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Toxicity of the pharmaceuticals finasteride and melengestrol acetate to benthic invertebrates 全文
2020
Gilroy, Ève A. M. | Bartlett, Adrienne J. | Gillis, Patricia L. | Bendo, Nicholas A. | Salerno, Joseph | Hedges, Amanda M. | Brown, Lisa R. | Holman, Emily A. M. | Stock, Naomi L. | de Solla, Shane R.
The toxicity of endocrinologically active pharmaceuticals finasteride (FIN) and melengestrol acetate (MGA) was assessed in freshwater mussels, including acute (48 h) aqueous tests with glochidia from Lampsilis siliquoidea, sub-chronic (14 days) sediment tests with gravid female Lampsilis fasciola, and chronic (28 days) sediment tests with juvenile L. siliquoidea, and in chronic (42 days) sediment tests with the amphipod Hyalella azteca and the mayfly Hexagenia spp. Finasteride was not toxic in acute aqueous tests with L. siliquoidea glochidia (up to 23 mg/L), whereas significant toxicity to survival and burial ability was detected in chronic sediment tests with juvenile L. siliquoidea (chronic value (ChV, the geometric mean of LOEC and NOEC) = 58 mg/kg (1 mg/L)). Amphipods (survival, growth, reproduction, and sex ratio) and mayflies (growth) were similarly sensitive (ChV = 58 mg/kg (1 mg/L)). Melengestrol acetate was acutely toxic to L. siliquoidea glochidia at 4 mg/L in aqueous tests; in sediment tests, mayflies were the most sensitive species, with significant growth effects observed at 37 mg/kg (0.25 mg/L) (ChV = 21 mg/kg (0.1 mg/L)). Exposure to sublethal concentrations of FIN and MGA had no effect on the (luring and filtering) behaviour of gravid L. fasciola, or the viability of their brooding glochidia. Based on the limited number of measured environmental concentrations of both chemicals, and their projected concentrations, no direct effects are expected by these compounds individually on the invertebrates tested. However, organisms are exposed to contaminant mixtures in the aquatic environment, and thus, the effects of FIN and MGA as components of these mixtures require further investigation.
显示更多 [+] 显示较少 [-]Effects of sulfonylurea herbicides chlorsulfuron and sulfosulfuron on enzymatic activities and microbial communities in two agricultural soils 全文
2020
Medo, Juraj | Hricáková, Nikola | Maková, Jana | Medová, Janka | Omelka, Radoslav | Javoreková, Soňa
Sulfonylurea herbicides are widely used for weed control in agriculture, and they are suspected to alter microbial communities and activities in the soil. This study investigates the impact of two sulfonylurea herbicides chlorsulfuron and sulfosulfuron on microbial community and activity in two different soils taken from two sites in west part of the Slovak Republic. The soil from the Malanta site was silt-loam luvisol with pH₍H₂O₎ 5.78 while the soil from the Stefanov site was sandy-loam regosol with pH₍H₂O₎ 8.25. These soils were not treated by sulfonylurea herbicides at least for 2 years prior to the study. In laboratory assay, the herbicides were applied to soil in their maximal recommended doses 26 and 25 g per hectare of chlorsulfuron and sulfosulfuron, respectively. Their effect was evaluated on the 3rd, 7th, 14th, 28th, 56th, and 112th day after application to soil. Illumina high-throughput amplicon sequencing of the 16S rRNA gene and ITS region was used to monitor changes on prokaryotic and fungal community composition. Enzymatic activity was evaluated using 11 substrates. Physiological profile of microbial community was analyzed using Biolog© ecoplates. Significant changes in enzymatic activity caused by the application of herbicides were found during the first 28 days. The application of herbicides altered the activity of cellobiohydrolase, arylsulphatase, dehydrogenase, phosphatase, and FDA hydrolase. Chlorsulfuron caused a more varying response of enzymatic activity than sulfosulfuron, and observed changes were not the same for both soils. In Malanta soil, chlorsulfuron decreased dehydrogenase activity while it was increased in the Stefanov soil. Phosphatase activity was decreased in both soils on 7th and 14th day. There were only minor changes in prokaryotic or fungal community or physiological profiles regarding pesticide application. Differences between soils and incubation time explained most of the variability in these parameters. Diversity indices, physiological parameters, and enzymatic activity decreased over time. The results have shown that chlorsulfuron and sulfosulfuron can affect the function and activity of the soil microbial community without significant change in its composition.
