This study proposes an improved activation for hydrogen peroxide and persulfate using Fe-modified diatomite (MD) to favorably lead the reaction to generate hydroxyl and sulfate radicals to degrade the contaminants phenanthrene and anthracene. Diatomite was modified by impregnating it with a mixture of ferrous (Fe²⁺) and ferric (Fe³⁺) ions in the form of precipitated iron oxides and hydroxides. The raw and synthesized materials were characterized by powder X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size by laser diffraction, chemical microanalysis of the elements by energy-dispersive X-ray, and scanning electron microscopy (SEM). Batch experiments were performed to compare the new activator material (modified diatomite) with traditional methods of activation for these oxidants and to statistically study the optimum ratio between the amount of this material and the concentration of one oxidant to the degradation of the contaminants phenanthrene and anthracene. The characterization results showed that the materials are amorphous and that the Fe ion concentration was 4.78 and 17.65 % for the raw and modified diatomites, respectively. This result shows a significant increase in the amount of iron ions after synthesis. Comparing the traditional activation method with the modified diatomite, the results of batch experiments showed that the synthesized material presents significant catalytic activity for the oxidation of these contaminants, using sodium persulfate and hydrogen peroxide as oxidants. The analysis of the variables results showed that the concentration of the oxidant has higher significance than the amount of the catalyst.

The objectives of the survey were to analyse the structure of the mollusc communities in the mining subsidence reservoirs that were created as a result of land subsidence over exploited hard coal seams and to determine the most predictive environmental factors that influence the distribution of mollusc species. The reservoirs are located in urbanised and industrialised areas along the Trans-Regional Highway, which has a high volume of vehicular traffic. They all have the same sources of supply but differ in the physical and chemical parameters of the water. In total, 15 mollusc species were recorded including four bivalve species. Among them Anodonta cygnea is classified as Endangered according to the Polish Red Data Book of Animals and also as Near Threatened according to the European Red List of Non-marine Molluscs. Eleven of the 15 mollusc species are included on the European Red List of Non-marine Molluscs as Least Concern. Conductivity, pH and the concentration of calcium were the parameters most associated with the distribution of mollusc species. Canonical correspondence analysis showed that Potamopyrgus antipodarum, Radix balthica, Physella acuta, Gyraulus crista and Pisidium casertanum were associated with higher conductivity and lower pH values. A. cygnea, Anodonta anatina and Ferrissia fragilis were negatively influenced by these parameters of the water. The results of this survey showed that the mining subsidence reservoirs located in urbanised and industrialised areas provide refuges for rare and legally protected species and that they play an essential role in the dispersal of alien species as well.

A kind of volcanic tephra (VT) as abundant natural mineral in China was studied for phosphate (P) removal from rural micro-polluted wastewater. Physical and chemical properties of VT were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), UV-visible diffuse reflectance spectrometry, and Fourier transform infrared spectroscopy (FT-IR). The uptake of P decreased with the increase of the initial solution pH, and the optimum solution pH required for maximum P removal rate was 2.0. Zeta potential analyses were carried out to vividly describe the surface charges at different solution pH. The equilibrium data were both fitted well for Langmuir and Freundlich isotherm models. Thermodynamic parameters including changes in standard enthalpy (ΔH⁰), standard entropy (ΔS⁰), and standard Gibbs free energy (ΔG⁰) were calculated. The removal of P was predominantly based on ion-exchange process when the initial solution pH in the range of 2.0–6.0. A given dose of VT can be recycled for eight times. VT minerals were attempted for P removal from rural micro-polluted wastewater collected in Shanghai, China containing 50 mg L⁻¹P, and the removal rate was determined to be nearly 100 % with the capacity of 0.5 mg P/g VT minerals. All our results indicated that VT could be a promising choice for P removal from micro-polluted wastewater in rural area with the distinct advantages of being low cost and environmentally benign.

