The impact of nanoparticles on fish health is still a matter of debate, since nanotechnology is quite recent. In this study, freshwater benthonic juvenile fish Prochilodus lineatus were exposed through water to three concentrations of TiO₂ (0.1, 1, and 10 μg l⁻¹) and ZnO (7, 70, and 700 μg l⁻¹) nanoparticles, as well as to a mixture of both (TiO₂ 1 μg l⁻¹ + ZnO 70 μg l⁻¹) for 5 and 30 days. Nanoparticle characterization revealed an increase of aggregate size in the function of concentration, but suspensions were generally stable. Fish mortality was high at subchronic exposure to 70 and 700 μg l⁻¹ of ZnO. Nanoparticle exposure led to decreased acetylcholinesterase activity either in the muscle or in the brain, depending on particle composition (muscle—TiO₂ 10 μg l⁻¹; brain—ZnO 7 and 700 μg l⁻¹), and protein oxidative damage increased in the brain (ZnO 70 μg l⁻¹) and gills (ZnO 70 μg l⁻¹ and mixture) but not in the liver. Exposed fish had more frequent alterations in the liver (necrosis, vascular congestion, leukocyte infiltration, and basophilic foci) and gills (hyperplasia and epithelial damages, e.g., epithelial disorganization and epithelial loss) than the control fish. Thus, predicted concentrations of TiO₂ and ZnO nanoparticles caused detectable effects on P. lineatus that may have important consequences to fish health. But, these effects are much more subtle than those usually reported in the scientific literature for high concentrations or doses of metal nanoparticles.

From April 2008 to November 2009, a field decomposition experiment was conducted to investigate the effects of sediment burial on macro (C, N) and microelement (Pb, Cr, Cu, Zn, Ni, and Mn) variations in decomposing litter of Phragmites australis in the coastal marsh of the Yellow River estuary. Three one-off sediment burial treatments [no sediment burial (0 mm year⁻¹, S₀), current sediment burial (100 mm year⁻¹, S₁₀), and strong sediment burial (200 mm year⁻¹, S₂₀)] were laid in different decomposition sites. Results showed that sediment burials showed significant influence on the decomposition rate of P. australis, in the order of S₁₀ (0.001990 day⁻¹) ≈ S₂₀ (0.001710 day⁻¹) > S₀ (0.000768 day⁻¹) (p < 0.05). The macro and microelement in decomposing litters of the three burial depths exhibited different temporal variations except for Cu, Zn, and Ni. No significant differences in C, N, Pb, Cr, Zn, and Mn concentrations were observed among the three burial treatments except for Cu and Ni (p > 0.05). With increasing burial depth, N, Cr, Cu, Ni, and Mn concentrations generally increased, while C, Pb, and Zn concentrations varied insignificantly. Sediment burial was favorable for C and N release from P. australis, and, with increasing burial depth, the C release from litter significantly increased, and the N in litter shifted from accumulation to release. With a few exceptions, Pb, Cr, Zn, and Mn stocks in P. australis in the three treatments evidenced the export of metals from litter to environment, and, with increasing burial depth, the export amounts increased greatly. Stocks of Cu and Ni in P. australis in the S₁₀ and S₂₀ treatments were generally positive, evidencing incorporation of the two metals in most sampling times. Except for Ni, the variations of C, N, Pb, Cr, Cu, Zn, and Mn stocks in P. australis in the S₁₀ and S₂₀ treatments were approximated, indicating that the strong burial episodes (S₂₀) occurred in P. australis marsh in the future would have little influence on the stocks of these elements. With increasing burial depths, the P. australis was particularly efficient in binding Cu and Ni and releasing C, N, Pb, Cr, Zn, and Mn, implying that the potential eco-toxic risk of Pb, Cr, Zn, and Mn exposure might be very serious. This study emphasized the effects of different burials on nutrient and metal cycling and mass balance in the P. australis marsh of the Yellow River estuary.

Nitrogen removal by anaerobic ammonia oxidation (anammox) of granular sludge is a globally important emerging technology. The ammonium adsorption properties of anammox granular sludge were studied at varying initial ammonium concentration and sludge concentration. Factors affecting the absorption process as temperature, pH, salinity, and metal cations were also examined. The experimental results indicated that ammonium adsorption by anammox granular sludge occurred quickly (in about 20 min). The optimal pH was 7.0 and the ammonium adsorption process was significantly affected by temperature, salinity, and metal cations. The experimental data were modeled using Langmuir, Freundlich, and Temkin adsorption isotherms and the ammonium adsorption process was fit to the Freundlich isotherm. The kinetic results indicated that the experimental data fit well to a pseudo-second-order model. Both intraparticle diffusion and boundary layer diffusion could affect the ammonium adsorption rate. The thermodynamic parameters ΔG₀, ΔH₀, and ΔS₀ were evaluated and suggested that ammonium adsorption was spontaneous and exothermic. These findings indicate that the adsorption of ammonium should be incorporated into models for nitrogen removal, particularly for the use of anammox granular sludge.

Little research has been conducted on the occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment despite being increasingly impacted by these contaminants. This article reviews data on the occurrence of PPCPs in seawater, sediment, and organisms in the marine environment. Data pertaining to 196 pharmaceuticals and 37 personal care products reported from more than 50 marine sites are analyzed while taking sampling strategies and analytical methods into account. Particular attention is focused on the most frequently detected substances at highest concentrations. A snapshot of the most impacted marine sites is provided by comparing the highest concentrations reported for quantified substances. The present review reveals that: (i) PPCPs are widespread in seawater, particularly at sites impacted by anthropogenic activities, and (ii) the most frequently investigated and detected molecules in seawater and sediments are antibiotics, such as erythromycin. Moreover, this review points out other PPCPs of concern, such as ultraviolet filters, and underlines the scarcity of data on those substances despite recent evidence on their occurrence in marine organisms. The exposure of marine organisms in regard to these insufficient data is discussed.

