Recently, the World Health Organization’s International Association for Research on Cancer classified outdoor air pollution as carcinogenic to humans and puts air pollution in the same category as tobacco smoke, UV radiation, and plutonium. The ambient air is polluted by emissions from motor vehicles, industrial processes, power generation, household combustion of solid fuel, and other sources. Dust storms lead to particulate levels that exceed internationally recommended levels, especially near the Sahara. However, this source of air pollution appears to be under-studied, particularly in the literature devoted to human health impacts in West Africa. More than 50 % of the total dust emitted into the atmosphere comes from the Sahara. These aerosols contribute to increase the concentrations of particles smaller than 10 μm (PM₁₀), which are breathable particles. This study is the first designed to assess the real impact of Saharan dust on air quality and respiratory health of children in a region of West Africa. Dust events having affected the Northern Benin during the dry seasons between 2003 and 2007 were determined. The analyzed health data are the monthly rates of acute lower respiratory infections (ALRI). Over the entire study period, 61 days of dust events were observed in the region. They recorded on average a daily PM₁₀concentration of 1017 μg m⁻³, more than 18 times higher than that calculated on all days without dust events. The study also highlighted a mean increase of 12.5 % of ALRI rates during the months recording dust events. The use of daily health data should help to refine these initial results in the future.

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 Park River watershed (PRW), a sub-basin of the Lower Connecticut River watershed, has experienced increased urbanization over the last century as the city of Hartford and its surrounding towns have grown and developed. We present watershed-wide and outflow scale maps of the trace metals Cd, Cu, Zn, and Pb to determine patterns of contamination in fine (<63 μm) stream sediment. Results are compared to established sediment quality guidelines (SQG) and probable effect concentrations (PEC) for each metal. Throughout the watershed, higher concentrations of trace metals are observed in the more urbanized south branch of the PRW. In this sub-basin, there are more industries that use, and waste, metals in their manufacturing processes that contribute to acutely high concentrations of metals in the fine bedload sediments. Impervious surfaces are examined as well in the context of the entire watershed. While an increase in metals can be attributed to an increase in impervious surfaces, these increases do not generally exceed SQGs and PECs. Two focused mapping studies were conducted at the storm water outflow of the West Hartford Landfill and the Trout Brook Sanitary Sewer Overflow (SSO). The purpose of these studies was to analyze the local effects of natural stream features such as channel bar deposits next to the outfalls. We determined that the sediment directly below the two outfalls often exceeded the PEC, while the accumulated sediment around the channel bar deposits was not contaminated beyond background stream levels. We believe mapping at both the small (watershed) and large (outfall) scale can be helpful in future urban studies to determine the extent of trace metal sediment contamination in both channelized and natural sections and may provide a useful method for sediment mitigation endeavors.

A novel mesoporous, nanocomposite, magnetically separable adsorbent, namely activated alumina (γ-Al₂O₃)/ferrite (Ni₀.₅Zn₀.₅Fe₂O₄) microfibers have been successfully prepared by the sol–gel process. These nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers are formed after calcination of the precursor at 450 °C for 3 h, and characterized with high aspect ratios and uniform diameters of 1–10 μm. In the nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers, the spherical γ-Al₂O₃particles are homogeneously embedded on the microfiber. Their specific surface areas and magnetic properties are significantly influenced by the γ-Al₂O₃content and calcination conditions. With the designed γ-Al₂O₃mass fraction of 0.2 and the calcination temperature of 550 °C, the γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers possess a high specific surface area of 118.3 m²/g and saturation magnetization (Mₛ) of 20.4 Am² kg⁻¹, respectively. The adsorption behaviors of the nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers were examined using the Congo red and methyl blue dyes as the adsorbate. The adsorption kinetics, effects of the adsorbent dosage and solution pH, adsorption isotherms, and regeneration of the microfiber adsorbents were investigated. The pseudo-second-order model can be used to describe the adsorption kinetics. The resultant isotherm data are well fitted by the Temkin model, implying that the dyes adsorption on the γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers is a multilayer adsorption combined with some degrees of chemical interactions. Considering the simple synthesis process, high adsorption and unique magnetic property, these mesoporous, magnetic, nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers can be used as a highly efficient, fast, and convenient adsorbent for dyes removal.Highlights The magnetic mesoporous Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers were synthesized. Adsorption kinetics and adsorption isotherms were investigated. The separation, regeneration, and adsorption efficiency were enhanced.

