Methylmercury (MeHg) in sediment is difficult to be determined due to its low concentration and binding compounds like sulfide and organic matter. Moreover, wet sediment samples have been suggested to behave differently from certified reference materials in MeHg analysis. Optimal pretreatment procedure for MeHg determination in sediments has not been ascertained and whether the procedure could apply to sediment samples with complex matrix merits further research. This work firstly compared recovery results of five pretreatment procedures for MeHg determination using ERM-CC580. Using the optimal pretreatment procedure, recovery results were analyzed in different sediment samples after manipulation of moisture content, organic matter, and acid volatile sulfide. The procedure using CuSO₄/HNO₃ as leaching solutions and mechanical shaking as extraction method was proved to produce the most satisfactory recovery results (100.67 ± 6.75%, mean ± standard deviation). And when moisture content varied from 20 to 80%, average recovery results in sediment samples ranged from 100 to 125%. Furthermore, before and after the manipulation of organic matter or acid volatile sulfide, spiking recovery results varied little and were all within acceptable limit (85~105%). Therefore, the procedure of CuSO₄/HNO₃-mechanical is proposed as a universal pretreatment method for MeHg determination in sediment samples with various characteristics.

The aim of this study was to evaluate changes in hematological parameters of O. niloticus exposed to sublethal concentrations of the imidacloprid in order to utilize these parameters as biomarkers of exposure. Fish with an average weight of 68.5 ± 2.0 g were exposed to sublethal concentrations of imidacloprid (1.405, 2.810, 14.050, and 28.1 mg L⁻¹) for 7 days. Blood samples were collected by puncture of the tail vein. Blood samples were used to determine the number of erythrocytes, hemoglobin level, hematocrit number, total plasma protein concentration, total and differential leukocytes count, and thrombocytes number. All tested concentrations caused changes in fish leukogram. Concentrations from 14.050 mg L⁻¹ reduced the number of erythrocytes and total plasma proteins. The tilapia exposed to 28.1 mg L⁻¹ had a significant increase in the number of thrombocytes. Although considered slightly toxic to fish, sublethal concentrations of imidacloprid in aquatic environments, even if it does not cause immediate death, may compromise the health and long-term survival of these animals. The sublethal responses adopted for evaluation toxicity in this study were sensitive and adequate to show the extent to which pesticide can affect non-target organisms. This study recommends the use of blood parameters as biomarkers of exposure of fish to pesticides.

The trade-off between energy savings and emission reductions of an activated sludge process is a multi-objective problem relating to several potentially conflicting objectives. Therefore, the optimal modification of an anaerobic–anoxic/nitrifying/induced crystallization (A2N-IC) process by multi-objective optimization method was studied in this work. The multi-objective optimization model comprised three evaluative indices, (effluent quality (EQ), operation cost (OC), and total volume (TV) of structures), and 14 process parameters (decision variables) solving by non-dominated sorting genetic algorithm II (NSGA-II) in MATLAB. The trade-off relationships among EQ, OC, and TV were investigated under 30 days of dynamic influent with different constraint conditions. A series of Pareto solutions were obtained, and one Pareto solution was selected for further analysis. Results showed improved effluent concentrations of chemical oxygen demand (COD), total nitrogen (TN), ammonia-nitrogen (NH₄⁺-N), and total phosphorous (TP) under the optimized strategy compared to the original strategy, where the average effluent concentrations decreased by 2.22, 0.47, 0.13, and 0.02 mg/L, respectively. The values of EQ and OC decreased from 0.015 kg/day and 0.15 ¥/m³ to 0.0023 kg/day and 0.12 ¥/m³, respectively, while the TV increased from 0.31 to 0.33 m³. These results indicated that the multi-objective optimization method is useful for modifying activated sludge processes.

