Weathering of sulphide minerals produces a great variety of efflorescences of soluble sulphate salts. These minerals play an important role for environmental pollution, since they can be either a sink or a source for acidity and trace elements. This paper aims to characterise surface waters affected by mining activities in the Sierra Minera of Cartagena-La Union (SE, Spain). Water samples were analysed for trace metals (Zn, Cd, Pb, Cu, As and Fe), major ions (Na⁺, K⁺, Ca²⁺ and Mg²⁺) and anions (F⁻, Cl⁻, NO₃⁻, CO₃²⁻, SO₄²⁻) concentrations and were submitted to an “evaporation-precipitation” experiment that consisted in identifying the salts resulting from the evaporation of the water aliquots sampled onsite. Mineralogy of the salts was studied using X-ray diffraction and compared with the results of calculations using VISUAL MINTEQ. The study area is heavily polluted as a result of historical mining and processing activities that has produced large amount of wastes characterised by a high trace elements content, acidic pH and containing minerals resulting from the supergene alteration of the raw materials. The mineralogical study of the efflorescences obtained from waters shows that magnesium, zinc, iron and aluminium sulphates predominate in the acid mine drainage precipitates. Minerals of the hexahydrite group have been quantified together with minerals of the rozenite group, alunogen and other phases such as coquimbite and copiapite. Calcium sulphates correspond exclusively to gypsum. In a semiarid climate, such as that of the study area, these minerals contribute to understand the response of the system to episodic rainfall events. MINTEQ model could be used for the analysis of waters affected by mining activities but simulation of evaporation gives more realistic results considering that MINTEQ does not consider soluble hydrated salts.

The aim of this study was to extend the knowledge on the antioxidant effect of extra-virgin olive oil (EVOO) in the liver of broiler chickens not subjected to any form of insult. A total of 120 male broiler chickens (Hubbard strain) were divided into three groups and fed ad libitum with three isoenergetic diets from hatching until slaughter age (49 days) on a completely randomized design. The dietary treatments consisted of 2.5 % added oil or fat from three sources as follows: diet containing sunflower oil (SFO); diet containing lard (LRD), and diet containing extra-virgin olive oil (EVOO). The activity of the main antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GS-Px) and glutathione S-transferase (GST), and lipid peroxidation as thiobarbituric acid-reactive substances (TBARS) content, was measured in the liver of chickens. The susceptibility to undergo lipid peroxidation was assessed by exposing liver homogenate to 30 °C or to an ascorbate/iron mixture as pro-oxidant system. Dietary oil or fat type improved significantly (P < 0.05) the body weight and gain as well as feed efficiency in birds fed EVOO compared to those fed with the other treatments. Supplementing EVOO in the diet significantly (P < 0.05) reduced lipid peroxidation by increasing antioxidant defense system. These findings, besides adding more results on the antioxidant effect of extra-virgin olive oil on liver of other experimental model other than rats and humans, could be significant for animal welfare, with consequent benefits for both producers and consumers.

This study compared the behaviors of two classic advanced oxidation processes (AOPs), hydroxyl radical-based AOPs (•OH-based AOPs) and sulfate radical-based AOPs (SO₄ •⁻-based AOPs), represented by UV/ hydrogen peroxide (H₂O₂) and UV/peroxydisulfate (PDS) systems, respectively, to degrade humic acid (HA) in the presence of halide ions (Cl⁻ and Br⁻). The effects of different operational parameters, such as oxidant dosages, halide ions concentration, and pH on HA degradation were investigated in UV/H₂O₂/Cl⁻, UV/PDS/Cl⁻, UV/H₂O₂/Br⁻, and UV/PDS/Br⁻ processes. It was found that the oxidation capacity of H₂O₂ and PDS to HA degradation in the presence of halides was nearly in the same order. High dosage of peroxides would lead to an increase in HA removal while excess dosage would slightly inhibit the efficiency. Both Cl⁻ and Br⁻ would have depressing impact on the two AOPs, but the inhibiting effect of Br⁻ was more obvious than that of Cl⁻, even the concentration of Cl⁻ was far above that of Br⁻. The increasing pH would have an adverse effect on HA decomposition in UV/H₂O₂ system, whereas there was no significant impact of pH in UV/PDS process. Furthermore, infrared spectrometer was used to provide the information of degraded HA in UV/H₂O₂/Cl⁻, UV/PDS/Cl⁻, UV/H₂O₂/Br⁻, and UV/PDS/Br⁻ processes, and halogenated byproducts were identified in using GC-MS analysis in the four processes. The present research might have significant technical implications on water treatment using advanced oxidation technologies.

