With industrialization, great amounts of trace elements and heavy metals have been excavated and released onto the surface of the earth and dissipated into the environments. Rapid screening technology for detecting major and trace elements as well as heavy metals in variety of environmental samples has been most desired. The objectives of this study were to determine the detection limits, accuracy, repeatability, and efficiency of an X-ray fluorescence spectrometer (Niton XRF analyzer) in comparison to the traditional analytical methods, inductively coupled plasma optical emission spectrometer (ICP-OES) in screening of major and trace elements of environmental samples including estuary soils and sediments, contaminated soils, and biological samples. XRF is a fast and non-destructive method for measuring the total concentration of multi-elements simultaneously. Contrary to ICP-OES, XRF analyzer is characterized by the limited preparation required for solid samples, non-destructive analysis, increased total speed and high throughout, decreased production of hazardous waste, and low running costs as well as multi-elemental determination and portability in the fields. The current comparative study demonstrates that XRF is a good rapid, non-destructive screening method for contaminated soils, sediments, and biological samples containing high concentrations of major and trace elements. Unfortunately, XRF does not have sensitive detection limits for most trace elements as ICP-OES, but it may serve as a rapid screening tool for locating hot spots in uncontaminated field soils and sediments, such as in the US Department of Energy’s Oak Ridge site.

The adsorption capacities of six biosorbents (Pseudomonas aeruginosa, Pseudomonas fluorescens, Escherichia coli, Chlorella vulgaris, and Spirulina platensis) for Zn(II) ions under batch condition have been studied. The optimum pH range was found to be 5.0−6.0. The amount of adsorbed Zn(II) ions were between 18 and 128 mg/g. Characterization of biosorption equilibrium was evaluated with Langmuir and Dubinin-Radushkevich model using non-linear regression. The adsorption capacities of Ca-alginate, chitosan, and immobilized Spirulina platensis-maxima cells were also determined in packed-bed column in continuous system. The results show, free Spirulina cells have the highest adsorption capacity for Zn(II) ions (128 mg/g). The chitosan-Spirulina system has slightly decreased adsorption capacity 98 mg/g per dry weight content. Thomas and Yoon-Nelson models were fitted for the evaluation of experimental data.

The carbon balance of secondary dry tropical forests of Mexico’s Yucatan Peninsula is sensitive to human and natural disturbances and climate change. The spatially explicit process model Forest-DeNitrification-DeComposition (DNDC) was used to estimate forest carbon dynamics in this region, including the effects of disturbance on carbon stocks. Model evaluation using observations from 276 sample plots in a tropical dry forest in the Yucatan Peninsula indicated that Forest-DNDC can be used to simulate carbon stocks for this forest with good model performance efficiency. The simulated spatial variability in carbon stocks was large, ranging from 5 to 115 Mg carbon (C) ha⁻¹, with a mean of 56.6 Mg C ha⁻¹. Carbon stocks in the forest were largely influenced by human disturbances between 1985 and 2010. Based on a comparison of the simulations with and without disturbances, carbon storage in the year 2012 with disturbance was 3.2 Mg C ha⁻¹, lower on average than without disturbance. The difference over the whole study area was 154.7 Gg C, or an 8.5 % decrease. There were substantial differences in carbon stocks simulated at individual sample plots, compared to spatially modeled outputs (200 m²plots vs. polygon simulation units) at some locations due to differences in vegetation class, stand age, and soil conditions at different resolutions. However, the difference in the regional mean of carbon stocks between plot-level simulation and spatial output was small. Soil CO₂and N₂O fluxes varied spatially; both fluxes increased with increasing precipitation, and soil CO₂also increased with an increase in biomass. The modeled spatial variability in CH₄uptake by soils was small, and the flux was not correlated with precipitation. The net ecosystem exchange (NEE) and net primary production (NPP) were nonlinearly correlated with stand age. Similar to the carbon stock simulations, different resolutions resulted in some differences in NEE and NPP, but the spatial means were similar.

