Global deterioration of water, air, and soil quality by the release of toxic chemicals from anthropogenic pollutants is becoming a serious global problem. The extensive use of copper oxide nanoparticles (CuO NPs) can be environmentally hazardous when these NPs enter the atmosphere. The present study aimed to evaluate the role of CuO NPs on plant growth, photosynthetic capacity, and bioactive compounds, as well as their transcriptional level changes in Brassica rapa seedlings. Chlorophyll, carotenoid, and sugar content decreased, while proline and anthocyanins were significantly enhanced in the CuO NP-treated seedlings compared with the untreated controls. Reactive oxygen species (ROS), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) production were also enhanced in the seedlings exposed to CuO NPs, which could have caused DNA damage that was detected by a DNA laddering assay. The glucosinolate (GSL) and phenolic compound content were significantly increased in CuO NP-treated seedlings compared with that in control seedlings. Transcriptional variation of genes associated with oxidative stress (CAT, POD, and GST), R2R3-type MYB involved in GSL (BrMYB28, BrMYB29, BrMYB34, and BrMYB51), and phenolic compounds (ANS, PAP1, PAL, and FLS) biosynthesis was analyzed using real-time polymerase chain reaction. Significant upregulation of CAT, POD, GST, BrMYB28, BrMYB29, BrMYB34, BrMYB51, ANS, PAP1, PAL, and FLS genes was observed in seedlings exposed to different concentrations of CuO NPs relative to the untreated seedlings. Therefore, we suggest that the use of CuO NPs could stimulate the toxic effects and enhance phytochemicals (i.e., glucosinolates and phenolic compounds) in B. rapa.

The reduced natural water sources on the one hand and the large amount of wastewater produced by the textile industry on the other hand lead to the requirement of an effective reuse of textile wastewater. In this study, the treatment of textile wastewater by the reverse osmosis membrane system and membrane capacitive deionization (MCDI) system has been investigated to improve the quality and the recovery rate of the effluent for reclamation. The maximum chemical oxygen demand (COD) removal efficiency obtained at 10 bar was 96.3% for BW30 reverse osmosis membrane. Diversified operating conditions, including working voltage and flow rate, were investigated systematically in the MCDI system which is an effective water purification technology. According to the obtained experimental results, the COD removal efficiency was thoroughly increased by rising the working voltage (from 0.2 to 1.2 V) and the flow rate (from 5 to 17.5 ml/min). The flow rate and the working voltage at which the COD from textile wastewater removal ratio was the highest were 10 ml/min and 1.2 V, respectively. A life cycle approach has also been implemented for the comparison of environmental impact assessment of the two desalination systems. In this study, a life cycle approach has been implemented for the comparison of environmental friendly impact assessment of the two desalination systems. It is concluded that MCDI system is much more environmental friendlier with 5641 times less values for damage assessment categories, on average.

Endocrine disrupter, like bisphenol A (BPA) and bisphenol S (BPS), is frequently detected in the subsurface environment, imposing threats to the groundwater quality and public health. However, current understanding of environmental fate and transport of BPA/BPS is still not clear, especially with respect to those in the subsurface media with trapped non-aqueous phase liquids (NAPLs). In this study, the effect of residual NAPLs on the retention and transport of BPA/BPS in the saturated sand and soil media was investigated using column experiments. The results showed that residual NAPLs (i.e., xylene and perchloroethylene (PCE)) inhibited the transport of BPA in the sand columns, and the inhibit effect of xylene was greater than that of PCE. While the presence of NAPLs showed little influence on the transport of BPS in the sand columns, in soil A (sandy soil), the residual NAPLs had similar effect on the retention and transport of BPA and BPS. Both BPA and BPS showed higher retention in the soil B columns than in the sand and soil A columns due to soil B’s higher organic matter contents, which can strongly sorb BPA/BPS. The presence of residual NAPLs reduced the retention of BPA/BPS in the soil B columns because the NAPLs blocked the sorption sites of the soil organic matter for BPA/BPS. This study demonstrates the importance of residual NAPLs, types of media, properties of contaminants, and their interactions to the fate and transport of BPA/BPS in saturated porous media.

