This study investigated the formation of volatile carbonaceous disinfection by-products (DBPs) and nitrogenous DBPs from chlorination of oxytetracycline. Six DBPs were identified including chloroform (CF), 1,1-dichloroacetone, 1,1,1-trichloroacetone (TCP), dichloroacetonitrile (DCAN), trichloroacetonitrile, and trichloronitromethane. DBP yields varied with different reaction conditions, including chlorine concentration, reacting time, pH, and bromide concentration. The highest DBP yields were found at Cl₂/C mass ratio and reaction time of 5 and 3 days, respectively. The solution pH had significant influence on CF, DCAN, and 1,1,1-TCP formation. The concentration of CF increased with the increase of pH, while DCAN and 1,1,1-TCP yields were high at acidic pH and decreased greatly under alkaline conditions. In the presence of bromide, the DBP composition shifted to multiple bromide compounds, including bromodichloromethane, dibromochloromethane, bromoform, bromochloroacetonitrile, and dibromoacetonitrile.

Histochemical and biochemical approaches were used to investigate the phytotoxicity induced by microcystin-LR (MC-LR) in the shoots of Brassica rapa seedlings. MC-LR exposure was able to induce oxidative stress by triggering the over-generation of reactive oxygen species (ROS) including superoxide anion radical (O₂ [Sʸᵐᵇᵒˡ: ˢᵉᵉ ᵗᵉˣᵗ] ⁻ ) and hydrogen peroxide (H₂O₂) in the shoots of B. rapa. MC-LR exposure led to the significant increase in the concentration of endogenous nitric oxide (NO) in B. rapa. However, such increase was completely suppressed by the treatment with nitrate reductase (NR) inhibitor NaN₃, while L-NMMA, a NO synthase (NOS) inhibitor, had only slight effect on the content of endogenous NO in MC-LR-treated plant. These data suggested that NR-dependent pathway was the main source for endogenous NO generation under MC-LR stress. Afterwards, treatment with NaN₃ reduced the ROS generation, lipid peroxidation, and loss of membrane integrity in MC-LR-treated plant. MC-LR stress induced the increase in the expression of superoxide dismutase, ascorbate peroxidase, and catalase. However, such an effect could be reversed by the treatment with NaN₃. These results indicate that NR-dependent NO production mediates MC-LR-induced oxidative stress by triggering the over-generation of ROS in B. rapa.

The use of membranes prepared with alginate and chitosan to adsorb paraquat aqueous solution was evaluated as a potential alternative technique for remediation of contaminated water. Production of bilayer membranes was based on the electrostatic interaction between alginate (a polyanion) and chitosan (a polycation). Herbicide adsorption experiments were performed using three different membranes, consisting of pure alginate, pure chitosan, and a chitosan/alginate bilayer. Adsorption was characterized using the Langmuir and Freundlich isotherm models, as well as by applying pseudo-first order and pseudo-second order kinetic models. The potential use of the membranes in environmental applications was evaluated using water collected from the Sorocabinha River in São Paulo State, Brazil. The results indicated that interactions between the membranes and the herbicide were strongly related to the type of biopolymer and the physical–chemical characteristics of the herbicide.

The present work discusses the startup and operation of different biotrickling filters during the simultaneous removal of NH3, H2S, and ethyl mercaptan (EM) for odor control, focusing on (a) the impact of pH control in the stability of the nitrification processes during reactor startup and (b) the crossed effects among selected pollutants and their by-products. Two biotrickling filters were packed with poplar wood chips (R1 and R2A), while a third reactor was packed with polyurethane foam (R2B). R2A and R2B presented a pH control system, whereas R1 did not. Loads of 2–10 g N–NH3 m−3 h−1, 5–16 g S–H2S m−3 h−1, and 1–6 g EM m−3 h−1 were supplied to the bioreactors. The presence of a pH control loop in R2A and R2B proved to be crucial to avoid long startup periods and bioreactors malfunctioning due to biological activity inhibition. In addition, the impact of the presence of different concentrations of a series of N species (NH 4 + , NO 2 − , and NO 3 − ) and S species (SO 4 2− and S2−) on the performance of the two biotrickling filters was studied by increasing their load to the reactors. Sulfide oxidation proved to be the most resilient process, since it was not affected in any of the experiments, while nitrification and EM removal were severely affected. In particular, the latter was affected by SO 4 2− and NO 2 − , while nitrification was significantly affected by NH 4 + . The biotrickling filter packed with polyurethane foam was more sensitive to crossed effects than the biotrickling filter packed with poplar wood chips.

