Principal component analysis (PCA) was performed on chemical data of two sediment cores from an urban freshwater lake in Copenhagen, Denmark. X-ray fluorescence (XRF) core scanning provided the underlying datasets on 13 variables (Si, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Cd, and Pb). Principal component analysis helped to trace geochemical patterns and temporal trends in lake sedimentation. The PCA models explained more than 80 % of the original variation in the datasets using only two or three principal components. The first principal component (PC1) was mostly associated with geogenic elements (Si, K, Fe, Rb) and characterized the content of minerogenic material in the sediment. In the case of both cores, PC2 was a good descriptor emphasized as the contamination component. It showed strong linkages with heavy metals (Cu, Zn, Pb), disclosing changing heavy-metal contamination trends across different depths. The sediments featured a temporal association with contaminant dominance. Lead contamination was superseded by zinc within the compound pattern which was linked to changing contamination sources over time. Principal component analysis was useful to visualize and interpret geochemical XRF data while being a straightforward method to extract contamination patterns in the data associated with temporal elemental trends in lake sediments.

Textile industry is responsible for a large amount of polluted water released daily, mainly due to the dyes used. This article has aimed to study and improve methodologies for degrading textile effluents containing the dyes Acid Red 151 and Acid Blue 40 using an electrolytic reactor. Different solutions were prepared for the experiments in the electrolytic reactor with a 70 % TiO₂/30 % RuO₂anode. The textile effluents underwent 0 (control), 3, and 30 min treatment intervals. A suspension of Saccharomyces cerevisiae cells was used for toxicity tests and performed at the same day that samples were collected. The same test was applied to the samples after 15 days resting in order to verify changes in toxicity. The electrolytic treatment successfully removed the color in all effluents. However, the process efficiency varies according to the dye used and the experimental conditions, such as current and NaCl concentration. Also, it was observed that treatments longer than 30 min are very toxic to S. cerevisiae cells because of the high concentration of Cl₂.

Graphene oxide (GO) nanosheets were used as adsorbent material for the removal of clofibric acid (CA) which was difficult to be removed from wastewater by traditional wastewater treatment technique. Adsorption kinetics, adsorption equilibrium, and effect of pH, ionic strength, and humic acid (HA) of the adsorption of CA onto the GO nanosheets in aqueous solution were investigated in detail. Adsorption isotherm studies indicated that the Langmuir isotherm equation fitted the sorption isotherm data better than Freundlich model and the maximum adsorption capacity of GO nanosheets for CA was 994 mg g⁻¹. In addition, adsorption kinetics data showed that the sorption of CA on GO nanosheets reached equilibration within a few minutes and were well fitted by pseudo second-order model. The results of the effects of environment factors indicated that CA sorption on GO nanosheets was weakly affected by ionic strength and strongly depended on pH and HA because of the structure of CA and the large number of oxygen-containing function groups presented on the surface of GO nanosheets. Besides, the removal efficiency of GO nanosheets for CA was reduced at pH >4 and enhanced at pH <4 in the presence of HA.

The study was aimed at determining whether potentially pathogenic free-living amoebae (FLA) and Legionella pneumophila can be found in lakes serving as a natural cooling system of a power plant. Water samples were collected from five lakes forming the cooling system of the power plants Pątnów and Konin (Poland). The numbers of investigated organisms were determined with the use of a very sensitive molecular method—fluorescence in situ hybridization (FISH). The result of the present study shows that thermally altered aquatic environments provide perfect conditions for the growth of L. pneumophila and amoebae. The bacteria were identified in the biofilm throughout the entire research period and in the subsurface water layer in July and August. Hartmanella sp. and/or Naegleria fowleri were identified in the biofilm throughout the entire research period.

The potential of the activated carbon prepared from the empty fruit bunch of oil palm wastes to remove bisphenol A (BPA) from aqueous media was investigated. The experiments were performed by varying the contact time, activated carbon dose, initial BPA concentration, and pH of the solution. The Langmuir, Freundlich, and Temkin isotherm models were employed to discuss the adsorption behavior. The equilibrium data were perfectly represented by the Langmuir isotherm with R²of 0.9985. The maximum monolayer adsorption capacity of the activated carbon was found to be 41.98 mg/g. Kinetic studies indicated that the adsorption process followed the pseudo-second-order kinetic with a rate constant of 0.3 × 10⁻³/min. The activated carbon was characterized by means of Fourier transform infrared spectrometry, Brunauer–Emmett–Teller, and field emission scanning electron microscopy analyses. The results of the present study indicate that the activated carbon prepared from the empty fruit bunch is a promising candidate as a low-cost bio-adsorbent for the removal of BPA from aqueous solution.

The thiol-ene-based P(Penta3MP4/PEGDA/AAc) hydrogels were prepared by UV curing technique, then characterized and used as adsorbents for the investigation of the effect of process parameters such as pH of solution, contact time, and initial concentration of solution, on the removal of Ag(I) from aqueous solution. The results indicate that the adsorption of Ag(I) ions from aqueous solutions is strongly dependent on pH under experimental conditions. Both Langmuir and Freundlich isotherm models were applied to experimental data, and the results show that the adsorption process is well fitted to the Langmuir isotherm model. Selectivity, reusability, and applicability of hydrogels to radiographic film waste were investigated.

