Toxic Effects of Copper‐Based and Synthetic Organic Pesticides on Activated Sludge

Toxic effects of five commonly used pesticides on the biomass of a municipal activated sludge system were determined on the basis of the reduction in the oxygen uptake rate (OUR) and specific oxygen uptake rate (SOUR). Toxicity levels of the selected pesticides were determined by employing a modified OECD 209 (Organisation for Economic Cooperation and Development) method which was performed as batch experiments using a respirometer. Copper sulphate (CuSO₄ · 5 H₂O), copper oxychloride (Cu₂Cl(OH)₃), copper calcium oxychloride (CaCu₃Cl₂(OH)₆) as copper‐based pesticides and chlorsulphuron (C₁₂H₁₂ClN₅O₄S), 2,4‐dichlorophenoxyacetic acid (2,4‐D) (C₈H₆Cl₂O₃) as synthetic organic pesticides were selected for the experiments. The EC₅₀ values were determined to be 78, 249 and 281 mg/L for CuSO₄ · 5 H₂O, Cu₂Cl(OH)₃ and CaCu₃Cl₂(OH)₆, respectively. Corresponding values for C₁₂H₁₂ClN₅O₄S and 2,4‐D were 860 and 3664 mg/L, respectively. Results indicated that toxicity effects of copper‐based pesticides were higher than that of synthetic organic pesticides. CuSO₄ · 5 H₂O was found to exert the highest toxicity among the copper‐based pesticides, whereas, C₁₂H₁₂ClN₅O₄S was determined to be the most toxic among the organic pesticides on activated sludge biomass.     

Seasonal variations in soil radon emanation: long-term continuous monitoring in light of seismicity

Soil gas radon release patterns have been monitored continuously for more than 3 years in the Eastern Mediterranean Province (EMP) (Southern Turkey), alongside regional seismic events, providing a multidisciplinary approach. In the period from January 2008 to January 2011, 14 earthquakes M _L ≥4 occurred in the study area. By monitoring the sites for more than 3 years, the site-characteristic patterns of soil radon emanation of each site have become evident. Radon emanation data show seasonal (semi-annual) variation characteristics; high soil radon values are between May and October and low soil radon values are between November and April. With available rainfall data, the soil gas radon data can be more reliably evaluated. It is shown in this paper that if radon emanation data are available over sufficiently long periods of time and baseline data (and their seasonal variations) are known with certainty for each monitoring site, then the observation of positive anomalies might provide a correlation or connection to seismic activity.     

Kinematics of landslide estimated by repeated GPS measurements in the Avcilar region of Istanbul, Turkey

The aim of this study is to analyze the spatial and temporal behavior of the landslide located in Avcilar region which is situated between Kucukcekmece and Buyukcekmece Lakes in the north-west of Marmara region, Turkey. A network consisting of 10 sites has been surveyed four times from November 2007 to May 2009 using Global Positioning System (GPS). The deformation analysis has been applied to determine the landslide movement parameters of the sites using GPS measurements of the four epochs. The reliable and high precision deformation rates are presented in terms of displacement vectors, velocity vectors and changes of accumulated strain. Landslides of the region are characterized from a regional GPS network. Each site has statistically different temporal behavior and significant relative motions and the region has irregular landslide movements.     

The Strandja Massif and the İstanbul Zone were once parts of the same palaeotectonic unit: new data from Triassic detrital zircons

Spatially continuous rock assemblages that share similar environmental evolution or structural features can be classified as a single tectonic unit. This approach enables to link dispersed units or massifs with each other and sometimes can be subjective, depending on the classification criteria. The relationship and the nature of the contact between the Strandja Massif and the ?stanbul Zone have been controversial due to the Cainozoic cover. Amalgamation of these units was claimed as early as the Aptian-Albian.

Lower Triassic sedimentary rocks, which are overlain by the Carboniferous flysch with a N-verging thrust fault are exposed NW of the ?stanbul Zone. This study reveals the spatial relationship between the Strandja Massif and the ?stanbul Zone deduced from the U-Pb dating and Lu-Hf isotopes of the detrital zircons from these Lower Triassic clastics. Our results show that the early Triassic basin was fed from a provenance that included arc-related Upper Carboniferous-Lower Permian magmatic rocks which is much more likely to be the Strandja Massif than the ?stanbul Zone. The second outcome of this study is that a unit that previously assigned to Palaeozoic turned out to be Triassic, which brings the Strandja Massif farther to the east, into the northern ?stanbul Zone.     

Allowable Bearing Capacity of Shallow Foundations Based on Shear Wave Velocity

Firstly, the historical background is presented for the determination of ultimate bearing capacity of shallow foundations. The principles of plastic equilibrium used in the classical formulation of the ultimate bearing capacity are reviewed, followed by a discussion about the sources of approximations inherent in the classical theory. Secondly, based on a variety of case histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting, an empirical formulation is proposed for the determination of allowable bearing capacity of shallow foundations. The proposed expression corroborates consistently with the results of the classical theory and is proven to be reliable and safe, also from the view point of maximum allowable settlements. It consists of only two soil parameters, namely, the in-situ measured shear wave velocity, and the unit weight. The unit weight may be also determined with sufficient accuracy, by means of another empirical expression, using the P-wave velocity. It is indicated that once the shear and P-wave velocities are measured in-situ by an appropriate geophysical survey, the allowable bearing capacity is determined reliably through a single step operation. Such an approach, is considerably cost and time-saving, in practice.