Nanoscale zero-valent iron (nZVI) was synthesized and used for the removal of Sb(III) and Sb(V) from aqueous solutions. Results showed that more than 90 % of antimony would be removed in 15 min and that all of antimony could be removed with appropriate nZVI dosage in 90 min. The influence of pH value and possible impurities was investigated. The pH of 4 was found as the optimum pH. Discussion and speculation about the mechanism were presented according to X-ray photoelectron spectroscopy and transmission electron microscopy data. A sheet-like structure was observed after a 90-min reaction, and antimony was detected on the surface by energy-dispersive X-ray spectroscopy. Both Sb(III) and Sb(V) partially reduced in the process. The presence of humic acid transformed the morphology of nZVI but barely influenced the removal efficiency. Competing ions showed diverse influence between Sb(III) and Sb(V). The overall results indicated that nZVI was an efficient and suitable material for the removal of antimony.

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.

The comparative effectiveness for hexavalent chromium reduction and removal from irrigation water, using three selected plant species (Phragmites australis, Salix viminalis, and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. The above plant species were irrigated, in a continuous mode, with water, contaminated with 10 mg/L of hexavalent chromium. Hexavalent chromium and total chromium have been measured in all plant tissues species and in the drainage water. Total chromium removal from water was ranging from 56 % (Phragmites) to 70 % (Salix). After 360 days of growth, the chromium content of the contaminated soil dropped from 70 (initial) to 32, 36, and 41 mg Cr/kg₍dᵣy ₛₒᵢₗ₎, for Salix, Phragmites, and Ailanthus, respectively. Salix and Phragmites accumulated the highest amount of chromium in the roots (2,029 and 1,800 mg Cr/kg₍dᵣy ₜᵢₛₛᵤₑ₎, respectively), compared with 358 mg Cr/kg₍dᵣy ₜᵢₛₛᵤₑ₎for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Crⱽᴵreduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems, while Salix indicated the highest chromium translocation from roots to leaves. Toxicity effects, expressed as root growth rate inhibition, indicated that Salix is the most chromium-tolerant species, with Ailanthus in the antipode.

The distribution of selected elements in individual fractions of organic matter from anthropogenically contaminated soils was investigated. The attention was paid especially at Hg. Furthermore, contents of S, Mg, Mn, Fe, Cu, Zn and Pb were also measured. The decomposition of organic matter to particular fractions was carried out by the resin DAX-8. Ten soil samples were collected, and the Advanced Mercury Analyzer (AMA-254) was used for the determination of the total Hg content. The two highest Hg values reached up to the concentration 10.5 mg kg⁻¹, and in the highest one, it was almost 29 mg kg⁻¹. In each extract, mercury was measured by inductively coupled plasma mass spectrometry (ICP-MS), for other elements, inductively coupled plasma optical emission spectrometry (ICP-OES) was applied. Results of the analysis show that the Hg content bound to the humic acids is inversely proportional to the content of Mg, Mn, Fe and Cu. However, this dependence was not confirmed by the samples with the mercury content above 10 mg kg⁻¹. In the case of fulvic acids, the relationship between Hg and S was observed and has again an inverse character.

Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 μg L⁻¹) for an initial concentration of 1,000 μg L⁻¹. Maximum capacity at pH 4 and 17 % iron was 18.12–40.82 mg of arsenic/g of D-Fe and at pH 4 and 10 % iron was 18.48–29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10 % and 17 % iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.

The main purpose of this study was to evaluate the mercury (Hg) bioaccumulation in the Egyptian mongoose (Herpestes ichneumon), a terrestrial predator species with an essential role in the Iberian ecosystems food chain. Differences between males and females and the effect of age in mercury body burdens were studied, as well as the geographical distribution of mercury in tissues of the studied species. Total mercury (T-Hg) was determined in muscle, liver, lungs, heart, spleen, kidneys, blood, brain, fat and pelage of the Egyptian mongoose from 14 locations, encompassing the distribution range of the element in the species. In order to study differences between ages, males and females, 20 individuals from one sampling location were analysed. Total mercury concentrations ranged between 0.01 and 13 μg g⁻¹(dry weight (dw)) and followed the order from the least to the most contaminated: fat < brain < lungs < heart < spleen < muscle < kidneys < liver < pelage < blood. Differences between males and females were only significant for muscle and pelage mercury levels, suggesting uptake rates and metabolic processes to be similar between genders. Despite a similar accumulation pattern with age between males and females, differences between ages were significant only for females, as a result of a higher range of male mercury body burdens. Organic mercury (O-Hg) was analysed in muscle and liver, and its percentage ranged from 83 to 96 %, reflecting the high trophic level of the species. None of the observed mercury levels reached the lethal or toxic values established for terrestrial predators (20 to 100 μg g⁻¹wet weight), suggesting that despite its predatory position in terrestrial food webs, the risk of mercury associated toxicity is low.