Уточнить поиск
Результаты 3511-3520 из 4,924
Toxic (Al, Cd, and Pb) and trace metal (B, Ba, Cu, Fe, Mn, Sr, and Zn) levels in tissues of slaughtered steers: risk assessment for the consumers
2019
Rodríguez-Marín, Nieves | Hardisson, Arturo | Gutiérrez, Ángel José | Luis-González, Gara | González-Weller, Dailos | Rubio, Carmen | Paz, Soraya
The levels of toxic metals (Al, Cd, Pb) and trace metals (B, Ba, Cu, Fe, Mn, Sr, Zn) were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) in the muscle (sirloin and chuck) and liver from a total of 180 samples of steers (less than 2 years old) (Bos taurus) of foreign and local origin slaughtered on the island of La Palma (Canary Islands, Spain). As regards toxic metals, Al was the metal with the highest contents in both tissues of the foreign steers (3.75 mg/kg in the muscle and 55.3 mg/kg in the liver) and the local steers (5.60 mg/kg in the muscle and 8.65 mg/kg in the liver). In conclusion, the present study confirmed that beef is a source of trace elements, mainly Fe and Zn. In addition, the consumption of this type of beef did not show significant intakes of toxic metals (Al, Cd, and Pb) and, therefore, the consumption of the steer muscle and liver does not pose a toxicological risk for Spanish consumers.
Показать больше [+] Меньше [-]Design and synthesis of organic rectorite-based composite nanofiber membrane with enhanced adsorption performance for bisphenol A
2019
Sun, Zhiming | Yuan, Fang | Zhang, Xinchao | Zhu, Rui | Shen, Xinyi | Sun, Bingyan | Wang, Bin
Nowadays, most of mineral-based adsorbents are powder form, which makes them inconvenient to collect and always easy to cause secondary pollution. In this work, an organic rectorite composite nanofiber membrane (SRt-PAN) was designed and prepared by electrospinning technique. The as-received composite nanofiber membranes were characterized by XRD and SEM analysis, proving the homodisperse and existence of SRt in PAN nanofiber membrane. A series of batch experiments for BPA adsorption were carried out to investigate the effect of different adsorption parameters, including initial concentration, pH, and temperature of pollutant solution. The influences of modifier dosage and adsorbent dosage on the adsorption performance were investigated as well. On the basis of the experiment results, the adsorption process could be well described by the pseudo-second-order model and the Langmuir isotherm. In addition, the thermodynamic parameters indicate that this adsorption process is exothermic and spontaneous. Moreover, compared with pure nanofiber membranes and organic rectorite powders, the resultant SRt-PAN adsorbents exhibited higher adsorption capacity, superior reusability, and adsorption stability. It is indicated that the hydrophobicity surface of organic rectorite should be the key factor to not only the intimate interfacial combination between the mineral and PAN, but also the enhancement of BPA adsorption capacity.
Показать больше [+] Меньше [-]Derivation of the predicted no-effect concentration for organophosphate esters and the associated ecological risk in surface water in China
2019
Xing, Liqun | Wang, Lichao | Xu, Bin | Li, Aimin
Organophosphate esters (OPEs), as re-emerging contaminants considered to be a potential health concern, are ubiquitous in the environment and have been widely investigated. However, little is known on the safe OPE concentrations in the water quality criteria for the protection of the aquatic environment, which is an indispensable part of environmental management. In the present study, aquatic acute and chronic predicted no-effect concentrations (PNECs) of six frequently detected OPEs were derived from the hazardous concentrations for 5% of species (HC₅s), respectively. The acute PNECs for the selected OPEs ranged from 17.70 to 3562 μg/L, while the chronic PNECs ranged from 4.6 × 10⁻⁴ to 61.85 μg/L. Among these OPEs, tricresyl phosphate (TCrP) exhibited the lowest acute PNEC, while tris(1,3-dichloro-2-propyl) phosphate (TDCPP) presented chronic PNEC, which indicated that it has a higher toxicity effect on the aquatic environment. Furthermore, the aquatic ecological risks of individual OPEs (except for TDCPP) were deemed to be relatively low in Chinese surface water; however, the aquatic ecological risks of TDCPP and ΣOPEs indicated that they have potential adverse effects and should be considered as a potential health concern. The probability of 5% of aquatic organisms being affected by ΣOPEs was in the range of 0.21 to 17.39% based on the joint probability curve method.
