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41.
Genetic transformation is gaining importance for developing plant types suitable to metal accumulate and/or hyperaccumulate. In this study, the transgenic tobacco plant which transferred the ScMTII gene from Saccharomyces cerevisiae to wild type tobacco cultivar Petite Havana (SR1) was grown on soils with low and high cadmium (Cd) and zinc (Zn) concentrations in a growth chamber for 6 weeks and compared to wild type tobacco for Cd and Zn accumulation. Cadmium and Zn accumulations in the transgenic and wild type tobacco plants were increased with the increasing Cd and Zn concentrations. Unlike Zn, the transgenic plant accumulated significantly higher amount of Cd compared to the wild type control plants. Shoot Cd concentrations of transgenic tobacco in higher Cd dosages reached the above the hyperaccumulation threshold value of 100 mg Cd kg?1 in the dry weight (DW). Transgenic tobacco accumulated 354, 400, 372, and 457 mg Cd kg?1 DW, for 10, 20, 40, and 80 mg Cd kg?1 soil treatments, respectively. These values are 3.5–4.5‐fold higher than that of Cd hyperaccumulation threshold value. With 10 mg kg?1 Cd treatment, the bioconcentration factor (BCF) of transgenic tobacco plants for Cd reached up to 35 in which the threshold value for BCF should be at least 10. Our results showed that the transgenic tobacco may be used as a good Cd hyperaccumulator plant and for phytoextraction of Cd contaminated soils, but not for Zn. 相似文献
42.
The statistical behavior of wave energy at a site strongly depends on the wave characteristics. Wave energy converters fail to produce energy when there are no sufficiently available wave heights. Hence, evaluation of return periods and risk values of the minimum wave height becomes important for wave energy studies. A time index representing the minimum wave height is proposed here for ocean wave applications. Persistence plays a significant role in the calculation of return period and risk. Although ignoring the serial independence makes calculations easy, it leads to overestimations of the real status. In this paper, return periods and risk values are compared with each other by taking into consideration independent and dependent situations. Application of the study is achieved for the stations located in the Pacific Ocean and Gulf of Mexico. 相似文献
43.
Mehmet Simav Hasan Yildiz Ali Türkezer Onur Lenk Emin ?zsoy 《Studia Geophysica et Geodaetica》2012,56(1):215-230
Sea level trends and interannual variability at Antalya and Menteş tide gauges are investigated during the 1985–2001 period,
quantifying the roles of atmospheric, steric and local land motion contributions. Tide gauge sea level measurements, temperature/salinity
climatologies and GPS data are used in the analyses and the results are compared with the output of a barotropic model forced
by atmospheric pressure and wind. The overall sea level trends at two tide gauges collocated with GPS are in the range of
5.5 to 7.9 mm/yr during the study period, but showing different behaviour in the sub-periods 1985–1993 and 1993–2001 due to
variations in the contributing factors both in space and time. After the removal of the atmospheric forcing and steric contribution
from sea level records, the resulting trends vary between 1.9 to 4.5 mm/yr in Antalya and −1.2 to −11.6 mm/yr in Menteş depending
on the period considered. Vertical land movement estimated from GPS data seems to explain the high positive residual trend
in Antalya during the whole period. On the other hand, the source of the highly negative sea level trend of about −14 mm/yr
in Menteş during 1985–1993 could not be resolved with the available datasets. Interannual variability of wind and atmospheric
pressure appear to dominate the sea level at both tide gauges during the study period. Atmospheric and steric contributions
together account for ∼50% of the total sea level variance at interannual time scales. Mass induced sea level variations which
were not considered in this study may help to close the sea level trend budgets as well as to better explain the interannual
sea level variance. 相似文献
44.
Muhammad Khurshid Mohammad Nafees Abdullah Khan Mehmet Somuncu Ashfaq Ahmad Khan Wajid Rashid 《地理学报(英文版)》2019,29(10):1758-1770
Journal of Geographical Sciences - Pastoralism is a viable socio-economic system-shaped by landless and agro-pastoral communities in many pastoral regions of the world. This system is mainly based... 相似文献
45.
This work describes the potential usability of neutralized red mud for the removal of organochlorine pesticides (OCPs) from aqueous solutions. After examination on the adsorption capability of neutralized red mud for all studied OCPs, the experiments were performed by employing aldrin as a model compound. The effect of several parameters, such as contact time, pH of the solution, initial aldrin concentration, and dosage of the adsorbent was evaluated by batch experiments. The determination of OCPs was carried out using traditional liquid–liquid extraction followed by a GC coupled with µ‐electron capture detector (GC‐µECD). The results showed that adsorption equilibrium time depended upon the initial aldrin concentration and adsorption followed the second‐order kinetic model. Kinetic study also indicated that the film diffusion mechanism was a main rate control mechanism. The removal was explained by considering the electrostatic interactions between metal oxides surface of the neutralized red mud and inductively charged centers (negative charge (d?) of chlorine atoms and positive charge (d+) of π‐cloud aromatic ring) of the aldrin molecules. In comparison to the Langmuir isotherm model, the Freundlich model better represented the adsorption data. The neutralized red mud was also succesfully employed for the removal of OCPs from real water samples, including tap water and surface (lake) water, fortified with studied OCPs. 相似文献
46.