显示更多 [+] 显示较少 [-]Study on the influencing factors of removal of NOX from cement kiln flue gas by sewage sludge as a denitration agent 全文
2020
Xiao, Xiang | Luo, Jun | Huang, Haizhen | Xu, Zhenghui | Wu, Haiwen | Huang, Jianhang | Fang, Ping
Experimental study on the influencing factors of using sewage sludge as a denitration agent for cement industry was carried out on a self-made laboratory-scale fluid-bed reactor. Results indicate that sludge combustion at 900 °C shows an ideal NOX (the sum of NO and NO₂) removal activity under simulated working conditions of cement precalciner. The optimal removal efficiency of NOX can reach 70.36 ± 3.59% in the presence of cement raw meal (CRM) at a sludge particle size range of 0.18–0.25 mm and the sludge dosage of 0.75 g/min. Besides, the NOX removal efficiency increases to 76.94 ± 5.02% in the absence of CRM, indicating that cement raw meal inhibits the NOX removal. This phenomenon may be attributed to the fact that CRM has promotion effect on NH₃ produced and obvious inhibitory effect on CO produced; while NH₃ and CO play a leading role in NOX reduction, the combined effect leads to the decrease of NOX removal. Moreover, the relationship between the composition of CRM on the inhibition of NOX removal is MgO < CaCO₃ < CRM < Al₂O₃ <Fe₂O₃. Meanwhile, the effect of additive variety on the sludge denitration activity indicates that urea significantly promotes the NOX removal, which is attributed to the decomposition of urea to form NH₃. The stability experiment shows that sludge denitration efficiency remains stable above 70% in the presence of CRM and can reach over 80% when adding appropriate urea. This method can realize the removal of NOX in the cement kiln flue gas and the resource utilization of sludge. It is a promising method for sludge disposal.
显示更多 [+] 显示较少 [-]Enhanced interlayer trapping of Pb(II) ions within kaolinite layers: intercalation, characterization, and sorption studies 全文
2020
Maged, Ali | Ismael, Ismael Sayed | Kharbish, Sherif | Sarkar, Binoy | Peräniemi, Sirpa | Bhatnagar, Amit
Lead (Pb(II)) pollution in water poses a serious threat to human health in many parts of the world. In the past decades, research has been aimed at developing efficient and cost-effective methods to address the problem. In this study, dimethyl sulfoxide (DMSO) and potassium acetate (K-Ac) intercalated kaolinite complexes were synthesized and subsequently utilized for Pb(II) removal from water. The intercalation of kaolinite with DMSO was found to be useful for expanding the interlayer space of the clay mineral from 0.72 to 1.12 nm. Kaolinite intercalation with K-Ac (KDK) increased the interlayer space from 1.12 to 1.43 nm. The surface area of KDK was found to be more than threefold higher as compared to natural kaolinite (NK). Batch experimental results revealed that the maximum Pb(II) uptake capacity of KDK was 46.45 mg g⁻¹ which was higher than the capacity of NK (15.52 mg g⁻¹). Reusability studies showed that KDK could be reused for 5 cycles without substantially losing its adsorption capacity. Furthermore, fixed-bed column tests confirmed the suitability of KDK in continuous mode for Pb(II) removal. Successful application of intercalated kaolinite for Pb(II) adsorption in batch and column modes suggests its application in water treatment (especially removal of divalent metals).
