Spatial and temporal variation of moisture content in the soil profiles of two different agricultural fields of semi-arid region

Modeling spatio-temporal variation of soil moisture with depth in the soil profile plays an important role for semi-arid crop production from an agro-hydrological perspective. This study was performed in Guvenc Catchment. Two soil series that were called Tabyabayir (TaS) and Kervanpinari (KeS) and classified as Leptosol and Vertisol Soil Groups were used in this research. The TeS has a much shallower (0–34 cm) than the KeS (0–134 cm). At every sampling time, a total of geo-referenced 100 soil moisture samples were taken based on horizon depths. The results indicated that soil moisture content changed spatially and temporally with soil texture and profile depth significantly. In addition, land use was to be important factor when soil was shallow. When the soil conditions were towards to dry, higher values for the coefficient of variation (CV) were observed for TaS (58 and 43 % for A and C horizons, respectively); however, the profile CV values were rather stable at the KeS. Spatial variability range of TaS was always higher at both dry and wet soil conditions when compared to that of KeS. Excessive drying of soil prevented to describe any spatial model for surface horizon, additionally resulting in a high nugget variance in the subsurface horizon for the TaS. On the contrary to TaS, distribution maps were formed all horizons for the KeS at any measurement times. These maps, depicting both dry and wet soil conditions through the profile depth, are highly expected to reduce the uncertainty associated with spatially and temporally determining the hydraulic responses of the catchment soils.     

An aerobiological study on pollen grains in the atmosphere of North-West Turkey

A continuous aerobiological survey of the atmosphere of Bursa was carried out from 1st January 2003 to 31st December 2004 by means of the volumetric method using a Lanzoni trap. During 2 years, a total of 57,124 pollen grains/m(3), which belonged to 66 taxa and 869 unidentified pollen grains, were recorded. In the region investigated, Pinus sp., Olea sp., Platanus sp., Cupressaceae/Taxaceae, Quercus sp., Poaceae, Moraceae, Urticaceae, and Castanea sp. were responsible for the greatest amounts of pollen. During the study period, the pollen concentration reached the highest level in May. A correlation analyses was made between the daily fluctuations of the main pollen types and meteorological parameters.     

Equilibrium and kinetic studies on biosorption of Hg(II), Cd(II) and Pb(II) ions onto microalgae Chlamydomonas reinhardtii

The microalgae Chlamydomonas reinhardtii was used for the biosorption of Hg(II), Cd(II) and Pb(II) ions. The maximum adsorption of Hg(II) and Cd(II) ions on Chlamydomonas reinhardtii biomass was observed at pH 6.0 and the corresponding value for Pb(II) ions was 5.0. The biosorption of Hg(II), Cd(II) and Pb(II) ions by microalgae biomass increased as the initial concentration of Hg(II), Cd(II) and Pb(II) ions increased in the biosorption medium. The maximum biosorption capacities of microalgae for Hg(II), Cd(II) and Pb(II) ions were 72.2+/-0.67, 42.6+/-0.54 and 96.3+/-0.86 mg/g dry biomass, respectively. The affinity order for algal biomass was Pb(II)>Hg(II)>Cd(II). FT-IR analysis of algal biomass revealed the presence of amino, carboxyl, hydroxyl and carbonyl groups, which were responsible for biosorption of metal ions. Biosorption equilibrium was established in about 60 min and the equilibrium was well described by the Freundlich biosorption isotherms. Temperature change in the range of 5-35 degrees C did not affect the biosorption capacity. The microalgae could be regenerated using 0.1 M HCl, with up to 98% recovery, which allowed the reuse of the biomass in six biosorption-desorption cycles without any considerable loss of biosorption capacity.     

Comparison of environmental flow assessment methods with a case study on a runoff river–type hydropower plant using hydrological methods

This paper focuses on the environmental flow assessment (EFA) methods that maintain the river ecosystem and its integrity for hydropower plants (HPP) with their implementations on a run-off river type HPP. EFA is a crucial phenomenon in terms of electricity production and sustaining river integrity simultaneously. The novelty of this study is that it consists both a comparison of widely used preferred EFA methods and a detailed investigation of the river with pre and post-dam flow regimes. The research shows that by expanding the content and scope of the methods, their relative reliabilities increase. However, this situation requires much more expert, money, and time. Apart from most of the relevant literature, pre and post-dam situations are investigated with a flow duration curve (FDC). It is concluded that the dramatic difference between the flow characteristics of pre and post-dam situations affects long-term aquatic life. Furthermore, a case study is conducted using the selected hydrological flow assessment methods, Tennant and Tessman methods, and comparisons are made. The calculated flows are compared with monthly average flow values before dam construction, projected environmental flow data, and the current situation. Accordingly, Tennant’s “good classification” is proposed to determine the environmental flow (EF) for the considered case study.     

Determining the heavy metal pollution in Denizli (Turkey) by using Robinio pseudo-acacia L

The leaves of Robinia pseudo-acacia L. (Fabaceae) were evaluated as a biomonitors of heavy metal contamination in Denizli city, Turkey. Concentrations of Fe, Zn, Pb, Cu, Mn and Cd were determined in washed and unwashed leaves and soils collected from a wide range of sites with different degrees of metal pollution (industry, urban roadside, suburban) and from a rural (control) site by atomic absorption spectrometry. All the elements that measured were found to be at high levels in samples collected at industrial sites, except for lead and copper which were found at high levels in samples collected from urban roadsides that associated with the road traffic. The strong correlation between the degree of contamination and concentrations in all plant leaves assessed display that the leaves of R. pseudo-acacia reflect the environmental changes accurately, and that they seem as an effective biomonitor of environmental quality in areas subjected to industrial and traffic pollutions.     

