Уточнить поиск
Результаты 1331-1340 из 6,548
Remediation of resins-contaminated soil by the combination of electrokinetic and bioremediation processes Полный текст
2020
Ma, Jing | Zhang, Qi | Chen, Fu | Zhu, Qianlin | Wang, Yifei | Liu, Gangjun
In this work, soil contaminated by petroleum resins was remediated by electrokinetic-bioremediation (EK-BIO) technology for 60 days. A microbial consortium, comprising Rhizobium sp., Arthrobacter globiformis, Clavibacter xyli, Curtobacterium flaccumfaciens, Bacillus subtilis, Pseudomonas aeruginosa and Bacillus sp., was used to enhance the treatment performance. The results indicate that resin removal and phytotoxicity reduction were highest in the inoculated EK process, wherein 23.6% resins was removed from the soil and wheat seed germination ratio was increased from 47% to around 90% after treatment. The microbial counts, soil basal respiration and dehydrogenase activity were positively related to resins degradation, and they could be enhanced by direct current electric field. After remediation, the C/H ratio of resins decreased from 8.03 to 6.47. Furthermore, the structure of resins was analyzed by Fourier-transform infrared spectroscopy, elemental analysis, and ¹H nuclear magnetic resonance (¹H NMR) before and after treatment. It was found that the changes of the structure of resins took place during EK-BIO treatment and finally led to the reduction of aromaticity, aromaticity condensation and phytotoxicity.
Показать больше [+] Меньше [-]Pre-ozonation of surface water: An effective water treatment process to reduce the risk of infection by Giardia in drinking water Полный текст
2020
Kondo Nakada, Liane Yuri | Urbano dos Santos, Luciana | Guimarães, José Roberto
Giardia is a protozoan parasite of primary concern for the drinking water industry. High contact times are required for Giardia inactivation by chlorination, while ozonation may be effective at much lower Ct products. In this study, we have assessed the occurrence of Giardia cysts in raw water, and in chlorinated or ozonated water from a drinking water treatment plant (DWTP) in Brazil, over a 16-month period. Moreover, we analyzed the effects of primary disinfection on cysts, and calculated the infection risk caused by the occurrence of Giardia cysts in raw water, chlorinated or ozonated water. Furthermore, we assessed the correlation of Giardia cysts with indicator bacteria in raw water. Data referring to concentration of Giardia cysts in raw water showed adherence to a gamma distribution at a significance level α = 0.05. The detection frequency and the mean concentration of Giardia cysts were higher in raw water (86.6%, 26 cysts∙L⁻¹), than in chlorinated (46.1%, 15.7 cysts·L⁻¹) or ozonated water (43.5%, 11.1 cysts·L⁻¹). Overall, Giardia non-viable cysts were detected more frequently in ozonated water (80%) than in chlorinated water (68.2%) or raw water (37.7%). Ozonation and chlorination resulted, respectively, in ≈27.5- and ≈13- fold reduction of Giardia infection risk, when compared to the risk calculated for raw water. Total coliform and Escherichia coli proved to be suitable surrogates to predict the occurrence of Giardia cysts in raw surface water, however, the indicator bacteria may not be suitable surrogates to predict the disinfection of Giardia cysts, as no correlation was found between indicator bacteria and Giardia cysts in treated water. To our knowledge, this is the first study reporting the efficacy of chlorine and ozone at Ct products actually applied at a full-scale drinking water treatment plant against Giardia cysts naturally occurring in the source water, i.e. real situation. Ozonation has proven more efficient than chlorination against Giardia cysts in surface water. Escherichia coli proved to be suitable surrogate to predict Giardia cysts in raw surface water.
