Gulls were assessed as sentinels of contamination in the coastal zone of the Southern Baltic, research material being obtained from dead birds collected on Polish beaches and near fishing ports in 2009–2012. In feathers and blood of four gull species: herring gull (Larus argentatus), common gull (Larus canus), black-headed gull (Chroicocephalus ridibundus), and great black-backed gull (Larus marinus), concentration of total mercury (HgT) was assayed, taking into account the type of feathers, sex, and age. Stable isotopes (δ¹⁵N, δ¹³C) were used as tracers of trophic position in the food web. In the study, feathers and blood were compared as non-invasive indicators of alimentary exposure introducing mercury into the system. In order to do that, the correlations between mercury concentrations in the blood, feathers, and the birds’ internal tissues were examined. The strongest relations were observed in the liver for each species R ²Cₒₘₘₒₙ Gᵤₗₗ = 0.94, p = 0.001; R ²Bₗₐcₖ₋ₕₑₐdₑd Gᵤₗₗ = 0.89, p = 0.001; R ²Gᵣₑₐₜ Bₗₐcₖ₋bₐcₖₑd Gᵤₗₗ = 0.53, p = 0.001; R ²Hₑᵣᵣᵢₙg Gᵤₗₗ = 0.78, p = 0.001. While no correlation was found with feathers, only developing feathers of juvenile herring gulls were found to be a good indicator immediate of exposure through food (R ²ₘᵤₛcₗₑ = 0.71, p = 0.001; R ²ₖᵢdₙₑyₛ = 0.73, p = 0.001; R ²ₕₑₐᵣₜ = 0.89, p = 0.001; R ²ₗᵤₙgₛ = 0.86, p = 0.001; R ²bᵣₐᵢₙ = 0.83, p = 0.001). Additionally, based on studies of herring gull primary feathers, decrease of mercury concentration in the diet of birds over the last two decades is also discussed.

A method for simultaneously determining the levels of aniline, benzidine, microcystin variants (microcystin-LR, RR, and YR) and carbaryl in water was developed based on ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC-MS/MS). The chromatographic conditions were optimized for the trace determination. Without sample enrichment, the method detection limit for all test compounds ranged from 0.040 to 0.155 μg/L; meanwhile, the recoveries for all test compounds were 83.1–114%. Precision, indicated by the relative standard deviation, was <12.9%. The results meet the requirements for the determination of these compounds. Without the need to clean up the samples, the results of the analysis of samples from wastewater and surface water demonstrated that the UPLC-MS/MS method has the capability to analyze complex matrices in the trace-level monitoring of wastewater samples.

A novel bag filter + powdered activated carbon technique is here proposed to address the low utilization rate of powdered activated carbon and the low dioxin removal rate associated with the conventional activated carbon injection + bag filter technique, better known as the fly ash + activated carbon + bag technique. In this method, dibenzofuran serves as a dioxin simulant. The effect of the adsorption temperature and dibenzofuran inlet concentration on the adsorption performance of activated carbon was studied using a filter cloth adsorption device with an inner diameter of 25 mm, and the adsorption performances of fly ash, activated carbon, and fly ash +5% activated carbon were compared. The results showed that activated carbon exhibited a higher adsorption efficiency and remained highly efficient longer than fly ash +5% activated carbon. When the dibenzofuran inlet concentration was 0.0956 g/m³ (about one million times the concentration of dioxin in the flue gas of incinerated waste), the duration of the high-efficiency (>90%) adsorption of the powdered activated carbon (thickness 1.2 mm) on the filter cloth was over 7 h. These results prove that the replacement of fly ash + activated carbon + filter bag with powdered activated carbon + bag filter can significantly improve the removal efficiency of the dioxin in waste incineration flue gas and the utilization rate of activated carbon.

This study was conducted to assess the hyperaccumulation and phytoremediation potential of copper (Cu) and lead (Pb) in Hardy ‘Limelight’ Hydrangea (Hydrangea paniculata) and the common sunflower (Helianthus annuus). The study also investigated the capacity of these two plants to transpire the metals in a temperature-controlled greenhouse. Plants were grown for 4 weeks and periodically watered with known elemental concentrations of copper oxide nanoparticles, copper sulfate, and lead nitrate. Both H. annuus and H. paniculata accumulated significant amounts of Cu and Pb to be classified as hyperaccumulator species. H. annuus took up significant amounts of Cu in the shoots, specifically the leaves (Cu max. = 1368 ppm), and easily translocated it from stem to leaf (translocation factor (TF) ranged from 2.7 to 81.0). Pb was not as easily taken up and translocated (TF = 0.6) as Cu was by this species. H. paniculata took up Cu and Pb in high concentrations but preferentially stored more metals in the stems (Cu max. = 1757 ppm; Pb max. = 780 ppm) than in the leaves (Cu max. = 126 ppm; Pb max. = 35 ppm). The translocation ability of H. paniculata was much lower for both metals compared to H. annuus. Both Cu and Pb transpired from H. annuus at concentrations of 0.04 and 0.005 ppm, respectively.

This study evaluates the treatment efficacy and biogas yield of an integrated system composed of a plug-flow biodigester (with sludge recirculation) followed by polishing in a stabilization pond. The system was operated in real scale for 12 months at ambient temperature and under continuous flow. The volumetric yields of biogas varied according to the organic loads applied, between 114 and 294 Kg COD day⁻¹, reaching levels of 0.026 to 0.173 m³ m⁻³ day⁻¹, with concentrations of CH₄ between 56 and 70%. The monthly biogas productions were between 378.5 and 2186.1 m³ month⁻¹ equal to an energy potential of approximately 2070 to 19,168 KWh month⁻¹.The average yearly removals of BOD₅,₂₀ and COD by the integrated treatment system were 70 and 86%, respectively. The average annual removals of NH₄ and TKN were 88.5 and 85.5%, respectively. The pH values were always near neutral, and the alkalinity was in ranges propitious for anaerobic digestion. The results of this study indicate good efficacy in terms of removal of organic matter and nitrogen compounds, with the added benefits of generation of energy and use of the treated effluent as biofertilizer, enabling significant cost reductions to cattle farmers.

