Stable isotope analyses were performed on gas samples collected within two instrumented biocovers, with the goal of evaluating CH₄ oxidation efficiencies (f ₀). In each of the biocovers, gas probes were installed at four locations and at several depths. One of the biocovers was fed with biogas directly from the waste mass, whereas the other was fed through a gas distribution system that allowed monitoring of biogas fluxes. While the f ₀ values obtained at a depth of 0.1 m were low (between 0.0% and 25.2%) for profiles with poor aeration, they were high for profiles with better aeration, reaching 89.7%. Several interrelated factors affecting aeration seem to be influencing f ₀, including the degree of water saturation, the magnitude of the biogas flux and the temperature within the substrate. Low f ₀ values do not mean necessarily that little CH₄ was oxidized. In fact, in certain cases where the CH₄ loading was high, the absolute amount of CH₄ oxidized was quite high and comparable to the rate of CH₄ oxidation for cases with low CH₄ loading and high f ₀. For the experimental biocover for which the CH₄ loading was known, the oxidation efficiency obtained using stable isotopes (f ₀ = 55.67% for samples taken inside flux chambers) was compared to the value obtained by mass balance (f ₀ = 70.0%). Several factors can explain this discrepancy, including the high sensitivity of f ₀ to slight changes in the isotopic fractionation factor for bacterial oxidation, α ox, uncertainties related to mass flow metre readings and to the static chamber method.

This study was undertaken with the aim of investigating the effect of Cd2+ and Ni2+ containing solutions on selected physiological parameters (metal uptake, chlorophyll a fluorescence, assimilation pigment composition, thiobarbituric acid-reactive substance production, and ergosterol content) in the lichens Peltigera rufescens and Cladina arbuscula subsp. mitis growing on historic copper mine-spoil heaps at Ľubietová-Podlipa, Slovakia. Physiological measurements did not confirm significantly higher sensitivity to Cd and Ni of the cyanolichen P. rurescens compared to the green-algal lichen C. arbuscula subsp. mitis. Under natural conditions, C. arbuscula subsp. mitis is able to grow directly on copper mine heaps of Central Slovakia, while P. rufescens grows only on their margins. A crucial factor for this limited distribution of P. rufescens may be, at least in part, the higher intracellular accumulation of metals. Although lichen photobionts are generally regarded as key elements of lichen sensitivity, further research is necessary to elucidate this point since the higher levels of intracellular Cd and Ni do not allow to regard cyanobacterial photobionts of P. rufescens as more sensitive than the eukaryotic ones of C. arbuscula subsp. mitis.

Chemical mass balance (CMB) and principal component analysis (PCA) are used together for source identification and source apportionment in this air pollution modeling study. Source profile sets, each of which contains five source profiles based on ten pollutant species, were generated using a computer program. Another algorithm was implemented to produce ten random data sets, which was composed of 100 simulated measurement results for all of ten pollutant species. Ten source profile sets were selected. Five of them contained sources of dissimilar characteristics, whereas the other five were chosen from those of similar emission profiles. Ten simulated data sets for each source profile set were used in the analyses. PCA was applied to all simulated data sets; a number of principal factors were extracted and interpreted. The identified sources for each data set were used in fitting with CMB analyses, and source contributions were estimated. The performance of PCA-CMB combination was evaluated in the aspect of percent variance explained, percent apportionment, R ², and χ ². PCA was able to explain 89.6% to 100% of the variance within the data sets used. Two to five sources were extracted depending on the characteristics of source profile sets used. CMB was found to be successful in the aspect of percent apportionment since 95.4% to 100% of mass concentrations were apportioned. The values of R ² and χ ² were found out to range from 0.981 to 1.000 and from 0.000 to 29.947, respectively. Evaluating overall results from the analyses, PCA-CMB combination produced satisfactory results in the aspect of source identification and source apportionment.