Показать больше [+] Меньше [-]Long-term willows phytoremediation treatment of soil contaminated by fly ash polycyclic aromatic hydrocarbons from straw combustion Полный текст
2020
Košnář, Zdeněk | Mercl, Filip | Tlustoš, Pavel
A three-year experiment was conducted to investigate willows of Salix × smithiana Willd. (S. smithiana) phytoremediation of soil contaminated by polycyclic aromatic hydrocarbons (PAHs) derived by fly ash from biomass combustion. The total removal of ash PAHs in phytoremediation treatment was 50.9% after three consecutive years while the ash PAHs were decreased in natural attenuated soil by 9.9% in the end of the experiment. The ash and spiked PAHs with low and medium molecular weight were susceptible to be removed in higher rates than high molecular weight PAHs. Lower bioconcentration factors of individual PAHs were observed in willow shoots than in roots. The estimated relative direct removal of PAHs by S. smithiana in phytoremediation was significantly lower than 1% suggesting that the contribution of S. smithiana to take up PAHs from soil was negligible and the degradation of PAHs occurred mainly in soil. Phytoremediation using S. smithiana could be seen as a feasible and environmentally friendly approach of arable soils impacted by a PAH contaminated biomass fly ash.
Показать больше [+] Меньше [-]Comparison of pollutant source tracking approaches: Heavy metals deposited on urban road surfaces as a case study Полный текст
2020
Hong, Nian | Yang, Bo | Tsang, Daniel C.W. | Liu, An
A range of source tracking approaches have been developed to identify sources in the environmental pollution research field. A comparison of source tracking approaches is essential for a better understanding and practical applications of these approaches. This study compared the commonly used source tracking approaches, namely positive matrix factorization (PMF), Unmix, flag element ratio (FER), and chemical mass-balance based stochastic approach (SCMD). A case study was illustrated for tracing heavy metals (Pb, Zn, Cr, Cu, and Ni) attached to road deposited sediments, which can significantly influence urban road stormwater quality. The results indicated that the accuracy of PMF and Unmix are affected by the number of chemical species used and whether useful markers can be identified for particular sources. However, this does not have an essential influence on FER and SCMD. PMF and Unmix are easier on data preparation and calculation processes but more difficult for source identification process than FER and SCMD. This study also provided recommendations related to the selection of source tracking approach based on different study scenarios and result requirements. These study results are able to provide important guidance for undertaking effective source tracking and devising environmental pollution mitigations.
Показать больше [+] Меньше [-]Sex-dependent locomotion and physiological responses shape the insecticidal susceptibility of parasitoid wasps Полный текст
2020
Andreazza, Felipe | Haddi, Khalid | Nörnberg, Sandro D. | Guedes, Raul Narciso C. | Nava, Dori E. | Oliveira, Eugênio E.
The adaptive fitness of insect species can be shaped by how males and females respond, both physiologically and behaviorally, to environmental challenges, such as pesticide exposure. In parasitoid wasps, most toxicological investigations focus only on female responses (e.g., survival and especially parasitism abilities), leaving the male contributions to adaptive fitness (survival, locomotion, mate search) poorly investigated. Here, we evaluated the toxicity of the spinosyn insecticide spinosad against the South American fruit fly, Anastrepha fraterculus, and we used the parasitoid wasp Diachasmimorpha longicaudata (Ashmead) to evaluate whether sex-linked locomotory and physiological responses would influence the susceptibility of these organisms to spinosad. Our results revealed that D. longicaudata males were significantly more susceptible (median lethal time (LT₅₀) = 24 h) to spinosad than D. longicaudata females (LT₅₀ = 120 h), which may reflect the differences in their locomotory and physiological (e.g., respiratory) responses to mitigate insecticide exposure. Compared to D. longicaudata females, male wasps were lighter (P < 0.001), walked for longer distances (P < 0.001) and periods (P < 0.001), and exhibited higher sensilla densities in their tarsi (P = 0.008), which may facilitate their intoxication with the insecticide. These findings indicate that male parasitoids should not be exempt from insecticide selectivity tests, as these organisms can be significantly more affected by such environmental challenges than their female conspecifics.
Показать больше [+] Меньше [-]Phytoremediation of polluted soils and waters by native Qatari plants: Future perspectives Полный текст
2020
Al-Thani, R.F. | Yasseen, B.T.
