Research On The Method For Characterizing Heavy Metal Speciation In Manure And Its Application

In this paper, we made the research and improvement on the speciation analysis of heavy metals in organic fertilizer based on the Tessier SES. After comprehensive analysis, we made our research on two aspects. One is from the point of choosing more effective extractants about the fractions of exchangeable and bound to carbonates. The other is from the point of choosing the right extraction times about the fractions of metals bound to Iron & Manganese oxides and bound to Organic Matter. The main results are as follows.1. The research on the choice of extractants about the fraction of exchangeable metals showed that 1 mol/L NH4OAc(pH=7.0) solution was more suitable extractant for the extraction of exchangeable metals in organic manure. It can significantly reduce the interference on the fraction of bound to Iron & Manganese oxides (P<0.05).And it can also reduce the interference on other fractions in some degree.2. The research on the choice of extractants about the fraction of metals bound to carbonates showed that it can effectively dissolve carbonates, and promote the release of metals bound to carbonates, which can make a complete extraction of metals bound to carbonates. It had less destructiveness on organic carbon compared with NaOAc, which means it significantly reduced the interference on the fraction of metals bound to organic matter (P<0.05). At the same time, it had little effect on the silicate, which means it had less interference on the residual fraction.3. The research on the extraction times about the fraction of metals bound to Iron & Manganese oxides showed that the fraction of metals bound to Iron & Manganese oxides should be extracted twice, which can not only make a complete extraction of Cu and Zn bound to Iron & Manganese oxides, but also reduce the interference on metals bound to organic matter and the residual.4. The research on the extraction times about the fraction of metals bound to organic matter showed that the fraction of metals bound to organic matter should be extracted twice, which can not only make a more complete extraction of metals bound to organic matter, but also reduce the interference on other fractions.5. Analysis on the speciations of Cu, Zn, Pb, Mn by Tessier SES and the modified method showed that both methods had reasonable recovery rates, and the average recovery rate of modified method was higher than that of Tessier SES, which means the modified method had a higher accuracy.Compared with Tessier SES, the modified method significantly increased the distribution proportion of Cu, Zn and Pb bound to organic matter and bound to Iron & Manganese oxides, but did not has some effect on the fractions of exchangeable metals and metals bound to carbonates. The modified method also increased the distribution proportion of Mn in some degree, but has little effect on metals bound to organic matter, bound to Iron & Manganese oxides and exchangeable metals.The results also showed that Cu, Zn in organic fertilizer were mainly existed as bound to organic matter and bound to Iron & Manganese oxides. Pb was mainly existed as the residual and bound to organic matter. Mn was mainly existed as bound to Iron & Manganese oxides.