The degradation ability of newly isolated bacterial strain Ochrobactrum anthropi toward polychlorinated biphenyls (PCBs) was examined under aerobic conditions. The strain was isolated from historically PCB-contaminated sediments from Strážsky canal in eastern Slovakia, surrounding of the former PCB producer. The degradation ability of the strain was enhanced by addition of other substrates and degradation inducers—biphenyl, glucose, both biphenyl and glucose, ivy leaves, and pine needles. The adaptation of cells membrane toward PCBs in the presence of abovementioned substrates was evaluated with the changes in fatty acid composition (membrane saturation, cis–trans isomerization, and changes in branched fatty acids synthesis). The highest induction of PCB degradation and lowest cell adaptation in liquid medium was achieved using ivy leaves. On the other hand, lowest degradation was achieved when PCBs were added alone. Similar low degradation was observed in the presence of glucose addition together with biphenyl. Contrary, highest growth stimulation under the applied condition was observed. Obtained results indicated that addition of glucose together with biphenyl induced PCB degradation via bacterial growth stimulation, not via the induction of activity of degradation enzymes. Cut ivy leaves (containing terpenoic compounds serving as degradation inducer and structural analog of biphenyl) increased PCB removal from contaminated sediment by O. anthropi. Results indicate the degradation ability of O. anthropi toward penta-, hexa-, and hepta-chlorinated PCB congeners. The degradation of congeners with more than five chlorine atoms per molecule was detected in higher extent compared to dichlorinated congeners.

The objective of this study was to compare the relative impact of humic and non-humic natural organic matter (NOM) on the aggregation behaviors of engineered TiO₂nanoparticles (nano-TiO₂). After exposure of nano-TiO₂to varying concentrations of Suwannee River fulvic acid (SRFA) and Bacillus subtilis exudate in high and low ionic strength (IS) solutions at pH 3 to pH 7.5, aggregation behaviors were evaluated via dynamic light scattering (DLS) measurements and sedimentation studies. Although pH, IS, and NOM concentration exerted strong controls on nano-TiO₂aggregation behaviors, suspensions exposed to either SRFA or bacterial exudate at normalized dissolved organic carbon (DOC) concentrations exhibited remarkably similar behaviors. In high IS systems, nano-TiO₂exposed to either SRFA or bacterial exudate sedimented rapidly, except in the presence of high NOM concentrations at pH 6 and 7.5. Low IS treatments exhibited a larger range of effects. In fact, relative to NOM-free controls, nano-TiO₂aggregates in SRFA and bacterial exudate exposures sedimented up to 14 times faster at pH 3 and up to 13 times slower at pH 7.5. Adsorption of organic molecules onto nano-TiO₂can enhance aggregation via colloidal bridging and/or charge neutralization, or with more complete surface coverage, can diminish aggregation via electrostatic repulsion and/or steric hindrance. Collectively, these data suggest that solution pH, IS, and NOM concentration, and to a lesser extent NOM origin, can control the fate and mobility of nano-TiO₂in geologic systems.

Land use specific deposition velocities of atmospheric trace gases and aerosols—particularly of reactive nitrogen compounds—are a fundamental input variable for a variety of deposition models. Although the concept is known to have shortcomings—especially with regard to bi-directional exchange—the often limited availability of concentration data and meteorological input variables make it a valuable simplification for regional modeling of deposition fluxes. In order to meet the demand for an up-to-date overview of recent publications on measurements and modeling studies, we compiled a database of ammonia (NH₃) deposition velocities published from 2004 to 2013. Observations from a total of 42 individual studies were averaged using an objective weighing scheme and classified into seven land use categories. Weighted average and median deposition velocities are 2.2 and 2.1 cm s⁻¹for coniferous forests, 1.5 and 1.2 cm s⁻¹for mixed forests, 1.1 and 0.9 cm s⁻¹for deciduous forests, 0.9 and 0.7 cm s⁻¹for semi-natural sites, 0.7 and 0.8 cm s⁻¹for urban sites, 0.7 and 0.6 cm s⁻¹for water surfaces, and 1.0 and 0.4 cm s⁻¹for agricultural sites, respectively. Thus, values presented in this compilation were considerably lower than those found in former studies (e.g., VDI 2006). Reasons for the mismatch were likely due to different land use classification, different averaging methods, choices of measurement locations, and improvements in measurement and in modeling techniques. Both data and code used for processing are made available as supplementary material to this article.

