Enteric viruses enter surface waters through discharge of sewage treatment plants. They have a high environmental resistance and persistence and have low infectious doses. The aim of this study was to investigate the efficiency of polishing pond in the removal of viruses and bacteria. The samples were taken approximately once a week at the influent of secondary treatment (n = 39), effluent of secondary treatment (n = 39), and polishing pond (tertiary treatment, n = 29). Human adenoviruses (HAdV) were detected in 82–100 % of wastewater samples, whereas 62–79 % of the samples were positive for human polyomavirus (HPyV). The median concentrations ranged from 6.8 × 10³ genome equivalents/l (HAdV) to 6.0 × 10³ genome equivalents/l (HPyV). The concentration of HAdV and HPyV did not change significantly during the wastewater treatment. For somatic coliphages and bacteria an overall reduction of 1.84–2.65 log₁₀ has been detected. Based on the data collected, this type of tertiary treatment achieved a significant reduction in bacteria and phages, but not for viruses.

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 aims of this study were to investigate the presence of mercury (Hg) contamination in shrimp ponds in the south of Thailand and to isolate Hg-resistant purple nonsulfur bacteria (PNSB). Contamination by total mercury (HgT) in water and sediment samples ranged from <0.0002 to 0.037 μg/L and from 30.73 to 398.84 μg/kg dry weight. In all water and sediment samples, the concentration of HgTwas less than the Thai, Hong Kong, and Canadian standard guidelines. Of the Hg-resistant PNSB, six strains detoxified Hg²⁺by volatilization to Hg⁰using their mercuric reductase enzyme. The ability of PNSB to resist Hg²⁺in aerobic dark conditions was better than in microaerobic light, and this corresponded with their Hg reductase activities (dark condition 15.75, 12.62, and 12.16 U/mg protein for strains SSW15-1, SRW1-5, and SSS2-1, respectively). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were the same under both incubating conditions at 2.40 mg/L for SRW1-5 and 1.60 mg/L for SSW15-1. However, both values under light condition of SSS2-1 were 3.20 mg/L while under dark-condition MIC and MBC values were 3.20 and 4.00 mg/L. The half maximal inhibitory concentration (IC₅₀) values of Hg²⁺on strains SSS2-1, SRW1-5, and SSW15-1 under dark and light conditions were 2.16, 1.23, and 0.90; and 1.66, 1.11, and 0.80 mg/L, respectively. They were identified using 16S ribosomal RNA (rRNA) genes establishing that SSS2-1 and SSW15-1 were Afifella marina, while SRW1-5 was Rhodovulum sulfidophilum. These strains can potentially be used to treat Hg-contaminated shrimp ponds.

Metalaxyl, an important phenylamide fungicide, is widely used for controlling fungal diseases caused by pathogens of the orders Peronosporales and Pythiales. Under laboratory conditions, metalaxyl was applied to soil samples at the recommended field rate (1×FR) and double of recommended field rate (2×FR) for two and three times. Soil subsamples were taken at 0, 1, 3, 7, 14, 28, and 45 days after the last application of metalaxyl for determination of metalaxyl residues and 7, 14, 28, and 56 days for enumeration of cultivable microorganisms and DGGE profile of soil microbial community. Soil incubation experiments revealed that metalaxyl was degraded faster in the third application than in the second application of the fungicide, half-lives of metalaxyl decreasing from 16.2 to 9.9 days for recommended field rate and 22.1 to 20.0 days for double of recommended field rate. Soil bacterial and fungal populations decreased in the first 14 days and then recovered to the control levels; population of actinomycetes did not alter in the first 28 days but increased at the end of the experiment after the second application. However, after the third treatment, temporary increase in soil bacteria population, nonsignificant inhibition effect on fungal population, and obvious stimulation effect on actinomycetes number were observed. DGGE results showed that successive inputs of metalaxyl altered the bacterial community structure. There were differences in the persistence and effects of metalaxyl on microbial community between the second and the third metalaxyl treatments.

Soil thawing can affect the turnover of soil carbon (C) and nitrogen (N) and their release into the atmosphere. However, little has been known about the release of C and N during the thawing of alpine soils in the Qinghai-Tibet Plateau. This study investigated the effects of soil thawing on the release of CO₂, CH₄, and N₂O from alpine peatland soils and alpine meadow soils through an indoor experiment and determined the changes in the dissolved organic C (DOC), dissolved organic N (DON), NO₃ ⁻-N, NH₄ ⁺-N, and NO₂ ⁻-N concentrations in the soils after soil thawing. The freeze–thaw treatments were performed by incubating the soil columns at mild (−5 °C) and severe (−15 °C) for 14 days, and then at 5 °C for 18 days. The control columns were incubated at 5 °C. During thawing, the cumulative CO₂ emissions from the severely frozen alpine peatland soils and alpine meadow soils were 36 and 85 % higher than those from the control soils, and the cumulative N₂O emissions were 3.9 and 5.8 times higher than those from the control soils. However, the thawing after mild freezing produced no significant effects. The two freezing temperatures significantly increased the release of CH₄ from the alpine peatland soils, but the thawing of the severely frozen soils reduced the CH₄ uptake of the alpine meadow soils by 27 %. After the severely frozen alpine peatland soils thawed, the concentrations of DOC, DON, NO₃ ⁻-N, NH₄ ⁺-N, and NO₂ ⁻-N increased significantly, but NO₂ ⁻-N showed no significant changes for the alpine meadow soils. After thawing with mild freezing, DOC in the alpine peatland soils and NH₄ ⁺-N, NO₂ ⁻-N, and DOC in the alpine meadow soils showed no significant changes. This study indicates that the potential for release of C and N from alpine soils during thawing periods strongly depends on the freezing temperature and soil types.

