Research of Soil Activated Ions Extractant and Preliminary Test Results

Active constituents in soil can reflect the status of the actual pollution and harm to the environment, and selection of the appropriate extractant is a key technology to accurately evaluate active soil components. The existing extractant method has been limited to different elements and different soil types with complicated extraction steps, a long experimental period and poor reproducibility. A new type of activated ions extractant (AIE) has been developed in this study. The new extracting solution, already designated AIE, is composed of 0.25 mol/L CH₃COOH-0.25 mol/L NH₄OAc-0.005 mol/L DTPA-0.2% C₆H₄(OH)₂. Extraction experiment results of the national standard substances show that AIE extraction agent can effectively extract active components (available P, available K, available Mn and available Cu) in soil with good versatility. AIE extracting results in comparison with three extraction extractants such as Mehlich 3, AB-DTPA and HCl, show that the extraction effect of AIE on nutrition component base cations (K, Na, Ca, Mg) is higher than that of AB-DTPA and HCl extraction agents, and the extraction effect of AIE and Mehlich 3 have the same trend. Extraction effects of AIE on Fe, Mn, P and heavy metals were 70% better than the three kinds of extracting agents mentioned. AIE was suitable for the extraction of nutrition components and heavy metals, which can extract the available state and slow release state. The extraction method of different elements was the same and no need to process separately, and the experimental period was 3-5 times less than the existing extractant method, which was favourable for the analysis of quantities of samples. AIE extraction results have good reproducibility, and relative standard deviations of the other elements except Na were lower than 8%. AIE has strong buffering capacity, and a pH value range of 0.07-0.9 is in the buffering capacity of buffer solution, which is good for acidic and alkaline soils. The versatility is better than that of Mehlich 3 and AB-DTPA. The new extracting agent is a supplement and improvement of existing methods.