Nurcan Koleli

Differential response of rye, triticale, bread and durum wheats to zinc deficiency in calcareous soils

Field and greenhouse experiments were carried out to study the response of rye (Secale cereale L. cv. Aslim), triticale (× Triticosecale Wittmark. cv. Presto), two bread wheats (Triticum aestivum L, cvs. Bezostaja-1 and Atay-85) and two durum wheats (Triticum durum L. cvs. Kunduru-1149 and C-1252) to zinc (Zn) deficiency and Zn fertilization in severely Zn-deficient calcareus soils (DTPA-Zn=0.09 mg kg-1 soil). The first visible symptom of Zn deficiency was a reduction in shoot elongation followed by the appearance of whitish-brown necrotic patches on the leaf blades. These symptoms were either absent or only slight in rye and triticale, but occurred more rapidly and severely in wheats, particularly in durum wheats. The same was true for the decrease in shoot dry matter production and grain yield. For example, in field experiments at the milk stage, decreases in shoot dry matter production due to Zn deficiency were absent in rye, and were on average 5% in triticale, 34% in bread wheats and 70%, in durum wheats. Zinc fertilization had no effect on grain yield in rye but enhanced grain yield of the other cereals. Zinc efficiency of cereals, expressed as the ratio of yield (shoot dry matter or grain) produced under Zn deficiency compared to Zn fertilization were, on average, 99% for rye, 74% for triticale, 59% for bread wheats and 25% for durum wheats.These distinct differences among and within the cereal species in susceptibility to Zn deficiency were closely related to the total amount (content) of Zn per shoot, but not with the Zn concentrations in shoot dry matter. For example, the most Zn-efficient rye and the Zn-inefficient durum wheat cultivar C-1252 did not differ in shoot Zn concentration under Zn deficiency, but the total amount of Zn per whole shoot was approximately 6-fold higher in rye than the durum wheat. When Zn was applied, rye and triticale accumulated markedly more Zn both per whole shoot and per unit shoot dry matter in comparison to wheats.The results demonstrate an exceptionally high Zn efficiency of rye and show that among the cereals studied Zn efficiency declines in the order rye>triticale>bread wheat>durum wheat. The differences in expression of Zn efficiency are possibly related to a greater capacity of efficient genotypes to acquire Zn from the soil compared to inefficient genotypes.

The sequential use of washing and an electrochemical reduction process for the remediation of lead-contaminated soils

A two-step method for the remediation of three different types of lead (Pb)-contaminated soil was evaluated. The first step included soil washing with ethylenediaminetetraacetic acid (EDTA) to remove Pb from soils. The washing experiments were performed with 0.05 M Na2EDTA at 1:10 soil to liquid ratio. Following the washing, Pb removal efficiency from soils ranged within 50–70%. After the soil washing process, Pb2+ ions in the washing solution were reduced electrochemically in a fixed-bed reactor. Lead removal efficiency with the electrochemical reduction at –2.0 V potential ranged within 57–76%. The overall results indicate that this two-step method is an environmentally-friendly and effective technology to remediate Pb-contaminated soils, as well as Pb-contaminated wastewater treatment due to the transformation of toxic Pb2+ ions into a non-hazardous metallic form (Pb0).

Modeling Cd(II) adsorption to heterogeneous subsurface soils in the presence of citric acid using a semi-empirical surface complexation approach

Laboratory batch sorption experiments were conducted to understand the effect of citrate on cadmium sorption to heterogeneous subsurface soils. Our results indicate that citrate may have a pronounced effect on Cd(II) sorption depending on system conditions (e.g. pH, ligand concentration). While the presence of citrate had no effect on Cd(II) sorption at pH < 4, it led to a decrease in Cd sorption under slightly acidic to alkaline pH range depending on the concentration of citrate used. Maximum effect of citrate on Cd(II) sorption was observed at pHs between 5 and 7. This coincides with the observed range of maximum citrate adsorption and the formation of Cd-citrate complexes. A two-site non-electrostatic surface chemical model (SCM) based on the Generalized Composite (GC) approach was able to describe the experimental data well over a wide range of conditions, with only six different surface reactions including two ternary (Cd/citrate/soil) surface complexes. Although the semi-empirical surface model used in the simulations does not accurately represent the actual mechanisms at the molecular level, it is relatively simple, and can be effectively used in transport calculations as an alternative to the K(d) approach.

