خيارات البحث
النتائج 3031 - 3040 من 4,935
Aging as the main factor controlling PAH and polar-PAC (polycyclic aromatic compound) release mechanisms in historically coal-tar-contaminated soils النص الكامل
2019
Boulangé, Marine | Lorgeoux, Catherine | Biache, Coralie | Michel, Julien | Michels, Raymond | Faure, Pierre
In industrial sites, historically contaminated by coal tar (abandoned coking and manufactured gas plants), other families of organic pollutants than the 16 PAHs (polycyclic aromatic hydrocarbons) classified by the US-EPA can occur and induce potential risk for groundwater resources. Polar PACs (polycyclic aromatic compounds), especially oxygenated and nitrogenated PACs (O-PACs and N-PACs), are present in the initial pollution and can also be generated over time (i.e., O-PACs). Their aqueous solubilities are much greater than those of the PAHs. For these reasons, we need to increase our knowledge on polar PACs in order to better predict their behavior and the potential on-site risk. Batch leaching tests were carried out under various conditions of temperature, ionic strength, and availability of pollutants to determine the mechanisms and key parameters controlling their release. The results show a release of low-molecular-weight PAHs and polar PACs mainly by dissolution, while higher molecular weight PAHs are mainly released in association with colloids. Aging mainly controls the former mechanism, and ionic strength mainly controls the latter. Temperature increased both dissolution and colloidal mobilization. The Raoult law predicts the PAC equilibrium concentration for soils presenting high pollutant availability, but this law overestimates PAC concentration in aged soils (low pollutant availability). This is mainly due to limitation of PAC diffusion within coal-tar particles with aging. The most soluble PACs (especially polar PACs) are the most sensitive to aging. For better prediction of the PAC behavior in soils and water resources management, aging needs to be taken into account.
اظهر المزيد [+] اقل [-]Acute toxicity testing of TiO2-based vs. oxybenzone-based sunscreens on clownfish (Amphiprion ocellaris) النص الكامل
2019
Barone, Alexandra N. | Hayes, Caitlyn E. | Kerr, James J. | Lee, Ryan C. | Flaherty, Denise B.
Given the prevalence of skin cancer, sunscreens are recommended by dermatologists including the American Academy of Dermatology to protect skin from harmful ultraviolet rays. Unfortunately, this leads to an estimated 14,000 tons of sunscreen entering waterways each year. Many of the chemicals in sunscreens, such as oxybenzone and benzophenone-2, are indicated to have adverse effects on corals and other aquatic life. As an eco-conscious alternative, physical barrier sunscreens, such as non-nano-titanium dioxide (TiO₂), have been suggested as a replacement. This study examines the impact of a non-nano-TiO₂-based sunscreen over a nationally sold brand of sunscreen containing oxybenzone, on clownfish (Amphiprion ocellaris). Animals were evaluated for mortality, swimming behavior, and feeding behavior. Our data indicate that at an exposure level of 100 mg/L oxybenzone-containing sunscreen had a negative impact on mortality, leading to 25% death by the end of the 97-h testing period. Negative impacts on behavior were even more dramatic for the 100 mg/L oxybenzone-containing sunscreen, with 100% of the animals failing to feed over the first 49 h of testing and 100% of animals demonstrating abnormal swimming behavior over the entire testing period. By comparison, the non-nano-(TiO₂) sunscreen at 100 mg/L had little (6.7%) negative impact on mortality and feeding. While swimming behavior was disrupted during the first 25 h of testing (26.7% abnormal movement), animals recovered well over the remainder of the testing period (out to 97 h).
