خيارات البحث
النتائج 211 - 220 من 3,208
CO2 dose–response functions for wheat grain, protein and mineral yield based on FACE and open-top chamber experiments النص الكامل
2015
Pleijel, Håkan | Högy, Petra
Data from three Swedish open-top chamber and four German FACE experiments were combined to derive response functions for elevated CO2 (eCO2) effects on Cd, Zn, Mn, protein, grain yield, grain mass and grain number of wheat. Grain yield and grain number were increased by ∼6% and ∼7%, respectively, per 100 ppm CO2; the former effect was linked to plant nitrogen status. Grain mass was not influenced by eCO2, whereas Cd concentration was reduced. Unlike Zn, Mn and protein, effects on Cd yield were not related to effects on grain yield. Yields of Mn, Zn and (weakly) protein were positively affected by eCO2. For protein, grain yield, grain mass and grain number, the results were consistent among the FACE and OTC experiments. A key conclusion was that yields of essential nutrients were enhanced (Mn > Zn > protein), although less than grain yield, which would not be expected from a simple dilution model.
اظهر المزيد [+] اقل [-]Monitoring of persistent organic pollutants in seawater of the Pearl River Estuary with rapid on-site active SPME sampling technique النص الكامل
2015
Huang, Siming | He, Shuming | Xu, Hao | Wu, Peiyan | Jiang, Ruifen | Zhu, Fang | Luan, Tiangang | Ouyang, Gangfeng
An on-site active solid-phase microextraction (SPME) sampling technique coupled with gas chromatography-mass spectrometry (GC–MS) for sampling and monitoring 16 polycyclic aromatic hydrocarbons (PAHs) and 8 organochlorine pesticides (OCPs) in seawater was developed. Laboratory experiments demonstrated that the sampling-rate calibration method was practical and could be used for the quantification of on-site sampling. The proposed method was employed for field tests which covered large amounts of water samples in the Pearl River Estuary in rainy and dry seasons. The on-site SPME sampling method can avoid the contamination of sample, the losses of analytes during sample transportation, as well as the usage of solvent and time-consuming sample preparation process. Results indicated that the technique with the designed device can address the requirement of modern environment water analysis. In addition, the sources, bioaccumulation and potential risk to human of the PAHs and OCPs in seawater of the Pearl River Estuary were discussed.
اظهر المزيد [+] اقل [-]How to assess species richness along single environmental gradients? Implications of potential versus realized species distributions النص الكامل
2015
van Goethem, Thomas M.W.J. | Huijbregts, Mark A.J. | Wamelink, G.W Wieger | Schipper, Aafke M.
Quantifying relationships between species richness and single environmental factors is challenging as species richness typically depends on multiple environmental factors. Recently, various methods have been proposed to tackle this challenge. Using a dataset comprising field observations of grassland vegetation and measured pH values, we compared three methods for deriving species richness response curves. One of the methods estimates species richness close to the maximum species richness observed at the sites, whereas the other two provide estimates of the potential species richness along the environmental gradient. Our response curves suggest that potential species richness of grasslands is slightly more sensitive to acidification than realized plant species richness. However, differences in corresponding environmental quality standards (EQS) for acidification were small compared to intrinsic spatial differences in natural soil pH, indicating that natural background values are more important to consider in the derivation of EQS for pH than methodological differences between the three approaches.
