Carcinogenic risk evaluation for human health risk assessment from soils contaminated with heavy metals

Human activities have progressively increased in recent years. Consequently, significant environment deterioration resulted. Soils have a particularly varied vulnerability to heavy metal pollution, especially in the vicinity of industrial areas. Heavy metal contamination of soil may induce risks and hazards to humans and the ecosystem, while toxic metals in soil can severely inhibit the biodegradation of organic contaminants. This paper is focused on human health risk assessment from extremely contaminated soil with heavy metals, mainly with carcinogenic elements. The study refers to an agricultural area in the vicinity of an old metallurgical processing industrial facility. The contaminants evaluated in the present paper are beryllium (Be), cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb). Contamination level is pointed out through laboratory analysis results of soil samples taken from 0–0.2 m, 0.2–0.4 m soil layers and up to 2.1 m soil depth. Some heavy metal concentrations (Cd, Cr and Pb) exceed the intervention thresholds for sensitive areas, as they are stipulated in the national regulation in Romania. The identified average concentration levels of Cd, Cr^VI and Pb in the first layer of the investigated land are 23.83, 7.71 and 704.22 mg/kg_d.w, respectively. The results show that the potential risk of human health is relevant (higher than the acceptable one after World Health Organization) and a possible solution for the remediation should become a major concern for the investigated area.     

Batch and Column Experiments to Support Heavy Metals (Cu,Zn, and Mn) Transport Modeling in Alluvial Sediments Between the Mogan Lake and the Eymir Lake,Gölbaşı, Ankara

This article describes laboratory batch sorption and column transport experiments that were conducted using heterogeneous alluvial sediments with a wide physical characteristic from wells, located between Lake Mogan and Lake Eymir, Gölbaşı, Ankara. The batch sorption experiment was conducted in two separate systems, that is, single and multicomponents. Single batch experiment was performed to determine equilibrium condition between the heavy metal ions and the soil adsorption sites. The sorption isotherms data from multibatch experiments were used to calculate the sorption parameters. Single batch experiment indicated that equilibrium was attained within 9 days from the start of the sorption test. As a result of multicomponents batch experiments, for Zn and Mn, the sorption process was well described by the Freundlich or Langmuir isotherm model, whereas sorption of Cu was better described by the linear isotherm model. The K_d of Cu were found to be highest in soil 1 (32550.350 L kg⁻¹) and lowest in soil 5 (18170.76 L kg⁻¹). The maximum and minimum sorption capacity values for Zn were found to be in soil 1 (10985.148 mg kg⁻¹) and in soil 2 (8597.14 mg kg⁻¹) units, respectively. [Correction added after online publication 15 July, 2010: In the preceding sentence, the words “minimum” and “maximum” were initially switched.] Similarly, soil 1 (7587.391 mg kg⁻¹) and soil 5 (4908.695 mg kg⁻¹) units provided the maximum and minimum values for Mn. In the column experiments, flow and tracer transport was studied under saturated conditions using conservative tracer to determine the transport parameters. Transport parameter values were obtained by curve-fitting using the nonlinear least-squares optimization code CXTFIT. Results of the column experiments indicated that the dispersivity values obtained for soil samples were in the range of 0.024 to 1.13 cm.     

Evolution of seismic hazard maps in Turkey

A review on the historical evolution of seismic hazard maps in Turkey is followed by summarizing the important aspects of the updated national probabilistic seismic hazard maps. Comparisons with the predecessor probabilistic seismic hazard maps as well as the implications on the national design codes conclude the paper.     

Full waveform inversion of SH‐ and Love‐wave data in near‐surface prospecting

We develop a two‐dimensional full waveform inversion approach for the simultaneous determination of S‐wave velocity and density models from SH ‐ and Love‐wave data. We illustrate the advantages of the SH/Love full waveform inversion with a simple synthetic example and demonstrate the method's applicability to a near‐surface dataset, recorded in the village ?achtice in Northwestern Slovakia. Goal of the survey was to map remains of historical building foundations in a highly heterogeneous subsurface. The seismic survey comprises two parallel SH‐profiles with maximum offsets of 24 m and covers a frequency range from 5 Hz to 80 Hz with high signal‐to‐noise ratio well suited for full waveform inversion. Using the Wiechert–Herglotz method, we determined a one‐dimensional gradient velocity model as a starting model for full waveform inversion. The two‐dimensional waveform inversion approach uses the global correlation norm as objective function in combination with a sequential inversion of low‐pass filtered field data. This mitigates the non‐linearity of the multi‐parameter inverse problem. Test computations show that the influence of visco‐elastic effects on the waveform inversion result is rather small. Further tests using a mono‐parameter shear modulus inversion reveal that the inversion of the density model has no significant impact on the final data fit. The final full waveform inversion S‐wave velocity and density models show a prominent low‐velocity weathering layer. Below this layer, the subsurface is highly heterogeneous. Minimum anomaly sizes correspond to approximately half of the dominant Love‐wavelength. The results demonstrate the ability of two‐dimensional SH waveform inversion to image shallow small‐scale soil structure. However, they do not show any evidence of foundation walls.     