A contamination by petroleum hydrocarbons was detected in a sandy aquifer below a petrochemical plant in Southern Italy. The site is located near the coastline and bordered by canals which, together with pumping wells, control submarine groundwater discharge toward the sea and seawater intrusion (SWI) inland. In this study, a three-dimensional flow and transport model was developed using SEAWAT-4.0 to simulate the density-dependent groundwater flow system. Equivalent freshwater heads from 246 piezometers were employed to calibrate the flow simulation, while salinity in 193 piezometers was used to calibrate the conservative transport. A second dissolved species, total petroleum hydrocarbons (TPH), was included in the numerical model to simulate the plumes originating from light non-aqueous-phase liquid. A detailed field investigation was performed in order to determine the fate of dissolved hydrocarbons. Fifteen depth profiles obtained from multilevel samplers (MLS) were used to improve the conceptual model, originally built using a standard monitoring technique with integrated depth sampling (IDS) of salinity and TPH concentrations. The calibrated simulation emphasises that density-dependent flow has a great influence on the migration pattern of the hydrocarbons plume. This study confirms that calibration of density-dependent models in sites affected by SWI can be successfully reached only with MLS data, while standard IDS data can lead to misleading results. Thus, it is recommended to include MLS in the characterization protocols of contaminated sites affected by SWI, in order to properly manage environmental pollution problems of coastal zones.

A batch sorption method was used to study the removal of few toxic metals onto the Late Cretaceous clays of Aleg formation (Coniacian–Lower Campanian system), Tunisia, in single, binary and multi-component systems. The collected clay samples were used as adsorbents for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. Results show that the natural clay samples were mainly composed of silica, alumina, iron and magnesium oxides. N2-adsorption measurements indicated mesoporous materials with modest specific surface area of <71 m2/g. Carbonate minerals were the most influencing parameters for heavy metal removal by natural clays in both single and multi-element systems. The affinity sequence was Pb(II)>Cu(II)>Zn(II)>Cd(II) due to the variable physical properties of the studied metals. The maximum adsorption capacity reached 131.58 mg/g in single systems, but decreased to <50.10 mg/g in mixed systems. In single, binary and muti-element systems, the studied clay samples removed substantial amounts of heavy metals, showing better effectiveness than the relevant previous studies. These results suggest that the studied clay samples of the Late Cretaceous clays from Tunisia can be effectively used as natural adsorbents for the removal of toxic heavy metals in aqueous systems.

In this study, the role of Cyperus sp. was evaluated for removal of pollutants from swine wastewater. Vertical-flow pilot scale constructed wetlands (CWs) operating with a hydraulic retention time (HRT) of 72 h were monitored in a greenhouse, located in Viçosa, Brazil. Significant differences were observed for the following parameters: Kjeldahl nitrogen, total phosphorus, alkalinity and electric conductivity, with averages removals of 37.5 and 28.5%, 55.9 and 44.4%, 30.2 and 25.6 and 26.1% and 22.9% (for planted and unplanted CWs, respectively). The rate of dry matter yield from Cyperus sp. was 7.5 g m−2 day−1, and the nutrient uptake capacities were 21.8, 2.1, 14.0 and 0.9 g m−2 of N, P, K and Na, respectively. Evapotranspiration (2.7 mm day−1) was statistically higher in the planted CWs. Plants in the CWs are important for achieving high nutrient removal.