The olive mill wastewater (OMW) properties impose substantial practical and fiscal difficulties for effective management and dumping. A feasible and practical option is a regulated spreading of OMW into the soil. This study aimed to investigate the sustainable reuse of OMW through land application to enhance soil quality and wheat growth performance under rain-fed conditions. OMW was spread at 20, 40, 60, 80, and 120 m³ ha⁻¹ at two sites. Soil physical and chemical properties were measured after OMW application and after harvest. Wheat growth performance and leaf nutrient content were determined. This study revealed no deleterious influence of OMW application on soil properties and wheat growth at the two locations for all OMW application doses. The OMW land spreading improved significantly wheat growth by increasing the biological yield (BYLD) (8.4 to 36.5%), grain yield (GYLD) (20.1 to 79.4%), and harvest index (HI) (4.2 to 60.2%). Based on the measured soil chemical parameters and wheat grain yield, we can suggest that OMW application rate at 60 m³ ha⁻¹ could improve significantly wheat growth without significant negative impact on soil properties. In conclusion, we recommend using OMW as suggested in this study for wheat. However, still the long-term application of OMW assessment and local legislative adaptation of saving use are necessary.

A novel furnace throat structure was designed to reduce dust particle concentration in the flue gas emitted from the copper smelting industry. A two-stage turbulence model of the furnace throat based on the RNG k-ε model combined with the stochastic trajectory model was developed to analyze the gas flow and particle trajectories in this furnace throat structure. The resulting turbulent flow fields and particle trajectories under different operating conditions were shown and discussed. It indicates that the furnace throat plays an important role in separating the dust particles from the flue gas by applying centrifugal force and subsequent resistance force. Moreover, the effects of the radius of the inner flue, the number of the spiral plate, and the number of the spiral plate turns on the particle collection efficiency were analyzed to optimize the throat structure. The simulation results show that the furnace throat with inner flue radius of 0.05 m, two spiral plates, and two spiral plate turns has the highest particle collection efficiency. Furthermore, a series of experimental tests were conducted to validate the accuracy of the simulation results, and the measured experimental data show a good correlation with the numerical results.

The presence of heavy metals in food is a threat to human health. Exposure to heavy metals as a result of consumption of contaminated vegetables, as well as their toxicity, is a serious problem.Different branches of industry and the road traffic have a significant impact on environmental pollution with heavy metals. Municipal and industrial sewage also is an important source of those substances. Furthermore, the mineral content of vegetables depends on factors such as the natural content of trace elements in the environment, their levels in mineral fertilizers, and fertilizer doses. In the soil, a natural source of these metals is bedrock. In soils used for agricultural purposes, some quantities of metals are introduced together with fertilizers, both organic and mineral. Additionally, another sources of the metals are plant protection products.Heavy metal dynamics in the soil and their uptake by plants are influenced by soil properties, which play a key role in the bioavailability of these metals. Metal mobility and assimilation are also influenced by the addition of organic and inorganic matter. A significant body of evidence also suggest that the age of the soil plays an important role in modulation of metal bioavailability to plants.Apart from being influenced by the soil-related factors, absorption of metals differs in different types of plants. A significant variation in metal concentrations was also found depending on their location in plant tissues, on plant species, or even on varieties of the same species.

The fact that hairdressers are exposed to toxic substances through the handling of creams and smoothing products prompted this study whose aim was to quantify the occupational exposure of hairdressers to formaldehyde by comparing the results of exposure for different types of beauty salon. The study population consisted of 23 beauty salons located in the city of Bauru, São Paulo state, Brazil. The samples were collected by inhaled air tests during the most critical 15-min period of the hair straightening procedure and during the 8-h work shift. The concentrations of formaldehyde contained in the formulations of these products were also evaluated and compared with exposure levels. The results were evaluated according to the exposure limits prescribed in Brazilian (NR15) and North American (US OSHA and US NIOSH) standards. The analysis of the smoothing products showed concentrations of formaldehyde of between 3 and 11% in their compositions, i.e., up to 54 times above the 0.2% limit allowed by the National Agency of Sanitary Surveillance (ANVISA). The present study showed that hairdressers are chronically exposed to high concentrations of formaldehyde in the workplace and these exposures are mainly associated with the work process, where many variables of this process influence the intensity of exposure.