This study was performed to evaluate the ability of white-rot fungi to decolorize dye effluents. A total of 222 isolates of white-rot fungi were initially investigated to assess their ability to decolorize chemically different synthetic dyes in solid medium, resulting in selection of 25 isolates including four isolates of Berkandera adusta, five isolates of Ceriporia lacerata, three isolates of Irpex lacteus, one isolate of Perenniporia fraxinea, ten isolates of Phanerochaete spp., one isolate of Phlebia radiata, and one isolate of Porostereum spadiceum. Of the 25 isolates, B. adusta KUC9065, C. lacerata KUC8090, P. calotricha KUC8003, and P. spadiceum KUC8602 were finally selected on the basis of their ability to decolorize synthetic dyes in liquid medium, and were used to decolorize industrial effluents. B. adusta KUC9065 increased the transmittance of visible light by 71–92 %. Decolorization of wastewater by B. adusta KUC9065 was probably caused by the lignin-modifying enzymes produced by the fungus. In addition, the acute toxicity to Daphnia magna decreased from 2.5 to 2.1 and from 3.5 to 2.6 toxic units over 24 and 48 h, respectively.

Pirina, a waste of olive oil factory, was used as an adsorbent for the removal of remazol brilliant blue R (RBBR) from aqueous solution by adsorption process. The pirina was pretreated with HNO₃before batch adsorption experiments. The effects of contact time, initial concentration, pH, temperature, and ionic strength on dye removal were investigated. While the amount of the dye removed by the pirina was increasing with increasing initial concentration and temperature, it decreased with an increase in pH. Moreover, commercial activated carbon (CAC) was also used to compare with the pirina in removing the RBBR. The maximum amounts of the RBBR removed by the pirina and the CAC were 23.63 and 199.45 mg g⁻¹per unit mass of the adsorbents, and the removal efficiencies of them were found as 94.52 and 99.72 %, respectively. Ionic strength in the presence of NaCl and KCl had also a reducing effect on the removal efficiency. The adsorption isotherm was in the best harmony with Langmuir, Freundlich, and Temkin models. The adsorption kinetic obeyed the pseudo-second-order and the intra-particle diffusion models. The values of the r²from the pseudo-second-order kinetic and intra-particle diffusion were between 0.984–0.999 and 0.85–0.996, respectively. From thermodynamic studies, it was seen that the adsorption was of spontaneous and endothermic nature. The values of ΔG° of the adsorption were between −3,218 and −8,867 J mol⁻¹. The values of ΔH° and ΔS° were 50,134 J mol⁻¹and 179 J mol⁻¹ K⁻¹, respectively. Moreover, SEM and FT-IR studies were also performed.

During this study, the effect of applying several types of treated domestic wastewater on the translocation and accumulation of organic and inorganic micropollutants in soil and radish plants (Raphanus sativus L.) was examined. Primary (PTW), secondary (STW) and tertiary (TTW) treated wastewater as well as tap water (TW) were used for the irrigation of radish plants for a period (transplantating and harvesting) of 67 days. Higher concentrations of polycyclic aromatic hydrocarbons (PAHs) were observed in soils irrigated with PTW. The concentration of PAHs in radish roots ranged between 107.6 ± 12.1 μg/kg for plants irrigated with TTW and 124.1 ± 17.7 μg/kg for plants irrigated with PTW. The root concentration factors (RCFs) expressed as the ratio of PAH concentration in the root mass (dry weight) to the residual concentration in the soil varied from 1.6 to 1.9 indicating a higher accumulation of PAHs in the edible part of radishes than soil. Heavy metals were not detected in the wastewaters utilised and, as a result, no accumulation was found in either the soil or plants in comparison with tap water. RCFs for heavy metals were calculated between 0.91 and 0.99, 0.49 and 0.66, 0.004 and 0.005 for Cu, Zn and Ni, respectively. The results showed that radishes have the ability to concentrate PAHs when they are present in the wastewater and this could have associated health risks.

