خيارات البحث
النتائج 3451 - 3460 من 4,043
Simultaneous analysis 26 mineral element contents from highly consumed cultured chicken overexposed to arsenic trioxide by inductively coupled plasma mass spectrometry النص الكامل
2016
He, Ying | Sun, Bonan | Li, Siwen | Sun, Xiao | Guo, Ying | Zhao, Hongjing | Wang, Yu | Jiang, Guangshun | Xing, Mingwei
This study assessed the impacts of dietary arsenic trioxide (As₂O₃) on 26 mineral element contents in the liver and kidney of chicken. A total of 100 male Hy-line cocks were randomly divided into 2 groups (50 chickens in each group), including an arsenic-treated group (basic diet supplemented with As₂O₃ at 30 mg/kg) and a control group (basal diet). The feeding experiment lasted for 90 days and the experimental animals were given free access to feed and water. We determined 26 mineral elements in the liver and kidney by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that nine element levels (Al, Mn, Co, Cu, Zn, Se, Cd, Ba, and Pb) were significantly decreased (P < 0.05) in the liver of chickens exposed to As₂O₃ compared to the control chickens where three element levels (Ni, As, and Hg) increased significantly (P < 0.05). The results in the kidney showed that nine element levels (Al, K, Ca, Cr, Mn, Ni, Sb, Ba, and Pb) were significantly decreased (P < 0.05) in the chickens exposed to As₂O₃ compared to the control chickens where four element levels (Mo, As, Cd, and Hg) increased significantly (P < 0.05). These results suggest that supplementation of high levels of arsenic affected trace mineral levels in the liver and kidney of chicken, and the effects vary from organ to organ. The aim of this study is to provide references for further study of heavy metal poisoning by detecting the contents of minerals induced by arsenic in chicken.
اظهر المزيد [+] اقل [-]Mitigation of polar pesticides across a vegetative filter strip. A mesocosm study النص الكامل
2016
Franco, Jorge | Matamoros, Víctor
Vegetated filter strips (VFSs) are planted at the edge of agricultural fields to reduce pesticide run-off and its consequent potential toxicological effects on ecosystem biota; however, little attention has been paid to date to the attenuation of highly polar and ionisable pesticides such as phenoxyacid herbicides. This study assesses the effect of soil moisture, run-off flow and vegetation on the attenuation of MCPA, mecoprop, dicamba, dichlorprop, fenitrothion, atrazine and simazine by VFSs. Reactors measuring 5 m long by 0.1 m wide were each filled with 60 kg of soil from a real field VFS. VFSs planted with Phragmites australis and unvegetated control reactors were assessed. After a simulated rainfall event of 50 mm, two hydraulic loading rates (HLRs) were assessed (1 and 2 cm h⁻¹). These results were compared to those from the same systems under water-saturated conditions. The results show that VFSs reduced the peak inlet concentration and pesticide mass by more than 90 % and that the presence of vegetation increased that attenuation (82–90 % without vegetation and 90–93 % with vegetation, on average). The laboratory-scale study showed that such attenuation was due to sorption into the soil. The toxicity units of pesticides fell by more than 90 % in all cases, except under the water-saturated conditions, in which the decrease was lower (16 vs 54 %, for unvegetated and vegetated reactors). Therefore, the presence of vegetation was shown to be effective for reducing mass discharge of ionisable and highly polar pesticides into surface-water bodies.
