A study was undertaken using urban soils in Detroit, MI and reference materials (cerussite, anglesite, pyromorphite, apatite, goethite, calcite, pyrolusite, and peat) to determine which geochemical forms of Pb measured by sequential extraction analysis are bioaccessible. The results suggest that the water soluble (Pb-fulvic acid complexes), exchangeable, and part of the carbonateoccluded fractions are bioaccessible. The Fe oxideoccluded, Mn oxide-occluded, and higher molecular weight component of the organically bound fraction are not bioaccessible. Sequential extraction predicts the presence of detectable levels of bioaccessible Pb in the rhizosphere when the summed total is ≥90 mg kg-1 and labile Pb is ≥30 mg kg-1. Cerussite (paint-Pb) and anglesite (auto-Pb), recovered mainly in the carbonateoccluded fraction, may cause an overestimation of calcite-Pb. Pyromorphite and apatite Pb (bone) may cause an overestimation of Fe oxide-occluded Pb. © Springer Science+Business Media Dordrecht 2013.

The potential risk of surface and groundwater contamination by the heavy metals and radionuclides leached from uranium waste-rock piles (UWRP) is a major environmental concern in the uranium-mining district of Northern Saskatchewan, Canada. The main objective of this study was to evaluate the nickel and uranium leaching behaviour in the UWRP lithological materials. In addition to the chemical characterization, these selected UWRP geomedia samples were also subjected to the sequential extraction procedure, availability test to quantify leaching potential and cumulative leaching test (CLT). Sequential extractions results demonstrated substantial observed differences in the Ni and U distribution patterns among various operationally defined geochemical fractions. A large fraction of total Ni concentration was associated with non-labile residual fraction while U was mainly present in the labile fractions. The observed labile Ni and U concentrations also remained relatively high in the gneissic basement materials and underlying organic-rich lake sediment. In case of basement materials, both Ni and U concentrations in solution with the first CLT fraction exceeds their maximum permissible levels in both surface and groundwater. Leaching test results confirmed that Ni and U leachability depends on their total content distribution in various solid phase fractions, and several geochemical processes are controlling the solubility of Ni and U geochemical phases in the UWRP. Our experimental data suggest the potential for a long-term risk to surface and groundwater contamination from these UWRP.

We studied the isotopic composition of organic matter in the sediments of eight mountain lakes located in the Tatra Mountains (Western Carpathians, Poland). The sediments of the lakes were fine and course detritus gyttja, mud, and sand. The total organic carbon content varied from 0.5 to 53 %. The C/N ratio indicated that in-lake primary production is the major source of the organic matter in the lakes located above the treeline, whereas terrestrial plant fragments are the major organic compounds in the sediments of dystrophic forest lakes. We also found that a clear trend of isotopic curves toward lower values of δ ¹³C and δ ¹⁵N (both ~3 ‰) began in the 1960s. This trend is a sign of the deposition of greater amounts of NO ₓ from the combustion of fossil fuels, mainly by vehicle engines. The combustion of fossil fuels in electric plants and other factories had a smaller influence on the isotopic composition. This trend has been weaker since the 1990s. Animal and human wastes from pastures and tourism had a surprisingly minor effect on lake environments. These data are contrary to previous data regarding lake biota and suggest the high sensitivity of living organisms to organic pollution.

