Microbial community response to addition of polylactate compounds to stimulate hexavalent chromium reduction in groundwater

To evaluate the efficacy of bioimmobilization of Cr(VI) in groundwater at the Department of Energy Hanford site, we conducted a series of microcosm experiments using a range of commercial electron donors with varying degrees of lactate polymerization (polylactate). These experiments were conducted using Hanford Formation sediments (coarse sand and gravel) immersed in Hanford groundwater, which were amended with Cr(VI) and several types of lactate-based electron donors (Hydrogen Release Compound, HRC; primer-HRC, pHRC; extended release HRC) and the polylactate-cysteine form (Metal Remediation Compound, MRC). The results showed that polylactate compounds stimulated an increase in bacterial biomass and activity to a greater extent than sodium lactate when applied at equivalent carbon concentrations. At the same time, concentrations of headspace hydrogen and methane increased and correlated with changes in the microbial community structure. Enrichment of Pseudomonas spp. occurred with all lactate additions, and enrichment of sulfate-reducing Desulfosporosinus spp. occurred with almost complete sulfate reduction. The results of these experiments demonstrate that amendment with the pHRC and MRC forms result in effective removal of Cr(VI) from solution most likely by both direct (enzymatic) and indirect (microbially generated reductant) mechanisms.     

Large-scale aircraft observations of ultra-fine and fine particle concentrations in the remote Siberian troposphere: New particle formation studies

Ultra-fine particle number concentrations were measured over Siberia during two large-scale airborne measurement campaigns in April and September 2006. During both campaigns, an aircraft flew between Novosibirsk and Yakutsk, collecting every 200 km vertical profiles up to 7 km. This dataset was completed by 5 years of monthly profiles above Novosibirsk. Particle number concentration was measured in the size ranges 3–70 and 70–200 nm, along with other tracers. Free troposphere (FT) particle concentrations (N_3–200) varied between 60 and 460 cm^?3, inferior to boundary layer concentrations (100–7000 cm^?3). In April, high concentrations of ～500 cm^?3 were observed in a polluted air mass recently uplifted at 5–6 km altitude over eastern Siberia, with no sign of significant new particle formation. In September, particle concentrations decreased with altitude, but with a steeper gradient in N_70–200 compared to N_3–70, the latter accounting for 90% of the total particle concentration in the free troposphere at 6–7 km altitude. Because ultra-fine particles presumably have short lifetimes, these observed particles could have been formed in situ in the clean Siberian atmosphere. Two cases of possible nucleation with high concentration and N_3–70/N_70–200 ratios are reported for the September campaign, in the upper troposphere and in cloud outflow in the mid-troposphere. In the seasonal analysis, a FT N_3–70 maximum is found in July–August between 6 and 7 km altitude, with N_3–70 accounting for ～90% of N_3–200 supporting the hypothesis of in situ formation in the FT. A secondary FT maximum of N_3–70 was identified later in autumn. In the boundary layer, seasonally maximum N_3–70 concentrations were found over Novosibirsk in May and September, but not in summer, possibly due to scavenging by precipitations and a large condensational sink from biomass burning aerosols. Our dataset has a limited size resolution and no speciation capability; more investigation is thus required to understand the conditions leading to in situ nucleation processes in the Siberian air shed.     

Land Degradation at the Stara Planina Ski Resort

The environmental impacts of ski resorts in the Balkan region are great and can lead to landscape degradation and loss of land functionality. In this study, we present an example of the negative effects of human activities at the Stara Planina ski resort in southeastern Serbia. The objective of this study is detailed analysis of the characteristics of environmental impacts at the Stara Planina. The management of the ski area and ski slope development caused severe degradation of topsoil and native vegetation. The morphological characteristics of the area, lithological properties of the exposed material and climate conditions resulted in various geomorphic impacts, including rills, deep gullies, solifluctions and debris from rock weathering. Significant changes in land usage altered hydrological conditions, resulting in more frequent torrential floods in the downstream sections of the Zubska River and increased the sediment yield. Environmental impacts were analyzed in the immediate and wider zones of the ski resort in accordance with the specific topography and visual exposure. The restoration and erosion control measures have stopped degradation processes and helped to rehabilitate the appearance and functions of the landscape. The results show the importance of considering lithological (the type and characteristics of minerals present) and hydrological (precipitation, water storage capacity of soil, runoff) factors under the conditions of significant changes in land usage. The results of this investigation can contribute to the improvement of planning processes and the implementation of development projects in ski areas.     