اظهر المزيد [+] اقل [-]Development of a protocol to optimize electric power consumption and life cycle environmental impacts for operation of wastewater treatment plant النص الكامل
2016
Piao, Wenhua | Kim, Changwon | Cho, Sunja | Kim, Hyosoo | Kim, Minsoo | Kim, Yejin
In wastewater treatment plants (WWTPs), the portion of operating costs related to electric power consumption is increasing. If the electric power consumption decreased, however, it would be difficult to comply with the effluent water quality requirements. A protocol was proposed to minimize the environmental impacts as well as to optimize the electric power consumption under the conditions needed to meet the effluent water quality standards in this study. This protocol was comprised of six phases of procedure and was tested using operating data from S-WWTP to prove its applicability. The 11 major operating variables were categorized into three groups using principal component analysis and K-mean cluster analysis. Life cycle assessment (LCA) was conducted for each group to deduce the optimal operating conditions for each operating state. Then, employing mathematical modeling, six improvement plans to reduce electric power consumption were deduced. The electric power consumptions for suggested plans were estimated using an artificial neural network. This was followed by a second round of LCA conducted on the plans. As a result, a set of optimized improvement plans were derived for each group that were able to optimize the electric power consumption and life cycle environmental impact, at the same time. Based on these test results, the WWTP operating management protocol presented in this study is deemed able to suggest optimal operating conditions under which power consumption can be optimized with minimal life cycle environmental impact, while allowing the plant to meet water quality requirements.
اظهر المزيد [+] اقل [-]Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations النص الكامل
2016
Jin, Peng | Gao, Kunshan
Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations النص الكامل
2016
Jin, Peng | Gao, Kunshan
Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations 700 to 1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species' resilience to OA decreased after 2000 generations under high CO2 selection.
اظهر المزيد [+] اقل [-]Reduced resilience of a globally distributed coccolithophore to ocean acidification: Confirmed up to 2000 generations النص الكامل
2016
Jin, Peng | Gao, Kunshan
Ocean acidification (OA), induced by rapid anthropogenic CO2 rise and its dissolution in seawater, is known to have consequences for marine organisms. However, knowledge on the evolutionary responses of phytoplankton to OA has been poorly studied. Here we examined the coccolithophore Gephyrocapsa oceanica, while growing it for 2000 generations under ambient and elevated CO2 levels. While OA stimulated growth in the earlier selection period (from generations ~700 to ~1550), it reduced it in the later selection period up to 2000 generations. Similarly, stimulated production of particulate organic carbon and nitrogen reduced with increasing selection period and decreased under OA up to 2000 generations. The specific adaptation of growth to OA disappeared in generations 1700 to 2000 when compared with that at 1000 generations. Both phenotypic plasticity and fitness decreased within selection time, suggesting that the species' resilience to OA decreased after 2000 generations under high CO2 selection.
اظهر المزيد [+] اقل [-]SWAT: Agricultural water and nonpoint source pollution management at a watershed scale—Part II النص الكامل
2016
Volk, Martin | Bosch, David | Nangia, Vinay | Narasimhan, Balaji
This is the second part of a Special Issue on developments and applications of the Soil and Water Assessment Tool (SWAT) related to agricultural water and nonpoint source pollution management at a watershed scale (see Volk et al., 2016 for part I).
اظهر المزيد [+] اقل [-]Nutrient pollution from agricultural production
2016
Biodegradation of antibiotic ciprofloxacin: pathways, influential factors, and bacterial community structure النص الكامل
2016
Liao, Xiaobin | Li, Bingxin | Zou, Rusen | Dai, James Y. | Xie, Shuguang | Yuan, Baoling
Antibiotic ciprofloxacin is ubiquitous in the environment. However, little is known about ciprofloxacin dissipation by microbial community. The present study investigated the biodegradation potential of ciprofloxacin by mixed culture and the influential factors and depicted the structure of ciprofloxacin-degrading microbial community. Both the original microbiota from drinking water biofilter and the microbiota previously acclimated to high levels of ciprofloxacin could utilize ciprofloxacin as sole carbon and nitrogen sources, while the acclimated microbiota had a much stronger removal capacity. Temperature rise and the presence of carbon or nitrogen sources favored ciprofloxacin biodegradation. Many novel biotransformation products were identified, and four different metabolic pathways for ciprofloxacin were proposed. Bacterial community structure illustrated a profound shift with ciprofloxacin biodegradation. The ciprofloxacin-degrading bacterial community was mainly composed of classes Gammaproteobacteria, Bacteroidia, and Betaproteobacteria. Microorganisms from genera Pseudoxanthomonas, Stenotrophomonas, Phenylobacterium, and Leucobacter might have links with the dissipation of ciprofloxacin. This work can provide some new insights towards ciprofloxacin biodegradation.