显示更多 [+] 显示较少 [-]The role of ICT and financial development in CO2 emissions and economic growth 全文
2020
Raheem, Ibrahim D. | Tiwari, Aviral Kumar | Balsalobre-Lorente, Daniel
This study explores the role of the information and communication technology (ICT) and financial development (FD) in both carbon emissions and economic growth for the G7 countries for the period 1990 to 2014. Using PMG, we found that the ICT has a long-run positive effect on emissions, while FD is a weak determinant. The interactive term between the ICT and FD produces negative coefficients. Also, both the variables are found to impact negatively on economic growth. However, their interaction shows that they have mixed effect on economic growth, i.e., positive in the short run and negative in the long run. Policy implications were designed based on these results.
显示更多 [+] 显示较少 [-]Removal of boron and silicon by a modified resin and their competitive adsorption mechanisms 全文
2020
Bai, Shuqin | Han, Jue | Du, Cong | Li, Jiaxin | Ding, Wei
Boron and silicon are essential trace elements for living organisms. However, these are undesirable in excess amounts owing to the toxic effects of boron on plants, animals, and humans, and the silica scale formation by silicon in water treatment processes. Herein, a new diol-type adsorbent (T-resin) was synthesized by grafting tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) onto an ion-exchange resin (grafting amount is 1.2 mmol/g dry) to separate boron and silicon from a solution. The effects of pH, initial concentration, and coexisting anions, particularly, the effect of the coexistence of silicate ion on the adsorption of boron, were investigated. T-resin showed good adsorption properties for both boron and silicon in a wide pH range (pH 2–10). The adsorption of boron and silicon was effectively described by the Langmuir isotherm, and the maximum adsorption capacities of boron and silicon were 21.25 mg/g and 8.36 mg/g, respectively. In a competitive adsorption system, boron and silicon were simultaneously adsorbed on the T-resin, but the adsorption rate of boron was faster than silicon. However, silicon could replace the boron adsorbed on the resin, indicating that the adsorption of silicon was more stable than boron. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1:2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃]. Graphical abstract A new diol-type absorbent was synthesized by grafting tiron onto an ion-exchange resin to separate boron and silicon from a solution. Boron and silicon competitively adsorbed on the T-resin, and silicon could replace the boron adsorbed on the resin. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1: 2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃].
显示更多 [+] 显示较少 [-]Fate and migration of polybrominated diphenyl ethers in a workshop for waste printed circuit board de-soldering 全文
2020
Guo, Jie | Patton, Luorong | Wang, Jianbo | Hsu, Chen-Min
Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑₈PBDEs in TSP and PM₂.₅ in the workshop were 20.3 ng/m³ (24.7 μg/g) and 16.1 ng/m³ (115 μg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑₆PBDEs at the stack outlet (416 pg/m³) after gas treatment were lower than those in the stack pipe (1310 pg/m³) and hood inside (7440 pg/m³). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑₆PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.
显示更多 [+] 显示较少 [-]Influence of Pseudomonas japonica and organic amendments on the growth and metal tolerance of Celosia argentea L 全文
2020
Iqbal, Ameena | Mushtaq, Muhammad Umair | Khan, Aqib Hassan Ali | Nawaz, Ismat | Yousaf, Sohail | Zeshan, | Iqbal, Mazhar
In this study, a pot experiment was piloted in a greenhouse to evaluate the potential of Celosia argentea var. cristata L. for tolerating/accumulating heavy metals in synthetic wastewater in the presence of Pseudomonas japonica and organic amendment, i.e., moss and compost. Two-week-old seedlings were transferred to pots, and after 4 weeks, the bacterial strain was inoculated, then watered with synthetic wastewater for 5 weeks and harvested after 9 weeks. After harvesting, physiological and biochemical parameters, as well as metal contents of plants, were quantified. The results indicated highest growth and biomass production in moss- and compost-associated plants while highest metal uptake has been found in the presence of P. japonica and synthetic wastewater–irrigated plants. Synthetic wastewater–irrigated plants have shown highest Pb uptake of 2899 mg kg⁻¹ DW, while with P. japonica in soil those plants have shown highest Cd, Cu, Ni, and Cr uptake of 962, 1479, 1042, and 956 mg kg⁻¹ DW, respectively. The production of antioxidant enzymes, i.e., catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione-s-transferase (GST), was high in P. japonica–amended plants because of increased uptake of metals. It is concluded that moss and compost have improved growth while P. japonica improved metal accumulation and translocation to aerial parts with little involvement in plant growth.
