Dilek Turer

Heavy Metal Contamination in Soils of Urban Highways Comparison Between Runoff and Soil Concentrations at Cincinnati, Ohio

Rainfall runoff from urban roadways oftencontains elevated amounts of heavy metals in both particulate anddissolved forms (Sansalone and Buchberger, 1997). Because metalsdo not degrade naturally, high concentrations of them in runoffcan result in accumulation in the roadside soil at levels thatare toxic to organisms in surrounding environments. This studyinvestigated the accumulation of metals in roadside soils at asite for which extensive runoff data were also available.For this study, 58 soil samples, collected from I-75 nearCincinnati, Ohio, were examined using X-ray fluorescence, C-Sanalyzer, inductively coupled plasma spectroscopy, atomicabsorption spectrometry and X-ray diffraction. The resultsdemonstrated that heavy metal contamination in the top 15 cm ofthe soil samples is very high compared to local backgroundlevels. The maximum measured amount for Pb is 1980 ppm (at 10–15 cm depth) and for Zn is 1430 ppm (at 0–1 cm depth). Metal content in the soil falls off rapidly with depth, and metalcontent decreases as organic C decreases. The correlation toorganic C is stronger than the correlation to depth. The resultsof sequential soil extraction, however, showed lower amounts ofPb and Zn associated with organic matter than was expected basedon the correlation of metals to % organic C in the whole soil.Measurement of organic C in the residues of the sequentialextraction steps revealed that much of the carbon was not removedand hence is of a more refractory nature than is usual inuncontaminated soils. Cluster analysis of the heavy metal datashowed that Pb, Zn and Cu are closely associated to one another,but that Ni and Cr do not show an association with each other orwith either organic C or depth. ICP spectroscopy of exchanged cations showed that only 4.5%of Pb, 8.3% of Zn, 6.9% of Cu and 3.7% of Cr in the soil isexchangeable. Combined with the small amounts of metals bound tosoluble organic matter, this result shows that it is unlikelythat these contaminants can be remobilized into water. At thissite, clays are not an important agent in holding the metals inplace because of low amounts of swelling clays. Instead, insoluble organic matter is more important. Mass balancecalculations for Pb in soil showed that most of the Pb came fromexhausts of vehicles when leaded gasoline was in use, and thatabout 40% of this Pb is retained in the soil.This study shows that, highway environments being a relativelyconstant source of anthropogenic organic matter as well as heavymetals, heavy metals will continue to remain bound to organicmatter in-situ unless they are re-mobilized mechanically. Removalof these heavy metals as wind-blown dust is the most likelymechanism. Another possibility is surface run-off carrying themetals into surface drainages, bypassing the soil. This studyalso shows that for those countries still using leaded gasoline,important reductions in Pb contamination of soils can be achievedby restricting the use of Pb additives.

Combining Subsidence Analysis and Detrital Modes of Sandstones to Constrain Basin History: An Example from the Eastern Pontides of Turkey

Basin history is traditionally approached using either tectonic subsidence analysis or sandstone composition, but seldom both. The power of combining these two techniques is illustrated by consideration of the Pontide zone of Turkey. The Pontides are the onshore expression of the Black Sea basin, and understanding their evolution is important for petroleum and mineral exploration of the region. Many contrasting models have been proposed for the tectonic evolution of the eastern Pontides, but they have proved hard to evaluate. This study shows how combining subsidence analysis with sandstone petrography allows a more rigorous evaluation of these models than has hitherto been possible. Tectonic subsidence analysis was applied to measured stratigraphic sections from 10 different localities from the eastern Pontides. Each stratigraphic column was subjected to a backstripping process to assess the amount of the subsidence attributable to purely tectonic processes. To make the necessary calculations and to obtain subsidence curves, a spreadsheet program was developed. Using tectonic subsidence rates and shapes of curves, strike-slip, foreland, and fore-arc possibilities were eliminated for the tectonic setting of the basins. Also four synchronous subsidence events were recognized throughout the localities at 125 Ma, 98 Ma, 85 Ma, and 55 Ma. Modal compositions of sandstones place additional constraints on the possible tectonic settings of the basins studied. Petrography of the sandstone samples from the eastern Pontides showed that Liassic strata are rich in volcanic fragments; their likely tectonic setting was a backarc basin. By contrast, Upper Cretaceous and Eocene samples are rich in quartz, implying that a continental source dominated. The combination of the shapes of the subsidence curves, the rates of subsidence, the timing of the events, and the sandstone compositions are most consistent with the tectonic model of Banks and Robinson (1997).

Effect of electrode configuration on electrokinetic stabilization of soft clays

The effect of electrode configuration on electrokinetic strengthening of soft clays was assessed using a circular electrokinetic experimental setup with multiple electrode rods instead of a conventional rectangular setup with two plate electrodes. The experiments were carried out in three configurations where CaCl2 was used as a stabilizing agent in all, but the position of the anode was changed. In the first experiment the anode was in the central compartment, and in the second and third it was in the peripheral compartment, with the third experiment also having Ca(OH)2 added to the soil along with CaCl2. In the first experiment with the application of 10 V for 10 days, a 49% increase in shear strength was obtained in the cathode region. In the areas close to the anode and in the middle section, however, the shear strength was decreased by 26 and 11% respectively. In the second and third experiments the shear strength was increased in all regions (close to anode, middle, close to cathode) by 36, 60 and 137% and 25, 48 and 123% respectively. These results showed that the configuration with the anode positioned in the peripheral compartment works much better in obtaining an increase in shear strength throughout the sample.

Spatial distribution of coal quality parameters with respect to production requirements: an adaptive neuro-fuzzy application for the Can coal field (Turkey)

Determination of spatial distribution of coal quality parameters can ease management of the operations in coal mines. In this study, in order to provide guidance for the excavations, Can coal mine production map showing regions having suitable coal parameters as feed coals for a power plant and also for public sale was prepared using adaptive neuro-fuzzy inference system tool. Statistical relationships among calorific value, ash content and sulphur content were evaluated using the data obtained from boreholes opened in the mine between 2006 and 2009. According to the obtained production map, coals of Can mine are not suitable for public sale because of their high sulphur content and hence they should be blended with low sulphur coals to meet the requirements, before sale.