Study on Response Rule of the Microcystis aeruginosa Fluorescence on the Biological Toxicity of HgCl_2

[ Objective] The research aimed to study response rule of the M. aeruginosa fluorescence on the biological toxicity of HgCI2. [ Method ] M. aeruginosa as material, fluorescence intensity at its best excitation and emission wavelengths as measured indicator, influence of the HgCI2 at different mass concentrations on fluorescence intensity of the M. aeruginosa was discussed initially. [ Result] HgCI2 at different mass concentrations had different influences on M. aeruginosa. HgCI2 at low concentration （0.002 -0.004 mg/L）could promote photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming smaller. 0.010 -0.400 mg/L of HgCI2 inhibited photosynthesis of the M. aeruginosa. It showed as fluorescence value of the algae liquid becoming bigger. Moreover, inhibition effect increased as HgCI2 concentration rose, showing a positive correlation between HgCI2 concentration and toxicity （ R 2 = 0.963 5 ）. [ Conclusion ] The research provided new theoretical basis for quickly measuring water toxicity.

A highly hydrothermal stable copper-based catalyst for catalytic wet air oxidation of m-cresol in coal chemical wastewater

Catalytic wet air oxidation(CWAO) can degrade some refractory pollutants at a low cost to improve the biodegradability of wastewater. However, in the presence of high temperature and high pressure and strong oxidizing free radicals, the stability of catalysts is often insufficient, which has become a bottleneck in the application of CWAO. In this paper, a copper-based catalyst with excellent hydrothermal stability was designed and prepared. TiO_(2) with excellent stability was used as the carrier to ensure the longterm anchoring of copper and reduce the leaching of the catalyst. The one pot sol–gel method was used to ensure the super dispersion and uniform distribution of copper nanoparticles on the carrier, so as to ensure that more active centers could be retained in a longer period. Experiments show that the catalyst prepared by this method has good stability and catalytic activity, and the catalytic effect is not significantly reduced after 10 cycles of use. The oxidation degradation experiment of m-cresol with the strongest biological toxicity and the most difficult to degrade in coal chemical wastewater was carried out with this catalyst. The results showed that under the conditions of 140℃, 2 MPa and 2 h, m-cresol with a concentration of up to 1000 mg·L^(-1) could be completely degraded, and the COD removal rate could reach 79.15%. The biological toxicity of wastewater was significantly reduced. The development of the catalyst system has greatly improved the feasibility of CWAO in the treatment of refractory wastewater such as coal chemical wastewater.

Laboratory Research on the Performance of Fracturing Fluid System for Unconventional Oil and Gas Reservoir Transformation

Fracturing fluid is the blood of fracturing construction, which is very important for fracturing, which requires that fracturing fluid needs to have good performance. The three commonly used fracturing fluids for unconventional oil and gas reservoir transformation are: 1) Guar gum fracturing fluid;2) Water-based emulsion slippery water fracturing fluid;3) Oil-based emulsion slippery water fracturing fluid. In this paper, water samples and other experimental data provided by Mahu Oilfield are used to evaluate three different fracturing fluid systems in laboratory. The formulas of the three different fracturing fluid systems are: 1) Water-based emulsion slippery water fracturing fluid is clean slippery water fracturing fluid 0.1% JHFR-2D drag reducer + 0.2% JHFD-2 multifunctional additive;2) Oil-based emulsion slippery water fracturing fluid 0.1% A agent + 0.2% B agent;3) Guar gum fracturing fluid 0.1% guanidine gum + 0.5% drainage aid + 0.3% demulsifier. The compatibility, drag reduction performance, reservoir damage, residue content, anti-swelling performance, surface interfacial tension, viscosity and other properties of three different slippery water fracturing fluid systems were studied. Through laboratory experiments, the comprehensive indicators show that clean slippery water fracturing fluid has obvious advantages.