اظهر المزيد [+] اقل [-]Self-build packed-bed bioreactor for rapid and effective BOD estimation النص الكامل
2019
Pham, Thi Thuy Phuong | Nguyen, Phuc Hoang Duy | Nguyen, Thi Thuy Van | Duong, Huynh Thanh Linh
This work demonstrated a simple, low-cost, rapid, and effective biochemical oxygen demand (BOD) estimation system based on a packed-bed bioreactor that can be easily self-built on-site at a particular wastewater treatment plant for continuous monitoring of the influent and effluent. The use of natural microbial consortium that were collected from the target wastewater and immobilized on a cheap porous carrier simply by adhesion resulted in an acceptable accuracy of over 95%. The newly developed semi-continuous operating mode with peak-type signals was shown to be able to continuously estimate BOD at a high flow rate to overcome the flow dependence of the oxygen electrode, limit clogging issues, enhance the response time, and lower the limit of detection. The resulting packed-bed bioreactors could work continuously for 22 h with a coefficient of variance (CoV) of only 1.8% or for 13 h a day for several days with a maximum CoV of 1.4% and their response was observed to be stable over 80 consecutive measurements. They exhibited stable responses at a wide pH range of 6.5–8.5, which is also the recommended range for aerobic wastewater treatment, emphasizing the greater ease of use of natural microorganisms for BOD estimation.
اظهر المزيد [+] اقل [-]The protective efficacy of soursop fruit extract against hepatic injury associated with acetaminophen exposure is mediated through antioxidant, anti-inflammatory, and anti-apoptotic activities النص الكامل
2019
Al-Brakati, Ashraf Y. | Fouda, Manar S. | Tharwat, Ahmed M. | Elmahallawy, Ehab Kotb | Kassab, Rami B. | Abdel Moneim, Ahmed E.
In the current report, we examined the potential beneficial role of soursop fruit extract (SSFE) on liver injury induced by a single paracetamol (APAP) overdose (2000 mg/kg). Thirty-five Wistar albino rats were randomly divided into five groups as follows: control, SSFE, APAP, SSFE+APAP, and silymarin (SIL)+APAP. APAP intoxication was found to elevate alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and total bilirubin levels. Moreover, it increased the levels of malondialdehyde, nitrites, and nitrates and depleted glutathione, superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. APAP intoxication inactivated the nuclear factor erythroid 2-related factor 2 (Nrf2) defense pathway and upregulated the expression of heme oxygenase-1 (HO-1). APAP administration enhanced the activation of nuclear factor-kappa B (NF-κB), the elevation of tumor necrosis factor-alpha and interleukin 1-beta levels, and the upregulation of inducible nitric oxide synthase mRNA expression. In addition, APAP activated the overexpression of Bax protein, increased release of cytochrome c, and the downregulation of Bcl-2 protein. Finally, APAP-induced overexpression of transforming growth factor-beta (TGF-β) further suggested enhanced liver damage. On the other hand, SSFE pretreatment attenuated these biochemical, molecular, and histopathological alterations in the liver, which might be partially due to the regulation of hepatic Nrf2/HO-1 and downregulation of NF-κB and TGF-β.
اظهر المزيد [+] اقل [-]Selenium alleviates cadmium-induced inflammation and meat quality degradation via antioxidant and anti-inflammation in chicken breast muscles النص الكامل
2019
Tang, Kou-Kou | Li, Hui-Qin | Qu, Kui-Chao | Fan, Rui-Feng
Cadmium (Cd) as a widespread toxic heavy metal accumulates in animal food including chicken meat through food chain enrichment and finally threatens human health. Selenium (Se) is an essential mineral and possesses antagonistic effects on Cd-induced multiple organs’ toxicity in chickens. The objective of the present study was to reveal the antagonistic mechanisms of Se to Cd from the aspects of oxidative stress, inflammation, and meat quality in chicken breast muscles. Firstly, the results showed that Cd significantly elevated the levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and protein carbonyl, and declined the levels of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) to trigger oxidative stress in chicken breast muscles. However, Se treatment significantly alleviated Cd-induced oxidative stress by increasing the levels of GSH-Px, SOD, and CAT, and decreasing the levels of MDA, H₂O₂, and protein carbonyl. Secondly, Se obviously inhibited the expressions of Cd-activated inflammation-related genes including tumor necrosis factor (TNF-α), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducible nitric oxide synthase (iNOS), prostaglandin-endoperoxide synthase 2 (COX-2), and prostaglandin E synthase (PTGEs) in chicken breast muscles. Thirdly, meat quality-related parameters including pH₄₅ₘᵢₙ, ultimate pH (pHu), and drip loss were also detected, and the results showed that Se markedly recovered Cd-induced dropt of pH₄₅ₘᵢₙ and increase of drip loss in chicken breast muscles. In brief, these findings demonstrated that Se significantly alleviated Cd-induced oxidative stress and inflammation, and declined meat quality of chicken breast muscles.