Erdem Emin Maras Mustafa Caniberk Mehmet Serhat Odabas Burcu Degerli Süleyman Sirri Maras Hadi Hakan Maras 《Arabian Journal of Geosciences》2016,9(2):164
We investigated the relationships between mineral content and the physical and mechanical properties of landscape rock using a non-destructive remote sensing method applied in the laboratory. Using this technique, the spectral properties of the landscape rock could be collected at different wavelengths without harming the samples. Differences in spectral reflectance were compared with the physical and mechanical properties of the stone. Significant correlations were observed between reflectance values and the rocks’ mechanical and physical properties, with correlation coefficients of 95 to 99 %. However, establishing a correlation between two variables is not a sufficient condition to establish a causal relationship. Mineral densities and mineral content are characteristics used for the classification of landscape rock. We have concluded that although spectral signatures from landscape rock can be used for predicting which stones might have similar features when comparing two batches of stone, the high correlations we discovered cannot confirm a cause and effect relationship that would allow for the prediction of a rock’s physical and mechanical properties. Although this conclusion is disappointing, the mineral content and the significant correlations discovered by hyperspectral reflectance scanning can be used as supplementary information when comparing two samples of landscape rock. 相似文献
47.
The lignite coal researched by this study was subjected to a two‐stage activation process performed in the scope of obtaining active carbon from domestic resources. “Activation” and “carbonization” stages were used in the experiments. The modified lignite was produced by impregnating lignite with KOH and washing the activation product with 15% HCl solution after thermal treatment. Increasing KOH dosage also increased the removal efficiency. The variables investigated in adsorption experiments were contact time, initial concentration, pH, and sorbent dosage. Adsorption kinetics was fitted by using the pseudo‐first‐order equation, pseudo‐second‐order equation, and intra‐particle diffusion. Isotherm modeling was carried out using Langmuir, Freundlich, and Dubinin–Radushkevich equations. Selected target compound in this work is common environmental pollutant in waters. A commonly known effect of chloroform is its carcinogenic effect. Therefore, removal of these compounds from water is considerably important. Chloroform removal of 97% for was achieved by the use of Konya region activated lignite. 相似文献
48.
The aim of the study is to investigate the interaction between waters of Lake Girdev and groundwater in the allochthonous
limestone units exposed in the area between Lake Girdev and Kazanpınarı Spring, southwestern Turkey. The features analyzed
include the flow direction and apparent groundwater velocity, their relationship with Lake Girdev, and the effect of lithological
and structural features on the groundwater circulation. The results of a fluorescein tracer test indicate that groundwater
flows east-northeast and the apparent flow velocity ranges from 26.2 to 35.6 m h–1 between the injection site and various observation points. Tritium data suggest that the water of Lake Girdev and groundwater
are probably similar in age, and oxygen-18 isotope data indicate that water derived from Lake Girdev is the main source of
recharge to the aquifer. The aquifer is fed not only by Lake Girdev but also by rainfall percolating through allochthonous
limestones; together, these provide the discharge of springs in Elmalı Polje. The permeability of the allochthonous limestone
aquifer has been enhanced as a result of jointing and faulting.
Received, June 1997 / Revised, June 1998, March 1999 / Accepted, July 1999 相似文献
49.
In this study, the effect of the electron sound speed on the extraordinary wave propagation is calculated without an approximation
for either collisional or collisionless cases in the ionospheric plasma by using the real geometry of the Earth’s magnetic
field for the Northern Hemisphere. It is observed that there is no remarkable effect on the propagation of the extraordinary
wave, especially at reflection altitudes. But it is also observed that the magnitudes of k
2 (the square of the wave number) have changed every season, and the phase velocity of wave in warm ionospheric plasma has
increased. 相似文献
50.
Wet and dry spell analysis of Global Climate Model-generated precipitation using power laws and wavelet transforms 总被引:2,自引:2,他引:0
Ashok K. Mishra Mehmet ?zger Vijay P. Singh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):517-535
Climate model simulations for the twenty-first century point toward changing characteristics of precipitation. This paper
investigates the impact of climate change on precipitation in the Kansabati River basin in India. A downscaling method, based
on Bayesian Neural Network (BNN), is applied to project precipitation generated from six Global Climate Models (GCMs) using
two scenarios (A2 and B2). Wet and dry spell properties of monthly precipitation series at five meteorologic stations in the
Kansabati basin are examined by plotting successive wet and dry durations (in months) against their number of occurrences
on a double-logarithmic paper. Straight-line relationships on such graphs show that power laws govern the pattern of successive
persistent wet and dry monthly spells. Comparison of power-law behaviors provides useful interpretation about the temporal
precipitation pattern. The impact of low-frequency precipitation variability on the characteristics of wet and dry spells
is also evaluated using continuous wavelet transforms. It is found that inter-annual cycles play an important role in the
formation of wet and dry spells. 相似文献