As the largest polycyclic aromatic hydrocarbons (PAHs) emission country, China is suffering from severe PAHs pollution. Twenty-eight lakes in the middle and lower reaches of the Yangtze River region (MLYR), where numerous lakes are located in and play very important roles in the development of the local economy and society, were selected to investigate the levels and sources of the PAHs in this region and the related influence factors. Concentrations of the 16 PAHs (∑PAHs) in the sediments ranged from 221.0 to 2418.8 ng g⁻¹ (dry weight). The mean ∑PAHs was higher in the lower reaches than in the middle reaches. ∑PAHs in the sediments was positively correlated with the local gross domestic product (GDP), which implies that GDP was the key factor to affect the PAHs level in the sediments of study area. According to the composition of 16 PAHs, the 28 lakes were grouped into 3 clusters. Major PAHs sources for the three types of lakes were significantly different, which were biomass combustion, coal combustion, and vehicle/coal source, respectively. The total toxic benzo(a)pyrene equivalent (TEQᶜᵃʳᶜ) of the carcinogenic PAHs in the sediments varied from 12.9 to 472.9 ng TEQᶜᵃʳᶜ g⁻¹. Benzo(a)pyrene (BaP) and dibenzo(a,h)anthracene (DaA) were the two main contributors to total TEQᶜᵃʳᶜ.

Many coastal rivers have a system of cascade reservoirs, but the role of these reservoirs in regulating nutrient transport from watershed to coast is still unknown. In this study, phosphorus (P) in surface water and top sediment was investigated along the North Jiulong River (southeast China) under three hydrological conditions (high flow, medium flow and low flow) in 2012–2013, and P dynamics in a cascade reservoir (Xipi Reservoir) were studied on a monthly scale. Results showed that the concentrations of dissolved reactive phosphorus (DRP) consistently decreased longitudinally in the upper river with the lowest values observed in the section of cascade reservoirs, likely due to tributary inputs and in situ uptakes. The decrease was most rapid during base flow when DRP was highest in the free-flowing river section and lowest in cascade reservoirs. Results from monthly monitoring on the Xipi Reservoir showed general downriver decreases in DRP, total particulate phosphorus (TPP) and total phosphorus (TP) in the riverine zone and transition zone. Mass balance results on an annual basis suggest that the Xipi Reservoir (lacustrine zone) was an overall sink for TPP (6 % retention) but somewhat a source of DRP (−0.3 %) with TP retention (1 %). Even scaled up to the whole cascade reservoir system, P retention was low compared with worldwide reservoirs, which we ascribe to the high P loading and short hydraulic residence time. Nevertheless, major processes controlling P retention in coastal rivers with cascade reservoirs varied from sedimentation in the dry-cold season to biotic transformation in the wet-warm season, thereby affecting loading and composition of P from watershed to the coast. This study highlights the hydrological controls on the role of cascade reservoirs in regulating P retention and downriver fluxes in different seasons.

A process-oriented investigation of phosphate removal by ferric salt was carried out in this study. The kinetics of amorphous ferric phosphate (FePO₄(s)) formation has been investigated over the pH range of 6.0–8.0 using sulfosalicylic acid as a competitive ligand. The FePO₄(s) formation rate constants varied in a narrow range over the pH range examined in this study. And the maximum of (0.90 ± 0.11) × 10⁴ L mol⁻¹ s⁻¹ was obtained at pH 7.5 and the minimum value of (0.05 ± 0.01) × 10⁴ L mol⁻¹ s⁻¹ was obtained at pH 6.0. These values are two orders of magnitude lower than the rate constants for Fe(III) hydrolysis-precipitation, and hence, the extent of FePO₄(s) formation when ferric ions are added to aqueous solution is extremely low. Subsequently, the characteristics of the amorphous ferric oxide (AFO) with different ages were investigated, and it was found that the BET surface area, the average pore width, and the charge capacitance were various for different AFO with various ages. Phosphate adsorption by AFO was significantly affected by AFO aging and the manner of adding Fe(III), which was successfully described by a diffuse layer model. By using surface sites concentration obtained, the kinetics constant of AFO aging could be calculated by a functional equation at a certain pH and time. Graphic abstract Description of the precipitation and aging processes for the phosphate removal by Fe(III)-ions