The catalytic removal of Hg⁰ was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V₂O₅/TiO₂ and WO₃/TiO₂ catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg⁰. They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100–160 °C under the near-UV irradiation. The results indicated that V₂O₅/TiO₂ solely possessed the thermo-catalytic reactivity while WO₃/TiO₂ only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO₂, the removal efficiencies of Hg⁰ at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO₂ to nearly 90 % by WO₃/TiO₂ under the same operating conditions. The effects of doping amount of V₂O₅ and WO₃ were also investigated, and the results showed that 10 % V₂O₅ and 5 % WO₃/TiO₂ were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg⁰ was demonstrated that the highest concentration of Hg⁰ led to the best removal efficiencies for V₂O₅/TiO₂ and WO₃/TiO₂ at 140 and 160 °C, because high Hg⁰ concentration increased the mass transfer rate of Hg⁰ toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg⁰ was also investigated.

Geothermal energy is known to be a clean and renewable energy resource. However, geothermal fluid has significant impacts on surface water quality when disposed in an uncontrolled manner due to the high concentrations of numerous dissolved constituents and the elevated thermal content. The geothermal fluid in western Anatolia typically contains high concentrations of arsenic, boron, and lithium that are toxic to human and plant life. A river system in western Anatolia, Turkey, receives uncontrolled waste geothermal fluid discharge from three fields and is thermally and chemically contaminated. A one-dimensional water quality model is developed to assess the extent and strength of geothermal pollution in the river system. The calibrated and verified model results revealed that although both the point and nonpoint sources of contamination are influential in the water quality degradation, point discharges of waste geothermal fluid were responsible for dramatic increases in the contaminant concentrations and water temperature in the river. The model was later used to analyze the potential measures to improve the degraded water quality and compare the effectiveness of structural and non-structural mitigation scenarios.

The adsorption of ethyl acetate, a volatile organic compound, on activated carbons, synthesized from various precursors based on by-products and waste materials—polymer, biomass, coal tar pitch—was studied. The activated carbons were prepared by thermochemical treatment of the precursors, carbonization, and subsequent activation with water vapor. Surface and textural properties of obtained carbon adsorbents were characterized by low-temperature N₂ adsorption, Boehm’s method, etc. The activated carbons are distinguished by relatively high surface area and developed pore structure. The adsorption investigations were performed with water solutions of ethyl acetate, and the obtained results fit well the Langmuir model, as well as the Freundlich model. All activated carbons demonstrated considerably high adsorption capacity in the range 160–450 mg/g. The obtained data indicate that the adsorption ability of activated carbon toward ethyl acetate depends on the surface area, and it increases with increasing the content of mesopores, where ethyl acetate molecules are preferably adsorbed.

Seven full-scale wastewater treatment plants were investigated to highlight the effectiveness of each treatment stage on removing Escherichia coli. The primary sedimentation achieved an average E. coli removal efficiency of 30.5% which was much lower than the suspended solids (58%), thus, revealing the absence of a linear relationship between the two parameters. Biological processes proved to be very important in the removal of E. coli through adsorption inside the sludge flocs and complex decay (mortality). In biological processes with a long retention time, such as activated sludge denitrification-nitrification, the decay was very important, whereas in the more traditional activated sludge process, without nitrification, the contribution of adsorption and mortality was quite balanced. Overall, the mechanical-biological treatment achieved a removal efficiency of 91.8–96.5% depending on the process. Additional removal can be achieved by disinfection. The effectiveness of E. coli removal with sodium hypochlorite was strictly depended on the product of residual chlorine (C R) with the contact time (t). The experimental curve fitted the Collins model well, with a standard deviation of less than 7%.

A new procedure for the determination of chromium species in polluted environmental samples by flame atomic absorption spectrometry was developed in this work. A new material containing 1,5-diphenylcarbazone included in a polymeric matrix was prepared and employed as a solid-phase extraction material for selective separation of Cr(III) ions under dynamic conditions. Chromium(III) ions were retained on this sorbent with high efficiency and repeatability (95 %, RSD = 1 %) from solutions with pH 9.0. The quantitative recovery of analyte was obtained with 0.1 mol L⁻¹ EDTA. The concentration of Cr(VI) ions was calculated from the difference between the concentration of total chromium and Cr(III) ions. The prepared sorbent exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions in the presence of Cu(II), Ni(II), Mn(II) and Ca(II) ions. The accuracy of the separation method was proved by analysis of reference material of wastewater RES 10.2. The developed procedure was applied for chromium speciation analysis in municipal sewage samples.

Along the southeastern coast of Costa Rica, a variety of pesticides are intensively applied to produce export-quality plantains and bananas. In this region, and in other agricultural areas, fish kills are often documented by local residents and/or in the national news. This study examines principal exposure pathways, measured environmental concentrations, and selected toxicity thresholds of the three most prevalent pesticides (chlorpyrifos, terbufos, and difenoconazole) to construct a deterministic risk assessment for fish mortality. Comparisons of observed pesticide concentrations, along with estimated biological effects and observations during actual fish kills, highlight gaps in knowledge in correlating pesticide environmental concentration and toxicity in tropical environments. Observations of fish kill events and measured pesticide concentrations in the field, along with other water quality indicators, suggest that a number of environmental conditions can interact to cause fish mortality and that current species toxicity datasets may not be applicable for estimating toxicological or other synergistic effects, especially in tropical environments.