A simple, cost-effective, and efficient pretreatment method, namely, vortex- and shaker-assisted liquid–liquid microextraction (VSA-LLME) coupled with gas chromatography and mass spectrometry (GC-MS), is developed for determining 16 trace-level polycyclic aromatic hydrocarbons (PAHs) in offshore produced water. The parameters affecting the VSA-LLME performance including solvent volume, ion strength, shaking time, and centrifuge speed were optimized. Under the optimized condition, the enrichment factors range between 68 and 78. The method linearities (R ²) for all 16 PAHs were above 0.99 at concentration range between 10 and 200 ng/L. The recoveries of the method were 74–85 %, and the limits of detection were as low as 2 to 5 ng/L. The relative standard deviations (RSD%) were 6~11 %. The developed method was also validated in industrial wastewater sample and showed good capability in determination of 16 PAHs in offshore produced water. The developed method offers advantages including simplicity of operation, low cast, and high sensitivity.

Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer–Emmert–Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). These membranes were used for adsorption–desorption of platinum (Pt(IV)) and palladium (Pd(II)) from a fire assay (FA) leaching waste solution, and the effect of process parameters such as pH of solution, contact time, NFm dosage, temperature, and adsorption isotherms and kinetics studies on the recovery of Pt(IV) and Pd(II) from the waste solution were investigated. The adsorption equilibrium data fit better using the Langmuir model than the Freundlich model. Maximum adsorption capacities, Q ₘₐₓ, at 45 °C were found to be 69.93 and 112.36 mg/g for Pt(IV) and Pd(II), respectively. The activation energies (E ₐ) of Pt(IV) and Pd(II) were 27.90 and 20.29 kJ/mol, respectively. The best desorption reagent was a 1.0 M HCl–1.0 M thiourea (TU) solution for both Pd(II) and Pt(IV). Reusability studies showed that the adsorption capacity can remain up to 90 % after five times of usage. This study provides a promising NFm with an effective adsorption property for Pt(IV) and Pd(II) ions.

Mesostructured CuMnCeO ₓ catalysts were prepared and tested in chlorobenzene destruction. Mn and Cu phases enter CeO₂matrix with a fluorite-like structure to form Cu–Mn–O–Ce solid solution. Both synthesis protocol and metal-doping content affect the metal state, reducibility, and oxygen distribution of composites. The c₀.₁₅c₀.₁₅c₀.₇sample exhibits the highest activity with 90 % of chlorobenzene oxidized at around 250 °C. Enhanced oxygen concentration and mobility, and abundant oxygen vacancy promote the desorption of adsorbed Cl, which guarantees the superior stability of CuMnCeO ₓ . Incorporation of CuO and MnO ₓ effectively inhibits the formation of organic byproducts, such as phenolates, maleates, and o-benzoquinone, especially at elevated temperatures.

Previous studies with bioindicator organisms have used somatic length distributions, i.e., population structure, to understand the effects of management, environment, or a potential contaminant on populations. We describe a statistical approach to separate somatic length classes of Folsomia candida juveniles as an endpoint for the assessment of changes in population structure. Reproduction-survival bioassays were carried out with five different biochars applied at increasing concentrations. Multi-Gaussian models parameterized juvenile size class cohorts, and the biomass of each size class cohort was estimated. Population structure was modified by both material type as well as concentration. Both biomass and population structure were sensitive to effects not reflected in juvenile number, the classic endpoint. Treatments with more size classes and larger individuals were taken to represent favorable conditions, and less size classes and smaller individuals indicated less favorable conditions. This extension of the standardized test provided additional information about the demography of the population.

Glyphosate applied in association with atrazine provides the best cost/benefit for weed control for genetically modified corn. Therefore, the aim of this work was to evaluate the effects of applying glyphosate in mixture with atrazine on soil microbial population and on herbicides fate in a representative Oxisol from Brazil. The treatments consisted in applying the recommended field rate of glyphosate in association with 0, 1, and 2 times the recommended field rate of atrazine (and vice versa), plus the control (without herbicides application). The presence of atrazine temporarily (21 days) decreased soil microbial biomass (SMB) and increased soil carbon mineralization (SCₘᵢₙ, up to 13 times) and microbial metabolic quotient (qCO₂) due to the stresses caused by its toxicity. When the mixture was applied independent of the rates, SMB was recovered and the amounts of extractable and non-extractable¹⁴C-residues were the same for both herbicides at 63 days. These results suggest that glyphosate may mitigate atrazine’s temporary impact on soil microbes by supplying them nutrients during their adaptation.