Effective removal of sodium ion as efflorescence at soil surface using ammonium salts.

The existing methods for reclamation of saline-sodic soils are expensive, time-consuming, and require skilled engineering approaches. Therefore, new and fast techniques should be developed for the reclamation of these soils. This study was undertaken to evaluate if harvesting excessive salts via the soil with ammonium hexacyanoferrate (II) (AH) and ammonium perchlorate (AP) [0, 10, 20 and 40 mmol kg-1] is possible through dendritic crystal growth above the soil surface. Application of crystallization inhibitors increased the concentration of salts on the outer surface and thereby increased pHe at the top of the soil. Whereas the pHe of 0-5 cm layers were obtained as 7.30, 7.36 and 7.84, it increased to 9.94, 9.84 and 8.45 in 15-20 cm layers with 10, 20 and 40 mmol kg-1 AH application doses, respectively. Except for 5-10 cm of control and 10 mmol kg-1 AP application, the lowest pHe values were obtained from the 0-5 cm and gradually increased from bottom to top. For all AH and AP application doses, the highest electrical conductivity (ECe) values were obtained from the 15-20 cm and significantly increased from bottom to top. Application of AH and AP have transformed exchangeable Na+ to water-soluble Na+ and this situation has caused an increase in the concentration of water-soluble Na+ throughout the soil column. AH and AP applications have decreased exchangeable sodium percentage (ESP) in all of the layers. Whereas the ESP of control was 70.07% in 0-5 cm layer, it decreased to 62.44, 55.63 and 53.76% with 10, 20 and 40 mmol kg-1 AH application doses, respectively. Similar decreases were obtained for 5-10, 10-15 and 15-20 cm layers. Results obtained have shown that application of AH and AP to saline-sodic soil is an effective reclamation material to remove salts from soil surface within a short time, particularly in arid climates.

Solid-phase chelate extractive preconcentration of heavy metal ions prior to their ultratrace determination by microsample injection system coupled flame atomic absorption spectrometry.

Chromosorb-105 resin/1-(2-pyridylazo)-2-naphthol (PAN) system was developed for solid phase chelate extractive preconcentration of heavy metal ions. The metal ions on Chromosorb-105 resin column were eluted with 3.0 mL of 2.0 mol L-1 HNO3 and determined by microsample injection system coupled flame atomic spectrometry (MIS-FAAS) using 75.0 µL of sample solution for single element determination. The influence of pH, resin amount, reagent amount, flow rate and volume of eluent and sample solution was optimized. The quantitative recoveries (≥95%) of Fe(III), Zn(II), Cu(II) and Pb(II) ions were achieved at pH 9; resin amount, 700 mg; reagent amount, 6.0 µmol; flow rate of eluent and sample solution, 1.0 mL min-1 and 5.0 mL min-1, respectively. The limit of detection and limit of quantification of understudied analytes were found to be 0.17-1.74 µg L-1 and 0.40-2.98 µg L-1, respectively with preconcentration factor of 150-300. The proposed method was validated by analysis of waste water (BCR-715) as a certified reference material. The method was applied successfully for ultratrace determination of studied metal ions in tap water and hot spring water samples.