To examine the uptake of dioxin-like compounds (DLCs), common roaches (Rutilus rutilus) were exposed for 28 days to differently contaminated sediments from two major European rivers in a purpose-built facility. Dietary transfer of DLCs was investigated by exposing fish to sediments inoculated or non-inoculated with black worms (Lumbriculus variegatus). Dioxin-like polychlorinated biphenyls (DL-PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), measured via high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) in sediments and whole fish, were used to calculate toxicity equivalent quotients (TEQs). TEQs were compared with biological toxicity equivalent quotients (BEQs) determined via the 7-ethoxyresorufin-O-deethylase (EROD) assay, performed with mammalian (H4IIE) and fish (RTL-W1) liver cell lines. TEQs and BEQs indicated an uptake of sediment-borne DLCs by roach, which was independent of sediment contamination levels, but rather reflected sediment-specific characteristics. For most sediment treatments, DLC uptake did not increase with time. Highest congener-specific uptake (DL-PCB 123) was 10-fold compared to control. Exposure to worm-inoculated sediment of highest overall DLC contamination caused a 2-fold (TEQ and H4IIE BEQ) greater uptake of DLCs by fish compared to the respective non-inoculated treatment. H4IIE cells showed the greatest sensitivity (0.37 ± 0.25 pM TCDD) and the strongest correlation with TEQs (r ² = 0.79), hence, they seem to be best suited for DLC screening of sediments and biota, amended by compound-specific instrumental analysis if required.

The aims of the present work were (1) to evaluate oxidative stress biomarkers and AChE in two tissues of wild mussel (Mytilus galloprovincialis) of high biochemical activity and accumulation capacity (gills and digestive gland) and (2) to study the behaviour of these biomarkers in presence of heavy metals. For this, EA, TOS, TAC and AChE were measured in tissues of mussels exposed to binary combination of Pb, Cd and Cu. Mussels (n = 36) were exposed to one of the binary mixtures of Pb (1000 μg L⁻¹), Cd (100 μg L⁻¹) and Cu (100 μg L⁻¹) for 7 days, under controlled conditions. Gills and digestive gland were extracted and frozen at −80 °C until analysis. The automatic methods employed for the measurement of EA, TAC, TOS and AChE in M. galloprovincialis revealed higher levels of these biomarkers in digestive gland than gills. Study results suggest that gills would be the tissue of election for study oxidative stress markers, whereas digestive tissue should be selected for AChE measurements in case of evaluation of combined metal toxicity in mussels.

Sediment samples from University Lake (U.L.) and Anacostia River (A.R.) were collected to study the phosphorus (P) adsorption with pH at 3.65, 4.75, and 5.65. The surface micro-morphology and pore structures of sediment particles were obtained using a scanning electron microscopy and gas adsorption method, respectively. Fourier analysis was then applied to approximate the surface morphology, which was incorporated into the Langmuir isotherm to directly derive the model parameters for P adsorption simulation. Meanwhile, an empirical function of pH was introduced to represent the pH effect on P adsorption. A stronger P adsorption was observed for the A.R. sediment due to the more clay minerals, smaller median diameter, and a greater percentage of large pores, and the increasing pH resulted in a decrease of adsorption equilibrium constant as well as the P adsorption capacity, which was well reproduced by the adsorption isotherms. This study would benefit the mechanism study of the interactions between sediment particles and pollutants, providing references for understanding the pollutants’ transport in aqueous systems.

We present results of the 5-year monitoring of ambient O₃ concentrations in a Central European medium altitude mountain forested area. O₃ levels were measured at 11 sites between 714 and 1000 m a.s.l. in 2006–2010 vegetation seasons using Ogawa diffusive samplers. Our results reveal that O₃ exposure in the Jizerské hory Mts. was relatively high and comparable with polluted sites in Southern Europe and in higher altitudes. O₃ concentrations differed significantly between individual sites and in individual years. O₃ concentrations showed clear dependence on altitude at sites with similar aspect. Its gradient for the entire 5-year period under review equaled 3.5 ppb/100 m of altitude, ranging between nearly 5 ppb/100 m of altitude in 2006 and nearly 3 ppb/100 m of altitude in 2010. O₃ concentrations at the site with northern aspect were consistently significantly lower than at the site at similar altitude with southern aspect. O₃ concentrations measured at the forest edge were consistently lower than those measured at the same site but at the forest clearing. It is evident that the macro-setting of the O₃ monitoring site is crucial for obtaining reliable results with high representativeness for the area.