The Cadmium Phytoextraction Efficiency of ScMTII Gene Bearing Transgenic Tobacco Plant

ABSTRACT Cadmium pollution is a serious world-wide problem affecting the human health and the environmental quality. Phytoremediation, the use of green plants to remove, sequester or detoxify pollutants offers an environmentally-friendly alternative to engineering-based methods for remediation. The T2 generations of the ScMTII gene bearing transgenic and non-transgenic tobacco plants were grown hydroponically in Hoagland nutrition solution containing 0, 5 and 10 mg/L Cd in controlled growth room to determine their ability to uptake and accumulate Cd within the shoots and roots. There were no significant shoot and root dry weight differences between transgenic and non-transgenic tobacco plants. The ScMTII gene bearing transgenic tobacco plant accumulated 19.8% higher Cd than the non-transgenic tobacco plant in the above ground parts of the plant during the two weeks exposure period in hydroponic culture. In non-transgenic plant, however, Cd is accumulated mainly in the roots. The results of current study indicate that the use of the ScMTII gene bearing transgenic tobacco plant for Cd phytoremediation is limited. Further studies are needed to test the effectiveness of the ScMTII gene for phytoextraction of other heavy metal ions.

Movement and adsorption of methamidophos in clay loam and sandy loam soils

Laboratory batch and column experiments were performed to better understand the sorption and transport behaviour of commercial-grade methamidophos (Tamaron SL 600) in clay loam (CL) and sandy loam (SL) soils. The batch sorption experiments show that the soil texture and methamidophos concentration play a major role in the sorption and migration behaviour of methamidophos. At low surface coverage (q < 0.6 mg g−1), methamidophos sorbs onto the CL soil more strongly than onto the SL soil. However, for q > 0.6 mg g−1, the SL soil exhibits a much higher sorption affinity for methamidophos than the CL soil. The equilibrium isotherms for the sorption of methamidophos onto the SL and CL soils were non-linear, and were best described by the Freundlich equation. The results of column experiments indicate that the recovery of methamidophos during desorption was incomplete due to either partially irreversible sorption to high-energy surface sites or strongly rate-limited desorption. Methamidophos was more readily leached out from the SL soil column as consistent with the batch isotherm data.

The evaluation of toxicity and mutagenicity of various drinking waters in the human blood lymphocytes (HULYs) in vitro

The aim of the study was to evaluate the toxic and mutagenic effects of bottled purified and natural spring waters for drinking. The study presents the genotoxicologic results of drinking water samples packaged in polyethylene terephthalate (PET) bottles. Genotoxic agents have the potential to interact with DNA and may cause DNA damage. Endpoints analyzed included mitotic index (MI), replication index (RI), and sister chromatid exchange (SCE). An analysis of variance test (ANOVA) was performed to evaluate the results. A significant decrease in MI and RI was observed compared with negative control cultures, respectively, (p<0.05, p<0.01). It is found that SCE frequency increases compared with negative control. There is no significant difference between negative control and drinking water samples and among drinking water samples for sister chromatid exchange induction (p>0.05).

Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil

Laboratory batch sorption-desorption and column experiments were performed to better understand the effects of microbial exopolymeric substances (EPS) on Cr(III) sorption/desorption rates in the soil-water system. The experiments were carried out in two different modes: one mode (sorption) in which Cr(III) and EPS were applied simultaneously, and the other (desorption) included the sequential application of Cr(III) and EPS to the soil-water system. The batch sorption and desorption experiments showed that, while chromium(III) desorption was significantly enhanced in the presence of EPS relative to non-EPS-containing systems, the desorption rates were much smaller than the sorption rates, and the fraction dissolved by EPS accounted for only a small portion of the total chromium initially sorbed onto soil minerals. Similarly, the column experiments suggested that, while the microbial EPS led to an increase in Cr dissolution relative to non-EPS-containing systems, only a small portion of the total chromium initially added to the soil was mobilised. The differences observed in Cr sorption and desorption rates can be explained through the very low solubility and strong interactions of chromium species with soil minerals as well as the mass transfer effects associated with low diffusion rates. The overall results suggest that, while microbial EPS may play an important role in microbial Cr(VI) treatment in sub-surface systems due to the formation of soluble Cr-EPS complexes, the extent and degree of Cr mobilisation are highly dependent on the type of initial Cr sorption.