اظهر المزيد [+] اقل [-]Translocation and biotransformation of CuO nanoparticles in rice (Oryza sativa L.) plants النص الكامل
2015
Peng, Cheng | Duan, Dechao | Xu, Chen | Chen, Yongsheng | Sun, Lijuan | Zhang, Hai | Yuan, Xiaofeng | Zheng, Lirong | Yang, Yuanqiang | Yang, Jianjun | Zhen, Xiangjun | Chen, Yingxu | Shi, Jiyan
Metal-based nanoparticles (MNPs) may be translocated and biochemically modified in vivo, which may influence the fate of MNPs in the environment. Here, synchrotron-based techniques were used to investigate the behavior of CuO NPs in rice plants exposed to 100 mg/L CuO NPs for 14 days. Micro X-ray fluorescence (μ-XRF) and micro X-ray absorption near edge structure (μ-XANES) analysis revealed that CuO NPs moved into the root epidermis, exodermis, and cortex, and they ultimately reached the endodermis but could not easily pass the Casparian strip; however, the formation of lateral roots provided a potential pathway for MNPs to enter the stele. Moreover, bulk-XANES data showed that CuO NPs were transported from the roots to the leaves, and that Cu (II) combined with cysteine, citrate, and phosphate ligands and was even reduced to Cu (I). CuO NPs and Cu-citrate were observed in the root cells using soft X-ray scanning transmission microscopy (STXM).
اظهر المزيد [+] اقل [-]Research and demonstration to improve air quality for the U.S. animal feeding operations in the 21st century – A critical review النص الكامل
2015
Ni, Ji-Qin
There was an increasing interest in reducing production and emission of air pollutants to improve air quality for animal feeding operations (AFOs) in the U.S. in the 21st century. Research was focused on identification, quantification, characterization, and modeling of air pollutions; effects of emissions; and methodologies and technologies for scientific research and pollution control. Mitigation effects were on pre-excretion, pre-release, pre-emission, and post-emission. More emphasis was given on reducing pollutant emissions than improving indoor air quality. Research and demonstrations were generally continuation and improvement of previous efforts. Most demonstrated technologies were still in a limited scale of application. Future efforts are needed in many fundamental and applied research areas. Advancement in instrumentation, computer technology, and biological sciences and genetic engineering is critical to bring major changes in this area. Development in research and demonstration will depend on the actual political, economic, and environmental situations.
اظهر المزيد [+] اقل [-]Complexation of silver and dissolved organic matter in soil water extracts النص الكامل
2015
Settimio, Lara | McLaughlin, Mike J. | Kirby, Jason K. | Langdon, Kate A. | Janik, Les | Smith, Scott
Complexation of silver and dissolved organic matter in soil water extracts النص الكامل
2015
Settimio, Lara | McLaughlin, Mike J. | Kirby, Jason K. | Langdon, Kate A. | Janik, Les | Smith, Scott
An important aspect of the behaviour and fate of silver (Ag) in soils is the interaction with dissolved organic matter (DOM). The complexation and strength of binding of Ag+ with DOM in soil water extracts was examined and modelled based on a range of chemical and quality DOM measurements. Silver ion binding measured by addition of the 110mAg radioisotope in addition to a cation exchange resin technique were used to determine strongly complexed Ag in solutions. Silver was found to be up to 70% strongly complexed. The variability in Ag+ binding by DOM across different soils was closely related (R2 = 0.8) to the mid-infrared spectra of these extracts. The affinity of Ag+ for DOM was stronger in solutions containing a greater content of humic and aromatic structures. The ability of Ag+ to complex with DOM could result in increased mobilisation of this metal in the soil environment.
اظهر المزيد [+] اقل [-]Complexation of silver and dissolved organic matter in soil water extracts النص الكامل
2015
Settimio, L. | McLaughlin, M. | Kirby, J. | Langdon, K. | Janik, L. | Smith, S.
