Secherfield0547

tial induction of Stxs among strains carrying nearly identical Stx-prophages suggests a role of host bacteria in regulating Stxs production. Our study revealed diverse Stx-prophages in STEC O145H28 strains that were genotypically indistinguishable. Identification of a cattle isolate harboring a Stx2a-prophage associated with high virulence supports the premise that cattle, a natural reservoir of STEC, serve as a source of hypervirulent STEC strains.First flush is an important phenomenon commonlyused in stormwater treatment system design where only the highly concentrated initial part of the runoff hydrograph is subject to treatment. Despite the existing methods for estimating the first flush, a robust quantitative definition is difficult to find. This paper discusses a novel approach, where a new parameter is introduced to analyse the variability in the discharge of pollutants at different times throughout a runoff event and thereby enable the identification of first flush. It was found that due to variability in rainfall, the first flush runoff volume varies from event to event. Therefore, a static estimate of the first flush is not applicable for a runoff event. The Monte Carlo simulation undertaken strengthened the analysis by providing credible limits to the outcomes. Accordingly, an interval estimation was obtained in which the first flush runoff can vary, and it was found that most commonly, the first flush can exist through the initial 30%-50% of the runoff. Therefore, in order to treat the stormwater runoff with minimum risk of discharging high loads of pollutants to the receiving water environment, at least the initial 30% of the runoff should be subject to treatment. This understanding provides a fundamental basis for the design of robust stormwater treatment systems.Antibiotics are commonly used in livestock and poultry breeding along with organic arsenic. Through long-term accumulation, they can enter into the surrounding soil through various pathways and contaminate the soil. In this paper, tetracycline antibiotics (TCs) and roxarsone (ROX) contaminated soil were used as the representatives of the two kinds of veterinary drugs contaminated soil, respectively, to study the thermal desorption behavior and arsenic stabilization process. Different parameters like heating temperatures, heat duration, stabilizer type and dosage were optimized for effective removal of TCs and ROX. Furthermore, TCs and ROX removal path and ROX stabilization mechanism were explored. Results of the study showed that over 98% of tetracycline antibiotics and roxarsone were effectively removed at 300 °C for 60 min. The heat treatment process of TCs contaminated soil was controlled by the first-order kinetics. Based on the detection of degradation products and thermogravimetric analysis, the possible thermal degradation path of TCs and ROX was proposed. Navitoclax research buy Addition of FeSO4.7H2O (10% by weight) as stabilizer during the heat treatment process yielded 96.7% stabilization rate. Through the analysis of arsenic fractions, valence and the characterization of soil samples collected after the heat treatment, mechanism of arsenic stabilization in ROX was explored. The results show that thermal treatment combined with chemical stabilization technology can not only degrade TCs and ROX efficiently and completely, but also convert organic arsenic into inorganic state, which is conducive to better stabilization, and finally achieve effective and safe remediation of this kind of contaminated soil.The residual layer (RL) stores a large amount of pollutants, but its effect on near-surface pollution is unknown. In this study, a two-year continuous observation was performed in Beijing using a ceilometer. The generalized boundary layer includes the mixing layer and RL. The results showed that there is no significant seasonal difference in the generalized boundary layer height (GBLH). The average GBLHs in spring, summer, autumn and winter are 1155, 1139, 1036 and 1195 m, respectively. The diurnal variation characteristics of spring, summer and autumn are similar, and the RL disappears when the mixing layer height reaches its peak in the afternoon. In winter, the development of the mixing layer is weak, and there is a 33.8% chance that the RL cannot be breached, thus making the mixing layer height at noon much lower than the GBLH. The concentrations of PM2.5 in the mixing layer and RL are 89 and 52 μg m-3, respectively, and the probability that the PM2.5 concentration in the RL was higher than that near the ground was 38.9%. RL transport represents an important beginning of the pollution event during the winter mornings and afternoons in Beijing. This study is helpful to better understand the structure of the RL and its influence on air pollution.Biochar substrates and tidal flow (TF) and intermittent aeration (IA) operation modes have recently been applied to improve the treatment performance of constructed wetlands (CWs), but their roles in regulating greenhouse gas (GHG) emissions from CWs are still unclear. In this preliminary study, CO2, CH4 and N2O fluxes and associated microbial characteristics in four groups of subsurface-flow CWs, i.e., ceramsite CWs (C-CWs), biochar-amended CWs (B-CWs), intermittently aerated B-CWs (AB-CWs) and tide-flow B-CWs (TB-CWs), were comparatively investigated. The results showed that biochar amendment significantly mitigated CH4 and N2O fluxes from the CWs by supporting higher abundances of mcrA and nosZ genes and higher ratios of pmoA/mcrA and nosZ/(nirK + nirS), thus reducing global warming potential (GWP, a decrease of 55.8%), in addition to promoting total nitrogen (TN) removal by 41.3%, mainly by increasing the abundances and activities of nitrifiers and denitrifiers. The TF mode efficiently improved nitrogen removal, but it greatly increased GHG fluxes since large amounts of GHGs escaped from the empty CW matrix after water draining. IA abated GHG emissions from the CWs, mainly after aeration. TF and IA decreased the abundances of functional bacteria and archaea related to C and N transformation, except nitrifiers, and shaped the microbial community structures. The application of a biochar substrate and IA mode can facilitate the design and operation of CWs in a more ecologically sustainable way.