Distribution of chromium, cadmium, nickel and lead in agricultural soils collected from Kazanli-Mersin, Turkey

This study reports total levels of chromium, cadmium, nickel and lead in the agricultural land adjacent a factory producing chromate compounds in Kazanli-Mersin. Surface soil samples were collected from fields around the factory as well as from fields farther away to measure contamination due to aerial transportation and deposition of dust produced in the industrial process. Heavy metals in soil were extracted using wet digestion, and concentrations were measured by atomic absorption spectrophotometry. The concentrations were compared with Turkish maximum allowable concentration values. The metal concentrations averaged 80, 0.14, 228 and 431mg1kg-1 for chromium, cadmium, nickel and lead, respectively. Soil samples contaminated with chromium were mainly found 500–20001m from the factory and decreased with increasing distance from the factory. Elevated chromium and nickel concentrations were determined in the soils around the factory, especially to the northwest (prevailing wind) and west. Lead concentrations exceeded the limit in only roadside soils (4000 and 50001m to the west), but tended to increase in the vicinity of industrial activity (especially in the west, the northwest and the north). The cadmium concentration did not exceed the limit and was within the normal range for soils.

The Removal of Pb and Cd from Heavily Contaminated Soil in Kayseri, Turkey by a Combined Process of Soil Washing and Electrodeposition

ABSTRACT In this study, a combined system of soil washing and electrodeposition was designed to remove Pb (16381±643 mg/kg) and Cd (34347±1310 mg/kg) from contaminated soil. 0.05 M Na2EDTA was used as a chelating agent for the remediation of soil, taken from the nearby city Kayseri, Turkey. As a result of the batch extraction tests, maximum removals were determined as; at the 20:1 liquid: soil ratio for Pb is 60.7%, for Cd at the 30:1 liquid: soil ratio is 67.4%. An electrochemical treatment was applied to the waste washing solution which appeared to be the second pollutant after the Na2EDTA extraction from the soil. With extraction tests of Pb and Cd, being transformed from the solid phase to the liquid phase. The electrochemical treatment (electrodeposition), performed in three different potential (6 V, 8 V and 10 V) and maximum removal efficiencies, were found 99.7% and 80.3% at 10 V for Pb and Cd, respectively. Speciation tests (BCR) were carried out, both before and after the soil washing process, to evaluate the redistribution of metal fraction in the soil. The fraction, associated with the organic substance, was found as 10.67% for Pb and 1.81% for Cd. The metal bioavailability factor increased after soil washing, which indicates that EDTA could enhance the mobility of Pb and Cd.

Kadmiyum İle Kirlenmiş Toprakların Fitoektraksiyonla Arıtımında Transgenik Tütün Bitkisinin Kullanımının Araştırılması

Cadmium is one of the environmentally problematic heavy metals, because of its high mobility in soils, its ease and fast uptake by plant and very high toxic potential even at very low concentration. Thus its extraction from the polluted sites is environmentally important. Cadmium can be extracted from the soils either any of expensive remediation methods or phytoextraction which is a method with easy application, natural, and increasing usage. In this study, for fast and efficient removal of heavy metals, including Cd, Metallothionein II (MTII) gene isolated from Saccharomyces cerevisiae (Sc) and Sporamin vacuolar targeting signal gene isolated from sweet potatoes were added for bearing transgenic plant. The experiment was set up in spilt-plot in completely randomized design with three replications. Then the non-transgenic (Nicotiana tabacum L. cv Petit Havana SR1) and transgenic tobacco plants (p-S-ScMTII) were grown in pots containing 0, 0.2, 0.4, 0.8 and 1.6 mg/kg Cd up to flowering stage. Cadmium addition resulted in a slight decrease in growth but no toxicity symptoms were observed. There were no statistical differences in transgenic and non-transgenic plants for dry biomas and Cd concentration. However, Cd concentrations of shoots of both plants were increased upon increasing Cd concentration of soil. For 1.6 mg/kg Cd treatment, Cd concentration of transgenic and non-transgenic plants increased 13.8- 32.9 fold, respectively comparing to the control. Results suggested that S-ScMTII gene bearing transgenic plant did not improve Cd uptake in the studied range of soil Cd concentration. The efficiency of ScMTII gene for accumulation of Cd in shoots should be investigated at higher Cd concentration.