A first-to-date comprehensive climatological aspect of the regime of aerosol loading over the entire broader Greek region (19 E-30 E and 34 N-43 N) is obtained using pixel-level (50 km × 50 km) monthly aerosol optical depth (AOD) products derived from raw Level-2 (10 km × 10 km) MODIS-Terra AOD data at 550 nm. The AOD climatology (for the 8-year period from March 2000 to February 2008) indicates that the study region is significantly loaded by aerosols (mean regional AOD equal to 0.196 ± 0.030 on an annual basis, with values ranging from 0.126 up to 0.382 at pixel level). It is also found that our high-resolution AOD data can reveal spatial patterns that are not evident in studies based on lower resolution data. There is a distinct longitudinal gradient of AODs, with higher values in the eastern than western part of the Greek peninsula. There is also a strong latitudinal gradient with decreasing values from south to north attributed to the presence of the Sahara Desert in northern Africa. The annual AOD cycle presents double maximum values, in spring and summer, and minimum ones in winter. There is also a remarkable year-by-year variability of AOD levels, especially as to their maxima, influenced by varying transport of desert dust, from the south, or biomass burning aerosols, from the north, to the region under prevailing favorable synoptic conditions. In this work, the processing, consisting in averaging over space and time, is done applying/testing five different criteria varying in their flexibility/severity in both spatial and temporal data availability. The criteria selection affects the magnitude of computed regional mean AOD value modifying it by up to 19 %, although the patterns of geographical distribution of AOD and its intra-annual variability do not change drastically. © 2013 Springer Science+Business Media Dordrecht.

Aquaculture wastewaters, with oleic acid (C18:1 ω9) as the most representative contaminant fatty acid, were used as inoculum to perform enrichment cultures in mineral medium in the presence of oleic acid as the sole carbon and energy source, allowing isolation of four bacterial strains named DG1a, DG2a, DG1b and DG2b. 16S rRNA gene sequencing analysis assigned the four isolates to the species Pseudomonas aeruginosa. Among the isolates, P. aeruginosa strain DG2a showed degradation of fatty acids, including oleic acid (C18:1 ω9). The hydrophobicity features were investigated in strain DG2a, and a constitutive hydrophobicity in the bacterial cells was highlighted. The capability to produce biosurfactants by cells of the bacterial strain P. aeruginosa strain DG2a was evidenced both in the presence of oleic acid and of aquaculture wastewaters by revealing emulsifying activity, oil spreading tests, haemolytic and cetyltrimethylammonium bromide agar tests. Bacterial cultures containing raw biosurfactant were added to native wastewaters, showing a depletion of the oleic acid content. The use of the isolated bacterial strain P. aeruginosa strain DG2a and of the produced biosurfactant in bioremediation of aquaculture wastewaters is proposed, and the valorization of aquaculture wastewaters as raw material for biosurfactant production by using the isolate is moreover suggested.

Direct ultrafiltration and its combination with pretreatment by coagulation/flocculation/sedimentation using Moringa oleifera as coagulant to treat dairy industry wastewater were investigated. A single-channel tubular ceramic membrane with an average porosity of 0.1 μm was used at transmembrane pressures of 1, 2, and 3 bars, using the cross-flow filtration principle in a membrane filtration unit. Process efficiency was evaluated in terms of chemical oxygen demand (COD), apparent color, and turbidity removal, along with major requirements such as average permeate flux, percentage of fouling, and contribution of different resistances (resistances in series model) to the total resistance of the membrane. The highest removals for the evaluated parameters occurred in the combined coagulation/flocculation/sedimentation/ultrafiltration process. At a pressure of 2 bar, the removal of turbidity and apparent color was 99.9 % and that of COD was 98.5 %. For the combined process, the lowest percentage of fouling was 59.8 %, which occurred at 1 bar. The fraction of resistance due to fouling, which may indicate irreversible damage of the membrane, was lower in the process of coagulation/flocculation/sedimentation using M. oleifera as coagulant followed by ultrafiltration than in the process that treated dairy wastewater with direct ultrafiltration for all pressures. © 2013 Springer Science+Business Media Dordrecht.