Phytoremediation of polluted soils and waters by native Qatari plants: Future perspectives Полный текст
2020
Al-Thani, R.F. | Yasseen, B.T.
Because pollution is predicted to worsen and sources of quality water for agriculture and other human activities are limited, many countries have been motivated to seek novel water sources. Qatar relies on groundwater and water desalinization to meet its water needs, and additional water resources will be needed to avoid unexpected crises in the future. Industrial wastewater (IWW) is an alternative water source, and much research activities should be focused on developing innovative and contemporary approaches to removing pollutants from IWW. Phytoremediation methods, shown to be efficient methods of removing and degrading contaminants of various kinds from polluted waters and soils, require knowledge of the native plants and associated microorganisms. In Qatar, many native plants (monocot and dicot, indigenous or introduced) have been shown to be greatly effective in remediating polluted areas. This article is a guide for Qatari scientists aiming to identify promising native plants and associated microbes for IWW phytoremediation. In it, we review the basic components of bioremediation and summarize the principle phytoremediation approaches and preferred recycling options. The multiple mechanisms and methods of phytoremediation for cleansing polluted soils and waters are also discussed as are details of the metabolic reactions degrading the organic components of oil and gas. Finally, heavy metal accumulation is addressed. Wastewater from industrial and domestic activities is currently being used to create green areas around Doha, Qatar, and such areas could be at risk of contamination. Many native Qatari plants and soil-dwelling microbes are efficient at removing organic and inorganic contaminants from polluted soils and waters, and some are promising candidates for achieving a clean environment free of contaminants.
Показать больше [+] Меньше [-]Phytoremediation of polluted soils and waters by native Qatari plants: Future perspectives Полный текст
2020
Al-Thani, R.F. | Yasseen, B.T.
Because pollution is predicted to worsen and sources of quality water for agriculture and other human activities are limited, many countries have been motivated to seek novel water sources. Qatar relies on groundwater and water desalinization to meet its water needs, and additional water resources will be needed to avoid unexpected crises in the future. Industrial wastewater (IWW) is an alternative water source, and much research activities should be focused on developing innovative and contemporary approaches to removing pollutants from IWW. Phytoremediation methods, shown to be efficient methods of removing and degrading contaminants of various kinds from polluted waters and soils, require knowledge of the native plants and associated microorganisms. In Qatar, many native plants (monocot and dicot, indigenous or introduced) have been shown to be greatly effective in remediating polluted areas. This article is a guide for Qatari scientists aiming to identify promising native plants and associated microbes for IWW phytoremediation. In it, we review the basic components of bioremediation and summarize the principle phytoremediation approaches and preferred recycling options. The multiple mechanisms and methods of phytoremediation for cleansing polluted soils and waters are also discussed as are details of the metabolic reactions degrading the organic components of oil and gas. Finally, heavy metal accumulation is addressed. Wastewater from industrial and domestic activities is currently being used to create green areas around Doha, Qatar, and such areas could be at risk of contamination. Many native Qatari plants and soil-dwelling microbes are efficient at removing organic and inorganic contaminants from polluted soils and waters, and some are promising candidates for achieving a clean environment free of contaminants. | Scopus
Показать больше [+] Меньше [-]Ny-Ålesund-oriented organic pollutants in sewage effluent and receiving seawater in the Arctic region of Kongsfjorden Полный текст
2020
Choi, Younghun | Kim, Kitae | Kim, Deokwon | Moon, Hyo-bang | Jeon, Junho