A combined evaluation of the characteristics and antibiotic resistance induction potential of antibiotic wastewater during the treatment process

Antibiotic wastewater contains a variety of pollutant stressors that can induce and promote antibiotic resistance(AR)when released into the environment.Although these substances are mostly in concentrations lower than those known to induce AR individually,it is possible that antibiotic wastewater discharge might still promote the AR transmission risk via additive or synergistic effects.However,the comprehensive effect of antibiotic wastewater on AR development has rarely been evaluated,and its treatment efficiency remains unknown.Here,samples were collected from different stages of a cephalosporin production wastewater treatment plant,and the potential AR induction effect of their chemical mixtures was explored through the exposure of the antibiotic-sensitive Escherichia coli K12 strain.Incubation with raw cephalosporin production wastewater significantly promoted mutation rates(3.6×10^(3)-9.3×10^(3)-fold)and minimum inhibition concentrations(6.0-6.7-fold)of E.coli against ampicillin and chloramphenicol.This may be attributed to the inhibition effect and oxidative stress of cephalosporin wastewater on E.coli.The AR induction effect of cephalosporin wastewater decreased after the coagulation sedimentation treatment and was completely removed after the full treatment process.A Pearson correlation analysis revealed that the reduction in the AR induction effect had a strong positive correlation with the removal of organics and biological toxicity.This indicates that the antibiotic wastewater treatment had a collaborative processing effect of conventional pollutants,toxicity,and the AR induction effect.This study illustrates the potential AR transmission risk of antibiotic wastewater and highlights the need for its adequate treatment.

Quantitative analyses of relationships between ecotoxicological effects and combined pollution

The responses of wheat Triticum aestivum, rice Oryza sativa, earthworms Eisenia foetida, and prawns Penaeus japonicus to combined acetochlor-Cu, Cd-Zn were studied in hy-droponic and soil-culturing systems using the methods of ecotoxicology. In particular, system-atically quantitative analyses were documented by field experiments. Results showed that ecotoxicological effects under the combined pollution were not only related to chemical proper-ties of pollutants but also dependent on the concentration level of pollutants, in particular on the combination of concentrations of pollutants in ecosystems. Additionally, species of organisms, especially the type of ecosystem, determined the influences. To some extent, biological tissue targets attacked by pollutants were an important factor.

Biodegradation of Phthalate Esters by a Newly Isolated Acinetobacter sp. Strain LMB-5 and Characteristics of Its Esterase

Phthalate esters （PAEs） are extensively applied in industry, and they migrate to environment during the process of production, employ, and treatment and axe difficult to be degraded in nature. However, some microorganisms could use them as the carbon source to growth. In this study, an Acinetobacter sp. strain LMB-5, capable of utilizing PAEs, was isolated from a vegetable greenhouse soil. The degradation capability of strain LMB-5 was also investigated by incubation in mineral salt medium containing different PAEs, dimethyl phthalate （DMP）, diethyl phthalate （DEP）, di-n-butyl phthalate （DBP）, and di-（2-ethylhexyl） phthalate （DEHP）. The strain could grow well with DMP, DEP, DBP, and DEHP. When the concentration of DBP increased from 100 to 400 mg L-1, the half-life extended from 9.5 to 15.5 h. In the concentration range of DBP, the degradation ability of strain LMB-5 could be described by first-order kinetics. During the biodegradation of DBP, three intermediates, 1,2-benzenedicaxboxylic acid,butyl methyl ester, DMP, and phthalic acid （PA） were detected, and the proposed pathway of DBP was identified. By analysis of bioinformatics, one esterase was cloned from the genome of LMB-5 and expressed in Escherichia coll. It displayed an ability to break the ester bonds of DBP. The enzyme exhibited maximal activity at pH 7.0 and 40 ℃ with DBP as the substrate. It was activated by Cu2＋ and Fe3＋ and had a high activity in the presence of low concentrations of methanol or dimethylsulfoxide （each 10%, volume：volume）. The Acinetobacter sp. strain LMB-5 may make a contribution to the remediation of soils polluted by PAEs in the future.

