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Sonocatalytic degradation of rhodamine B in presence of CdS Full text
2018
Song, Limin | Li, Yamiao | Zhang, Shujuan
A novel sonocatalyst CdS was prepared by a facile precipitation method, and characterized by X-ray powder diffraction, transmission electron microscopy, UV-vis absorption spectroscopy, and photoluminescence spectroscopy. Comparative sonocatalytic degradation experiments were carried out in different conditions under ultrasonic irradiation and with rhodamine B (RhB) used as the model substrate. Results indicate that CdS is a highly active sonocatalyst. The efficiency of RhB sonodegradation in aqueous solutions within 4 h is up to 70% after the addition of CdS. Abundant •OH during the RhB sonodegradation was detected, which may be responsible for the high sonodegradation rate over CdS under ultrasonic radiation.
Show more [+] Less [-]Dissipation kinetics and risk assessments of tricyclazole during Oryza sativa L. growing, processing and storage Full text
2018
Meng, Zhiyuan | Chen, Xiaojun | Guan, Lingjun | Xu, Zhiying | Zhang, Qingxia | Song, Yueyi | Liu, Fang | Fan, Tianle
Because of the increase of people’s attention to food safety, monitoring the residue of pesticide in rice is becoming more and more important. Commercial and home processing techniques have been used to transform paddy rice into rice products for human or animal consumption, which may reduce the pesticide content in rice. The degradation of tricyclazole during different stages of commercial and home processing and storage was assessed in this paper. Many researches studying the occurrence and distribution of pesticide residues during rice cropping and processing have been reported. Rice samples were extracted with acetonitrile, the extracts were enriched, and then residues were analyzed by liquid chromatography/tandem mass spectrometry method. The dissipation dynamics of tricyclazole in rice plant, soil, and paddy water fitted the first-order kinetic equations. The dissipation half-lives of tricyclazole in the rice plant, water, and soil at dosage of 300~450 g a.i. hm ⁻² were 4.84~5.16, 4.64~4.85, and 3.57~3.82 days, respectively. The residue levels of tricyclazole gradually reduced with different processing procedures. What is more, decladding process could effectively remove the residues of tricyclazole in raw rice, and washing process could further remove the residues of tricyclazole in polished rice. Degradation dynamic equations of tricyclazole in the raw rice and polished rice were based on the first-order reaction dynamic equations, and the half-lives of the degradation of tricyclazole was 43.32~58.24 days and 46.83~56.35 days in raw rice and polished rice. These results provide information regarding the fate of tricyclazole in the rice food chain, while it provides a theoretical basis for systematic evaluation of the potential residual risk of tricyclazole.
Show more [+] Less [-]Effect of inorganic and organic solutes on zero-valent aluminum-activated hydrogen peroxide and persulfate oxidation of bisphenol A Full text
2018
Arslan-Alaton, Idil | Olmez-Hanci, Tugba | Ozturk, Tugce
The effect of varying inorganic (chloride, nitrate, sulfate, and phosphate) and organic (represented by humic acid) solutes on the removal of aqueous micropollutant bisphenol A (BPA; 8.8 μM; 2 mg/L) with the oxidizing agents hydrogen peroxide (HP; 0.25 mM) and persulfate (PS; 0.25 mM) activated using zero-valent aluminum (ZVA) nanoparticles (1 g/L) was investigated at a pH of 3. In the absence of the solutes, the PS/ZVA treatment system was superior to the HP/ZVA system in terms of BPA removal rates and kinetics. Further, the HP/ZVA process was not affected by nitrate (50 mg/L) addition, whereas chloride (250 mg/L) exhibited no effect on the PS/ZVA process. The negative effect of inorganic anions on BPA removal generally speaking increased with increasing charge in the following order: NO₃⁻ (no inhibition) < Cl⁻ (250 mg/L) = SO₄²⁻ < PO₄³⁻ for HP/ZVA and Cl⁻ (250 mg/L; no inhibition) < NO₃⁻ < SO₄²⁻ < PO₄³⁻ for PS/ZVA. Upon addition of 20 mg/L humic acid representing natural organic matter, BPA removals decreased from 72 and 100% in the absence of solutes to 24 and 57% for HP/ZVA and PS/ZVA treatments, respectively. The solute mixture containing all inorganic and organic solutes together partly suppressed the inhibitory effects of phosphate and humic acid on BPA removals decreasing to 46 and 43% after HP/ZVA and PS/ZVA treatments, respectively. Dissolved organic carbon removals were obtained in the range of 30 and 47% (the HP/ZVA process), as well as 47 and 57% (the PS/ZVA process) for the experiments in the presence of 20 mg/L humic acid and solute mixture, respectively. The relative Vibrio fischeri photoluminescence inhibition decreased particularly for the PS/ZVA treatment system, which exhibited a higher treatment performance than the HP/ZVA treatment system.
