Global NEST Journal

Here the effectiveness of cation selective membranes, produced for divalent mercury (Hg2+) preconcetration from aqueous bodies, is examined. To this end, the behavior of PVC-based membranes, functionalized with dithizone for mercury complexation, is examined by means of Energy Dispersive X-ray Fluorescence (EDXRF) and total reflection - X-ray absorption near-edge structure (TXRF–XANES) techniques. In our previous works, we successfully immobilized dithizone on PVC-based thin film substrates, creating novel Hg-selective membranes, and identified the optimal experimental parameters affecting mercury sorption from water samples. Nonetheless, the question remains, to what extent dithizone is responsible for mercury complexation on the membrane surface, or it just improves the membrane’s active surface area thus simply improving the adsorptive effect. Using the EDXRF technique it appears that membranes functionalized with dithizone has a much higher efficiency (by up to threefold) in preconcetrating mercury from water matrices, compared to the non-functionalized membranes. Then, the membranes were also examined by means of TXRF–XANES and it was identified that indeed mercury-dithizone complex is produced on the membrane surface, which is responsible for the much higher mercury sorption, compared to the non-functionalized membranes. Also, the XANES mercury-dithizone spectrum is presented. Given polymer membrane simple manufacturing procedure and their low cost this study works towards establishing a new method for very low concentration mercury analysis (sub-ppb levels) as well as mercury collection from aqueous bodies, provided that the membranes are produced and used in large-scale routine works.

The main objective of this study was to determine the effect of land use change on runoff in Chenar Rahdar watershed. Land use map of the studied basin was determined using Landsat satellite imagery for 2004 and 2015 using ENVI software. After applying the necessary corrections to the images and field surveys to take the educational points, supervised classification technique and maximum probability algorithm were applied to mapping land use change in the study area. According to results, 6 classes of land use were investigated (bare land, rain fed land, forest land, water agriculture land, rangelands and urban lands). In this study, 21 model parameters were calibrated with monthly runoff using 2004-2012 data and validated using 2012-2015 data. The efficiency coefficient for calibration and validation were between 0.88 and 0.94, respectively. The land use changes trend within the time interval showed that the highest percentage of incremental changes is related to urban lands with 108.45%, whereas, the highest decline was observed for agricultural land with 12.46%. In order to investigate the effect of land use change on surface runoff, different land use maps were applied to SWAT model, supposing constant condition for other parameters of the model. The results show that surface runoff increased by 11%, in 2015 compared to 2004. Comprehensive water management can reduce surface runoff in the watershed. The results showed that if all uncertainties were minimized, the calibrated SWAT model can give acceptable runoff simulation results regarding the land use change. These results can be useful for water and environmental resource managers.

Application of municipal sewage sludge (MSS) to agricultural soils is a current practice in EU. European legislation permits its use in agriculture when concentrations of metals in soil do not exceed the maximum permissible limits. In order to study the influence of MSS on cotton yield and soil properties, a filed experiment was conducted in a soil classified as Typic Xerochrepts located in Lamia area, central Greece, for two consecutive years. The experimental design was complete randomized blocks with four treatments: Control (C ), inorganic fertilization (IF), application of 6000 dry kg ha-1 MSS, and 10000 dry SS kg ha-1, each replicated 4 times. The results showed that MSS application in both rates, increased significantly cotton yield compared to control equally to inorganic fertilization. Soil properties, at the end of the second year of MSS application, were significantly affected by MSS application in a positive way i.e. pH decreased slightly, but organic matter content, available phosphorus, total nitrogen concentrations exchangeable potassium and available zinc and copper increased significantly. The potentially toxic elements lead, chromium, and nickel were not significantly affected by MSS application in both application rates compared to control.

Oilfield wastewater or produced water is a complex mixture contains oil, organic and inorganic matter and other compounds dissolved in water that ranges from fresh to brine. Discharging produced water pollute soil surface and underground water and create environment hassle. The objective of this study is to investigate and summarize the novel method of fluidization processes, used for the treatment of oilfield produced water and oil refinery wastewater. Characteristics of oilfield produced water and oil refinery wastewater from different field and various methods for treating these wastewaters are discussed. Oilfield produced water and oil refinery wastewater are strongly acidic (pH 3-4), have a high chemical oxygen demand (1200-2600 mg/L), high polyphenol content (23 mg/L) and are highly variable. Primary attention is focused on the fluidization treatment of oilfield produced water and oil refinery wastewater, mainly by inverse fluidization. Finally, areas where further research and attention are required are identified.