Показать больше [+] Меньше [-]Recovery of heavy metals from waste printed circuit boards: statistical optimization of leaching and residue characterization
2019
Khayyam Nekouei, Rasoul | Pahlevani, Farshid | Golmohammadzadeh, Rabeeh | Assefi, Mohammad | Rajarao, Ravindra | Chen, Yen-Hao | Sahajwalla, Veena
Despite attempts to enhance the recycling of waste printed circuit boards (WPCBs), the simultaneous recovery of major metals of WPCBs using an efficient approach is still a great challenge. This study mainly concerned with applying an effective statistical tool to optimize the recovery of metal content (i.e., Cu, Fe, Zn, Pb, Ni, Sn, and Al) embedded in WPCBs using a leaching agent without any additive or oxidative agent. Another target was to optimize a multi-response recovery process by minimizing time, energy, and acid consumption during the leaching. Effective parameters and their levels, including leaching time (20–60 min), temperature (25–45 °C), solid to liquid (S/L) ratio (1/8–1/20 g/ml), and acid molarity (1–2.7 M), were optimized. A well-established statistical approach (i.e., response surface methodology (RSM)) was applied to precisely quantify and interpret the effects. General optimum conditions for nine responses were introduced with the desirability of ≈ 85%. Finally, the solid residue of leaching was characterized and results showed the morphology, structure, and composition of the residue content (i.e., polymers and ceramics) remained the same after the leaching, indicating the neutral behavior of the leaching process on these two materials. Also, thermal behavior and phase analysis of the original WPCBs and leaching residue were compared and analyzed. Graphical abstract
Показать больше [+] Меньше [-]Sequential coupling of bio-augmented permeable reactive barriers for remediation of 1,1,1-trichloroethane contaminated groundwater
2019
Wang, Wenbing | Wu Yanqing,
Sequential coupling of high-density luffa sponge (HDLS) immobilized microorganism and permeable reactive barriers (IM Bio-PRBs) was superior to intimate coupling of free microorganism and permeable reactive barriers (FM Bio-PRBs) for remediation of 1,1,1-trichloroethane contaminated groundwater. IM Bio-PRBs had much better performance to removal 1,1,1-trichloroethane (1,1,1-TCA) and prevent the transport of 1,1,1-TCA and inorganic ions (NO₃⁻, PO₄³⁻, and SO₄²⁻). The majority of them were prevented and accumulated in upgradient of IM Bio-PRBs. 1,1,1-TCA and inorganic ions in there contributed to the much faster growth of microorganism in upgradient aquifer. Therefore, the removal of 1,1,1-TCA and consumption of inorganic ions in upgradient of Bio-PRBs played a constructive role in reducing the processing load of following zero-valent iron (ZVI) PRBs and the negative effect of free microorganism cells (biological clogging) and inorganic ions (chemical clogging) on Bio-PRB permeability. In addition, IM Bio-PRBs were more conducive to accelerate the removal of 1,1,1-TCA in long-term remediation and 1,1,1-TCA residual concentration significantly lower than the safety standard of 0.2 mg L⁻¹. The change of terminal by-products of 1,1,1-TCA contaminated groundwater in Bio-PRBs showed that 1,1,1-TCA could be effectively de-chlorinated and mineralized in Bio-PRBs. The reductant H₂S (prolong the service life of ZVI-PRBs) was much more produced and utilized in IM Bio-PRBs. Taken together, sequentially coupled IM Bio-PRBs had a better overall performance, and its service life could be prolonged. It was a different design and idea to update conventional PRB remediation technology and theory.
Показать больше [+] Меньше [-]Correction to: Occurrence of polybrominated diphenyl ethers in floor and elevated surface house dust from Shanghai, China
2019
Niu, Dong | Qiu, Yanling | Li, Li | Zhou, Yihui | Du, Xinyu | Zhu, Zhiliang | Chen, Ling | Lin, Zhifen
The article Occurrence of polybrominated diphenyl ethers in floor and elevated surface house dust from Shanghai, China, written by Dong Niu, Yanling Qiu, Li Li, Yihui Zhou, Xinyu Du, Zhiliang Zhu, Ling Chen and Zhifen Lin, was originally published electronically on the publisher’s internet portal
Показать больше [+] Меньше [-]Effects of phosphorus on absorption and transport of selenium in rice seedlings
2019
Li, Ying Ying | Yu, Shu Hui | Zhou, Xin Bin
The effects of different concentrations of phosphorus (P) on absorption and transfer of selenium (Se) in rice seedlings were studied by hydroponics experiment. The interaction between iron plaque and phosphorus on absorption and transport of selenium were studied by adding a large amount of iron-induced iron plaque, to provide a theoretical basis for rational application of phosphate fertilizer in the selenium bio-strengthening process of rice. The results showed that phosphorus deficiency may result in the formation of reddish brown iron oxide coating on the root surface of rice. The formation of root iron plaque of rice is related to concentration of phosphorus, and low concentration of phosphorus (0–1.5 mmol L⁻¹) can increase the amount of root iron plaque. Compared P deficiency culture and 2 mmol L⁻¹ P culture, Se content in the shoots and roots decreased by 76 and 47%, respectively. Addition of Fe²⁺ significantly reduced biomass of shoot and had no significant effect on the roots; when the P concentration increased from 0.1 to 0.3 mmol L⁻¹, transfer coefficient of Se decreased. Therefore, both root iron plaques induced by phosphorus deficiency and iron addition have a strong adsorption effect on selenium, which reduces the transport of selenium from the rice roots to the shoots. In the lower range of phosphorus concentration, low phosphorus can promote selenium content of rice shoot, while higher on the contrary. In the practice of rice production, proper management of phosphorus nutrient is of great significance to control selenium content in rice grain.