显示更多 [+] 显示较少 [-]Experimental investigation of biodiesel production from Madhuca longifolia seed through in situ transesterification and its kinetics and thermodynamic studies 全文
2020
Mani, Yuvarani | Devaraj, Thiruselvi | Devaraj, Kubendran | AbdurRawoof, Salma Aathika | Subramanian, Sivanesan
The present investigation aims to develop simultaneous extraction and conversion of inedible Madhuca longifolia seed oil into biodiesel by one-step acid-catalyzed in situ transesterification/reactive extraction process. Six different types of pretreatment were used to assess maximum yield of biodiesel. The maximum yield of 96% biodiesel was acquired with ultrasonic pretreatment at 1% moisture content, 0.61 mm seed grain size, 55 °C temperature, 400 rpm stirring speed, 15 wt% catalyst (H₂SO₄) concentration, and with 1:35 seed oil to methanol ratio in a time period of 180 min. This reaction kinetics precedes first order also the finest value of rate constant and activation energy were calculated as 0.003 min⁻¹ and 14.840 kJ mol⁻¹. The thermodynamic energy properties ΔG, ΔH, and ΔS are computed as 96457.172 J/mol, 12121.812 J/mol K, and − 257.12 J/mol K correspondingly. The enumerated outcome illustrates a heat absorb non-spontaneous/endergonic and endothermal reaction. The result of proposed work unveils ultrasonic pretreatment escalates the biodiesel efficiency and reactive extraction exemplifies the clean, cost-effective single-step approach for production of biodiesel from non-edible sources.
显示更多 [+] 显示较少 [-]Evaluation of the radiological quality of water released by a uranium mining in Brazil 全文
2020
de Souza Pereira, Wagner | Kelecom, Alphonse | Lopes, Jose Marques | do Carmo, Alessander Sá | de Azevedo Py Júnior, Delcy | da Silva, Ademir Xavier
A mine in an area of naturally occurring radioactive materials (NORM), characterized by acid mine drainage, generates effluents with natural radionuclide concentrations, usually above the limits authorized by the regulator. The plant exploiting NORM controls the water quality and discharges it into the aquatic environment after meeting technical requirements. Downstream, water usage is unrestricted. In order to reach activity concentrations in the released effluents below the authorized values, the facility applies a chemical treatment to the effluent. Then, to ensure the effectiveness of the treatment, the facility performs sampling of treated effluent and determines the activity concentration of natural radionuclides (Uₙₐₜ, ²²⁶Ra, and ²¹⁰Pb from the uranium series and ²³²Th and ²²⁸Ra from the thorium series). In the current study, the proportion and distribution of these radionuclides between the soluble and particulate fractions were determined. The measured activity concentrations were compared with the values proposed by the World Health Organization and Brazilian legislation, as well as other authorities, as regards the potable use from the radioprotection point of view. It was observed that the radionuclides are not in secular equilibrium. The fractions contribute differently to the total release of radionuclide, and there is no linear relationship between the fractions. The average activity concentrations did not result in radiological restrictions to water use, and the committed effective dose due to ingestion was estimated at 0.06 mSv y⁻¹. Therefore, there is no radiological restriction to water use, since the dose which was found was below the constraint value for the public.
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