The drastic desiccation of the Aral Sea has led to severe desertification of the former lake areas. Dust storms occur frequently, causing regional environmental degradation of the Aral basin and a serious ecological disaster. Knowledge of the temporal variability in dust emissions and the potential diffusion characteristics of dust aerosol originating from the Aral Sea basin in recent years are, however, lacking. To address this knowledge gap, we studied the interannual and intraannual changes in dust aerosol from the Aral Sea basin and its potentially seasonal diffusion characteristics from 2005 to 2013 using Ozone Monitoring Instrument (OMI) aerosol data (2005–2013) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Results show that the OMI aerosol index (AI) annual mean, standard deviation, median, and maximum values exhibit a strong increasing trend because of the continuous decrease in the water level since 2005. The annually mean OMI AI increases to 1.47 by 2013. Peak AI values are recorded in spring (March–May) and early winter (November–January of the following year), indicating notifying seasonal differences. The potential distance and height of air parcel trajectories to the northeast are greater than those to the west and south, whereas the air parcel trajectory proportion of the former is lower than that of the latter. The potential transport distance of dust aerosol to the northeast is greatest in spring and winter. This transport distance is less in autumn, with the minimum observed in summer. Dust transport distance to the west and south in different seasons is not significantly different. The present results may help in further understanding the emission, long-range transport, and deposition of dust from the dry lake bed of the Aral Sea as well as providing a motivation for the sensible use and protection of these tail-end lakes.

Returning crop residue may result in nutrient reduction in soil in the first few years. A two-year field experiment was conducted to assess whether this negative effect is alleviated by improved crop residue management (CRM). Nine treatments (3 CRM and 3 N fertilizer rates) were used. The CRM treatments were (1) R0: 100 % of the N using mineral fertilizer with no crop residues return; (2) R: crop residue plus mineral fertilizer as for the R0; and (3) Rc: crop residue plus 83 % of the N using mineral and 17 % manure fertilizer. Each CRM received N fertilizer rates at 270, 360, and 450 kg N ha⁻¹ year⁻¹. At the end of the experiment, soil NO₃-N was reduced by 33 % from the R relative to the R0 treatment, while the Rc treatment resulted in a 21 to 44 % increase in occluded particulate organic C and N, and 80 °C extracted dissolved organic N, 19 to 32 % increase in microbial biomass C and protease activity, and higher monounsaturated phospholipid fatty acid (PLFA):saturated PLFA ratio from stimulating growth of indigenous bacteria when compared with the R treatment. Principal component analysis showed that the Biolog and PLFA profiles in the three CRM treatments were different from each other. Overall, these properties were not influenced by the used N fertilizer rates. Our results indicated that application of 17 % of the total N using manure in a field with crop residues return was effective for improving potential plant N availability and labile soil organic matter, primarily due to a shift in the dominant microorganisms.

The morphological, physiological, and biochemical parameters of 6-week-old seedlings of Scots pine (Pinus sylvestris L.) were studied under deficiency (1.2 nM) and chronic exposure to copper (0.32, 1, 2.5, 5, and 10 μM CuSO₄) in hydroculture. The deposit of copper in the seed allowed the seedlings to develop under copper deficiency without visible disruption of growth. The high sensitivity of Scots pine to the toxic effects of copper was shown, which manifested as a significant inhibition of growth and development. The loss of dominance of the main root and a strong inhibition of lateral root development pointed to a lack of adaptive reorganization of the root system architecture under copper excess. A preferential accumulation of copper in the root and a minor translocation in aerial organs confirmed that Scots pine belongs to a group of plants that exclude copper. Selective impairment in the absorption of manganese was discovered, under both deficiency and excess of copper in the nutrient solution, which was independent of the degree of development of the root system. Following 10 μM CuSO₄ exposure, the absorption of manganese and iron from the nutrient solution was completely suppressed, and the development of seedlings was secured by the stock of these micronutrients in the seed. The absence of signs of oxidative stress in the seedling organs was shown under deficiency and excess of copper, as evidenced by the steady content of malondialdehyde and 4-hydroxyalkenals. Against this background, no changes in total superoxide dismutase activity in the organs of seedlings were revealed, and the increased content of low-molecular-weight antioxidants was observed in the roots under 1 μM and in the needles under 5 μM CuSO₄ exposures.