Cr(VI) adsorption from aqueous solutions on peanut husk modified with formaldehyde (PeH-F) and peanut husk modified with formaldehyde and Fe (PeH-FFe) was evaluated as a function of shaking time, initial pH, chromium concentration, and temperature. Results showed that the Cr(VI) is preferentially adsorbed by PeH-FFe at pH 2 than pH 6. It also was found that the chromate equilibrium sorption capacity for PeH-FFe is at least six times higher than for PeH-F. The optimum pH to remove chromium is 2 for both materials; however, PeH-FFe has a higher efficiency for the chromium removal. Finally, Cr(VI) adsorption also depends on chromium concentration and temperature. The adsorption data as a function of concentration obey Linear, Freundlich, and Langmuir isotherms at pH 2 and 6. The Cr(VI) maximum capacity of PeH-FFe at pH 2 was 33.11 mg Cr(VI)/g, slightly higher than that at pH 6 (31.75 mg Cr(VI)/g). The linear isotherm shows that the pH affect the Cr(VI) distribution into the aqueous/solid phases. The negative value of ΔH and positive values of ΔG indicate that the chromium adsorption process is an exothermic and non-spontaneous process. The characterization of the peanut husk modified with formaldehyde and peanut husk modified with formaldehyde and Fe by scanning electron microscopy, Raman, and IR spectroscopies as well as the textural characteristics of the no-living biomasses were also considered in this work. © 2013 Springer Science+Business Media Dordrecht.

Input/output budgets for cadmium (Cd), lead (Pb) and mercury (Hg) in the years 1997–2011 were monitored and determined for 14 small forest-covered catchments across Europe as part of the Integrated Monitoring program on the effects of long-range pollutants on ecosystems. Metal inputs were considered to derive from bulk deposition, throughfall and litterfall. Outputs were estimated from run-off values. Litterfall plus throughfall was taken as a measure of the total deposition of Pb and Hg (wet + dry) on the basis of evidence suggesting that, for these metals, internal circulation is negligible. The same is not true for Cd. Excluding a few sites with high discharge, between 74 and 94 % of the input Pb was retained within the catchments; significant Cd retention was also observed. High losses of Pb (>1.4 mg m⁻² year⁻¹) and Cd (>0.15 mg m⁻² year⁻¹) were observed in two mountainous Central European sites with high water discharge. All other sites had outputs below or equal to 0.36 and 0.06 mg m⁻² year⁻¹, respectively, for the two metals. Almost complete retention of Hg, 86–99 % of input, was reported in the Swedish sites. These high levels of metal retention were maintained even in the face of recent dramatic reductions in pollutant loads.

Sediment cores were collected from ten eutrophic lakes in South Dakota to determine the lateral extent of sediment-bound mercury (Hg) concentrations and to assess the relationship between watershed and land use characteristics with lake Hg fish tissue consumption advisory (>1.0 mg Hg/kg fish tissue) status. Advisory lakes were characterized as having higher sediment Hg and organic matter and lower total sulfur content compared to non-advisory lakes, and results highlight the importance of sulfide and organic carbon availability associated with potential Hg methylation biogeochemical processes. Advisory lakes generally had higher percentage of areal development and grasslands, higher catchment to lake area, and lower percentage of wetlands compared to non-advisory lakes. These results signify the importance of minimizing watershed sediment transport and associated organic carbon loading as effective Hg fish tissue lake management strategies.

Chemical reagents used by the textile industry are very diverse in their composition, ranging from inorganic compounds to polymeric compounds. Strong color is the most notable characteristic of textile effluents, and a large number of processes have been employed for color removal. In recent years, attention has been directed toward various natural solid materials that are able to remove pollutants from contaminated water at low cost, such as sugarcane bagasse. Cell immobilization has emerged as an alternative that offers many advantages in the biodegradation process, including the reuse of immobilized cells and high mechanical strength, which enables metabolic processes to occur under adverse conditions of pH, sterility, and agitation. Support treatment also increases the number of charges on the surface, thereby facilitating cell immobilization processes through adsorption and ionic bonds. Polyethyleneimine (PEI) is a polycationic compound known to have a positive effect on enzyme activity and stability. The aim of the present study was to investigate a low-cost alternative for the biodegradation and bioremediation of textile dyes, analyzing Saccharomyces cerevisiae immobilization in activated bagasse for the promotion of Acid Black 48 dye biodegradation in an aqueous solution. A 1 % concentration of a S. cerevisiae suspension was evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated for 240 h using UV–vis spectrophotometry. The analysis revealed significant relative absorbance values, indicating the occurrence of biodegradation in both treatments. Therefore, S. cerevisiae immobilized in sugarcane bagasse is very attractive for use in biodegradation processes for the treatment of textile effluents.