Show more [+] Less [-]Toxicity of aqueous mixture of phenol and chlorophenols upon photosensitized oxidation initiated by sunlight or vis-lamp Full text
2018
Foszpańczyk, Magdalena | Drozdek, Emilia | Gmurek, Marta | Ledakowicz, Stanisław
It is well established that aquatic wildlife in marine and freshwater of the European Union is exposed to natural and synthetic endocrine disruptor compounds (EDCs) which are able to interfere with the hormonal system causing adverse effects on the intact physiology of organisms. The traditional wastewater treatment processes are inefficient on the removal of EDCs in low concentration. Moreover, not only the efficiency of treatment must be considered but also toxicological aspects. Taking into account all these aspects, the main goal of the study was to investigate the photochemical decomposition of hazardous phenolic compounds under simulated as well as natural sunlight from the toxicity point of view. The studies were focused on photodegradation of 2,4-dichlorophenol as well as mixture of phenol, 2-chlorophenol and 2,4-dichlorophenol. Photosensitized oxidation process was carried out in homogeneous and heterogeneous system. V. fischeri luminescence inhibition was used to determine the changes of toxicity in mixture during simulated and natural irradiation. The photodegradation was carried out in three kinds of water matrix; moreover, the influence of presence of inorganic matter on the treatment process was investigated. The experiments with natural sunlight proved applicability of photosensitive chitosan for visible-light water pollutant degradation. The results of toxicity investigation show that using photosensitive chitosan for visible-light, the toxicity of reaction mixture towards V. fischeri has significantly decreased. The EC₅₀ was found to increase over the irradiation time; this increase was not proportional to the transformation of the parent compounds.
Show more [+] Less [-]Combined effects of binary antibiotic mixture on growth, microcystin production, and extracellular release of Microcystis aeruginosa: application of response surface methodology Full text
2018
Wang, Zhiyuan | Chen, Qiuwen | Hu, Liuming | Wang, Min
The interactive effects of binary antibiotic mixtures of spiramycin (SP) and ampicillin (AMP) on Microcystis aeruginosa (MA) in terms of growth as well as microcystin production and extracellular release were investigated through the response surface methodology (RSM). SP with higher 50 and 5% effective concentrations in MA growth was more toxic to MA than AMP. RSM model for toxic unit approach suggested that the combined toxicity of SP and AMP varied from synergism to antagonism with SP/AMP mixture ratio decreasing from reversed equitoxic ratio (5:1) to equitoxic ratio (1:5). Deviations from the prediction of concentration addition (CA) and independent action (IA) model further indicated that combined toxicity of target antibiotics mixed in equivalent ratio (1:1) varied from synergism to antagonism with increasing total dose of SP and AMP. With the increase of SP/AMP mixture ratio, combined effect of mixed antibiotics on MA growth changed from stimulation to inhibition due to the variation of the combined toxicity and the increasing proportion of higher toxic component (SP) in the mixture. The mixture of target antibiotics at their environmentally relevant concentrations with increased total dose and SP/AMP mixture ratio stimulated intracellular microcystin synthesis and facilitated MA cell lysis, thus leading to the increase of microcystin productivity and extracellular release.