Treatability studies in real contaminated soils are essential to predict the feasibility of microbial consortium augmentation for field-scale bioremediation of contaminated sites. In this study, the biodegradation of a mixture of seven PAHs in a manufactured gas plant (MGP) soil contaminated with 3967 mg kg⁻¹ of total PAHs using novel acid-, metal-tolerant, N-fixing, P-solubilizing, and biosurfactant-producing LMW and HMW PAH-degrading bacterial combinations as inoculums was compared in slurry- and solid-phase microcosms over natural attenuation. Bioaugmentation of 5 % of bacterial consortia A and N in slurry- and solid-phase systems enhanced 4.6–5.7 and 9.3–10.7 % of total PAH degradation, respectively, over natural attenuation. Occurrence of 62.7–88 % of PAH biodegradation during natural attenuation in soil and slurry illustrated the accelerated rate of intrinsic metabolic activity of the autochthonous microbial community in the selected MGP soil. Monitoring of the total microbial activity and population of PAH degraders revealed that the observed biodegradation trend in MGP soil resulted from microbial mineralization. In the slurry, higher biodegradation rate constant (k) and lower half-life values (t ₁/₂) was observed during bioaugmentation with consortium N, highlighting the use of bioaugmentation in bioslurries/bioreactor to achieve rapid and efficient bioremediation compared to that of a static solid system. In general, natural attenuation was on par with bioaugmentation. Hence, depending on the type of soil, natural attenuation might outweigh bioaugmentation and a careful investigation using laboratory treatability studies are highly recommended before the upscale of a developed bioremediation strategy to field level.

A hazard assessment was conducted of contaminants found at inflow and outflow monitoring stations of the Water Conservation Areas (WCAs) in South Florida. WCAs (1, 2A, 2B 3A, 3B) lie north of Everglades National Park (ENP) and southeast of Lake Okeechobee, span almost 1400 mi², and serve a number of water resource functions which include food control for three major counties, delivering water to ENP, and water storage during dry downs and for recharging groundwater. Measured concentrations of contaminants in sediment and water were evaluated at 13 monitoring stations in the WCAs using a screening benchmark approach. Chemicals of potential ecological concern (COPECs) included herbicides, organochlorine pesticides, organochlorine industrial chemicals, and heavy metals. Of the stations, total cadmium was a COPEC at nine of them. Most sites had maximum detected concentrations of cadmium that exceeded state of Florida (USA) water quality criteria standards. Beryllium, copper, mercury, methylmercury, and zinc (measured as total metal concentration) also exceeded surface water criteria at several sites. Several organochlorine chemicals in sediment were COPECs; chlordane, polychlorinated biphenyls, and p,p′-DDT with its metabolites (p,p′-DDD and p,p′-DDE) had more than 200 sediment benchmark exceedences. Mercury in fish tissue was a COPEC at S5A when compared to a no-effect residue value for survival. Greater potential hazards were observed at northern monitoring sites than southern sites around the WCAs. The hazard assessment approach for screening water quality data described in this article can help focus higher tier risk assessment work, including laboratory, field, and data analysis studies, on contaminants with greater potential for adverse biological effects.

Adsorption of arsenic (III, V) from aqueous solution onto the synthesized α-Fe₂O₃/MCM-41 nanocomposite adsorbent, as function of contact time, initial concentration of the solution, temperature, pH, and presence of other anionic species, has been investigated. Characterization of adsorbent was performed via XRD, FT-IR, TGA, TEM, and N₂ adsorption–desorption techniques. The synthesized adsorbent belonged to the group of mesoporous materials with the mean pore diameter of 2.37 nm, specific surface area of 507.5 m² g⁻¹, and total pore volume of 0.571 cm³ g⁻¹. The experimental data were analyzed by Langmuir, Freundlich, and Dubinin-Radushkevich (D–R) adsorption isotherms. Based on Langmuir isotherm, the maximum adsorption capacities at 298 K in the concentration range of 2–200 ppm were 133.3 and 102.1 mg g⁻¹ for As(ш) and As(v), respectively. The adsorption experiments at different contact times indicated that the kinetics of adsorption accurately followed the pseudo-second-order rate equation. Thermodynamics parameters were calculated, and it was found that the adsorption process was spontaneous, exothermic, and favored at lower temperatures. The capability of regeneration and reusability of adsorbent was also examined in alkaline solutions.