Ny-Ålesund, one of four permanent settlements on Spitsbergen in Svalbard, is a research town that includes scientific institutes from many countries. Because of daily-used chemicals (e.g., pharmaceutical and personal care products (PPCPs)) used by residents in the area, generated sewage is considered as a point source in the Kongsfjorden. The aim of the present study was to identify and quantify organic pollutants in the effluent and along the shoreline and offshore via target, suspect, and non-target screening using liquid chromatography–high-resolution mass spectrometry. We tentatively identified 30 compounds using the suspect and non-target screening methods in effluent samples from our first visit to the settlement in 2016. Among these, 3 were false positive, 24 were confirmed, and the 3 remaining compounds were not confirmed because of a lack of reference standards. Of the confirmed, 21 were quantifiable and considered target compounds for the 2nd year study. The quantified compounds in the effluent samples in 2017 totaled 17, including PPCPs, pesticides, perfluorinated compounds, and their metabolites. Some of the compounds, such as caffeine, paraxanthine/theophylline, acetaminophen, cetirizine, diethyl toluamide (DEET), and icaridin, were also detected in the receiving seawater. The concentration range was from 4 to 280,000 ng/L in the effluent and 2–98 ng/L in the seawater. Other 24 compounds were tentatively identified in the second-year effluent samples. Five were further confirmed using reference standards. Prioritization was performed on the 47 substances screened in Ny-Ålesund using the exposure and toxicity index. As the result, the top seven substances of concern present were perfluorooctanesulfonic acid (PFOS), triphenyl phosphate (TPHP), irbesartan, DEET, acetaminophen, caffeine, and paraxanthine/theophylline. As the effluent was identified as a source of the concerned organic pollutants, an emission reduction strategy should take place for protection of Arctic Fjorden environment.
Показать больше [+] Меньше [-]Oxygen mobility and microstructure properties-redox performance relationship of Rh/(Ce,Zr,La)O2 catalysts Полный текст
2020
Wang, Ting | Zhou, Ren-xian
Rh/(Ce,Zr,La)O₂ (CZL) catalysts with different Ce/Zr molar ratios of 1:0, 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:8 and 0:1 were prepared. The relationship of microstructure, dynamic oxygen mobility and the redox properties with catalytic activity for HC, CO and NOₓ eliminations were investigated. The results demonstrate that CZL mixed oxide with Ce/Zr ratio of 1:1 exhibits the largest OSC values as 904.3 umol·g⁻¹ and structural defects. The increase of oxygen vacancies and structural defects would promote the interaction between Rh species and CZL mixed oxides, which further promotes the stabilization of RhOₓ particles and enhances the oxygen storage/release ability. Rh/CZLx catalysts with Ce/Zr molar ratio of 1:1–1:4 exhibit better catalytic activity and wider dynamic operation window due to their higher DOSC.
Показать больше [+] Меньше [-]Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance Полный текст
2020
Mahbub, Khandaker Rayhan | King, William L. | Siboni, Nachshon | Nguyen, Viet Khue | Rahman, Mohammad Mahmudur | Megharaj, Mallavarapu | Seymour, Justin R. | Franks, Ashley E. | Labbate, Maurizio
Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance Полный текст
2020
Mahbub, Khandaker Rayhan | King, William L. | Siboni, Nachshon | Nguyen, Viet Khue | Rahman, Mohammad Mahmudur | Megharaj, Mallavarapu | Seymour, Justin R. | Franks, Ashley E. | Labbate, Maurizio
Antibiotic resistance genes (ARGs) in the environment are an exposure risk to humans and animals and is emerging as a global public health concern. In this study, mercury (Hg) driven co-selection of ARGs was investigated under controlled conditions in two Australian non-agricultural soils with differing pH. Soils were spiked with increasing concentrations of inorganic Hg and left to age for 5 years. Both soils contained ARGs conferring resistance to tetracycline (tetA, tetB), sulphonamides (sul1), trimethoprim (dfrA1) and the ARG indicator class 1 integron-integrase gene, intI1, as measured by qPCR. The last resort antibiotic vancomycin resistance gene, vanB and quinolone resistance gene, qnrS were not detected. Hg driven co-selection of several ARGs namely intI1, tetA and tetB were observed in the alkaline soil within the tested Hg concentrations. No co-selection of the experimental ARGs was observed in the neutral pH soil. 16S rRNA sequencing revealed proliferation of Proteobacteria and Bacteriodetes in Hg contaminated neutral and alkaline soils respectively. Multivariate analyses revealed a strong effect of Hg, soil pH and organic carbon content on the co-selection of ARGs in the experimental soils. Additionally, although aging caused a significant reduction in Hg content, agriculturally important bacterial phyla such as Nitrospirae did not regrow in the contaminated soils. The results suggest that mercury can drive co-selection of ARGs in contaminated non-agricultural soils over five years of aging which is linked to soil microbiota shift and metal chemistry in the soil.