The objective of this study was to determine the efficiency of a portable total mercury analyzer (OhioLumex RA-915+) in comparison with traditional analytical methods, such as inductively coupled plasma atomic emission spectrometry and cold vapor atomic absorption. The quick mercury analytical procedure with the direct mercury analyzer without sample pretreatment (such as sample digestion) was optimized for a variety of environmental samples, including contaminated soil and plant samples. The efficiency was evaluated using practical parameters, such as time required for analysis, sample amount, mercury species, accuracy, and precision/reproducibility, as well as using statistical analysis. Our results demonstrate that these three instrumental methods yielded similar mercury concentration values and statistical data, while the mercury direct analyzer had the advantages of not requiring for sample digestion and only requiring a small quantity of samples for distribution of mercury in a single root, a single root hair, and sub-regions of a single leaf of plants. These factors are used to justify use of the portable direct mercury analyzer under field conditions and validation of the results.

Most previous studies investigating controls on nitrous oxide (N2O) emissions have relied on plot-scale experiments and focused on relative homogeneous biotic and abiotic factors such as soil, vegetation, and moisture. We studied soil N2O flux at 11 chamber sites along a 620 m topographic gradient in upstate New York, USA, aiming at identifying patterns of N2O flux and correlating them to hydrological factors and soil substrate properties along the gradient. The topographic gradient is a complex slope with an overall gradient of 8%, covering plant communities of pasture, forest, alfalfa field, and riparian area from the top to the bottom. Mean fluxes of N2O measured from late March to May ranged from 4.45 to 343 μg N m−2 h−1, and these fluxes were not significantly different among chamber sites located in different communities. With the descending of the slope, N2O fluxes increased with the increase of soil water content, except for the riparian site. Statistically, N2O fluxes were not strongly correlated with soil temperature, soil bulk density, and water filled pore space (p > 0.05). Instead, strong correlations (p < 0.05) were found between N2O fluxes and soil C and N content including NO 3 − , NH 4 + , total organic carbon, and C/N ratio. Multiple linear regression analyses including both soil physical and substrate properties highlighted the significance of soil NO 3 − content and C/N ratio in regulating N2O fluxes along the gradient.

Nonpoint stormwater runoff remains a major threat to surface water quality in the USA. More effective stormwater control measures can be designed by understanding patterns in pollutant export with respect to the runoff hydrograph. In particular, nutrient concentrations in urban stormwater can cause deleterious effects in sensitive watersheds in the Southeast and Mid-Atlantic USA. A year-long study captured stormwater samples from 36 storm events at two catchments (one primarily impermeable and the other substantially wooded) and analyzed for total suspended solids and various nutrient species. Using these data, the first flush effect (the assumption that the initial portion of a rainfall-runoff event is more polluted than the later portions) was evaluated based on several published methods and definitions. Based on an analysis of multiple methodologies, the ranking of first flush strength among the pollutants was total suspended solids (TSS) > ammonia (NH₃) > total Kjeldahl nitrogen > NO₂-NO₃ > total phosphorus > orthophosphate (O-PO₄). Nitrogen species generally displayed a stronger first flush than phosphorus species, with O-PO₄ showing the weakest first flush effect. Various relationships ° climate, land use, and the first flush strength were also explored. Of the rainfall characteristics analyzed, total rainfall and runoff volume each inversely affected the first flush strength of TSS on the more impervious catchment. Although orthophosphate did not have a strong first flush effect, the relative first flush strength for O-PO₄ increased with increasing rainfall or runoff. Land use did not influence the first flush strength of the pollutants. On average, most pollutants exhibited a slight first flush effect, but substantial pollutant loading still occurred in the latter portion of the storm’s total runoff volume. Thus, treating the majority of a storm’s total pollutant load requires capturing a commensurate fraction of runoff volume.