In this study, the impact of the curing temperature on leaching behaviour and durability of GGBS-MgO-CaO (GMC)-stabilized/GMC-solidified Pb/Zn-contaminated clay soils was investigated. Toxicity characteristic leaching procedure (TCLP) test, wetting-drying cycles, freeze-thaw cycles and unconfined compression strength (UCS) test were carried out. The influence of curing temperature, binder dosage and curing time on the performance of these samples was investigated. The results show that the leachability and the durability of all samples were improved by increasing curing temperature, curing time and binder dosage. GMCs are more functional in immobilizing Pb compared with Zn, especially in immobilizing high Pb–contaminated soils. The mass loss and Pb/Zn leachability of all samples increased, while their strength decreased after cyclic wetting-drying and cyclic freeze-thaw. Furthermore, curing at 21 °C and 45 °C, the freeze-thaw resistance of 10% GMC-treated soil (GMC10) was found better than that of 10% Portland cement–treated soil (PC10). After 10 cycles of wetting-drying, GMC10 is more chemically stable than PC10.

This study was conducted to acquire novel insight into differences between bulk (16S rDNA) and metabolically active (16S rRNA) prokaryotic communities in the sediment of a hypereutrophic lake (Japan). In the bulk communities, the class Deltaproteobacteria and the order Methanomicrobiales were dominant among bacteria and methanogens. In the metabolically active communities, the class Alphaproteobacteria and the order Methanomicrobiales and the family Methanosaetaceae were frequently found among bacteria and methanogens. Unlike the bulk communities of prokaryotes, the composition of the metabolically active communities varied remarkably vertically, and their diversities greatly decreased in the lower 20 cm of sediment. The metabolically active prokaryotic community in the sediment core was divided into three sections based on their similarity: 0–6 cm (section 1), 9–18 cm (section 2), and 21–42 cm (section 3). This sectional distribution was consistent with the vertical pattern of the sedimentary stable carbon and nitrogen isotope ratios and oxidation–reduction potential in the porewater. These results suggest that vertical disturbance of the sediment may influence the communities and functions of metabolically active prokaryotes in freshwater lake sediments. Overall, our results indicate that rRNA analysis may be more effective than rDNA analysis for evaluation of relationships between actual microbial processes and material cycling in lake sediments.

Fecal indicator bacteria (FIB) inhabiting stream sediments have become a concern with regard to recreational and irrigation water quality. Sediments contain higher concentrations of E. coli and other FIB than the overlying water column. The objective of this work was to evaluate the effect of temperature oscillations on the populations of both E. coli and enterococci in sediments and the water column. The study was conducted in a microcosm system with flow-through chambers representing a small stream with two different sediment textures. Bovine manure was freshly collected and mixed with both clayey and sandy sediment. Temperatures within the chambers oscillated from 17° to 28 °C which is representative of a diurnal summer temperature range for Maryland; the control chambers were kept at 22 °C. The effect of temperature oscillations differed depending on the sediment texture. Bacterial populations in the sandy sediment immediately increased before net die-off began. Conversely, in the chambers with the clayey sediments, there was no immediate increase in concentrations in the oscillation chambers as compared to the controls. There were significantly higher populations of both E. coli and enterococci within the oscillation sandy texture chambers compared to the control constant temperature chambers; that was not the case in the clayey sediment chambers. The die-off rates in the sandy sediments were greater than those in the clayey sediments; in the latter, bacteria populations remained almost constant throughout the experiment. Temperature oscillations should be simulated in experiments designed to estimate and compare inactivation rates for fecal indicator bacteria in sediments for future inferences on microbial water quality.