The transformation of less toxic Cr(III) species to harmful Cr(VI) is worth concerning. Compared with free Cr(III), however, the photo-oxidation of Cr(III)–organic acid complexes is seldom reported. In this study, Cr(III)–malate complex was synthesized and purified, and its photo-oxidation was investigated to reveal the potential conversion pathway of Cr(III) to Cr(VI). The results indicated that Cr(III)–malate complex could be gradually photo-oxidized to Cr(VI) through a ligand–metal charge transfer path. Higher pH and stronger light intensity promoted the conversion process. A 50-μM Cr(III)–malate complex was almost completely oxidized to Cr(VI) within 420-min irradiation of 500 W medium-pressure mercury lamp at pH 12. The introduction of H₂O₂, considered as a direct source of hydroxyl radicals (·OH) in the presence of Cr(II), markedly enhanced the yield of Cr(VI), and a complete oxidation of Cr(III)–malate complex (50 μM ) was realized within 20 min. Under a weak acidic condition, the production of Cr(VI) was coupled with the reduction of Cr(VI) by malic acid and its free radical generated from Cr(III)–malate complex, leading a gradual decrease in Cr(VI) concentration with the reaction.

Microcystis aeruginosa, the most common toxic cyanobacterial bloom, could cause severe environmental problem by producing and releasing lethal cyanobacterial toxins to water body. This study investigated the electron beam irradiation for the inactivation of M. aeruginosa. The treatment process was monitored via the measurement of chlorophyll a concentration, optical density, photosynthesis, and antioxidant enzymes. At low electron beam irradiation dose (1.0 kGy), its performance is not desirable. High dosage of electron beam irradiation (2.0–5.0 kGy) can dramatically decrease chlorophyll a concentration, optical density, and photosynthesis rate and affect activities of antioxidant enzymes. The transmission electron microscopy measurement indicates that electron beam irradiation treatment cause significant damages on integrity and morphology. Our results demonstrate that electron beam irradiation is a promising technique for quick and efficient inactivation of M. aeruginosa in aqueous solution.

The aim of the present study was the decolourisation of mixture of two dyes belonging to different groups by two Pseudomonas fluorescens strains (Sz6 and SDz3). Influence of different incubation conditions on decolourisation effectiveness was evaluated. Dyes used in the experiment were diazo Evans blue (EB) and triphenylmethane brilliant green (BG). Another goal of the experiment was the estimation of toxicity of process by-products. Incubation conditions had a significant influence on the rate of decolourisation. The best results were reached in shaken and semistatic samples (exception Evans blue). After 24 h of experiment in semistatic conditions, BG removal reached up to 95.4 %, EB 72.8 % and dyes mixture 88.9 %. After 120 h, all tested dyes were completely removed. In most cases, dyes were removed faster and better by strain Sz6 than SDz3. At the end of the experiment, in majority of the samples, decrease of phyto- and zootoxicity was observed.

Cemented paste backfill has been proposed in the mining industry for managing metal mill tailings. Low sulfide tailing (0.49 wt%) samples were prepared into different cemented pastes that were mixed with flocculants (polymerized aluminum chloride). The best mixing proportions of tailings, binder, flocculant, and filling structure (containing 0.5 wt% of ordinary Portland cement in one paste layer, 100 g/L polymerization aluminum chloride) were determined through leaching experiment. The addition of polymerization aluminum chloride improved the mechanical property of the paste. The strength of the cemented pastes by adding 100 g/L flocculant met the requirement of mine backfill. The cemented paste could also fix heavy metals, as shown in the paste leachate analysis of copper (Cu, about 0.01–0.08 mg/L of concentration) and chromium (Cr, about 0.03 mg/L of concentration). In summary, results from this study demonstrate that tailings can be managed by cemented paste backfill technique, preventing its contamination of the environment.