressively polar solvents plus a crude extract. The sediments were collected from an impacted area of an estuary otherwise regarded as pristine, whose stressors result mostly from aquaculture effluents and hydrodynamic shifts that enhance particle deposition. Compared to a reference scenario, the most polar extracts yielded highest cytotoxicity while higher genotoxicity (including oxidative damage) was elicited by non-polar solvents. While the former caused effects similar to those expected from biocides, the latter triggered effects compatible with known pro-mutagens like PAHs, even though the overall levels of toxicants were considered of low risk. The results indicate that the approach may constitute an effective line-of-evidence to infer on the predominant set of hazardous contaminants present in complex environmental mixtures.

The long-term ecological risk of micropollutants, especially endocrine disrupting chemicals (EDCs) has threatened reclaimed water quality. In this study, estrogenic activity and ecological risk of eight typical estrogenic EDCs in effluents from sewage plants were evaluated. The estrogenic activity analysis showed that steroidal estrogens had the highest estrogenic activity (ranged from 10−1 to 103 ng-E2/L), phenolic compounds showed weaker estrogenic activity (mainly ranged from 10−3 to 10 ng-E2/L), and phthalate esters were negligible. The ecological risk of the estrogenic EDCs which was characterized by risk quotient ranged from 10−4 to 103, with an order in descending: steroids estrogens, phenolic compounds and phthalate esters. The eight estrogenic EDCs were scored and sorted based on the comparison of the estrogenic activity and the ecological risk, suggesting that 17α-ethynylestradiol (EE2), estrone (E1) and estradiol (E2) should be the priority EDCs to control in municipal sewage plants.

The discharge of wastewater from sewage treatment plants is one of the most common forms of pollution to river ecosystems, yet the effects on aquatic invertebrate assemblages have not been investigated in a controlled experimental setting. Here, we use a mesocosm approach to evaluate community responses to exposure to different concentrations of treated wastewater effluents over a two week period. Multivariate analysis using Principal Response Curves indicated a clear, dose-effect response to the treatments, with significant changes in macroinvertebrate assemblages after one week when exposed to 30% effluent, and after two weeks in the 15% and 30% effluent treatments. Treatments were associated with an increase in nutrient concentrations (ammonium, sulfate, and phosphate) and reduction of dissolved oxygen. These findings indicate that exposure to wastewater effluent cause significant changes in abundance and composition of macroinvertebrate taxa and that effluent concentration as low as 5% can have detectable ecological effects.

Thallium is a highly toxic metal whose environmental concentrations, distributions and behaviour are not well understood. In the present study we measure the concentrations of Tl in filtered and unfiltered samples of rain, tap, river, estuarine and waste waters collected from south west England. Dissolved Tl was lowest (<20 ng L⁻¹) in tap water, rain water, treated sewage and landfill effluents, estuarine waters, and rivers draining catchments of sandstones and shales. Concentrations up to about 450 ng L⁻¹ were observed in rivers whose catchments are partly mineralized and where metal mining was historically important, and the highest concentration (∼1400 ng L⁻¹) was measured in water abstracted directly from an abandoned mine. Compared with other trace metals measured (e.g. As, Cd, Co, Cr, Cu, Ni, Pb, Zn), Tl has a low affinity for suspended particles and undergoes little removal by conventional (hydroxide precipitation) treatment of mine water.