Phytostabilization has great practical significance and flexibility in the ecological restoration of mining tailings and remediation of heavy metals polluted soils. However, potential use of metallophytes in phytostabilization is limited by a lack of knowledge of many basic plant processes. A mining ecotype (ME) Athyrium wardii, Pb/Cd phytostabilizer, and a non-mining ecotype (NME) A. wardii were grown in a pot experiment to investigate the chemical characteristics of the rhizosphere when exposed to the Cd polluted soils. Rhizobags were used to collect rhizosphere and bulk soils, separately. The results indicated that the ME A. wardii was more efficient in Cd accumulation in the root than NME after growing in Cd polluted soils for 50 days in a green house. Soil solution pH and dissolved organic carbon (DOC) concentration in the rhizosphere of ME A. wardii were higher than in the bulk soil and initial values (before planting), whereas the increment in the ME A. wardii were greater than NME. Owing to the increasing of rhizosphere soil pH, exchangeable Cd significantly decreased, whereas the other Cd species were increased with increasing soil DOC values. It is assumed that the ME A. wardii was effective in stabilizing Cd from the mobile fraction to non-mobile fractions. Results from this study suggest that rhizosphere alkalinization and the exudation of high amounts of dissolved organic matter (DOM) to reduce heavy metal mobility might be the two important mechanisms involved in the metal tolerance/accumulation of ME A. wardii.

The potential for bioremediation of chromium pollution using bacteria was investigated in this study. Five chromium-removing bacteria strains were successfully isolated from Cr(VI)contaminated soils and identified by their 16S rRNA gene sequences. The optimum growth temperature (30–40 °C) and pH (8.5–11) for the five isolates were investigated. The effect of initial Cr(VI) concentrations (0–1,575 mg L⁻¹) on bacterial growth was also studied. Results showed that Pseudochrobactrum saccharolyticum strain W1 had high chromium-removing ability and could grow at Cr(VI) concentrations from 0 to 1,225 mg L⁻¹. To our knowledge, this is the first report of chromium removal by a member of the Pseudochrobactrum genus. Sporosarcina saromensis W5 had the highest chromium-removing rate of 0.79 mg h⁻¹ mg⁻¹biomass. Exopolysaccharide (EPS) production and components of the five bacteria strains were also investigated, and a positive relationship was found between the bacterial chromium removal and EPS production.

Particles derived from humic acid, as p(HA), are synthesized in a single step via a water-in-oil microemulsion system employing different cross-linkers such as divinylsulfone (DVS), glutaraldehyde (GA), epichlorohydrine (ECH), and adipochloride (AC). The different phenolic groups on humic moieties are connected via these cross-linkers to form particles. The prepared p(HA) particles were successfully used in the removal of toxic organo-phenolic such as phenol (Ph), 4-nitrophenol (4-NPh), 4-chlorophenol (4-CPh), 2-chlorophenol (2-CPh), and 2,3-dichlorophenol (2,3-CPh) from aqueous environments. Various parameters such as pH, contact time, reusability of particles, and the initial concentration of adsorbate are investigated. It is found that the absorption capacity of p(HA) particles for Ph is 180 mg/g, and the maximum absorption amount is obtained at pH 6. Furthermore, the reuse experiments are shown that p(HA) particles can release the absorbed Ph by the treatment of methanol, and an absorption capacity of 85 % is attainable up to five consecutive absorption and release cycles. p(HA) particles are characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) techniques.

Larval black flies (Diptera: Simuliidae), which inhabit streams and rivers, are both filter-feeders and a dominant part of the macroinvertebrate community. As filter-feeders, these insects are potentially an important entrance point for mercury into lotic food webs. The objectives of our study were to (1) document mercury concentrations in the water column, streambed sediments, and larval black fly tissue in select streams in coastal Alabama, USA, over both spatial (among streams) and temporal (across and within season) gradients and (2) determine if levels of mercury in stream ecosystems can be predicted based on stream predictors. Mercury was found consistently in both the black fly larval tissues and streambed sediments but was not detected in the water column. The range of total mercury found in larval tissue and stream sediments varied between 23.73–142.05 and 0.60–56.98 ppb, respectively. Mean mercury levels in both tissue and sediments show significant variation among summer, fall, and spring collections. In addition, mercury levels in tissue and sediments were significantly associated with dissolved oxygen, conductivity, or temperature within a season.

The extracellular polymeric substance (EPS) extracted from waste-activated sludge after short-time aerobic digestion was investigated to be used as a novel biosorbent for Cd²⁺removal from water. The sorption kinetics was well fit for the pseudo-second-order model, and the maximum sorption capacity of the EPS (430.3 mg Cd²⁺/g EPS) was markedly higher than those of the reported biosorbents. Both Langmuir model and Freundlich model commendably described the sorption isotherm. The Gibbs free energy analysis of the adsorption showed that the sorption process was feasible and spontaneous. According to the results of multiple analytical techniques, the adsorption process took place via both physical and chemical sorption, but the electrostatic interaction between sorption sites with the functional groups and Cd²⁺was the major mechanism.