Sex ratio estimations of loggerhead sea turtle hatchlings by histological examination and nest temperatures at Fethiye beach, Turkey

Hatchling sex ratios in the loggerhead turtle (Caretta caretta) were estimated by placing electronic temperature recorders in 21 nests at Fethiye beach during 2000–2002. Over the seasons, the mean temperature in the middle third of the incubation period ranged from 26.7 to 32.1°C, and incubation periods ranged from 49 to 67 days. Based on the mean temperatures during the middle third of the incubation period, and on histologically sexed dead hatchlings, the sex ratios of hatchlings at Fethiye beach were roughly equal, i.e. 60–65% of the hatchlings were females. This contrasts with the highly female-skewed sex ratios in loggerhead turtles elsewhere; Fethiye has a relatively high proportion of male hatchlings. For endangered sea turtles, the knowledge of hatchling sex ratios at different beaches, coupled with appropriate conservation measures, can make an important contribution to their survival.     

Removal of Ni(II) and Cu(II) ions using native and acid treated Ni-hyperaccumulator plant Alyssum discolor from Turkish serpentine soil

Alyssum discolor biomass was collected from serpentine soil and was used for removal of metal ions. The plant species grown on serpentine soils are known to be rich with metals ions and thus have more capability for accumulating heavy metals. Native and acid-treated biomass of A. discolor (A. discolor) were utilized for the removal of Ni(II) and Cu(II) ions from aqueous solutions. The effects of contact time, initial concentration, and pH on the biosorption of Ni(II) and Cu(II) ions were investigated. Biosorption equilibrium was established in about 60 min. The surface properties of the biomass preparations were varied with pH, and the maximum amounts of Ni(II) and Cu(II) ions on both A. discolor biomass preparations were adsorbed at pH 5.0. The maximum biosorption capacities of the native, and acid-treated biomass preparations for Ni(II) were 13.1 and 34.7 mg g⁻¹ and for Cu(II) 6.15 and 17.8 mg g⁻¹ dry biomass, respectively. The biosorption of Ni(II) and Cu(II) ions from single and binary component systems can be successfully described by Langmuir and Freundlich isotherms. When the heavy metal ions were in competition, the amounts of biosorbed metal ions on the acid treated plant biomass were found to be 0.542 mmol g⁻¹ for Ni(II) and 0.162 mmol g⁻¹ for Cu(II), the A. discolor biomass was significantly selective for Ni(II) ions. The information gained from these studies was expected to indicate whether the native, and acid-treated forms can have the potential to be used for the removal and recovery of Ni(II) ions from wastewaters.     

Sustainable natural resource management and environmental assessment in the Salt Lake (Tuz Golu) Specially Protected Area

The Salt Lake Specially Protected Area is a unique ecosystem for both agricultural activities and natural life in Turkey. In the present study, an attempt was made to develop a conceptual land use strategy and methodology, taking into account ecological factors for regional development in the Salt Lake Specially Protected Area. A detailed Geographic Information System (GIS) analysis was done to create a comprehensive database including land use, land suitability, and environmental factors (soil, climate, water quality, fertilizing status, and heavy metal and pesticide pollution). The results of the land suitability survey for agricultural use showed that, while 62.6% of the study area soils were classified as best and relatively good, about 15% were classified as problematic and restricted lands, only 22.2% of the study area soils were not suitable for agricultural uses. However, this is not enough to derive maximum benefit with minimum degradation. Therefore, environmental factors and ecological conditions were combined to support this aim and to protect the ecosystem. Excessive irrigation practices, fertilizer and pesticide application, and incorrect management practices all accelerate salinization and degradation. In addition to this, it was found that a multi-layer GIS analysis made it easy to develop a framework for optimum land use and could increase the production yield preserving the environmental conditions. Finally, alternative management and crop patterns were undertaken to sustain this unique ecosystem, considering water, soil, climate, land use characteristics, and to provide guidance for planners or decision makers.     

Biosorption of Cr(VI) by free and immobilized Pediastrum boryanum biomass: equilibrium, kinetic, and thermodynamic studies

Background and purpose

The biosorption of Cr(VI) from aqueous solution has been studied using free and immobilized Pediastrum boryanum cells in a batch system. The algal cells were immobilized in alginate and alginate?Cgelatin beads via entrapment, and their algal cell free counterparts were used as control systems during biosorption studies of Cr(VI).

Methods

The changes in the functional groups of the biosorbents formulations were confirmed by Fourier transform infrared spectra. The effect of pH, equilibrium time, initial concentration of metal ions, and temperature on the biosorption of Cr(VI) ion was investigated.

Results

The maximum Cr(VI) biosorption capacities were found to be 17.3, 6.73, 14.0, 23.8, and 29.6?mg/g for the free algal cells, and alginate, alginate?Cgelatin, alginate?Ccells, and alginate?Cgelatin?Ccells at pH?2.0, which are corresponding to an initial Cr(VI) concentration of 400?mg/L. The biosorption of Cr(VI) on all the tested biosorbents (P. boryanum cells, alginate, alginate?Cgelatin, and alginate?Ccells, alginate?Cgelatin?Ccells) followed Langmuir adsorption isotherm model.

Conclusion

The thermodynamic studies indicated that the biosorption process was spontaneous and endothermic in nature under studied conditions. For all the tested biosorbents, biosorption kinetic was best described by the pseudo-second-order model.