Hydrophilic carbonaceous nanoparticles (HNPs) of uniform sizes with a good degree of dispersion in water were produced from a commercial carbon black by nitric acid treatment. The surface treatment, performed at different reaction times, generates a variable number of oxygen functional groups, mainly carboxylic, which enhance the nanoparticles hydrophilicity and heavy metal adsorption capability. The HNPs were characterized by a number of analytical techniques, including FTIR spectroscopy, thermal and elemental analysis, N₂ adsorption, dynamic light scattering, and zeta-potential measurements. The acid–base properties of the functional groups on the HNPs surface were also investigated by coulometric–potentiometric titrations. Cadmium adsorption tests were carried out in stirred reactors containing colloidal aqueous suspensions of HNPs and HNPs supported over silica. The effects of several parameters, such as the cadmium concentration, the temperature, and the solution pH, were studied. Sorbents showed an appreciable cadmium adsorption capability at different temperatures and in a wide range of pH values comparable or superior to several carbon-based sorbents, indicating a feasible use in commercial units.

Surface modification of the silica nanoparticles was performed using trithiocyanuric acid (TCA-SNPs) so as to enhance the adsorption of Ag⁺ from aqueous solutions. The surface modification to the adsorbent was characterized by Fourier transform infrared spectroscopy, transmission electron microscope, and X-ray photoelectron spectroscopy. The Ag⁺ adsorption capacity was found to increase with increase in the solution pH, with the optimal pH being 5.0. The Ag⁺ adsorption isotherm was generated at 25 °C at the optimal solution pH and the maximum adsorption capacity was found to be 80 mg/g, significantly higher than the adsorption capacity reported for other adsorbents in literature. The increase in adsorption capacity was attributed to the presence of thiol groups on the surface of the modified adsorbents. Additionally, the adsorption kinetics was estimated at 25 °C, which indicated very high rates of adsorption initially, with rapid reduction in rate of adsorption with time. Both adsorption isotherms as well as the adsorption kinetics were modeled with popular models. The adsorption isotherm was found to match with the Langmuir model while the adsorption kinetics was found to match with the pseudo-second-order kinetic model. The adsorption-desorption cycles indicate the TCA-SNPs to be stable adsorption performance and retain high adsorption efficiency ensuring commercial adoption. A relatively low adsorption of other ions such as Mn²⁺, Cu²⁺, Ni²⁺, Co³⁺ as compared to Ag⁺ was ensured.

Water quality assessment typically includes the determination of chemical oxygen demand (COD) by oxidation of organic matter with Cr(VI) in an acidic medium followed by digestion. Unfortunately, the required reagents are harmful and the reaction times are rather long. We investigated earlier the use of H₂O₂ as a more environmentally friendly oxidizing agent to replace the hazardous chromates. In the present study, we have furthered this possibility by incorporating the use of H₂O₂ in the presence of UV light. A protocol has been devised and tested with standards and real samples that replaces toxic Cr(VI), halves the amount of silver sulfate required, and greatly reduces the necessary reaction time, thus yielding a faster and more environmentally sound method.

Graphene oxide (GO) and graphene oxide modified with methyl-β-cyclodextrin denoted as GO-mβCD were prepared and applied as adsorbents to determine the adsorption characteristics of Pb(II) from aqueous solutions. The characteristic results of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) showed that mβCD was successfully physically attached to GO to form the GO-mβCD nanocomposite. The adsorption equilibrium and kinetics of the adsorbents were well described by Langmuir isotherm and pseudo-second-order models, respectively. The maximum Pb(II) adsorption capacity of GO-mβCD (at pH = 6 and room temperature) was determined as 312.5 mg/g which was significantly higher than that of GO (217.39 mg/g). This indicates that the modification of GO with mβCD enhances the adsorption capacity of GO. The desorption studies show that the adsorbent GO-mβCD can be used for at least five cycles with non-significant loss of its initial adsorption capacity for Pb(II) ions.

Adsorption isotherms were constructed to evaluate the potential use of water lettuce (Pistia stratiotes) dry biomass for the biosorption of zinc and cadmium. One gram of dry biomass of this plant was treated with five increasing doses of zinc (1.8, 18, 50, 79, and 105 mg L⁻¹) and four doses of cadmium (0.01, 0.1, 1, and 10 mg L⁻¹), for nine collection times (1, 3, 6, 12, 24, 36, 48, 60, and 72 h). The levels of these metals were determined by atomic absorption spectrophotometry. To evaluate changes in the surface morphology of the dry biomass, scanning electron microscopy (SEM) images were taken of the samples subjected to the greatest contamination, and these were compared with the images of the samples without zinc and cadmium (control). The ISOFIT software was used to select the isotherm model that best fit the biosorption of metals by water lettuce dry biomass. The linear model was determined to be the best-fitting isotherm model, because it had the lowest corrected Akaike information criterion (AICc) value and a Akaike weight (AICw) value closest to one, which indicates the high affinity of the biosorbent for the adsorbates evaluated. The results for both metals demonstrated greater than 70% reductions in the concentrations of the metals in the contaminated solutions. The SEM images indicated changes in the morphology of the contaminated biomass, thus demonstrating the biosorption mechanisms and confirming the potential of the dry biomass of this plant for use in the remediation of solutions contaminated with zinc and cadmium.