Exploring the potential of applying proteomics for tracking bisphenol A and nonylphenol degradation in activated sludge

A significant percentage of bisphenol A and nonylphenol removal in municipal wastewater treatment plants relies on biodegradation. Nonetheless, incomplete information is available concerning their degradation pathways performed by microbial communities in activated sludge systems. Hydroquinone dioxygenase (HQDO) is a specific degradation marker enzyme, involved in bisphenol A and nonylphenol biodegradation, and it can be produced by axenic cultures of the bacterium Sphingomonas sp. strain TTNP3. Proteomics, a technique based on the analysis of microbial community proteins, was applied to this strain. The bacterium proteome map was obtained and a HQDO subunit was successfully identified. Additionally, the reliability of the applied proteomics protocol was evaluated in activated sludge samples. Proteins belonging to Sphingomonas were searched at decreasing biomass ratios, i.e. serially diluting the bacterium in activated sludge. The protein patterns were compared and Sphingomonas proteins were discriminated against the ones from sludge itself on 2D-gels. The detection limit of the applied protocol was defined as 10^?3 g TTNP3 g^?1 total suspended solids (TSSs). The results proved that proteomics can be a promising methodology to assess the presence of specific enzymes in activated sludge samples, however improvements of its sensitivity are still needed.     

Evaluating the effect of vehicle impoundment policy on illegal construction and demolition waste dumping: Israel as a case study

Construction and demolition (C&D) waste dumped alongside roads and in open areas is a major source of soil and underground water pollution. Since 2006, Israeli ministry for environmental protection enacted a policy of vehicle impoundment (VI) according to which track drivers caught while dumping C&D waste illegally have their vehicles impounded. The present study attempted to determine whether the VI policy was effective in increasing the waste hauling to authorized landfill sites, thus limiting the number of illegal unloads of C&D waste at unauthorized landfill sites and in open areas. During the study, changes in the ratio between the monthly amount of C&D waste brought to authorized landfills sites and the estimated total amount of C&D waste generated in different administrative districts of Israel were examined, before and after the enactment of the 2006 VI policy. Short questionnaires were also distributed among local track drivers in order to determine the degree of awareness about the policy in question and estimate its deterrence effects. According to the study’s results, in the district of Haifa, in which the VI policy was stringently enacted, the ratio between C&D waste, dumped in authorized landfill sites, and the total amount of generated C&D waste, increased, on the average, from 20% in January 2004 to 35% in October 2009, with the effect attributed to the number of vehicle impoundments being highly statistically significant (t = 2.324; p < 0.05). By contrast, in the Jerusalem and Southern districts, in which the VI policy was less stringently enforced, the effect of VI on the above ratio was found to be insignificant (p > 0.1). The analysis of the questionnaires, distributed among the local truck drivers further indicated that the changes observed in the district of Haifa are not coincident and appeared to be linked to the VI policy’s enactment. In particular, 62% of the truck drivers, participated in the survey, were aware of the policy and 47% of them personally knew a driver whose vehicle was impounded. Furthermore, the drivers estimated the relative risk of being caught for unloading C&D waste in unauthorized sites, on the average, as high as 67%, which is likely to become a deterrent on its own. Our conclusion is that the VI policy appears to have a deterring effect on truck drivers, by encouraging them to haul C&D waste to authorized landfill sites. As we suggest, the research methodology implemented in the study and its results may help policy makers in other regions and countries, which experience similar environment enforcement problem, to analyze policy responses.     

Copper complexation by dissolved organic matter and uncertainty assessment of their stability constants

The interaction of Cu with dissolved organic matter (DOM, extracted from an organic forest floor) was investigated and the resulting data was evaluated in terms of their uncertainty. The speciation of Cu over ‘free’ Cu (as analysed by diffusive gradients in thin films (DGT)), dissolved Cu–DOM complexes and precipitated Cu–DOM was determined as a function of pH (3.5, 4.0 and 4.5) and Cu/C ratio. The dissolved organically bound fraction was highest at pH 4.5, but this fraction decreased with increasing Cu/C ratio, which was observed for all pH levels. In the range of Cu/C=7×10⁻⁵–2.3×10⁻² (mol/mol) the precipitated fraction was very small. The speciation of both Al and Fe was not affected by increasing Cu concentrations. From a continuous distribution model using the Scatchard approach, we calculated the optimal fit and corresponding upper and lower 95% uncertainty bounds of the overall stability constants (K_o) with the shuffled complex evolution Metropolis (SCEM) algorithm. Although the optimal equation fitted the data very well, the uncertainty of the, according to literature, most reliable approach to establish stability constants, was still large. Accordingly, the usually reported intrinsic stability constants exhibited large uncertainty ranging from logK_i=6.0–7.1 (optimal 6.7) for pH 3.5, logK_i=6.5–7.1 (optimal 6.8) for pH 4.0, and logK_i=6.4–7.2 (optimal 6.8) for pH 4.5 and showed only little effect of pH.