The large spatial heterogeneity in soil physico-chemical and microbial parameters challenges our ability to predict and model pesticide leaching from agricultural land. Microbial mineralization of pesticides is an important process with respect to pesticide leaching since mineralization is the major process for the complete degradation of pesticides without generation of metabolites. The aim of our study was to determine field-scale variation in the potential for mineralization of the herbicides glyphosate, bromoxyniloctanoate, diflufenican, and bentazone and to investigate whether this variation can be predicted by variations in basic soil parameters. Sixty-five soil samples were sampled from an agricultural, loamy field in Silstrup, Denmark, from a 60 × 165 m rectangular grid. The mineralization potential of the four pesticides was determined using a 96-well microplate ¹⁴C-radiorespirometric method. Initial mineralization rates were determined using first-order kinetics for glyphosate and bromoxyniloctanoate and zero-order kinetics for diflufenican and bentazone. The mineralization rates of the four pesticides varied between the different pesticides and the different soil samples, but we could not establish correlations between the pesticide mineralization rates and the measured soil parameters. Only the glyphosate mineralization rates showed slightly increasing mineralization potentials towards the northern area of the field, with increasing clay and decreasing OC contents. The mineralization potentials for glyphosate and bentazone were compared with 9-years leaching data from two horizontal wells 3.5 m below the field. The field-scale leaching patterns, however, could not be explained by the pesticide mineralization data. Instead, field-scale pesticide leaching may have been governed by soil structure and preferential flow events.

Carbamazepine (CBZ) is a representative of a group of compounds found in our rivers that have been classified as upcoming contaminants. Its pharmacological activity to treat mood and neurological disorders is based on its effects on ion channels, but effects on aquatic organisms have not yet been thoroughly investigated.In our initial analysis, we compared CBZ effects on two microalgae species differing in CBZ sensitivity: Parachlorella kessleri and Neochloris pseudoalveolaris. While we observed a stimulation in the growth rate in cultures of P. kessleri in the presence of 10 μg L⁻¹ CBZ, no effect on growth rates of N. pseudoalveolaris cultures could be documented at this concentration. Any higher tested CBZ concentration led to growth inhibition.To gain insight into these effects, biochemical and physiological parameters of these two microalgae species were measured in the presence of CBZ in a concentration-dependent manner.As the severe inhibition of growth rate correlated with a significant inhibition of most tested parameters in cultures of N. pseudoalveolaris, the primary reason for the adverse effect of CBZ on cultures of this microalgae species could not be identified. In cultures of N. pseudoalveolaris, experimental data indicate that inhibition of growth rate occurs when the microalgae are no longer able to compensate for adverse CBZ-induced ROS effects.Analysis of the CBZ response of cultures of P. kessleri showed a reduction of growth stimulatory effect if the CBZ concentration exceeds a threshold value. In general, cultures of P. kessleri show a great potential to withstand CBZ as an environmental pollutant.

The processing, storage, and flux of inorganic carbon in rivers and streams play an influential role in the lateral transfer of atmospheric and terrestrial carbon to the marine environment. Quantifying and understanding this transfer requires a rapid and accurate means of measuring representative concentrations of dissolved inorganic carbon (DIC) and CO₂in field settings. This paper describes a field method for the determination of DIC based on the direct measurement of dissolved CO₂using a commercial carbonation meter. A 100-mL water sample is combined with 10 mL of a high ionic strength, low-pH, citrate buffer, mixed well, and the dissolved CO₂concentration is measured directly. The DIC is then calculated based on the dissolved CO₂concentration, buffer-controlled ionic strength, pH, and temperature of the mixture. The method was accurate, precise, and comparable to standard laboratory analytical methods when tested using prepared sodium bicarbonate solutions up to 40 mM DIC, North Atlantic seawater, commercial bottled waters, and carbonate spring waters. Coal mine drainage waters were also tested and often contained higher DIC concentrations in the field than in subsequent laboratory measurements; the greatest discrepancy was for the high-CO₂samples, suggesting that degassing occurred after sample collection. For chemically unstable waters and low-pH waters, such as those from high-CO₂mine waters, the proposed field DIC method may enable the collection of DIC data that are more representative of natural settings.

The presence of multicomponent nonaqueous phase liquid (NAPL) source zones in the subsurface can significantly complicate remediation efforts, transport predictions, and the development of accurate risk assessments. A series of flow-cell experiments was conducted to investigate the effectiveness of two different enhanced-solubilization agents for the removal of a multicomponent dense nonaqueous phase liquid (DNAPL) source zone from homogeneous porous media. The source zone consisted of an equal 1:1:1 mole mixture of cis-1,2-dichloroethene (DCE), trichloroethene (TCE), and tetrachloroethene (PCE) with NAPL saturation (Sn) targeted between 8 and 14 %. Solutions (5 wt%) of hydroxypropyl-β-cyclodextrin (HPCD) and sodium dodecyl sulfate (SDS) were flushed through the flow-cell system until nearly complete contaminant removal was achieved. Analysis of elution curves indicate that SDS was approximately 10 times more efficient at removing all three components from the system compared to HPCD. Although enhancement factor magnitudes vary for each specific contaminant component and enhanced-solubilization agent, the lowest-solubility contaminant component (i.e., PCE) consistently experienced the greatest relative solubility enhancement during flushing. SDS was generally superior when evaluated on a recovery basis; however, HPCD outperformed SDS for all contaminant components when compared based on moles-contaminant to moles-reagent removal efficiency analysis. Contaminant mass flux reduction analysis showed that enhanced-solubilization flushing (HPCD and SDS) resulted in general inefficient contaminant removal behavior. Raoult’s Law could be used to successfully predict aqueous contaminant concentrations from the multicomponent DNAPL source zone, indicating that dissolution processes were relatively ideal during both HPCD and SDS enhanced-solubilization flushing. These findings suggest that multicomponent NAPL source dissolution and removal depend upon the flushing agent itself and of the solubility and properties of the individual components of the NAPL mixture. The selection of a particular enhanced-flushing agent should be evaluated carefully prior to remediation as the dissolution, removal, and mass flux behavior of each component can vary significantly.

