Nonlinear sorption and isotherm nonlinearity of organic compounds by widely used porous resins such as XAD-7 are commonly interpreted as adsorption due to their large surface area. However, through displacement experiments using saturated 4-nitrophenol as the displacer, we observed that the nonlinear sorption and isotherm nonlinearity of selected organic compounds (i.e., naphthalene, nitrobenzenes, phenols and anilines) by XAD-7 was captured by a nonlinear partition mechanism rather than the adsorption mechanism. Nonlinear sorption of organic compounds by XAD-7 includes a nonlinear/displaced fraction and a linear/non-displaced fraction. A dual-mode (DM) model, including a nonlinear Dubinin-Ashtakhov (DA) model component and a linear model component, was developed to describe the nonlinear/displaced fraction and the linear/non-displaced fraction, respectively. The capacity of these two fractions are dependent on their solubility in water or octanol with positively linear relationships but not their molecular size, supporting the nonlinear partitioning mechanism. Besides van-der-waals force, hydrogen-bonding is primarily responsible for the nonlinear partitioning of phenols and anilines into XAD-7, while π-π interaction is responsible for the nonlinear partitioning of naphthalene and nitrobenzenes. The explored nonlinear partitioning mechanism for XAD-7 implies that the nonlinear sorption of organic compounds by porous resins should be recognized for their recovery and applications as sorbents.

Although macrophytes are known to play vital roles in aquatic ecosystems, most quantitative aquatic toxicity data focus on fishes, water fleas, or algae, with limited ecotoxicity data published on macrophytes. Salvinia natans is a fast-growing plant commonly found in freshwater habitats. In this study, we verified a suitable disinfectant for preventing foreign contamination and formulated a culture medium for ensuring high productivity of S. natans. Finally, we established methodology for S. natans to be used in ecotoxicity testing of heavy metals and pesticides. As global regulations are being developed to harmonize guidelines and laboratory test species, S. natans is emerging as a potential candidate. The toxicity data publicly available for S. natans are very limited; hence, this study reports an advantageous culturing technique to optimize healthy growth of this species in the laboratory and presents optimal toxicity results, achieved by modifying the currently available test guidelines for Lemna. Our findings expand the currently limited range of test species for aquatic toxicity assays. We conclude that S. natans could serve as a valuable test species for aquatic toxicity assays.

The molecular mechanism of evaluating 17β-estradiol (E₂)-induced toxicity in female Daphnia magna has not been determined. In this study, the transcriptome of D. magna was analyzed after exposure to three different concentrations (0, 10, and 100 ng L⁻¹) of E₂ at 3, 6, and 12 h. The results showed 351–17,221 significantly up-regulated and 505–10,282 significantly down-regulated genes (P < 0.05). Overall, the selected largest 10,282 (10 ng L⁻¹vs control at 12 h) down-regulated and 17,221 (100 vs 10 ng L⁻¹) up-regulated genes were identified; following annotation, pathways in cancer and RNA transport were found to be enriched according to the interaction network. Among all completed comparisons, KEGG pathways related to the immune system, cancer, disease infection, and active compound metabolism were identified by short time series expression miner analysis. A different set of genes fluctuated in a “U”-shaped pattern over time and at different concentrations of E₂, whereas some genes associated with disintoxication showed a reverse “U”-shaped response as E₂ administration was increased. These results suggest that E₂ exposure caused transcriptional changes in the immune system, disintoxication, disease prevention, and the protein degradation pathway.

This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F⁻) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N₂ gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F⁻ removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F⁻ removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F⁻ removal are 900 °C and 650 °C, respectively.

Plasticizers are marketed in high volumes and Di(2-ethylhexyl) phthalate (DEHP) is frequently detected in the environment and human populations. Industry had largely relied on DEHP until regulation started to restrict its marketing in 1999 due to environmental and human health concerns. The aim of this study was to obtain spatial-temporal trends for DEHP and its substitutes in German rivers. We have investigated suspended particulate matter (SPM) samples from the German Environmental Specimen Bank (ESB) for the presence of 23 plasticizers, i.e. 17 phthalates and 6 non-phthalates. The samples were collected in the last 10 years at 13 sites in large river basins in Germany such as the Rhine, Elbe and Danube. A decrease in DEHP concentrations was observed at all sampling sites between the mid-2000s and 2017. The maximum concentration for DEHP was determined in 2006 in samples from Rehlingen/Saar (6720 ng/g dry weight (dw)). By 2017, the DEHP concentration in Rehlingen had dropped to 2080 ng/g dw. Currently, Diisononyl phthalate (DINP) is the plasticizer with the highest levels in the SPM samples (maximum value 4150 ng/g dw in Rehlingen/Saar). Our results show that novel plasticizers such as Diisononylcyclohexane-1,2-dicarboxylate (DINCH) spread rapidly in surface waters after their market introduction. We have found several plasticizers of emerging concern in the environmental samples, the further use of which is currently under review under the EU chemicals regulation (REACH, registration, evaluation, authorisation and restriction of chemicals). In particular for Di(2-propylheptyl) phthalate (DPHP) a significant increase in concentration was observed at almost all sites between the mid-2000s and 2017, for example in Prossen/Elbe from 24 ng/g dw (2005) to 1380 ng/g dw (2017).