The aim of this study was to investigate the effect of autochthonous microorganisms present in soil collected from heavy metal (HM) uncontaminated (Pb ≈ 59 mg kg⁻¹, Cd ≈ 0.4 mg kg⁻¹, Zn ≈ 191 mg kg⁻¹), moderately (Pb ≈ 343 mg kg⁻¹, Cd ≈ 12 mg kg⁻¹, Zn ≈ 1876 mg kg⁻¹), and highly (Pb ≈ 1586 mg kg⁻¹, Cd ≈ 57 mg kg⁻¹, Zn ≈ 3280 mg kg⁻¹) contaminated sites on Zea mays elemental composition, physiological status, and growth parameters. For this purpose, half of the collected soil was sterilized and soil characterization was performed. After 45 days of cultivation, the presence of HM in the soil negatively affected photosynthesis and transpiration rates, relative chlorophyll content, anthocyanins index, chlorophyll fluorescence parameters, and content of oxidative stress products (H₂O₂ and Malondialdehyde) of Zea mays, while soil sterilization had a positive effect on those parameters. Average percentage of colonization of root segments by arbuscular mycorrhiza fungi decreased with an increase of HM contamination in the soil. The increase in shoot concentration of HMs, particularly Cd and Zn, was a result of contaminated soils sterilization. Aboveground biomass of maize cultivated on sterilized soil was 3-fold, 1.5-fold, and 1.5-fold higher for uncontaminated, moderately contaminated and highly contaminated soils respectively when compared to nonsterilized soils. Contrary to our expectation, autochthonous microflora did not improve plant growth and photosynthetic performance; in fact, they had a negative effect on those processes although they did reduce concentration of HMs in the shoots grown on contaminated soils.

Aquatic organisms might be exposed episodically or continuously to chemicals for long-term periods throughout their life span. Pesticides are one example of widely used chemicals and thus represent a potential hazard to aquatic organisms. In addition, these chemicals may be present simultaneously in the environment or as pulses, being difficult to predict accurately how their joint effects will take place. Therefore, the aim of the present study was to investigate how Daphnia magna (clone k6) exposed throughout generations to a model pesticide (the fungicide carbendazim) would react upon an exposure to another chemical compound (triclosan) and to a mixture of both chemicals (carbendazim and triclosan). Responses of daphnids continuously exposed to carbendazim and kept in clean medium will be compared using immobilization tests and the comet assay (DNA integrity). The results showed that triclosan presented similar toxicity to daphnids exposed for 12 generations (F12) to carbendazim (similar 48-h-LC₅₀ values for immobilization data), when compared with daphnids kept in clean medium. However, at subcellular level, daphnids previously exposed to carbendazim for 12 generations (F12) showed different responses than those from clean medium, presenting a higher toxicity; a general higher percentage of DNA damage was observed, after exposure to a range of concentrations of triclosan and to the binary combination of triclosan + carbendazim. The patterns of toxicity observed for the binary mixture triclosan + carbendazim were generally similar for daphnids in clean medium and daphnids exposed to carbendazim, with a dose level deviation with antagonism observed at low doses of the chemical mixture for the immobilization data and a dose ratio deviation with synergism mainly caused by triclosan for DNA damage. With this study, we contributed to the knowledge on long-term induced effects of carbendazim exposure, while looking at the organismal sensitivity to another chemical (triclosan) and to a mixture of carbendazim and triclosan using lethality as an endpoint at the individual level and DNA damage as a subcellular endpoint.

Due to the dramatically increasing production of excess sludge during biological wastewater treatment, the development of an economical, efficient, and environmentally friendly sludge dewatering method is highly required. Herein, Bdellovibrio-and-like organisms (BALOs), a group of predatory bacteria were applied for waste sludge dewaterability enhancement and biomass reduction and the potential biolysis mechanisms were elaborated. Generally, the satisfying biolysis performance was obtained for the sludge with the moderate total solid (TS) content (1.5–2.5%). Within 24-h sludge biolysis with our isolated and enriched BALOs, the sludge specific resistance to filtration value as the dewaterbility index reached the maximal reduction rate of 65.3 ± 6.4%. Meanwhile, the concentrations of released soluble nitrogen and phosphorous significantly increased by 57.4 ± 3.3 and 56.7 ± 6.1%, respectively. Moreover, the contents of tightly bound extracellular polymeric substances (EPS) dramatically decreased after sludge biolysis while the loosely bound EPS contents increased, which implied the disruptions of sludge flocs structure for sludge dewaterability improvement. High-throughput sequencing results revealed the remarkable shift of sludge’s microbial community structure after biolysis treatment. The relative abundances of the dominant genera Ferruginibacter, Pseudomonas, and Thermomonas related to denitrification or flocs structure stabilization dramatically decreased. The noticeable increasing populations of Comamonas and Hyphomicrobium in abundances suggested the potential re-growth of the surviving microbial cells in response to BALO invasions. Overall, BALO predation could disintegrate the waste sludge structure, promote the cell lysis and the intracellular substances release, and cause the variations of microbial community compositions to efficiently improve the sludge dewaterability.