We analyzed, for the first time, the different fractions of metals present in the spent catalyst and changes they undergone during bioleaching and chemical leaching. Before bioleaching, Al (83.9 %) was found mainly in the residual fraction of the pretreated spent catalyst. Ni (61.3 %) was mainly present in the exchangeable fraction exhibiting its high environmental mobility. V (58.5) and Mo (49.3 %) mainly existed in the oxidizable fraction suggesting that highly oxidizing conditions would liberate these metals from the spent catalyst. During bioleaching with Acidithiobacillus thiooxidans, almost complete solubilization of the exchangeable as well as of reducible fraction was observed. Due to strong acidic conditions, part of oxidizable fraction of these metals was also solubilized. Bioleaching also affected the fractionation of metals remaining in the treated spent catalyst. At the end of the process, most of the metals remaining in the spent catalyst were found in the more stable fractions ensuring the safe disposal of spent catalyst. The leaching yields and fractionation behavior of metals during chemical leaching was found to be identical. The results of the present study strongly suggest that bioleaching is an effective method for removing metals from the spent catalyst.

The objective of the current study was to estimate the dose in human tissues after inhalation exposure to airborne particulate matter-bound metals at a landfill site. Field measurements have revealed that the 8-h permissible exposure limit set by the Occupational Safety and Health Administration for particulate matter (PM₁₀) was not exceeded for the working personnel at an outdoor weighing facility in the Akrotiri landfill (Chania, Greece). However, PM₁₀concentrations were exceeding the EU health protection standards (50 μg/m³). Furthermore, dust emanating from landfill operations contains traces of heavy metals due to the nature of materials (e.g., sludge, batteries) which have been deposited over the lifetime of the landfill. In addition, particulate matter-bound metals concentrations at the landfill are enhanced by refuse truck emissions (e.g., exhaust, tire wear dust, brake wear dust, road surface wear dust and resuspension of deposited PM on a road surface) and resuspension from the surface of the composting site. Estimations of particle-bound metals dose in the human body were performed for arsenite (ASᴵᴵᴵ), lead (Pb) and cadmium (Cd). The Exposure Dose Model (ExDoM) in conjunction with a Physiologically Based PharmacoKinetic (PBPK) model was applied to determine the dose for an adult Caucasian male worker. The ExDoM was used to estimate the human exposure and the deposition, dose, clearance, retention of particulate matter-bound metals in the human respiratory tract and the mass transferred to the gastrointestinal tract and blood. The PBPK model was developed to describe the movement of metals from the blood into the tissues as a blood-flow-limited model. The results showed that after 1 day of exposure to PMAₛIII, the major accumulation occurs in the lung, muscle and liver. In addition, for PMPb, the major accumulation occurs in the bone, blood and muscle whereas as regard PMCdthe major accumulation occurs in the other tissues (the rest of the body), kidney and liver. The results indicate an increased health risk for an adult Caucasian male worker at the landfill site due to exposure to elevated particulate matter concentrations and their associated metallic content.

Lacustrine sedimentation and trace metal accumulation are naturally occurring processes that can be altered by anthropogenic activities. Indices of sediment or metal dynamics are important for the management and operational use of man-made reservoirs and their drainage basins. In this study, we compared two reservoirs in Virginia, USA, to quantify the effect of varying watershed characteristics on sediment and metal fluxes. Lake Pelham is a human-impacted reservoir surrounded by agricultural fields and anthropogenic developments, whereas Lake Moomaw is an undeveloped reservoir surrounded by moderate to extremely sloping forested landscapes. Three sediment cores were taken from each reservoir to estimate²¹⁰Pb-based sediment accumulation rates, organic matter content, and indices of trace metal enrichment and accumulation. The average²¹⁰Pb-based sediment accumulation rates were 0.348 ± 0.053 and 0.246 ± 0.043 g cm⁻² year⁻¹for Lake Pelham and Lake Moomaw, respectively. The sediment trace metal results showed strong correlation with sediment organic content, and both reservoirs had moderate to high enrichment of Cu and little enrichment of Zn and Pb. Overall, Lake Moomaw had relatively low sediment accumulation and metal enrichment. Comparatively, Lake Pelham had significantly greater metal concentrations, which were highest in the upper reaches of the reservoir. Lake Pelham also had higher sediment accumulation rates and higher metal enrichment, reflecting the impact of human development within the greater watershed. Results from this study suggest that urbanization can increase reservoir sediment and metal fluxes, but atmospheric deposition is also important in forested watersheds that have not undergone anthropogenic land-use change.

Adsorption and removal of cadmium ions from simulated industrial wastewater using hydrophilic and hydrophobic commercial silica nanoparticles are reported. These results are compared with those obtained using sol–gel silica nanoparticles. Two types of dense commercial pyrogenic silica nanoparticles with different chemical groups on the surface were used to adsorb cadmium ions: Aerosil A130VS and R972. The pore absence in these particles reduces the surface area and, consequently, the concentration of active chemical groups appropriated for adsorption, as compared with the sol–gel particles that are highly porous; this effect is partially compensated by the small sizes available for these commercial particles. The concentration of cadmium ions was reduced: from 109 to 0.01 ppm for A130VS, from 138 to 1.44 ppm for R972, and from 123 to 0.005 ppm for sol–gel. The flocculation kinetics was obtained using dynamic light scattering and the amount of adsorbed cadmium in the sediment using atomic absorption spectroscopy.