Spatial and seasonal mobilization trends of metals in surface water were evaluated in the US–Mexico San Pedro River (SPR). Water samples were collected at five sampling stations for the analysis of dissolved oxygen, pH, electric conductivity, sulfates, and metals (Cd, Cu, Fe, Mn, Pb, and Zn). Quality of the water was characterized through Ecological Criteria of Water Quality (ECWQ) established in Mexico and Water Quality Criteria (Environmental Protection Agency (EPA)). High total metal concentrations were detected as follows: Fe > Cu > Mn > Zn > Pb > Cd. Metal concentrations were slightly higher in dry season than in rainy season: Cd (below detection limit (BDL)–0.21 mg L⁻¹), Cu (BDL–13 mg L⁻¹), Fe (0.16–345 mg L⁻¹), Mn (0.12–52 mg L⁻¹), Pb (BDL–0.48 mg L⁻¹), and Zn (0.03–17.8 mg L⁻¹). Low pH and dissolved oxygen values as well as high sulfate content were detected in both seasons. High values of metals (Cd, Cu, Fe, Mn, Pb, Zn) were detected at station E1 representing pollution source, as well as at stations E2 (Cd, Cu, Fe, Mn), E3 (Fe, Mn, Pb), and E4 and E5 (Fe, Mn). Detected concentrations exceeded maximum permissible established in ECWQ and Water Quality Criteria (EPA). Efflorescence salts on sediments in the dry season could increase levels of metals in water column. This study provides valuable information on the potential mobility of metals in surface water of SPR located in an arid environment where transport processes are strongly linked to climate. The information derived from this study should help the regional and national authorities to address present environmental regulations.

The outstanding biological performance and non-food utilization of bioenergy grass possibly make it to be the best candidate for phytoremediation of heavy metal-contaminated soil, but evidence is limited. In this study, we conducted pot experiments to quantify the performance of two promising energy grasses, Arundo donax and Miscanthus sacchariflorus, in the phytoremediation of Zn- and Cr-contaminated soil. The results showed that (1) the biomass and root length of the two grasses were firstly increased and then kept stable or slightly decreased with increasing soil Zn/Cr concentration, implying that the two grasses had strong tolerance to Zn/Cr contamination; (2) the Zn/Cr concentration in the grass roots was two to seven times of that in the shoots, while both of them were positively correlated with the Zn/Cr concentration in soil; (3) the total accumulation of Zn/Cr in the grass (shoots + roots) was firstly determined by their concentration in the shoots and secondly determined by the shoots’ biomass, indicating that most of the Zn/Cr could be removed from contaminated soil by harvesting the aboveground parts; (4) the accumulating amount of the two grasses for Zn were 17.5 and 12.1 mg plant⁻¹, respectively; while the accumulating amount for Cr were 3.9 and 2.9 mg plant⁻¹, respectively. Taken together, the two energy grasses had strong tolerance and high accumulating ability for Zn/Cr, and therefore, they are promising candidates for the phytoremediation of Zn-/Cr-contaminated soil.

Poultry feed is often supplemented with low dosages of antibiotic to promote growth, making farms and animal processing facilities potential point sources of antibiotic-resistant fecal bacteria to aquatic ecosystems. In 2010 and 2011, we detected high concentrations of fecal indicator bacteria (FIB) in effluent released from a poultry processing plant into a headwater stream in Greenville, South Carolina. The FIB pollution became undetectable in 2012 with the plant under new management. To determine the plant’s impacts on the stream, we compared the genetic variations of Escherichia coli populations from upstream and downstream of the plant and from reference streams in the same watershed by classifying each isolate into an E. coli reference collection (ECOR) phylogenetic group. For tetracycline-resistant E. coli isolates, we analyzed the resistance genes, minimum inhibitory concentrations (MICs), gene transferability, and plasmid incompatibility groups (Inc). Distributions of ECOR groups upstream and downstream of the plant differed significantly in 2011 but not in 2012. The resistance genes tet(A) and tet(B) were prevalent, with tet(A) more likely to be found on the promiscuous IncP plasmid. A higher percentage of isolates having both tet(A) and tet(B) was found downstream in 2011 than in 2012. Dual-gene isolates did not have higher MICs than single-gene isolates but were more likely to transfer tet(A) on IncP. We propose that the processing plant acted not only as a point source of FIB but also as a factor influencing gene transferability. Additionally, given the results from 2012, the FIB impacts of the processing plant appeared to be reversible.