The effect of direct current (DC) on phenol biodegradation under aerobic/anaerobic condition was investigated in this study using a bioelectrochemical reactor. It was found that phenol biodegradation was inhibited with current ranged from 10 to 40 mA. The growth of biomass was reduced to 43.2 ± 6.6 % for aerobic sludge and 38.6 ± 7.3 % for anaerobic sludge, but the loosely bound extracellular polymer substances (LB–EPS) were increased 91.2 ± 1.3 % for aerobic sludge and 62.8 ± 0.8 % for anaerobic sludge as the current increased from 10 to 40 mA. Adenosine triphosphate (ATP) content of aerobic sludge was also reduced 0.481 ± 0.04-fold and 0.512 ± 0.05-fold lower and 1.34 ± 0.13-fold higher than that of the control when the current was increased from 10 to 40 mA. The results of phosphate buffer saline adding treatment indicated that lower pH caused by a DC above 10 mA was responsible for the reduced phenol biodegradation, leading to the reduction of biomass. However, lower intensity of current (5 mA) had no significant impact on phenol degradation rate, pH, LB–EPS, ATP content, and cell growth of aerobic/anaerobic sludge. These results give us a more detailed understanding of the effects of electricity on the treatment of phenol containing wastewater.

Adsorption of six neutral (chlorpyrifos, α-endosulfan, fenthion, parathion, parathion metyl, and cis permethrin) and six basic (pirimicarb, prochloraz, prometryn, pirimiphos ethyl, quinoxyfen, and triadimefon) pesticides was measured in ten natural soils in order to unravel the parameters influencing soil sorption. Linear regression confirmed that organic carbon content of soil is the determinant factor of soil sorption along with a secondary role of clay in the case of basic pesticides. Concerning pesticides themselves, their potential to be absorbed is governed by hydrophobic, electrostatic, and polar interactions. Electrostatic interactions can be expressed by considering the molecular fraction of positively charged species (F⁺). The combination of these parameters led to good prediction models, where the two expressions of lipophilicity, octanol-water partition (logP) and distribution coefficient (logD), showed similar performance. Finally, the role of electrostatic interactions to soil sorption and their successful expression by F⁺ parameter was further confirmed using artificial adjustment of the acidity of one soil at different pH values not covered by the natural acidity of the investigated soils.

Selenium is an essential trace element for many organisms, including humans, but it is bioaccumulative and toxic at higher than homeostatic levels. Both selenium deficiency and toxicity are problems around the world. Mines, coal-fired power plants, oil refineries, and agriculture are important examples of anthropogenic sources, generating contaminated waters, and wastewaters. For reasons of human health and ecotoxicity, selenium concentration has to be controlled in drinking-water and in wastewater, as it is a potential pollutant of water bodies. In this regard, in the present study, the ability of sunflower (Helianthus annuus L.) to tolerate and accumulate selenium was assessed in hydroponic culture as a model of rhizofiltration system. Selenium content and the chlorophyll parameters of sunflower plant treated using different concentrations of selenium in two forms of sodium selenite and sodium selenate were measured to clarify (1) the response of sunflower to selenium tolerance capacity and (2) the relationship between selenium, chlorophyll fluorescence parameters, and photosynthetic pigments contents. The results showed that selenium content in sunflower plants significantly increased by increasing added selenium levels. Furthermore, Chl a and b were not impaired after 3 weeks from selenium exposure up to 3 mg L⁻¹ for both selenite and selenate. Moreover, sunflower plants have a high selenium tolerance capacity for hydroponic clean-up. Translocation of selenate from sunflower roots to shoots was easier comparing with selenite in concept of phytoremediation processes.

By convention, airborne particles ≤0.1 μm (100 nm) are defined as ultrafine particles (UFPs). UFPs can comprise a large number of particles in particulate matter with aerodynamic diameters ≤2.5 μm (PM₂.₅). Despite the documented respiratory health effects of PM₂.₅ and concerns that UFPs might be more toxic than larger particular matter, the effects of UFPs on the respiratory system are not well-described. Even less is known about the respiratory health effects of UFPs among particularly vulnerable populations including children. We reviewed studies examining respiratory health effects of UFPs in children and identified 12 relevant articles. Most (8/12) studies measured UFP exposure using central ambient monitors, and we found substantial heterogeneity in UFP definitions and study designs. No long-term studies were identified. In single pollutant models, UFPs were associated with incident wheezing, current asthma, lower spirometric values, and asthma-related emergency department visits among children. Also, higher exhaled nitric oxide levels were positively correlated with UFP dose among children with asthma or allergy to house dust mites in one study. Multivariate models accounting for potential copollutant confounding yielded no statistically significant results. Although evidence for a relationship between UFPs and children’s respiratory is accumulating, the literature remains inconclusive. Interpretation of existing data is constrained by study heterogeneity, limited accounting for UFP spatial variation, and lack of significant findings from multipollutant models.