Chemically prepared activated carbon derived from durian seed (DSAC) was used as adsorbent to adsorb Malachite green (MG) dye. The prepared DSAC was characterized using Brunauer–Emmet–Teller (BET), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and proximate analysis, respectively. Batch adsorption studies were carried out for the removal of MG dye from aqueous solutions by varying operational parameters like contact time, initial MG dye concentration, solution temperature, and initial solution pH. Maximum dye removal of 97 % was obtained at pH 8. Experimental data were analyzed by eight model equations—Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Radke–Prausnitz, Sips, Vieth–Sladek, and Brouers–Sotolongo isotherms—and it was found that the Freundlich isotherm model fitted the adsorption data the most. Adsorption rate constants were determined using pseudo-first-order and pseudo-second-order rate equations, Elovich, intraparticle diffusion, and Avrami kinetic model. The results clearly showed that the adsorption of MG dye onto DSAC followed the pseudo-second-order model, and the mechanism of adsorption was controlled both by film diffusion and intraparticle diffusion. Thermodynamic parameters such as ∆G, ∆H, and ∆S were also calculated for the adsorption process. The process was found to be spontaneous and endothermic in nature. This work provided an attractive adsorbent for the removal of MG dye from wastewaters.

The aims of this study were to assess sulfate adsorption in Japanese forest soils and to find and evaluate traces of past heavy anthropogenic sulfur deposition based on the degree of saturation as calculated based on the theoretical adsorption capacity determined by isotherm experiments and the amount of actual adsorbed sulfate. Investigations were conducted at two forest sites, a site in Yokkaichi that is exposed to serious air pollution containing sulfur compounds and a site in Inabu that is unpolluted. The distribution of phosphate-extractable sulfate concentration did not differ between the Yokkaichi site (1.11–13.2 mmol kg⁻¹) and the Inabu site (0.40–11.0 mmol kg⁻¹), and the values were higher than published data for North America and Europe. In contrast, the degree of sulfate saturation in soils of the Yokkaichi site was higher than that in soils of the Inabu site. These results indicate that the degree of sulfate saturation is valuable information for the evaluation of sulfur deposition history. The higher degree of saturation at Yokkaichi site may be due to enhanced sulfate adsorption by soils resulting from substantial past sulfur deposition.

This study focused on the pattern recognition of Malaysian air quality based on the data obtained from the Malaysian Department of Environment (DOE). Eight air quality parameters in ten monitoring stations in Malaysia for 7 years (2005–2011) were gathered. Principal component analysis (PCA) in the environmetric approach was used to identify the sources of pollution in the study locations. The combination of PCA and artificial neural networks (ANN) was developed to determine its predictive ability for the air pollutant index (API). The PCA has identified that CH₄, NmHC, THC, O₃, and PM₁₀are the most significant parameters. The PCA-ANN showed better predictive ability in the determination of API with fewer variables, with R²and root mean square error (RMSE) values of 0.618 and 10.017, respectively. The work has demonstrated the importance of historical data in sampling plan strategies to achieve desired research objectives, as well as to highlight the possibility of determining the optimum number of sampling parameters, which in turn will reduce costs and time of sampling.

This paper presents a comprehensive analysis of the pollutant emissions and intensity from Canada’s power stations. An analysis of National Pollutant Release Inventory (NPRI) and site generation data shows significant variability with the dominant emissions pathway being point-source air emissions. In general, power stations are a very small fraction of Canada’s direct facility and estimated diffuse emissions, as well as showing significant variability of pollutant intensities per megawatt or megawatt hour of capacity or generation. The evidence also suggests that increased scale does not lead to a lower pollutant intensity, and that transfers and disposal pollutant loads are substantial, often representing most of the total reported pollutants. Overall, this study provides a valuable insight into the current status of pollutant intensities from Canada’s power stations, possible improvements to the NPRI and a valuable benchmark for future studies and international comparisons.

To date, studies on the geological conditions in inland aquifers leading to pathways for upwelling deep saline groundwater due to pumping have not been published yet. Therefore, this paper conducted a theoretical modeling study to raise two hypotheses about deep saline-groundwater pathways leading to saltwater upconing below a pumping well in an inland aquifer based on the field situation at the Beelitzhof waterworks in southwestern Berlin (Germany), defined as follows: (1) there are windows in the Rupelian clay caused by glacial erosion, where their locations are uncertain, and (2) there are no windows in the clay, but the clay is partially thinned out but not completely removed by glacial erosion, so salt can merely come through the clay upward by diffusion and eventually accumulate on its top. These hypotheses were tested to demonstrate the impact of the lateral distance between windows in the clay and the well, as well as salt diffusion through the clay depending on its thickness on saltwater intrusion in the pumping well, respectively, using a density-dependent groundwater flow and solute transport model. Hypothesis 1 was validated with four scenarios that windows could occur in the clay at the site, and their locations under some conditions could significantly cause saltwater intrusion, while hypothesis 2 could be excluded, because salt diffusion through the clay with thickness greater than 1 m at the site was not able to cause saltwater intrusion.