Batch and column experiments to support heavy metals (Cu,Zn and Mn) in alluvial sediments

Laboratory batch sorption and column transport experiments were performed on heterogeneous alluvial soils with a wide range of physical characteristics from wells that are located in the region between Mogan Lake and Eymir Lake, Gölba??, Ankara. The mean values for the K _d of Cu were found to be highest in clay (32550.350 L/kg) and lowest in loamy sand (18170.76 L/kg). The minimum and maximum sorption capacity values (mean values) for Zn were found to be in clay (10985.148 mg/kg) and in silty loam (8597.14 mg/kg) units, respectively. Similarly, the minimum and maximum values for Mn were found in loamy sand (4908.695 mg/kg) and clay (7587.391 mg/kg) units. The non-linear least-squares optimization code “CXTFIT” was used to determine transport parameter values by curve-fitting. The results of the column experiments demonstrate dispersivity values within the range of 0.024–1.13 cm for soil samples.     

Seismic microzonation and earthquake damage scenarios for urban areas

A methodology for seismic microzonation and earthquake damage scenarios may be considered as composed of two stages. In the first stage, microzonation maps with respect to estimated earthquake characteristics on the ground surface are generated for an investigated urban area. The effects of local geological and geotechnical site conditions are taken into account based on site characterization with respect to representative soil profiles extending down to the engineering bedrock. 1D site response analyses are performed to calculate earthquake characteristics on the ground surface using as many as possible, hazard compatible real acceleration time histories. In the second stage, vulnerability of buildings and pipeline systems are estimated based on site-specific ground motion parameters. A pilot study is carried out to evaluate seismic damage in a district in Istanbul, Turkey. The results demonstrate the significance of site characterization and site response analysis in calculating the earthquake characteristics on the ground surface in comparison to simplified empirical procedures.     

A New Natural Secondary Reference Material for Garnet U-Pb Dating by TIMS and LA-ICP-MS

Gem quality andradite-rich garnet (IUC-1), obtained from the Miocene trachyte dome near Ankara city (Turkey), has been identified as a potential natural secondary reference material for U-Pb dating. In this study, U-Pb dating was performed in five different laboratories using isotope dilution TIMS and laser ablation ICP-MS to determine the homogeneity of euhedral garnet crystals. The U-Pb ID-TIMS data for IUC-1 yielded ²⁰⁷Pb/²³⁵U and ²⁰⁶Pb/²³⁸U ages of 20.9 ± 0.4 and 20.6 ± 0.8 Ma respectively, and these values are consistent with U-Pb LA-ICP-MS analyses, in which different garnet crystals yielded ages of 20.8 ± 0.1, 20.7 ± 0.1, 20.7 ± 0.2 and 20.2 ± 0.1 Ma. An andradite (IUC-2) from the Serçeören wollastonite skarn (Turkey) can be used as a secondary reference material provided detailed imaging of the crystals is undertaken. ID-TIMS data yielded ²⁰⁷Pb/²³⁵U and ²⁰⁶Pb/²³⁸U ages of 20.4 ± 0.4 and 20.9 ± 1.0 Ma respectively, and yielded U-Pb ages on different grains of 20.5 ± 0.1, 20.7 ± 1.0, 20.8 ± 1.7 and 20.9 ± 1.6 Ma. The assigned weighted mean age of IUC-1 (20.4 ± 0.5 Ma, 2s) is proposed as a 2023 reference value. IUC-1 garnet is expected to contribute significantly to rapidly developing garnet geochronology in the near future.     

Field reconnaissance on seismic performance of RC buildings after the January 24, 2020 Elazığ-Sivrice earthquake

Natural Hazards - A moderate earthquake with a magnitude Mw of 6.8 occurred in the Sivrice district of Elaz?? Province in Eastern Turkey on January 24th, 2020. The mainshock and long-term...     

Roles of hydrogeochemical evaluations in estimating protection zones of Koçpınar springs in Aksaray, central Anatolia, Turkey

The present study indicates estimation of protection zones of KoçpLnar springs in Aksaray area by means of hydrogeochemical methods. Relevant hydrogeochemical studies were carried out to achieve this objective. KoçpLnar springs emerge on strike-slip Hasanda<L fault set (HFS) along the Tuzgölü (Salt Lake) fault zone (TFZ) in central Anatolia. The outcrops of volcanic origin exhibit different hydrogeological properties in the study area. The hydrogeochemical evaluations of KoçpLnar springs represent good results about the available main groundwater flow systems that exist in this area. Marbles of Palaeozoic age form the main aquifer that recharges KoçpLnar springs. The CO₂ gas content of the spring waters is significantly high. Based on the ion concentrations, the water of this spring has mainly two hydrochemical facies: Ca-Mg-HCO₃ and Na-HCO₃. Although, the hydrochemical analyses showed that waters of these springs meet the drinking and irrigation water standards, the area around the springs is continuously being contaminated by both domestic and agricultural wastes. Therefore, detailed hydrogeological, hydrochemical and isotopic investigations were carried out to accurately estimate the protection zones of KoçpLnar springs. These studies showed that three main protection zones could be proposed against external pollution effects around the spring's area.     

On the geomagnetic lunar variation at Istanbul

Summary The article describes lunar daily magnetic variation inH, D andZ components of the earth's magnetic field at Istanbul. Maximum occurs at 10.03 l.hr. (lunar hour) in theH component, 3.38 l.hr. in theD and 2.15 l.hr. in theZ component, during the period 1949 to 1968. Also, the seasonal variation of the lunar magnetic variation has been determined and it is seen that the variation of the phase inD andZ are opposite from the phase of the lunar variation inH, and the amplitudes of the lunar variation inH, D andZ are greatest during the northern solstice.     

