Prediction of AMD generation potential in mining waste piles, in the sarcheshmeh porphyry copper deposit, Iran

This study investigates the possibility of acid mine drainage (AMD) generation in active and derelict mine waste piles in Sarcheshmeh Copper Mine produced in several decades, using static tests including acid–base accounting (ABA) and net acid-generating pH (NAGpH). In this study, 51 composite samples were taken from 11 waste heaps, and static ABA and NAGpH tests were carried out on samples. While some piles are acid producing at present and AMD is discharging from the piles, most of them do not show any indication on their AMD potential, and they were investigated to define their acid-producing potential. The analysis of data indicates that eight waste piles are potentially acid generating with net neutralization potentials (NNPs) of ?56.18 to ?199.3, net acid generating of 2.19–3.31, and NPRs from 0.18 to 0.44. Other waste piles exhibited either a very low sulfur, high carbonate content or excess carbonate over sulfur; hence, they are not capable of acid production or they can be considered as weak acid producers. Consistency between results of ABA and NAGpH tests using a variety of classification criteria validates these tests as powerful means for preliminary evaluation of AMD/ARD possibilities in any mining district. It is also concluded that some of the piles with very negative NNPs are capable to produce AMD naturally, and they can be used in heap leaching process for economic recovery of trace amounts of metals without applying any biostimulation methods.     

Drainage discharge impacts on hydrology and water quality of receiving streams in the wheatbelt of Western Australia

The use of surface and subsurface drainage to manage waterlogging and salinity in dryland (rainfed) and irrigated agricultural systems is common throughout the world. The drainage systems often discharge into natural streams. The same is true for the wheatbelt drainage systems in south-western Australia, where 11,000 km (ABS 2003) of artificial drains have been constructed within the last two decades. Prior to this study, the likely impacts of this discharge on the streambed chemistry and water quality of receiving streams were largely unknown. The study evaluated these impacts in creeks receiving the drainage discharge from engineering options in four river systems in south-western Australia. This study clearly showed elevated levels of metals ions, EC and pH in the stream water at treated sites relative to their levels at untreated sites. At most sites, impacts of drainage discharge were observed on the streambed electrical conductivity (EC) and pH (both in 1:5 extract) in the receiving streams; however, there was little evidence of impact on metal ion content in the streambed soil. The study found no clear differences in the dynamics of the watertable adjacent to streams whether they received drainage discharge or not, irrespective of the size of the artificial drainage systems.     

Trace metal contents in chewing gums and candies marketed in Turkey

Cu, Ni, Pb, Fe, Mn, Cr and Cd contents were determined in 17 different brands of chewing gum and candy samples available in local markets of Kayseri, Turkey. Concentration of selected trace metals were estimated using flame atomic absorption spectrometer after dry and wet digestion methods. Out of 17 brands of chewing gums and candies analysed, four were cocoa based, two were sugar based and other were of fruit based. Copper level ranged from 0.219 to 2.455 microg/g with an average of 1.390 microg/g. Nickel ranged from 0.120 to 2.588 microg/g with an average of 0.846 microg/g. Lead level ranged from 0.031 to 2.46 microg/g with an average of 0.746 microg/g. Iron level ranged from 3.963 to 9.863 microg/g with an average of 6.618 microg/g. Manganese level ranged from 1.872 to 5.067 microg/g with an average of 3.196 microg/g. Chromium ranged from 0.740 to 6.265 microg/g with an average of 2.473 microg/g and cadmium level ranged from 0.027 to 0.825 microg/g with an average of 0.296 microg/g. Cocoa based samples were found to have higher contents of the analysed metals than sugar and fruit based samples.     

Simultaneous derivatization and extraction of nitrophenols in soil and rain samples using modified hollow-fiber liquid-phase microextraction followed by gas chromatography–mass spectrometry

A simple and sensitive method based on a modified hollow-fiber liquid-phase microextraction followed by gas chromatography–mass spectrometry has been successfully developed for the extraction and simultaneous derivatization of some nitrophenols (NPs) in soil and rain samples. Microwave-assisted solvent extraction was used for the extraction of NPs from the soil, while the rain sample was directly applied to the previously mentioned method. Briefly, in this method, the analytes were extracted from aqueous samples into a thin layer of organic solvent (dodecane?+?10 % tri-n-octylphosphine oxide) sustained in the pores of a porous hollow fiber. Then, they were back-extracted using a small volume of organic acceptor solution (25 μl; 10 mg/L N-methyl-N-(trimethylsilyl)trifluoroacetamide, as derivatization reagent, in acetonitrile) that was located inside the lumen of the hollow fiber. Under the optimized extraction conditions, enrichment factors of 255 to 280 and limits of detection of 0.1 to 0.2 μg/L (S/N?=?3) with dynamic linear ranges of 1–100 μg/L were obtained for the analytes. The accuracy of the approach was tested by the relative recovery experiments on spiked samples, with results ranging from 93 to 113 %. The method was shown to be rapid, cost-effective, and potentially interesting for screening purposes.     