Show more [+] Less [-]Occurrence and risk assessment of fluoroquinolones and tetracyclines in cultured fish from a coastal region of northern China Full text
2018
Liu, Sisi | Dong, Guangbin | Zhao, Hongxia | Chen, Mo | Quan, Wenna | Qu, Baocheng
Occurrence and levels of 11 fluoroquinolones (FQs) and four tetracyclines (TC) in 14 cultured fish species from a coastal city in the northern China were investigated. Five FQs (ofloxacin, enoxacin, ciprofloxacin, enrofloxacin, and sarafloxacin) and oxytetracycline were detected. Lower detection frequencies of antibiotics were observed in the marine fish. The concentrations of ΣFQs ranged from not detectable (nd) to 130 ng/g wet weight (ww) (median, 7.2 ng/g ww), and the concentration range of ΣTCs was nd to 200 ng/g ww (median, nd ng/g ww). The Chinese snakehead contained the highest concentrations of ΣFQs (130 ng/g ww) and the small yellow croaker accumulated the highest concentrations of ΣTCs (200 ng/g ww), respectively. Although the calculated estimated daily intakes (EDI) suggested that the consumption of these cultured fish from this region was not associated with significant human health risks, this study provides useful information that will be helpful in the appropriate antibiotic use in aquaculture. To our knowledge, this can be the first report on the occurrence and levels of antibiotics in cage-cultured marine fish from the Bohai Rim region, China.
Show more [+] Less [-]Bioagents and silicon promoting fast early upland rice growth Full text
2018
de Sousa, ThatyanePereira | de Souza, AlanCarlos Alves | de Filippi, MartaCristina Corsi | Lanna, AnnaCristina | Cortês, MarcioVinicius | Pinheiro, HugoAlves | da Silva, GiseleBarata
Upland rice can overcome major challenges through the insertion of silicate fertilization and the presence of plant growth-promoting microorganisms (PGPMs) during its cultivation, as these factors promote an increase in vigor and plant disease resistance. Two consecutive experiments were conducted to evaluate the beneficial effects of silicon fertilization combined with the PGPM, Pseudomonas fluorensces, Burkholderia pyrrocinia, and a pool of Trichoderma asperellum, in upland rice seedlings, cultivar BRS Primavera CL: (a) E1, selecting PGPM type and Si doses for rice growth promotion and leaf blast supression, and (b) E2, evaluating physiological characteristics correlated with mechanisms involved in the higher vegetative growth in highlighted treatments from E1. In E1, 2 Si t ha⁻¹ combined with the application of T. asperellum pool or PGPM mixture increased 54% in root dry matter biomass and 35 and 65% in shoot and root lengths, respectively; it also suppressed 99% of rice blast severity. In E2, shoot and root dry matter biomass and length, photosynthetic rate, water use efficiency, total soluble sugar, and chloroplastidic pigments were superior in BRS Primavera CL seedlings treated with 2 Si t ha⁻¹ and T. asperellum pool or PGPM mixture. Higher salicilic and jasmonic acid levels were found in seedlings treated with Si and T. asperellum pool, individually. These physiological characteristics may explain, in part, the higher vigor of upland rice seedlings promoted by the synergistic effect between silicate fertilization and beneficial microorganisms.
Show more [+] Less [-]Grey relational analysis for evaluating the effects of different rates of wine lees-derived biochar application on a plant–soil system with multi-metal contamination Full text
2018
Xu, Min | Zhu, Qihong | Wu, Jun | He, Yan | Yang, Gang | Zhang, Xiaohong | Li, Li | Yu, Xiaoyu | Peng, Hong | Wang, Lilin
In this study, grey relational analysis (GRA) was used to investigate the effects of different application rates of wine lees-derived biochar on a plant–soil system with multi-metal contamination. A pot experiment was conducted to determine rice growth in multi-metal-contaminated soil amended with samples of wine lees-derived biochar, and 47 indicators (including soil properties, microbial activity, and plant physiology) were selected as evaluation indexes to assess the plant–soil system. The results indicated that higher wine lees-derived biochar application rates (2% W/W) were favorable for soil fertility, the bioconcentration factor (BF), and the mobility factor (MF, %) (with the exception of Cr, Zn, and Hg), but an application of 1% produced the highest plant growth, enzymatic activities, and bacterial diversity. The richness of the bacterial communities was reduced in the soil amended with the wine lees-derived biochar. According to the GRA assessment, the 1% application rate of wine lees-derived biochar was more suitable for restoring the holistic plant–soil system than were the application rates of 0, 0.5, and 2% (W/W). Furthermore, this study shows that GRA is a useful method for evaluating plant–soil systems.