This study was carried out to evaluate the linkages among herbaceous plant biomass (i.e., aboveground and litter biomasses) and diversity (Shannon-Wiener index) in riparian and non-riparian areas, land use, and lotic water quality (which included first- and second-order natural streams, a canal, and a reach of a lowland river). Herb stands selected were free from anthropogenic disturbances such as farming and construction activities for a period of 3 years (this was the dominant and peak frequency of disturbances of the study area). The results suggested that herb indicators are good representatives of the land use. However, land use explanations for herb indicators were complex and not universal for all lotic waters. The correlations between herb indicators and water quality were strong for the low-order natural streams. In these streams, herb indicators explained >36 % of the total variation with several statistically significant herb indicators. However, the large river section showed weak correlations. Furthermore, the canal’s hydrology (connectivity to sea) seemed to be more influential in shaping its water quality. This study demonstrated that the rehabilitation works with a span of 3–4 years using herbs in riparian and/or non-riparian areas could significantly improve water quality of low-order streams with natural origin.

Biodegradation of different tall oil soaps was studied in order to examine the behaviour of these bioproducts in natural environments and to study their biodegradation rates. The rates of biodegradation were studied by modelling the biodegradation phenomenon as a pseudo-first-order reaction. Biodegradation was studied in seven different environments. Four of these were water phases: groundwater in aerobic and anaerobic conditions, river water and Office of Environmental Compliance and Documentation (OECD) 301 F standard conditions. In addition, three solid phases, sand, acidic forest soil and topsoil, were used as a solid matrix. The results showed that the matrix and the concentration had a strong effect on both the rate and degree of the biodegradation reaction. As a result, all of the tall oil soaps were about 57–85 % biodegradable in OECD 301 F conditions, but only moderately biodegradable in Finnish river water taken in the summer. When compared to the sample taken in the autumn, the biodegradation degree was considerably higher. In groundwater, biodegradation degree was low, even negligible in anaerobic conditions. With ten times less sample content, the biodegradation degrees in groundwater and surface water increased to 60 % for all the tall oil soaps, with one soap, in particular, up to 80 % during 100 days of measurement. In the topsoil, biodegradation was vague, and in slightly acidic forest soil, the decomposition reactions were complex. This is probably due to gas formation in the side reactions. In sand, tall oil soaps did not biodegrade at all.

The use of magnetic micro- and nanoparticles for the removal of pollutants from wastewater is gaining increasing attention. Here, amine-functionalized magnetic microparticles (AFMMs) and carboxylic-functionalized magnetic microparticles (CFMMs) were synthesized by modifying the surface of Fe₃O₄with amino and carboxyl groups for fast and efficient removal of textile dyes from aqueous solution. The functionalized magnetic microparticles were characterized by TEM, SEM, FTIR, and VSM. The adsorption experiments were carried out by varying the regulating parameters like solution pH and adsorbent dosage and analyzed in terms of kinetic and isotherm models. It was demonstrated that simple electrostatic interactions between functionalized magnetic microparticles and adsorbates played a dominating role in the adsorption of textile dyes. The positively charged AFMMs adsorbed the negatively charged dyes vat blue (VB) and direct violet (DV) at pH 6 with the maximum removal percentages of 95.72 and 97.29 %, respectively. The maximum removal percentages of cationic dyes methylene blue (MB) and azure A chloride (AA) on the negatively charged CFMMs were 92.28 and 92.22 % at pH 11, respectively. Moreover, the adsorbed dyes could be desorbed completely from the surface of CFMMs at a lower pH, and AFMMs also allowed rapid removal of VB and DV in different water samples. All the results in the present work demonstrated that the functionalized magnetic microparticles as efficient, magnetically separable adsorbents are attractive for the removal of dye pollutants.

The purposes of this research were (1) to compare level of uptake and accumulation of Eu and Ce by wheat and rye seedlings grown in soil spiked with these metals, (2) to estimate short-term variations of Eu and Ce in soil and in plants and (3) to study effects of Eu and Ce accumulation on concentrations of other macro- and trace elements in the plants. The experiments were performed in a naturally illuminated greenhouse. Instrumental neutron activation analysis was used to determine concentrations of rare earth elements and essential nutrients and trace elements in the plants and soil. The experimental results indicate that addition of Eu and Ce to soil can lead to enhanced uptake of the trace elements by plants. Plants more easily accumulated Eu than Ce. Moreover, for rye, differences between amounts of Ce in the seedlings grown in Ce-spiked soil and in Ce-free soil were statistically insignificant. During the first hours after transfer of seedlings to soil spiked with Eu, concentration of Eu in the roots of both plant species increased significantly. An increase of leaf Eu concentration was also observed, however, these variations were not as marked as those in roots. During the following 10-day growth in the Eu-spiked soil, concentration of Eu in plants constantly increased. The bioaccumulation of Eu resulted in certain decrease of Eu in the rhizosphere soil. However, no variations in soil Ce concentrations were found. The accumulation of Eu and Ce in rye and wheat seedlings did not significantly affect concentrations of essential plant nutrients and other REEs.