Pretreatment of heterocyclic pesticide wastewater using ultrasonic/ozone combined process

Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe diameter, initial pH and 03 dosage on the COD removal were studied. The results showed that the ultrasonic/O3 process significantly improved the biodegradability and reduced the biological toxicity of the wastewater. The ratio of BODs/COD was increased from 0.03 to 0.55 and the EC50 increased from 11% to 52% under ultrasonic/O3 treatment. Low ultrasonic frequency brought better COD removal. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable. The influences of ultrasonic power and probe diameter were small. With an increase in O3 dosage, COD removal was effectively improved. The optimal operational parameters for the combined process on COD removal were ultrasonic frequency 20 kHz, initial pH 9.00, ultrasonic power 300 W and dosage of O3 454.8 mg/（L.min）, under which the efficiency of COD removal reached 67.2%.

Review of organic and inorganic pollutants removal by biochar and biochar-based composites

Biochar(BC)has exhibited a great potential to remove water contaminants due to its wide availability of raw materials,high surface area,developed pore structure,and low cost.However,the application of BC for water remediation has many limita-tions.Driven by the intense desire of overcoming unfavorable factors,a growing number of researchers have carried out to produce BC-based composite materials,which not only improved the physicochemical properties of BC,but also obtained a new composite material which combined the advantages of BC and other materials.This article reviewed previous researches on BC and BC-based composite materials,and discussed in terms of the preparation methods,the physicochemical properties,the performance of contaminant removal,and underlying adsorption mechanisms.Then the recent research progress in the removal of inorganic and organic contaminants by BC and BC-based materials was also systematically reviewed.Although BC-based composite materials have shown high performance in inorganic or organic pollutants removal,the potential risks(such as stability and biological toxicity)still need to be noticed and further study.At the end of this review,future prospects for the synthesis and application of BC and BC-based materials were proposed.This review will help the new researchers systematically understand the research progress of BC and BC-based composite materials in environmental remediation.

Effects of Silver Nanoparticles on Soil Ammonia-Oxidizing Microorganisms Under Temperatures of 25 and 5℃

The excellent bactericidal performance of silver nanoparticles （Ag NPs） has led to their wide applications, resulting in increasing concerns about their potential environmental impacts. This study evaluated the influences of different concentrations of Ag NPs （0, 1, 10, and 100 μg g^-1 dry soil） on the ammonia-oxidizing microorganisms in soil at cultivation temperatures of 25 and 5 ℃ for 37 d. The results showed that 1μg g^-1 dry soil of Ag NPs had no acute effects on the ammonia-oxidizing microorganisms. However, 10 and 100μg g^-1 dry soil of Ag NPs levels were found to significantly inhibit the activities of soil nitrification, with a decrease of 69.89% and 94.55%, respectively, at 25 ℃ and 61.65% and 83.79%, respectively, at 5℃ compared to the control （0 μg g^-1 dry soil of Ag NPs）. These levels of Ag NPs also obviously decreased soil urease activity from about 380.47 ± 0.07 （at 5℃） and 529.76 ± 13.44 （at 25℃） mg N g^-1 dry soil d^-1 to 61.70 ± 2.97 and 68.29 ± 8.22 mg N g^-1 dry soil d^-1, respectively, after 37 d of cultivation. Quantitative polymerase chain reaction showed the abundance of ammonia-oxidizing archaea and bacteria. For the same exposure time, the effects of Ag NPs on the activities of ammonia-oxidizing microorganisms and urease decreased with decreasing temperature. The threshold concentration of Ag NPs that induced negative effects on ammonia-oxidizing microorganisms was higher at 5 -C than at 25 -C. Therefore, the temperature has a major impact on the toxicity of Ag NPs to ammonia-oxidizing microorganisms and on the urease activity, with toxicity being reduced with decreasing temperature.