Show more [+] Less [-]Delivering environmental benefit from the use of Environmental Quality Standards: why we need to focus on implementation Full text
2018
Merrington, Graham | Peters, Adam | Whitehouse, Paul | Clarke, Robin | Merckel, Dan
The UK has adopted a broader approach to the introduction of Environmental Quality Standard (EQS) for the aquatic environment than many other jurisdictions around the world, with a greater focus on the implementation of scientifically derived standards. This follows the publication of a report by the Royal Commission on Environmental Pollution in 1998 which drew attention to the need to recognise that whilst an EQS is often just viewed as a numerical value, it also has other important characteristics that need to be recognised if it is to be a practical and effective regulatory tool. One of the aspects that has not always been recognised was that of implementation assessment, i.e. the steps needed to ensure that a standard actually delivers environmental benefit or improvements. In many jurisdictions, there is considerable technical and sometimes political emphasis on the numerical value of the EQS (e.g. the critical concentration in an environmental matrix like water), including the method of derivation, the scrutiny of the reliability and relevance of the ecotoxicity test data and extensive deliberations of unquantified uncertainties in relation to the choice of assessment factor. The regulatory value of an EQS only comes through a comparison against a measured environmental concentration, yet only relatively limited regulatory effort has historically been expended on this component of the classic environmental risk assessment paradigm. For example, there needs to be an acceptable (i.e. small) uncertainty in the EQS, an appropriate analytical method and detection limit in the correct matrix, a method to deliver a comparison with the EQS and a robust statistical method to draw unbiased conclusions about environmental risk. In addition, we argue that there is a case for checking the consequences of introducing a standard against field data, wherever possible. This validation of the EQS rarely happens currently. We explain what implementation assessment is and why it is needed. We give examples of how implementation assessment can be integrated with EQS derivation and also present examples of what happens when the focus is only upon the derivation of a numerical value. It is clear from this evidence that advances in derivation methods need to be coupled with practical solutions of implementation if we are to realise environmental benefit from an EQS in a cost-effective manner.
Show more [+] Less [-]Effect of injection pressure on performance, emission, and combustion characteristics of diesel–acetylene-fuelled single cylinder stationary CI engine Full text
2018
Srivastava, AnmeshKumar | Soni, ShyamLal | Sharma, Dilip | Jain, NarayanLal
In this paper, the effect of injection pressure on the performance, emission, and combustion characteristics of a diesel-acetylene fuelled single cylinder, four-stroke, direct injection (DI) diesel engine with a rated power of 3.5 kW at a rated speed of 1500 rpm was studied. Experiments were performed in dual-fuel mode at four different injection pressures of 180, 190, 200, and 210 bar with a flow rate of 120 LPH of acetylene and results were compared with that of baseline diesel operation. Experimental results showed that highest brake thermal efficiency of 27.57% was achieved at injection pressure of 200 bar for diesel-acetylene dual-fuel mode which was much higher than 23.32% obtained for baseline diesel. Carbon monoxide, hydrocarbon, and smoke emissions were also measured and found to be lower, while the NO ₓ emissions were higher at 200 bar in dual fuel mode as compared to those in other injection pressures in dual fuel mode and also for baseline diesel mode. Peak cylinder pressure, net heat release rate, and rate of pressure rise were also calculated and were higher at 200 bar injection pressure in dual fuel mode.
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