اظهر المزيد [+] اقل [-]Characterization of pH-fractionated humic acids with respect to their dissociation behaviour النص الكامل
2016
Klučáková, Martina
Humic acids were divided into several fractions using buffer solutions as extraction agents with different pH values. Two methods of fractionation were used. The first one was subsequent dissolution of bulk humic acids in buffers adjusted to different pH. The second one was sequential dissolution in buffers with increasing pH values. Experimental data were compared with hypothesis of partial solubility of humic acids in aqueous solutions. Behaviour of humic fractions obtained by sequential dissolution, original bulk sample and residual fractions obtained by subsequent dissolution at pH 10 and 12 agrees with the hypothesis. Results demonstrated that regardless the common mechanism, solubility and dissociation degree of various humic fractions may be very different and can be estimated using parameters of the model based on the proposed mechanism. Presented results suggest that dissolving of solid humic acids in water environment is more complex than conventional solubility behaviour of sparingly soluble solids.
اظهر المزيد [+] اقل [-]Developing biodiversity indicators on a stakeholders’ opinions basis: the gypsum industry Key Performance Indicators framework النص الكامل
2016
Pitz, Carline | Mahy, Grégory | Vermeulen, Cédric | Marlet, Christine | Séleck, Maxime
This study aims to establish a common Key Performance Indicators (KPIs) framework for reporting about the gypsum industry biodiversity at the European level. In order to integrate different opinions and to reach a consensus framework, an original participatory process approach has been developed among different stakeholder groups: Eurogypsum, European and regional authorities, university scientists, consulting offices, European and regional associations for the conservation of nature, and the extractive industry. The strategy is developed around four main steps: (1) building of a maximum set of indicators to be submitted to stakeholders based on the literature (Focus Group method); (2) evaluating the consensus about indicators through a policy Delphi survey aiming at the prioritization of indicator classes using the Analytic Hierarchy Process method (AHP) and of individual indicators; (3) testing acceptability and feasibility through analysis of Environmental Impact Assessments (EIAs) and visits to three European quarries; (4) Eurogypsum final decision and communication. The resulting framework contains a set of 11 indicators considered the most suitable for all the stakeholders. Our KPIs respond to European legislation and strategies for biodiversity. The framework aims at improving sustainability in quarries and at helping to manage biodiversity as well as to allow the creation of coherent reporting systems. The final goal is to allow for the definition of the actual biodiversity status of gypsum quarries and allow for enhancing it. The framework is adaptable to the local context of each gypsum quarry.
اظهر المزيد [+] اقل [-]Analysis of numerical simulations and influencing factors of seasonal manganese pollution in reservoirs النص الكامل
2016
Peng, Hui | Zheng, Xilai | Chen, Lei | Wei, Yang
Seasonal manganese pollution has become an increasingly pressing water quality issue for water supply reservoirs in recent years. Manganese is a redox-sensitive element and is released from sediment under anoxic conditions near the sediment–water interface during summer and autumn, when water temperature stratification occurs. The reservoir water temperature and water dynamic conditions directly influence the formation of manganese pollution. Numerical models are useful tools to quantitatively evaluate manganese pollution and its influencing factors. This paper presents a reservoir manganese pollution model by adding a manganese biogeochemical module to a water quality model—CE-QUAL-W2. The model is applied to the Wangjuan reservoir (Qingdao, China), which experiences manganese pollution during summer and autumn. Field data are used to verify the model, and the results show that the model can reproduce the main features of the thermal stratification and manganese distribution. The model is used to evaluate the manganese pollution process and its four influencing factors, including air temperature, water level, wind speed, and wind directions, through different simulation scenarios. The results show that all four factors can influence manganese pollution. High air temperature, high water level, and low wind speed aggravate manganese pollution, while low air temperature, low water level, and high wind speed reduce manganese pollution. Wind that travels in the opposite direction of the flow aggravates manganese pollution, while wind in the same direction as the flow reduces manganese pollution. This study provides useful information to improve our understanding of seasonal manganese pollution in reservoirs, which is important for reservoir manganese pollution warnings and control.
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