This study aims to investigate the effect of freeze-thaw on the sensitivity of two different strains of Escherichia coli bacteria, O157:H7 strain 961019 and E. coli ATCC 25922 strain, to UV irradiation. The O157:H7 strain was a toxin-producing E. coli, and the ATCC 25922 strain is an opportunistic pathogen that can cause urinary tract infection. Cells of the two E. coli strains were frozen at −7, −15, and −30 °C with one, three, and five freeze-thaw cycles prior to UV irradiation. The UV inactivation levels of the freezing-treated E. coli cells were compared with those without freezing (the controls). Freezing affected the sensitivity of the test microbes to UV light, and the effect was strain dependent. A significant increase in resistance to UV light was observed in the freezing-treated cells as compared to the control samples. The ATCC 25922 strain showed more resistance to UV irradiation than the O157:H7 strain 961019 in most cases. The O157:H7 strain 961019, on the other hand, became more resistant to UV with increased freeze-thaw cycles.

The levels and composition of particulate matter in Ash Meadows National Wildlife Refuge (NWR) that hosts the only population of the endangered Devil’s Hole pupfish (Cyprinodon diabolis) were examined to obtain baseline air quality information. PM₁₀ and PM₂.₅ mass concentrations were measured using continuous monitors over a period of 12 months. In addition, integrated PM₁₀ and PM₂.₅ filter samples were collected and a subset chemically analyzed for elements, ions, elemental carbon, and organic carbon. The average filter-based PM₁₀ (10.9 μg m⁻³) and PM₂.₅ (5.1 μg m⁻³) levels at Ash Meadows NWR are similar to those previously measured at rural and continental background sites in the southwestern USA. Mineral dust accounted for the largest percentage of aerosol mass, with the highest concentrations being measured during fall months of 2009. Elemental and organic carbon levels were generally low, except for August 29, 2009. During this event, transport of wildfire smoke was suggested, by the passage of air masses over wildfires in California, Utah, and Arizona. Ammonium sulfate varied with season, with the highest concentrations in spring and the lowest in fall and winter. Halite (NaCl) quantities were very low, except for the filter samples collected during a windy period on October 4, 2009 indicating the possible contribution of alkaline playa dust upwind of the site. Above average concentrations of crustal calcium compounds, including carbonates and gypsum, were measured in the PM₁₀ sample collected on November 9, 2009 as well as the two preceding months, ascribed to wind-driven dusty conditions prevailing throughout the late summer and fall of 2009.

Cr interactions with TiO₂were systematically studied using batch and spectroscopic investigations. Sorption of chromium on TiO₂at pH 4.5 increases with increasing Cr concentration. The sorption of Cr(III) is in good agreement with Langmuir isotherm model, whereas that of Cr(VI) is better accounted for by the Freundlich model. At pH 7.0, however, the uptake of Cr(III) by TiO₂is over 95 %, while the extent of Cr(VI) sorption on TiO₂is much less than that of pH 4.5. These results are consistent with SEM observations showing that precipitates of Cr(III) are dominant under neutral pH. The sorption of Cr(VI) on TiO₂decreases with increasing pH. However, Cr(VI) sorption decreases with increasing ionic strength below pH 4.5 whereas the sorption increases with ionic strength above pH 4.5. These observations suggest that Cr(VI) sorption is sensitive to ionic strength, and Cr(VI) could form weakly bound adsorption complexes at the TiO₂–water interface. Phosphate competes with Cr(VI) for TiO₂surface sites during sorption processes, and Cr(VI) desorption accelerates and increases in the presence of phosphate. It is noted that the reduction of Cr(VI) is induced by sunlight on the TiO₂surface, but not detected in acidic solution throughout batch experiments at pH ≥ 4.5 for 24 h.