Показать больше [+] Меньше [-]Investigating adsorption mechanism and surface complex formation modeling for aqueous sulfadiazine bonding on Fe/Mn binary oxides
2019
Yu, Jie | Wang, Hongjie | Ji, Qinghua
In aquatic environment, the existence of antibiotics including sulfadiazine (SDZ) has gain a huge attention. It is suggested that hydrous metal oxides have large potential to remove contaminants in water. The SDZ removal capability by ferric and manganese binary oxides (FMBO) was investigated, and the SDZ removal performance was compared with the ferric hydroxide (HFO) and manganese dioxide (HMO). Our results showed that SDZ removal was highly pH-dependent, but pH has less effect on uptake of SDZ on FMBO than that of the other two adsorbents. The surface acidity constant of FMBO was first calculated to be 6.31 and 8.48, respectively. The uptake process was successfully fitted for according to surface complex formation models (SCFM) and the results of modern surface analytical methods, such as FTIR and XPS, were also consistent with the surface complex uptake mechanism. The uptake of SDZ by FMBO ascribed to specific chemical interaction between the aniline group of SDZ and the hydroxyl groups from FMBO.
Показать больше [+] Меньше [-]Innovation and CO2 emissions: the complimentary role of eco-patent and trademark in the OECD economies
2019
Mensah, Claudia Nyarko | Long, Xingle | Dauda, Lamini | Boamah, Kofi Baah | Salmān, Muḥammad
Increasing global emissions has led to research on the role of innovations play combating emissions. Mitigations from innovation perspective have mainly been focused on the role of patent, ignoring the role of trademarks. We therefore investigate the mitigating power of patent and trademarks in the OECD economies, benchmarking patent as the traditional mitigation strategy. Examining the complimentary role, we created an interaction term between patent and trademark. Our study divided the OECD economies into four subpanels which are OECD America, OCED Asia, OECD Europe, and OECD Oceania. We employed the Im, Pesaran and Shin W-stat, Augmented Dickey-Fuller, and Phillips Perron unit root tests, as well as cross-sectional dependence and Westerlund cointegration tests for the preliminary test on the variables. We also adopted ARDL approach to cointegration, Granger causality test, and OLS in examining the relationship between CO₂ and patent, trademark, urbanization, and economic growth. Findings show that jointly, eco-patents and trademarks mitigate CO₂ emissions. Also, bidirectional or unidirectional causal relationship was established between our variables of study, an indication that most of our variables can be used in forecasting one other.
Показать больше [+] Меньше [-]Major, trace, and rare-earth elements in the zooplankton of the Laptev Sea in relation to community composition
2019
Lobus, Nikolay V. | Arashkevich, Elena G. | Flerova, Ekaterina A.
We investigated the concentrations of major, trace, and rare-earth elements in zooplankton in relation to species community composition from the eastern part of the Lena Delta to the continental slope of the Laptev Sea in September 2015. The elemental composition of zooplankton inhabiting different areas demonstrated similarities. Cross-shelf changes were found for only 4 (Li, Zn, As, and U) of the 56 elements analyzed. Zinc was the only element concentration of which successively reduced across coastal–open ocean gradient. Considering own and literary data, we can assume that the cross-shelf decrease of zinc accumulation in zooplankton is a universal pattern, manifested in different climatic and biogeochemical environmental conditions and with different species compositions of the zooplankton community. Cross-shelf changes were also established for Li, As, and U. However, the concentrations of these elements increased along the gradient. We assume that increased As concentration in zooplankton across the shelf–continental slope gradient of the Laptev Sea is associated with a change in the feeding behavior of the species of the zooplankton community. However, a sharp increase in the concentrations of Li and U in zooplankton was associated with the appearance of Calanus copepods in the community. The average total concentration of rare-earth elements and yttrium in zooplankton of the Laptev Sea was 752.8 ng g⁻¹ of dry weight. We found record high levels of rare-earth elements for zooplankton of the inner shelf, near the eastern part of the Lena Delta. From the inner shelf to the continental slope of the Laptev Sea, La, Ce, and Nd were the dominant rare-earth elements. The elemental composition of zooplankton in the Arctic Seas is characterized by a much lower content of major and trace elements in comparison with the zooplankton and total plankton of the ocean.
Показать больше [+] Меньше [-]