Heavy metals are present in a variety of products and can be released to the environment during product life cycles. The concentration of metals in municipal solid waste (MSW) reflects the amount of metals in products and is directly related to the amount of metals transferred to disposal sites. Measured monthly mean concentrations of cadmium, lead, and mercury in the ash from May 1995 through October 2007 at the Essex County, NJ incinerator and from May 2004 through November 2007 at the Warren County, NJ incinerator were used, along with air emissions data for mercury, to estimate the content of these metals in MSW. Estimated mean concentration and 95% confidence limits for cadmium in MSW at the Essex and Warren facilities, respectively, were 17.4 ± 0.1 and 10.1 ± 1.2 ppm. For lead, the corresponding values were 408 ± 41 and 239 ± 42 ppm, and for mercury, they were 2.6 ± 0.2 and 0.9 ± 0.2 ppm. A trend of increasing cadmium concentrations was found at both facilities. No change vs. time was observed in lead concentrations. Mercury concentration was found to be decreasing over time at the Essex facility.

An experimental approach for estimating the parameters for an extended biokinetic model (Peev et al. 2004) of micropollutant removal in wastewater treatment is presented and exemplarily performed with 2,6-naphthalene disulfonate (2,6-NDSA) and benzothiazole sulfonate (BTSA) as model compounds. In particular, a set of short-term batch experiments, consisting of a micropollutant degradation experiment and a biomass decay experiment, were carried out. Both experiments comprise only the chemical analysis of micropollutant substrate concentrations over time. The experimental data were used to determine the biokinetic parameters by applying and verifying the methodology introduced in a previous publication (Schoenerklee and Peev, 2008). The results suggest that the model assumption of competent heterotrophic biomass utilizing the target micropollutant as growth substrate, gives a satisfactory description of the micropollutant biodegradation process by mixed bacterial cultures.

Photocatalytic activity in titanium dioxide (TiO₂) has been extensively studied because of its potential use in sterilization, sanitation, and remediation applications. The aim of the study reported here was to assess the feasibility of “fixed” TiO₂ as the photocatalyst for inactivating pathogenic bacteria selected, Staphylococcus aureus and Escherichia coli, from a water stream. The investigation was undergone in a properly designed laboratory-scale evaluation. Using the system reported here, we obtained an effective bactericidal capability for E. coli and S. aureus with 90.0% and 98.0% after 30 and 10 min ultraviolet-A light irradiation with fixed TiO₂, respectively. Parameters such as the various initial bacteria concentration, TiO₂ concentrations, interruption of illumination, turbidity, and coexisted organic matters were examined to identify the removal efficiency in the photocatalytic reaction. Results indicated the negative effect by high bacteria concentration, coexisted organic matters, and turbidity on inactivation of bacteria, and positive effect on disinfection was associated with higher TiO₂ concentration. Furthermore, our results indicated that under the same experimental conditions, the removal efficiency of the system in synthetic water was performed better than that of crude water. This inferior removal capability in crude water is mainly caused by the negative effect from the unknown coexisted factors.

A pot experiment was conducted to study the effects of high concentrations of available Cu and Pb in soil originated from the vicinity of a copper foundry in Poland (Cu, 2,585–3,725 mg kg−1 d.wt.; Pb, 1,459–1,812 mg kg−1 d.wt.) on the growth and chemical constituents of Betula pendula seedlings. Control plants grew in unpolluted forest soil. Dry matter accumulation in the plants during the growing season and root/leaf mineral content were determined. Colonization of birch roots by ectomycorrhizal (ECM) fungi also was evaluated, as was soil dehydrogenase activity for influence of the metals on soil microorganisms. The heavy metals negatively affected seedling growth, ECM colonization, and soil dehydrogenase activity. A reverse relationship was found between ECM abundance and heavy metal concentrations in birch leaves, indicating the potential of mycorrhizas to protect the aboveground part of young silver birch seedlings from elevated environmental levels of Cu and Pb.

