Geostatistical analysis and hydrofacies simulation for estimating the spatial variability of hydraulic conductivity in the Jianghan Plain,central China

Hydrogeology Journal - This study evaluated the spatial variability of hydraulic conductivity (K) along the Han River watershed in the Jianghan Plain (China) by using different geostatistical...     

Equilibrium,Thermodynamic, and Kinetic Studies on Lead (II) Biosorption from Aqueous Solution by Saccharomyces cerevisiae Biomass

This paper presents a biosorption procedure for the preconcentration of Pb²⁺ ions using Saccharomyces cerevisiae biomass. The influence of several factors including pH, biomass dosage, contact time, and temperature on biosorption efficiency were optimized. At optimum value of all the equilibrium, thermodynamic, and kinetic parameters of Pb²⁺ ion biosorption was investigated by testing the Langmuir and Freundlich models and first and second order kinetic models were applied. The biosorption capacity of S. cerevisiae biomass was determined 89.6 mg/g, while the retained Pb²⁺ ions by S. cerevisiae were reversibly eluted using 5 mol/L HNO₃. Due to the high stability of S. cerevisiae the applied biomass can be used successively ten times with a slightly decrease (about 20%) in the recovery of Pb²⁺ ions. The calculated thermodynamic parameters, ΔG°, ΔH°, and ΔS° showed that the biosorption of Pb²⁺ ion onto S. cerevisiae biomass was feasible, spontaneous, and endothermic under examined conditions. The results of kinetic analysis showed that the biosorption processes of Pb²⁺ ions onto S. cerevisiae biomass followed pseudo second order kinetics.     

Fluctuating asymmetry in grass goby Zosterisessor ophiocephalus Pallas, 1811 inhabiting polluted and unpolluted area in Tunisia

Fluctuating asymmetry, a random deviation of bilateral traits, is assessed on grass goby Zosterisessor ophiocephalus Pallas, 1811 living in one disturbed site and in one unpolluted site Gulf of Gabes (Tunisia). Statistical analysis showed that assessed asymmetries are fluctuating. FA of orbital diameter, sub-orbital distance, pectoral fin and post-orbital length are higher in polluted site compared to control. Chemical pollution seems to be responsible for this high FA.     

Liquid hydrocarbon source-rock potential of mid-Cretaceous coals and coal measures in the Middle Benue Trough of Nigeria

Received: 23 March 1999 / Accepted: 25 August 1999     

A Study of Largest Active Region AR12192 of 24th Solar Cycle Using Fractal Dimensions and Mathematical Morphology

Solar System Research - An active region (AR) of the sun is an area of strong magnetic field. Sunspots are frequently formed in an AR. Solar activity exhibits in the form of solar flares and...     

Summer phytoplankton pigments and community composition related to water mass properties in the Gulf of Gabes

Variations in phytoplankton pigments and community composition were examined in the Gulf of Gabes in relationship to water mass properties, characterised by the influence of the Modified Atlantic Water and by the thermal stratification. Data were collected on board the R/V Hannibal during July 2005.Distinct water masses were identified using cluster analysis of temperature–salinity (T–S) characteristics. Three major clusters appeared based on the combined effects of temperature and salinity. The first cluster was identified as the cool and less salty bottom Modified Atlantic Water (MAW). The warmer and saltier Mediterranean Mixed Water (MMW) represented the second cluster. The third cluster was the Transition Water (TW) separating the two previous clusters.The pigment and taxonomic composition of these water masses were examined. Chlorophyll a was rather low (<200 ng l⁻¹). Chlorophyll b was generally the most abundant accessory pigment and fucoxanthin dominated the accessory pigments in the MAW. Proportions of chlorophyll a associated with different phytoplankton classes were estimated using CHEMTAX software, and did not present significant variations among water groups. The results pointed out variations in the relative contribution of each phytoplankton taxa in each station group. Chlorophytes and prasinophytes accounted for 65% of chlorophyll a in the MMW. Diatoms and chlorophytes were relatively abundant in the MAW contributing to almost 63% of chlorophyll a. An unstructured community, slightly dominated by prasinophytes, chlorophytes and cryptophytes, characterised the TW. Different trophic statuses were observed in these water masses, the MMW and the MAW being characterised by mesotrophy, while an oligotrophy was observed in the TW. Nutrient availability, particularly the P-limitation supported by the summer stratification, as revealed by the high N:P ratio (greater than 20), seems to enhance the development of small-sized phytoplankton, thereby supporting the regenerated production.     

Significant changes in the ENSO-monsoon relationship and associated circulation features on multidecadal timescale

Climate Dynamics - We observe significant changes in the ENSO–Indian summer monsoon rainfall (ISMR) relationship in past three multidecadal epochs (early epoch: 1931–1960, middle epoch:...     

Performance of fine-grained soil treated with industrial wastewater sludge

This paper is likely one of the very recent researches based on an experimental study, which aims to investigate some geotechnical performances of fine-grained soil treated with industrial wastewater sludge. The experimental program conducts the standard compaction, direct shear, California bearing ratio (CBR), and unconfined compressive strength (UCS) tests. The sludge proportions in samples of the soil + sludge mixtures are 0, 5, 10, 20, 30, 40, 50, 60, 70, and 80 % by dry weight of the mixture. The results indicate that the internal friction angle of untreated soil is significantly enhanced at most of the sludge dosages (p < 0.05). The CBR values offer that the soil quality can be improved to “good” rating quality to use “base” layers in stabilizations up to the 50 % sludge dosage. The contribution is also obtained by the UCS values that increase with the sludge addition. Moreover, the stress–strain responses promise to develop the ductility behavior due to the sludge inclusion. Consequently, the soil mixtures treated with the sludge have exhibited satisfactory geotechnical characteristics. Thus, this study suggests that the industrial wastewater sludge can be potentially employed for improvement of fine-grained soil in the stabilizations. The proposed soil stabilization with locally available industrial wastewater sludge can also provide recycling and sustainability to the environment.     

Relocation processing of selected earthquakes in the Gulf of Aqaba region

Earthquakes in the Gulf of Aqaba were compiled from the Jordan Seismological Observatory bulletins, Saudi Arabia (SNSN, King Abdulaziz City for Science and Technology), and Egypt (National Research Institute of Astronomy and Geophysics, Helwan) sources and were relocated after reexamining the P and S arrival times, testing the efficiency of stations used to determine the location of Aqaba events, calculating the average value of V _p/V _s, and choosing the best crustal model for the study area. The earthquake epicenters are distributed along the eastern side of the Gulf of Aqaba.