Показать больше [+] Меньше [-]Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance Полный текст
2020
Mahbub, K.R. | King, W.L. | Siboni, N. | Nguyen, V.K. | Rahman, M.M. | Megharaj, M. | Seymour, J.R. | Franks, A.E. | Labbate, M.
Antibiotic resistance genes (ARGs) in the environment are an exposure risk to humans and animals and is emerging as a global public health concern. In this study, mercury (Hg) driven co-selection of ARGs was investigated under controlled conditions in two Australian non-agricultural soils with differing pH. Soils were spiked with increasing concentrations of inorganic Hg and left to age for 5 years. Both soils contained ARGs conferring resistance to tetracycline (tetA, tetB), sulphonamides (sul1), trimethoprim (dfrA1) and the ARG indicator class 1 integron-integrase gene, intI1, as measured by qPCR. The last resort antibiotic vancomycin resistance gene, vanB and quinolone resistance gene, qnrS were not detected. Hg driven co-selection of several ARGs namely intI1, tetA and tetB were observed in the alkaline soil within the tested Hg concentrations. No co-selection of the experimental ARGs was observed in the neutral pH soil. 16S rRNA sequencing revealed proliferation of Proteobacteria and Bacteriodetes in Hg contaminated neutral and alkaline soils respectively. Multivariate analyses revealed a strong effect of Hg, soil pH and organic carbon content on the co-selection of ARGs in the experimental soils. Additionally, although aging caused a significant reduction in Hg content, agriculturally important bacterial phyla such as Nitrospirae did not regrow in the contaminated soils. The results suggest that mercury can drive co-selection of ARGs in contaminated non-agricultural soils over five years of aging which is linked to soil microbiota shift and metal chemistry in the soil. | Khandaker Rayhan Mahbub, William L. King, Nachshon Siboni, Viet Khue Nguyen, Mohammad Mahmudur Rahman, Mallavarapu Megharaj, Justin R. Seymour, Ashley E. Franks, Maurizio Labbate
Показать больше [+] Меньше [-]Environmental losses and driving forces of nitrogen flow in two agricultural towns of Hebei province during 1997–2017 Полный текст
2020
Wang, Fangfang | Wang, Yanhua | Cai, Zucong | Chen, Xi
Excessive nitrogen (N) losses from food production and consumption have resulted in noticeable environmental impacts, e.g., air pollution and climate change, saturation of soil N, and water eutrophication. In the present study, a rural-scale N flow model was constructed in Quzhou county, Hebei province to investigate the characteristics of the N flux, N use efficiency (NUE), and N loss and their driving factors in the food production and consumption system during 1997–2017. Our results show that the N fluxes of the crop-production subsystem (CPS), the livestock-breeding subsystem (LBS), and the household-consumption subsystem (HCS) all followed an upward trend. During 1997–2017, the N losses from the system were high (51.38%), and the CPS was a major source. When the N fertilizer application level was optimal (403–475 kg N ha⁻¹), the NUE in the CPS (NUEc) decreased sharply, resulting in a higher N cost than that observed at larger scales. For the LBS, the NUE of animal feed (NUEa) was high (46.37%); however, the waste utilization rate of the HCS was below 30%. The chemical fertilizer application level, feed input, animal-food demand, and livestock manure application level were closely related to the environmental N losses. Due to the lack of reasonable N treatment and utilization methods, the increasing N losses are expected to have a large future impact on environmental issues such as haze, soil acidification, and frequent algal blooms. Therefore, adjusting N management in the processes of food production and consumption is of great significance to the improvement of global NUE and reduction of environmental pollution.
Показать больше [+] Меньше [-]