اظهر المزيد [+] اقل [-]A novel application of membrane distillation to facilitate nickel recovery from electroplating wastewater النص الكامل
2019
Duong, Hung C. | Pham, Thao M. | Luong, Son T. | Nguyen, Ky V. | Nguyen, Diu T. | Ansari, Ashley J. | Nghiem, Long D.
In many years, the nickel electroplating technique has been applied to coat nickel on other materials for their increased properties. Nickel electroplating has played a vital role in our modern society but also caused considerable environmental concerns due to the mass discharge of its wastewater (i.e. containing nickel and other heavy metals) to the environment. Thus, there is a growing need for treating nickel electroplating wastewater to protect the environment and, in tandem, recover nickel for beneficial use. This study explores a novel application of membrane distillation (MD) for the treatment of nickel electroplating wastewater for a dual purpose: facilitating the nickel recovery and obtaining fresh water. The experimental results demonstrate the technical capability of MD to pre-concentrate nickel in the wastewater (i.e. hence pave the way for subsequent nickel recovery via chemical precipitation or electrodeposition) and extract fresh water. At a low operating feed temperature of 60 °C, the MD process increased the nickel content in the wastewater by more than 100-fold from 0.31 to 33 g/L with only a 20% reduction in the process water flux and obtained pure fresh water. At such high concentration factors, the membrane surface was slightly fouled by inorganic precipitates; however, membrane pore wetting was not evident, confirmed by the purity of the obtained fresh water. The fouled membrane was effectively cleaned using a 3% HCl solution to restore its surface morphology. Finally, the preliminary thermal energy analysis of the combined MD–chemical precipitation/electrodeposition process reveals a considerable reduction in energy consumption of the nickel recovery process.
اظهر المزيد [+] اقل [-]Characterization of the Cd(II) and nitrate removal by bacterium Acinetobacter sp. SZ28 under different electron donor conditions النص الكامل
2019
Su, Jun Feng | Gao, Chun Yu | Huang, Ting Lin | Bai, Xue Chen | Liang, Dong Hui | He, Lei
In this study, zero-valent iron (ZVI), nanoscale zero-valent iron (nZVI), Fe(II), and Mn(II) were investigated for their effects on mixotrophic denitrification coupled with cadmium (Cd(II)) adsorption process by Acinetobacter sp. SZ28. The removal rates of nitrate were 0.228 mg L⁻¹ h⁻¹ (ZVI), 0.133 mg L⁻¹ h⁻¹ (nZVI), 0.309 mg L⁻¹ h⁻¹ (Fe(II)) and 0.234 mg L⁻¹ h⁻¹ (Mn(II)), respectively. The Cd(II) removal efficiencies were 97.23% (ZVI), 95.79% (nZVI), 80.63% (Fe(II)), and 84.58% (Mn(II)), respectively. Meteorological chromatography analysis indicated that the characteristics of gas composition were different under different electron donor conditions. Moreover, characterization of bacterial metabolites produced by strain SZ28 under different conditions was analyzed. Sequence amplification identified the presence of the nitrate reductase gene (napA) and Mn(II)-oxide gene (cumA) in strain SZ28. The results of XRD and SEM indicated that ZVI, nZVI, Fe(II), and Mn(II) were oxidized into corresponding oxides. XPS spectra indicated that the Cd(II) was adsorbed onto biogenic precipitation.