2-Nitroso-1-naphthol as a selective reagent for preconcentration of cobalt by vortex assisted combined with solidification of organic droplet and its determination by flame atomic absorption spectrometry

Highly rapid and selective vortex-assisted liquid–liquid microextraction based on solidification of organic drop has been used for determination of cobalt ion. 2-Nitroso-1-naphthol (2N1N) was used as a selective complexing agent to form stable cobalt–2N1N complex which can be extracted with 1-undecanol at a short time by the assistance of vortex agitator system followed by its determination using flame atomic absorption spectrometry. In vortex assisted, vigorous vortex stream as well as the vibrant effect of vortex system cause very fine droplets of extraction solvent to be produced and extraction occurred at a short time. Some parameters influencing the extraction process such as pH of samples, concentration of 2-nitroso-1-naphthol, extraction solvent volume, extraction time, ionic strength and surfactant addition, as well as interferences were evaluated in detail and optimum conditions were selected. At the optimum conditions, the calibration curve was linear in the range of 15 to 400 μg L^?1 of cobalt ions. The relative standard deviation based on ten replicate analysis of sample solution containing 50 μg L^?1 of cobalt was 3.4 %. The detection limit (calculated as the concentration equivalent to three times of the standard deviation of the blank divided by the slope of the calibration curve after preconcentration) was 5.4 μg L^?1. The accuracy of the proposed method was successfully evaluated by the analysis of certified reference materials. This selective and highly rapid method was used for determination of cobalt ions in different water samples.     

Calibration and verification of a dissolved oxygen management model for a highly polluted river with extreme flow variations in Pakistan

A dissolved oxygen (DO) model is calibrated and verified for a highly polluted River Ravi with large flow variations. The model calibration is done under medium flow conditions (431.5 m³/s), whereas the model verification is done using the data collected during low flow conditions (52.6 m³/s). Biokinetic rate coefficients for carbonaceous biochemical oxygen demand (CBOD) and nitrogenous biochemical oxygen demand (NBOD) (i.e, K _cr and K _n ) are determined through the measured CBOD and ammonia river profiles. The calculated values of K _cr and K _n are 0.36 day^?1 and 0.34 day^?1, respectively. The close agreement between the DO model results and the field values shows that the verified model can be used to develop DO management strategies for the River Ravi. The biokinetic coefficients are known to vary with degree of treatment (DOT) and therefore need to be adjusted for a rational water quality management model. The effect of this variation on level of treatment has been evaluated by using the verified model to attain a DO standard of 4 mg/L in the river using the biokinetic rate coefficients as determined during the model calibration and verification process. The required DOT in this case is found to be 96 %, whereas the DOT is 86 % if adjusted biokinetic rate coefficients are used to reflect the effect of wastewater treatment. The cost of wastewater treatment is known to increase exponentially as the removal efficiency increases; therefore, the use of appropriate biokinetic coefficients to manage the water quality in rivers is important.     

Assessing the suitability of stream water for five different uses and its aquatic environment

Surface water is one of the essential resources for supporting sustainable development. The suitability of such water for a given use depends both on the available quantity and tolerable quality. Temporary status for a surface water quality has been identified extensively. Still the suitability of the water for different purposes needs to be verified. This study proposes a water quality evaluation system to assess the aptitude of the Selangor River water for aquatic biota, drinking water production, leisure and aquatic sport, irrigation use, livestock watering, and aquaculture use. Aptitude of the water has been classified in many parts of the river segment as unsuitable for aquatic biota, drinking water production, leisure and aquatic sport as well as aquaculture use. The water quality aptitude classes of the stream water for nine locations along the river are evaluated to contribute to decision support system. The suitability of the water for five different uses and its aquatic ecosystem are verified.     

Assessing implications of land use and land cover changes in forest ecosystems of NE Turkey

Monitoring land use and land cover change (LUCC) and understanding forest cover dynamics is extremely important in sustainable development and management of forest ecosystems. This study analyzed the spatial and temporal pattern of LUCC in the Yaln?zçam and U?urlu forest planning units which are located in the northeast corner of Turkey. The investigation also evaluates the temporal changes of the spatial structure of forest conditions through the spatial analysis of forest-cover type maps from 1972 and 2005 using geographical information systems and FRAGSTATS^TM. As an overall change between 1972 and 2005, there was a net increase of 1,823 ha in forested areas, and cumulative forest improvement accounted for 2.06 %. In terms of spatial configuration, the landscape structure in the study area changed substantially over the 33-year study period, resulting in fragmentation of the landscape as indicated by large patch numbers and smaller mean patch sizes, owing to heavy grazing, illegal cutting, and uncontrolled stand treatments.