Dynamic sub-surface characteristic and the active faults of the Genç District locating over the Bingöl Seismic Gap of the East Anatolian Fault Zone,Eastern Turkey

The Genç District is located on the Bingöl Seismic Gap (BSG) of the Eastern Anatolian Fault Zone (EAFZ) with its?~?34.000 residents. The Karl?ova Triple Junction, where the EAFZ, the North Anatolian Fault Zone, and the Varto Fault Zone meet, is only 80 km NE of the Genç District. To make an earthquake disaster damage prediction of the Genç District, carrying a high risk of disaster, we have (1) prepared a new geological map, and (2) conducted a single-station microtremor survey. We defined that three SW-NE trending active faults of the sinistral Genç Fault Zone are cutting through the District. We have obtained dominant period (T) as?<?0.2 s, the amplification factor (A) between 8 and 10, the average shear wave velocity for the first 30 m (Vs₃₀) as?<?300 m/s, and the seismic vulnerability index (Kg) as?>?20, in the central part of the Genç District. We have also prepared damage prediction maps for three bedrock acceleration values (0.25, 0.50, 0.75 g). Our earthquake damage prediction scenarios evidenced that as the bedrock acceleration values increase, the area of soil plastic behavior expands linearly. Here we report that if the average expected peak ground acceleration value (0.55–0.625 g) is exceeded during an earthquake, significant damage would be inevitable for the central part of the Genç District where most of the schools, mosques, public buildings, and hospitals are settled-down.

     

The measurement of soil gases and shallow temperature for determination of active faults in a geothermal area: a case study from Ömer–Gecek,Afyonkarahisar (West Anatolia)

Afyonkarahisar is a very important geothermal province of western Anatolia and has low and medium enthalpy geothermal areas. This study has been carried out for the preparation of distribution maps of soil gases (radon and carbon dioxide) and shallow soil temperature and the exploration of permeable tectonic regions associated with geothermal systems and reveal the origins of radon and carbon dioxide gases. The western district of the study area is characterized by the high radon concentration (168.30 kBq/m³), carbon dioxide ratio (0.30%), and soil temperature (21.0 °C) values. Fethibey and Demirçevre faults, which allow the circulation of geothermal fluids, have been detected in the distribution maps of radon, carbon dioxide, and shallow depth temperature and the directions of the curves in these maps correspond to the strikes of Demirçevre faults. The effect of the fault plays an important role in the change of carbon dioxide concentration along the W-E directional geological section prepared to determine the change of soil gas and shallow depth temperature values depending on lithological differences, fault existence, and geothermal reservoir depth. On the other hand, it was determined that Rn²²² concentration and soil temperature changed as a function of geothermal reservoir depth or lithological difference. Tuffs in Köprülü volcano-sedimentary units are the main source of radon due to their higher uranium contents. Besides, the carbon dioxide in Ömer–Gecek soils has geothermal origin because of the highest carbon dioxide content (99.3%) in non-condense gas. The similarities in patterns of soil temperature, radon, and carbon dioxide indicate that the variation in soil temperatures is related to radon and carbon dioxide emissions. It is concluded that soil gas and temperature measurements can be used to determine the active faults in the initial stage of geothermal exploration successfully.     

Climate change in Turkey for the last half century

Climate change and its urban-induced bias in selected Turkish cities is studied with a quality controlled temperature and precipitation data of Turkish stations in the period of 1950–2004. These stations are classified into two groups according to their populations; S1, including rural and suburban stations and S2, including large urban stations. Moving average signals, 365-day, and their digital low pass filtered versions are produced to eliminate the short term fluctuations and examine the possible trends or anomalies in climate data. Furthermore, ‘relative difference’ signals are introduced and applied to temperature and precipitation series to observe the actual local changes in the climate data independent from large-scale effects. Mann–Kendall test statistics are calculated for maximum, minimum, mean temperature and precipitation series and plotted on maps to determine any spatial trend patterns. Signal analysis show a cool period extending from early 1960s till 1993, generally with the lowest temperature values on 1992–1993 owing to the eruption of Mount Pinatubo. A last decade significant warming trend is observed in both of the series, S1 and S2, leading to 2000–2002 temperatures to be recorded as maximums in record history. The variability of urban precipitation series is generally larger than the rural ones, suggesting that urban stations can experience more frequent and severe droughts and floods. Though not significant, an increase in the urban precipitation compared to the rural one is also found. Spatial analysis resulted in significant warming in southern and southeastern parts of the country. Particularly, minimum temperature series show significant warming in almost all of the regions indicating the effect of urbanization. Significant decreases of precipitation amounts in the western parts of Turkey, such as Aegean and Trachea regions, are found. On the other hand, some Turkish northern stations show increases in precipitation of which some are significant.     

Flow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar,Turkey

Turbidity currents and their deposits can be investigated using several methods, i.e. direct monitoring, physical and numerical modelling, sediment cores and outcrops. The present study focused on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in eleven clusters of closely spaced thin beds. Depositional processes and sources for three of those eleven clusters are studied at three coring sites. Bathymetrical data and seismic reflection profiles are used to understand the specific geomorphology of each site. X‐ray, thin sections and CT scan imagery combined with grain‐size, geochemical and mineralogical measurements on the cores allow characterization of the turbidites. Turbidites included in each cluster were produced by remobilization of surficial slope sediment, a process identified in very few studies worldwide. Three types of turbidites are distinguished and compared with deposits obtained in flume studies published in the literature. Type 1 is made of an ungraded clayey silt layer issued from a cohesive flow. Type 2 is composed of a partially graded clayey sand layer overlain by a mud cap, attributed to a transitional flow. Type 3 corresponds to a graded clayey sand layer overlain by a mud cap issued from a turbulence‐dominated flow. While the published experimental studies show that turbulence is damped by cohesion for low clay content, type 3 deposits of this study show evidence for a turbulence‐dominated mechanism despite their high clay content. This divergence may in part relate to input variables, such as water chemistry and clay mineralogy, that are not routinely considered in experimental studies. Furthermore, the large sedimentological variety observed in the turbidites from one coring site to another is related to the evolution of a sediment flow within a field‐scale basin made of a complex physiography that cannot be tackled by flume experiments.