Abstract not available. | Lara Settimio, Mike J. McLaughlin, Jason K. Kirby, Kate A. Langdon, Les Janik, Scott Smith
اظهر المزيد [+] اقل [-]Perfluoroalkyl substances detected in the world's southernmost marine mammal, the Weddell seal (Leptonychotes weddellii) النص الكامل
2015
Routti, Heli | Krafft, Bjørn A. | Herzke, Dorte | Eisert, Regina | Oftedal, Olav
This study investigates concentrations of 18 perfluoroalkyl substances (PFAS) in blood plasma of adult lactating Weddell seals (Leptonychotes weddellii) (n = 10) from McMurdo Sound, Antarctica. Perfluoroundecanoic acid (PFUnDA) was detected in all samples at concentrations ranging from 0.08 to 0.23 ng/ml. Perfluorooctane sulfonate (PFOS), perfluorohexanoate (PFHxA) and perfluorotridecanoate (PFTriDA) were sporadically detected, while the remaining compounds were below the limit of detection. This is the first report of detectible concentrations of PFASs in an endemic Antarctic marine mammal species. We suggest that the pollutants have been subjected to long range atmospheric transportation and/or derive from a local source. A review of these and published data indicate that perfluoroalkyl carboxylates (PFCAs) dominate in biotic PFAS patterns in species feeding south of the Antarctic Circumpolar Current (ACC), whereas PFOS was the major PFAS detected in species feeding predominantly north of the current.
اظهر المزيد [+] اقل [-]Rapid identification of soil cadmium pollution risk at regional scale based on visible and near-infrared spectroscopy النص الكامل
2015
Chen, Tao | Chang, Qingrui | Clevers, J.G.P.W. | Kooistra, L.
Soil heavy metal pollution due to long-term sewage irrigation is a serious environmental problem in many irrigation areas in northern China. Quickly identifying its pollution status is an important basis for remediation. Visible-near-infrared reflectance spectroscopy (VNIRS) provides a useful tool. In a case study, 76 soil samples were collected and their reflectance spectra were used to estimate cadmium (Cd) concentration by partial least squares regression (PLSR) and back propagation neural network (BPNN). To reduce noise, six pre-treatments were compared, in which orthogonal signal correction (OSC) was first used in soil Cd estimation. Spectral analysis and geostatistics were combined to identify Cd pollution hotspots. Results showed that Cd was accumulated in topsoil at the study area. OSC can effectively remove irrelevant information to improve prediction accuracy. More accurate estimation was achieved by applying a BPNN. Soil Cd pollution hotspots could be identified by interpolating the predicted values obtained from spectral estimates.
اظهر المزيد [+] اقل [-]Bioaccumulation of hepatotoxins – A considerable risk in the Latvian environment النص الكامل
2015
Barda, Ieva | Kankaanpää, Harri | Purina, Ingrida | Balode, Maija | Sjövall, Olli | Meriluoto, Jussi
The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form a dynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002–2007. The freshwater unionids accumulated toxins efficiently, followed by snails. In contrast, Dreissena polymorpha and most lake fishes (except roach) accumulated much less hepatotoxins. Significant nodularin-R concentrations were detected also in marine clams and flounders. No transfer of nodularin-R and microcystins between lake and brackish water systems took place. Lake mussels can transfer hepatotoxins to higher organisms, and also effectively remove toxins from the water column. Obvious health risks to aquatic organisms and humans are discussed.
اظهر المزيد [+] اقل [-]Source identification of perylene in surface sediments and waterbird eggs in the Anzali Wetland, Iran النص الكامل
2015
Zamani, Mojtaba | Khorasani, Nematollah | Bakhtiari, Alireza Riyahi | Rezaei, Karamatollah
Following the marked increase of perylene concentration in southern coast of Caspian Sea, waterbird eggs were used as biomonitoring agents. Surface sediments and eggs of five bird species were collected from colonies in Anzali Wetland in the above coast for perylene analysis. The perylene concentrations in sediment and egg samples ranged within 70.6–204.4 and 25.5–43.2 ng/g dw, respectively. Diagnostic perylene ratios showed that the perylene found in all samples was of biogenic origin, possibly developing from terrestrial materials. The combination pattern of perylene was found to be similar in all samples. Conclusively, perylene observed in the area was transmitted from sediments in breeding areas into the eggs, so the eggs are biomonitoring agents and the prevalence of oxic conditions in surface sediments limits formation of perylene, reflecting perylene formation in the catchment area. We found that perylene distribution in surface sediments follows irregular patterns, representing significant effects from local inputs.
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