Investigation of a combined continuous flow system for the removal of Pb and Cd from heavily contaminated soil.

In this study, a combined continuous flow system was designed to remove Pb and Cd from heavily contaminated mine tailing soils. 0.05 M Na2EDTA was used as a chelating agent to remove Pb and Cd from polluted soil, taken from the vicinity of Kayseri ÇINKUR, Turkey. The initial concentrations of Pb and Cd were 16381 ±â€¯643 and 34347 ±â€¯1310 mg kg-1, respectively. The electrochemical treatment process was applied to the waste washing solution, which emerged after being extracted from soil column and contained Pb and Cd. Metal ions were transformed to the metallic form by applying the electrochemical treatment process to the washing solution, containing Pb2+ and Cd2+. At the end of the leaching experiment, which was done with a 50 g soil sample in the soil column system, Pb and Cd removal efficiencies from soil were 59.72% and 58.01%, respectively. Then, the soil column solution was subjected to electrolysis through a 48 h period at 10 V. The electrochemical removal efficiency of ions, which moved from column to solution, was 84.46% for Pb and 59.21% for Cd.

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 (Pb(0)).

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 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).

Monitoring of nuclear abnormalities in peripheral erythrocytes of three fish species from the Goksu Delta (Turkey): genotoxic damage in relation to water pollution.

Goksu Delta is a specially protected area in the Mediterranean region of Turkey. The delta is classified as a Wetland of International Importance according to the RAMSAR Convention on Wetlands of International Importance. Increases in population have recently taken place in this region due to heavy agricultural activities and discharges of anthropogenic wastes. In the present study, frequencies of erythrocytic nuclear abnormalities such as, micronuclei (MN) and nuclear buds (NB) were investigated in peripheral blood of three fish species; Clarias gariepinus (Catfish), Alburnus orontis (Bleak), and Mugil cephalus (Mullet) from Akgol (AG) and Paradeniz (PD) lagoons of Goksu Delta. Concentrations of heavy metals (Cu, Cd, Ni, Pb) were also measured in the water, sediment samples. MN and NA frequencies were elevated in fish from AG and PD lagoons in comparison with those from upstream regions. The results of this study indicate that the lagoons of Goksu Delta contaminated with genotoxic pollutants and that the genotoxicity is related to the agricultural activities and to the discharge of anthropogenic waste waters.

Evaluation of river water genotoxicity using the piscine micronucleus test.

The Berdan River, which empties into the Mediterranean Sea on the east coast of Turkey, receives discharges of industrial and municipal waste. In the present study, the in vivo piscine micronucleus (MN) test was used to evaluate the genotoxicity of water samples collected from different locations along the Berdan River. Nile tilapia (Oreochromis niloticus) were exposed in the laboratory for 2, 4, and 6 days, and micronuclei were evaluated in peripheral blood erythrocytes, gill cells, and caudal fin epithelial cells. A single dose of 5 mg/L cyclophosphamide was used as a positive control. In addition to micronuclei, nuclear abnormalities (NAs), such as binucleated cells and blebbed, notched, and lobed nuclei, were assessed in the erythrocytes, and chemical analyses were carried out to determine the amount of heavy metals in the water samples. MN and NA frequencies were significantly elevated (up to 2- to 3-fold) in fish exposed to river water samples taken downstream of potential discharges, and the elevated responses in gill and fin cells were related to the concentration of heavy metals in the water. MN frequencies (expressed as micronucleated cells/1,000 cells), in both treated and untreated fish, were greatest in gill cells (range: 0.80-3.70), and generally lower in erythrocytes (range: 0.50-2.80), and fin cells (range: 0.45-1.70). The results of this study indicate that the Berdan River is contaminated with genotoxic pollutants and that the genotoxicity is related to the discharge of wastes into the river water.

Speciation of chromium in 12 agricultural soils from Turkey.

The objective of the study was to speciate and to evaluate various soil Cr species in relation to soil properties. Surface soil samples were taken from outskirts of the Cr factory and applied a sequential extraction procedure. Extracts analyzed in atomic absorption spectrophotometry (AAS). Chromium was partitioned into exchangeable Cr, Cr bound to carbonate, Fe-Mn oxide, and organic matter, and residual Cr. The most common form of chromium was in the residual form, followed by the organic form. Very low concentrations of Cr were found in the exchangeable and carbonate forms. Mean values of the extractable forms of Cr, expressed in percentages of total soil contents were: 0.94% exchangeable, 0.80% carbonates, 2.13% oxides, 7.08% organics and 89.81% residual. Multiple regression analysis of analytical data revealed that soil pH, contents of organic matter and calcium carbonate were the most important factor controlling the distribution of Cr forms determined.

Effect of zinc fertilization on cadmium toxicity in durum and bread wheat grown in zinc-deficient soil.

The effect of increasing application of zinc (Zn) and cadmium (Cd) on shoot dry weight and shoot concentrations of Zn and Cd was studied in bread and durum wheat cultivars. Plants were grown in severely Zn-deficient calcareous soil treated with increasing Zn (0 and 10 mg kg(-1) soil) and Cd (0, 10 and 25 mg kg(-1) soil) and harvested after 35 and 65 days of growth under greenhouse conditions. Growing plants without Zn fertilization caused severe depression in shoot growth, especially in durum wheat and at high Cd treatment. Cadmium treatments resulted in rapid development of necrotic patches on the base and sheath parts of the oldest leaves of both wheat cultivars, but symptoms were more severe in durum wheat and under Zn deficiency. Decreases in shoot dry weight from increasing Cd application were more severe in Zn-deficient plants. Severity of Cd toxicity symptoms in durum and bread wheat at different Zn treatments did not show any relation to the Cd concentrations in shoot. Increasing Cd application to Zn-deficient plants tended to decrease Zn concentrations in Zn-deficient plants, whereas in plants with adequate Zn, concentrations of Zn were either not affected or increased by Cd. The results show that durum wheat was more sensitive to both Zn deficiency and Cd toxicity as compared to bread wheat. Cadmium toxicity in the shoot was alleviated by Zn treatment, but this was not accompanied by a corresponding decrease in shoot concentrations of Cd. Our results are compatible with the hypothesis that Zn protects plants from Cd toxicity by improving plant defense against Cd-induced oxidative stress and by competing with Cd for binding to critical cell constituents such as enzymes and membrane protein and lipids.