Radium and barium at GEOSECS stations in the Atlantic and Pacific

²²⁶Ra and Ba show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg. This demonstrates the usefulness of Ba as a “chemical analogue” of Ra. Box-model calculations indicate that the average deep-water excess of Ra over Ba should be about 10% relative to the surface. This is consistent with the observations outside the deep northeast Pacific. However, the uncertainties in the data are such that the regional variation in the primary input cannot be resolved. In the deep waters of the North Pacific there is in fact a large excess of Ra relative to Ba. The one detailed profile presently available (204) can be explained consistently by a simple vertical advection-diffusion model.     

Fluxes of metals to a manganese nodule radiochemical,chemical, structural,and mineralogical studies

Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (²³⁰Th,²³¹Pa,²³²Th,²³⁸U,²³⁴U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr^?1 for at least 0.5 Myr and accreting Mn at 200 μg cm^?2 kyr^?1. The bottom of the nodule had been growing in its collected orientation at about 12 mm Myr^?1 for at least 0.3 Myr and accreting Mn at about 700 μg cm^?2 yr^?1. Although the top of the nodule was enriched in iron relative to the bottom, the nodule had been accreting Fe 50% faster on the bottom.²³²Th was also accumulating more rapidly in the bottom despite a 20-fold enrichment of²³⁰Th on the top.The distribution of alpha-emitting nuclides calculated from detailed radiochemical measurements matched closely the pattern revealed by 109-day exposures of alpha-sensitive film to the nodule. However, the shape and slope of the total alpha profile with depth into the nodule was affected strongly by²²⁶Ra and²²²Rn migrations making the alpha-track technique alone an inadequate method of measuring nodule growth rates.Diffusion of radium in the nodule may have been affected by diagenetic reactions which produce barite, phillipsite and todorokite within 1 mm of the nodule surface; however, our sampling interval was too broad to document the effect. We have not been able to resolve the importance of nodule diagenesis on the gross chemistry of the nodule.     

Meridional distribution of226Ra in the eastern Pacific along GEOSECS cruise tracks

We present the distribution of²²⁶Ra in eight vertical profiles from the eastern Pacific. The profiles are located along a meridional trend near 125°W, from 43°S to 29°N. Surface²²⁶Ra concentrations are about 7 dpm/100 kg, except for the two stations south of 30°S where the higher values are due to the Antarctic influence. Deep waters show a distinctive south-to-north increase in the²²⁶Ra content, from about 26 to 41 dpm/100 kg near the bottom. Unlike in the Atlantic and Antarctic Oceans, the effect of²²⁶Ra injection from bottom sediments is clearly discernible in the area. The presence of this primary²²⁶Ra can be traced up to at least 1–1.5 km above the ocean floor, making this part of the sea bed among the strongest source regions for the oceanic²²⁶Ra. Numerical solutions of a two-dimensional vertical advection-diffusion model applied to the deep (1.2–4 km)²²⁶Ra data give the following set of best fits: upwelling velocity(V_z) = 3.5m/yr, vertical eddy diffusivity(K_z) = 0.6cm²/s, horizontal (north-south) eddy diffusivity(K_y) = 1 × 10⁷cm²/s, and water-column regeneration flux of²²⁶Ra(J) = 3.3 × 10^?5dpmkg^?1yr^?1 as an upper limit. These parametric values are in general agreement with one-dimensional (vertical) model fits for the Ra-Ba system. However, consideration of²²⁶Ra balance leads us to suspect the appropriateness of describing the vertical exchange processes in the eastern Pacific with constantV_z and K_z. If future modeling is attempted, it may be preferable to treat the area as a diffusion-dominant mixing regime with depth-dependent diffusivities.     

Radium and thorium isotopes in the surface waters of the East Pacific and coastal Southern California

A fiber extraction technique is used to concentrate Ra and Th isotopes from 1000 liters or more of seawater. Natural²²⁶Ra and²³⁴Th are used as yield tracers. In the equatorial Pacific the²²⁸Ra activity of surface water varies from 20 to 1 dpm/1000 kg and generally decreases away from continental shelf areas. Across the Peru Current System, this decrease is modeled as one-dimensional diffusion and indicates the possibility of two flow regimes with distinct characteristic mixing lengths and apparent eddy diffusivities of 10⁵ and 10⁷ cm²/s. The perturbing effects of advection and equatorial upwelling west of the Galapagos Islands are noted. Off the coast of Southern California a vertical²²⁸Ra distribution gives an apparent diffusivity of 1.6 cm²/s for the upper thermocline.²²⁶Ra concentrations near the coast appear to be higher than the open ocean values at comparable depths, which may reflect supply of this isotope from continental shelf sediments and/or upwelling. The insoluble daughter/soluble parent activity ratios²²⁸Th/²²⁸Ra and²³⁴Th/²³⁸U in the equatorial Pacific surface water display latitudinal trends which may be correlated with productivity variations. Near the coast of California these ratios reflect the differing oceanographic conditions north and south of Pt. Conception indicating a mean chemical removal time constant on the order of 4 months for Th and other highly reactive elements within the Southern California Bight. The²³²Th content of seawater sampled is less than 0.1 μg/1000 1; most of the published values for seawater²³²Th could well be too high. A comparison of the two methods of determining²²⁸Ra (via²²⁸Ac and via²²⁸Th) made on 64 seawater samples shows that the time delay required by the²²⁸Th method is more than compensated by its better analytical simplicity and precision.