اظهر المزيد [+] اقل [-]Aryl hydrocarbon receptor-mediated potencies in field-deployed plastics vary by type of polymer النص الكامل
2019
Schönlau, Christine | Larsson, Maria | Lam, Monika M. | Engwall, Magnus | Giesy, John P. | Rochman, Chelsea | Kärrman, Anna
Plastic is able to sorb environmental pollutants from ambient water and might act as a vector for these pollutants to marine organisms. The potential toxicological effects of plastic-sorbed pollutants in marine organisms have not been thoroughly assessed. In this study, organic extracts from four types of plastic deployed for 9 or 12 months in San Diego Bay, California, were examined for their potential to activate the aryl hydrocarbon receptor (AhR) pathway by use of the H4IIE-luc assay. Polycyclic aromatic hydrocarbons (PAH), including the 16 priority PAHs, were quantified. The AhR-mediated potency in the deployed plastic samples, calculated as bio-TEQ values, ranged from 2.7 pg/g in polyethylene terephthalate (PET) to 277 pg/g in low-density polyethylene (LDPE). Concentrations of the sum of 24 PAHs in the deployed samples ranged from 4.6 to 1068 ng/g. By use of relative potency factors (REP), a potency balance between the biological effect (bio-TEQs) and the targeted PAHs (chem-TEQs) was calculated to 24–170%. The study reports, for the first time, in vitro AhR-mediated potencies for different deployed plastics, of which LDPE elicited the greatest concentration of bio-TEQs followed by polypropylene (PP), PET, and polyvinylchloride (PVC).
اظهر المزيد [+] اقل [-]A study of “cancer villages” in Jiangsu Province of China النص الكامل
2019
Cheng, Yuanyuan | Nathanail, P. (Paul)
China’s economic boom has created many environmental and health challenges, including so-called cancer villages. This study, the first to use the lens of “cancer villages” at provincial level, examines the correlation between changes in Jiangsu cancer villages and economic and environmental quality indicators identified as being relevant, and hence to highlight environmental issues that should be mitigated to protect public health. Since 2001, 25 cancer villages have been reported in Jiangsu. The distribution pattern of these villages is of a cluster whose mean centre had moved from Suzhou city in 2001 to Taizhou in 2006 and 2011. By applying the buffer analysis tool of ArcGIS10.2.2 using 3-km and 5-km radius buffer, to examine the relationship between these cancer villages and the surrounding rivers, it was revealed that 76% of the villages fall within the 3-km buffer zone, and 88% are within the 5-km buffer zone. A fairly strong correlation between the cancer villages and annual GDP, as well as pollutant discharge, was found, with correlation coefficients of 0.94 for Jiangsu, 0.89 for Northern Jiangsu, 0.93 for Central Jiangsu, 0.83 for Southern Jiangsu and 0.64 for city level. The change of newly added cancer villages is significantly influenced by the discharge of sewage water (raising COD) and SO₂, and the peak of newly added cancer villages, as well as discharge of COD and SO₂ all occurred in 2005. For four cities, the total sewage water discharge and SO₂ emissions are consistent with the order of the distribution density of the villages. The phenomenon of cancer villages in China will gradually be resolved as the government takes effective measures to tackle environmental issues coupled with people’s increasing environmental and health awareness.
اظهر المزيد [+] اقل [-]Levels of organochlorine pesticide residues in fresh water fishes of three bird sanctuaries in Tamil Nadu, India النص الكامل
2019
Samidurai, Jayakumar | Subramanian, Muralidharan | Venugopal, Dhananjayan
Organochlorine pesticide (OCP) residues were determined in nine species of fresh water fishes caught from three bird sanctuaries in Tamil Nadu, India. A total of 302 fishes were analyzed for various types of OCPS. OCPs, namely hexachlorocyclohexane (HCH), dichloro diphenyl trichloroethane (DDT), heptachlor epoxide, endosulfan, and dieldrin were detected among various species of fishes. Among the various OCPs analyzed, HCH was the most frequently detected pesticides. Among the HCH isomers, β HCH contributed more than 50% to the Σ HCH. p,p’ DDT, the metabolites of DDT, had high percentage of occurrence. Among the cyclodiene insecticide residues, endosulfan was detected in more than 60% of the fishes. Varying levels of ΣOCPs (a sum of Σ HCH, Σ DDT, Σ endosulfan, heptachlor epoxide, and dieldrin) were detected in various fish species, although it was not significant (p > 0.05). However, significant variations in OCPs were observed among location and between seasons (p < 0.05). However, continuous monitoring is recommended to facilitate the early identification of risks not only to the fishes, but also to fish-eating birds breeding in these sanctuaries.
اظهر المزيد [+] اقل [-]