Sediment pollution by metals is of high interest considering that it can affect marine life. The estuaries' quality may be reflected by the environmental intertidal zone condition. Subsurface sediments collected at the nude tidal flats from three sampling stations in the Bahía Blanca Estuary were analyzed for total metals concentrations (Hg, Cd, Pb, and Cr), distribution, and geochemical partitioning. Most of the elements (Hg, Cd, and Cr) have shown highest concentration values in the industrial-influenced area. Maximum value of Pb was obtained where the main freshwater input discharges. Intertidal sediments have presented higher values of Cr than the subtidal ones. Cd and Pb contents near the industrial area were strongly higher in the subtidal zones. The distribution of Cd and Pb demonstrated the occurrence of a diffusion pattern from the land toward the sea, showing a dependence on both the metal itself and/or the source. Not all studied metals have shown the highest content in the fine fraction. The chemical partitioning in the fine fractions offered evidence that the tidal flats were an important source as well as sink of metals to the adjacent coastal area. The studies of intertidal sediments provide an integrative knowledge on the potential effects of different trace metals in the environment and they must be used in the contamination studies within coastal areas.

The evolution of microbial communities with increasing carbon tetrachloride concentrations was studied in two anaerobic columns containing sand and two different clay soils, one of which contained high levels of iron. Microbial communities were characterized through analysis of column effluents with denaturing gradient gel electrophoresis and quantitative polymerase chain reaction for archaea and eubacteria as inlet carbon tetrachloride concentrations were increased from 0.8 to 29 μM. Inhibition of microbial activity was observed in both columns, and was associated with the accumulation of chloroform at concentrations of 0.2 to 0.4 μM as inlet CT concentrations were increased to 2.4-3.0 μM in the low-iron clay column and approximately 16 μM in the iron rich clay column. Inhibition was indicated by decreasing rates of methanol and carbon tetrachloride degradation, decreases in effluent levels of DNA, and shifts in microbial communities of the columns. Even with the inhibition observed, in the iron-rich clay column CT degradation continued to the end of the study with inlet CT concentrations of 29 μM, in contrast to the low-iron clay column in which minimal CT degradation occurred once CT inlet concentrations exceeded 3 μM. The greater capacity for CT degradation in the column containing the iron-rich clay was hypothesized to be the result of reaction with biogenic ferrous iron produced by biological dissimilatory iron reduction.

The upper Great Egg Harbor River watershed in New Jersey's Coastal Plain is urbanized but extensive freshwater wetlands are present downstream. In 2006-2007, studies to assess levels of total mercury (THg) found concentrations in unfiltered streamwater to range as high as 187 ng/L in urbanized areas. THg concentrations were <20 ng/L in streamwater in forested/wetlands areas where both THg and dissolved organic carbon concentrations tended to increase while pH and concentrations of dissolved oxygen and nitrate decreased with flushing of soils after rain. Most of the river's flow comes from groundwater seepage; unfiltered groundwater samples contained up to 177 ng/L of THg in urban areas where there is a history of well water with THg that exceeds the drinking water standard (2,000 ng/L). THg concentrations were lower (<25 ng/L) in unfiltered groundwater from downstream wetland areas. In addition to higher THg concentrations (mostly particulate), concentrations of chloride were higher in streamwater and groundwater from urban areas than in those from downstream wetland areas. Methylmercury (MeHg) concentrations in unfiltered streamwater ranged from 0.17 ng/L at a forest/wetlands site to 2.94 ng/L at an urban site. The percentage of THg present as MeHg increased as the percentage of forest + wetlands increased, but also was high in some urban areas. MeHg was detected only in groundwater <1 m below the water/sediment interface. Atmospheric deposition is presumed to be the main source of Hg to the wetlands and also may be a source to groundwater, where wastewater inputs in urban areas are hypothesized to mobilize Hg deposited to soils.