The use of engineered nanomaterials (ENMs) increases concerns relating to their fate, behavior, and toxicity due to their increased exposure to the environment. These ENMs end up in wastewater treatment plants (WWTPs), and the bacteria in these systems are sensitive to compounds such as heavy metals, which reduces the functionality of the WWTP. In this work, the fate and behavior of Bi₂O₃-BiVO₄ in a WWTP using the OECD 303A guideline was studied. The Bi₂O₃-BiVO₄ NPs were synthesized through a hydrothermal and impregnation method. X-ray diffraction showed monoclinic phases of both Bi₂O₃ and BiVO₄ NPs. The effect of Bi₂O₃-BiVO₄ NPs was monitored using chemical oxygen demand (COD) and 5-day biological oxygen demand (BOD₅). The COD and BOD₅ for the sludge retention time where the NPs were added was > 70%. This showed that the NPs had no effect on the functionality of the treatment processes as it was further affirmed by the TPC measurements. Inductively coupled plasma–optical emission spectroscopy (ICP-OES) showed that the fate of the NPs was through the activated sludge than the effluent, whereby 90% of Bi and V were absorbed in the activated sludge and 10% in the effluent. The results indicate that the NPs have the potential to permeate through the environment segments through the wastewater sludge compared to the effluent. XRD analysis of the test sludge showed that the crystal phases of the heterojunction remained unchanged, and this could ascertain that the treatment conditions did not transform the NPs into toxic forms.

Cadmium (Cd) phytoextraction efficiency basically depends on Cd accumulation in their tissues. Thus, our aim in this study was to select biochemical, morpho-physiological, nutritional, and productive responses associated to Cd accumulation in the roots, stems and sheaths, and leaf blades of Panicum maximum cv. Massai (Massai grass), using the random forests analysis. Massai grass was exposed to combinations of three sulfur (S) concentrations (0.1, 1.9, and 3.7 mmol L⁻¹) and two Cd concentrations (0.0 and 0.1 mmol L⁻¹) in nutrient solutions. The dry biomass production of Massai grass exposed to Cd decreased by around 50% in relation to control. However, there were no visual symptoms of Cd toxicity in the shoot of this plant, even with Cd concentrations in their shoot exceeding 100 mg kg⁻¹ DW. The lowest dry biomass production of the plants exposed to Cd combined with the absence of visual symptoms of Cd toxicity indicates us that Massai grass is a bioindicator plant that can greatly cope with the Cd-induced stress, but in a little bit different way from other plants. Antioxidant enzymes apparently are not essential for Massai grass cope with Cd-induced stress, differently of other mechanisms (e.g., higher synthesis of thiol compounds and amino acids involved on reactive oxygen species (ROS) scavenging and Cd chelation). Probably, the plant responses that most explained Cd accumulation in Massai grass can be used to identify grasses with high capacity to accumulate Cd in phytoremediation programs with this group of plants.

The present study aims to assess the impact of a gold mine located in the southeastern part of Burkina Faso on local soil quality. This information is needed in order to determine any health hazards and potential remediation strategies as the mining site is expected to be turned over to the local community after the closure of the mine. For the purpose, total minor and trace elements analysis as well as a sequential extraction were performed and results were interpreted using different methodologies: enrichment factor (EF), geoaccumulation index (Igeo) computed using two separate background samples, and comparison to selected national standard. The soil analysis revealed a moderate to significant soil EF and Igeo with hotspots located closer to the ore processing plant and on the east side of the site, with a maximum arsenic concentration of 286.55 ± 12.50 mg/kg. Sequential extraction revealed, however, that less than 2% of the arsenic is found in the exchangeable part. Cobalt and zinc are more distributed in the different fractions than arsenic. Geogenic and anthropogenic contributions were revealed by the study. Graphical Abstract .

Plitvice Lakes National Park presents one of the most beautiful karst complexes in the world. Its waters are supersaturated with dissolved calcium carbonate (calcite) which is released and deposited in the form of tiny crystals as a result of water splashing at tufa barriers. Sulphates, present in the particulate matter (PM), can be deposited on the surface of the calcite. In the air, sulphate particles are formed by the oxidation of SO₂ in a series of chemical reactions as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006). Fast oxidation of SO₂ in nature can also take place on the surface of the calcite in the presence of ozone and is significantly enhanced by high humidity as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006) and Massey (Science of the Total Environment 227(2–3), 109–121, 1999). The resulting sulphates can destroy the surface of the calcite and indirectly influence the composition and quality of water. Hourly concentrations of ozone, PM₁₀ and PM₂.₅ at the monitoring station Plitvice Lakes in the period from 2012 to 2014 are presented. After assessing the observed values of both PM and ozone, presently there are no significant danger for Plitvice Lakes. However, this can change in the future so continuous monitoring will be necessary in the future.