Soil pollution is growing at an alarming rate in today’s industrialized world as a result of increasing anthropogenic activities, either intentional (e.g., use of fertilizers and pesticides, irrigation with untreated wastewater, or land application of sewage sludge) or accidental (e.g., oil spills or leaching from landfills). Terrestrial soil pollution from transportation fuels such as Diesel or Biodiesel is inevitable as they are part of life’s necessities. Biodiesel is considered an environmental friendly fuel due to its non-hydrocarbon composition and low particulate matter emission. However, there are still some controversies regarding biodiesel environmental toxicity to terrestrial life. Little is known about the ecotoxicity of plant-based biodiesels to soil organisms. In the present study, three ecotoxicological tests including an earthworm (Eisenia fetida) 14-day soil toxicity test, a filter paper contact toxicity test, and a cocoon hatchability test were performed to examine the toxic effects of three plant-based biodiesels - safflower methyl ester (SaME), castor methyl ester (CME), and castor ethyl ester (CEE), with Diesel fuel. Unlike Diesel, the biodiesels were less toxic based on low earthworm mortality in the soil toxicity test. However significant morbidity responses (e.g., weight loss, coiling, posterior and anterior fragmentation, and excessive discharge of coelomic fluid) were observed in earthworms exposed to biodiesel. Further, in the cocoon hatchability test, biodiesels were equally toxic to Diesel at 2% and 5% soil concentrations, with no hatching success.

In this study, we determined the concentrations of Cu, Zn, Ni, Cd, Pb and As and their subcellular distributions within the tissues of mussels (Bathymodiolus marisindicus) and snails (Gigantopelta aegis) from two hydrothermal vent regions, i.e., Tiancheng and Longqi, at Southwest Indian Ridge. Mussels collected from the two venting regions showed comparable concentrations for Ni and Pb, but Cu, Zn, Cd and As concentrations were significantly different in mussel gills between the two vent regions. Similar ranges of metal concentrations were found in the snails as those in the mussels, but most of the metals were mainly accumulated in the viscera, except for Ni. Similar subcellular partitioning of Cu, Zn and Cd was documented in different mussel tissues, with cellular debris (50%) being the predominant fraction, followed by equivalent values in other fractions. Lead was distributed in both cellular debris and metal-rich granules (MRG) fraction, whereas Ni was predominantly distributed in MRG (90%). Arsenic was mainly partitioned in cellular debris and metallothionein-like protein. However, deep-sea snails displayed elevated subcellular partitioning of Cu in the organelles (up to 60%) and may be more susceptible to Cu stress than the mussels. Our results demonstrated the metal-specificity of detoxification strategies in these deep-sea hydrothermal vent mollusks, and the mussels may be more adaptable to high metal exposures than the snails at hydrothermal vent.

As a strong reductant and highly active alkali, hydrazine (N2H4) has been widely used in chemical industry, pharmaceutical manufacturing and agricultural production. However, its high acute toxicity poses a threat to ecosystem and human health. In the present study, a ratiometric fluorescent probe for the detection of N2H4 was designed, utilizing dicyanoisophorone as the fluorescent group and 4-bromobutyryl moiety as the recognition site. 4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-enyl) phenyl 4-brobutanoate (DDPB) was readily synthesized and could specially sense N2H4 via an intramolecular charge transfer (ICT) pathway. The cyclization cleavage reaction of N2H4 with a 4-bromobutyryl group released phenolic hydroxyl group and reversed the ICT process between hydroxy group and fluorophore, turning on the fluorescence in the DDPB-N2H4 complexes. DDPB exhibits a low cytotoxicity, reasonable cell permeability, a large Stokes shift (186 nm) and a low detection limit (86.3 nM). The quantitative determination of environmental water systems and the visualization fluorescence of DDPB test strips provides a strong evidence for the applications of DDPB. In addition, DDPB is suitable for the fluorescence imaging of exogenous N2H4 in HeLa cells and zebrafish.

Rivers can receive the input of treated or untreated sewage effluents from wastewater treatment plants, urban and industrial discharges and agricultural run-off, becoming an important pathway for the transport and mobilization of pollutants to the oceans. In the present study, the occurrence of 20 PFAAs was determined in the water of Tagus River basin (Spain). PFAAs were detected in 76 out of 92 water samples collected during 5 years (2013–2018), being perfluorooctanesulfonic acid (PFOS) the predominant compound (<0.01–34 ng/L). The annual average PFOS concentrations (2.9–11 ng/L) detected in Tagus River were above the annual average environmental quality standards (AA-EQS) established in the Directive, 2013/39/EU (0.65 ng/L for inland surface waters) but below the maximum allowable concentration (MAC-EQS; 36000 ng/L). The levels of PFAAs detected in urban and industrial areas were statistically higher (p < 0.01) than those at background or remote areas. The mass flow rates amounted to <0.01–46 kg/y for PFOS and <0.01–22 kg/y for perfluorooctanoic acid (PFOA). A quantitative ecotoxicological risk assessment was conducted to evaluate the environmental potential risk related to PFAAs in the aquatic ecosystem. Risk characterization ratios (RCRwater, RCRsed and RCRoral, fish) were below 1 in all cases.

Microorganisms are useful biological indicators of toxicity and play a key role in the functioning of healthy soils. In this study, we investigated the residual toxicity of hydrocarbons in aged contaminated soils and determined the extent of microbial community recovery during in-situ bioremediation at subantarctic Macquarie Island. Previously identified microbial indicators of hydrocarbon toxicity were used to understand interactions between hydrocarbon concentrations, soil physicochemical parameters and the microbial community. Despite the complexity of the field sites, which included active fuel storage areas with high levels of soil heterogeneity, multiple spill events and variable fuel sources, we observed consistent microbial community traits associated with exposure to high concentrations of hydrocarbons. These included; reductions in alpha diversity, inhibition of nitrification potential and a reduction in the ratio of oligotrophic to copiotrophic species. These observed responses and the sensitivity of microbial communities in the field, were comparable to sensitivity estimates obtained in a previous lab-based mesocosm study with hydrocarbon spiked soils. This study provides a valuable and often missing link between the quite disparate conditions of controlled lab-based spiking experiments and the complexity presented by ‘real-world’ contaminated field sites.