Effects of Soil Organic Matter Conformation and Substrate Additions On the Formation and Release of Xenobiotic Bound Residues.

Aims

Our research is directed to investigate features of bioaccessibility and biodegradability of xenobiotic nonylphenol (NP). Especially research is developed to see the effects of soil organic matter (SOM) structural conformation by different metal cations on the mineralization and sorption of NP.

Methods

For the main experiments with altered SOM of sandy gley podzol topsoil was used. The structural configuration of SOM was altered by changing the cation composition by monovalent cation Na⁺ and polyvalent Ca²⁺ and Al³⁺. The short-term sorption studies were carried out. The bioaccessibility and biodegradability of ¹⁴C-labelled NP was investigated on the Respicond-apparatus (Nordren Innovations). In the degradation experiment the different substrate additions were used: glucose, alanine, catechol and sawdust.

Results

Sorption of NP on investigated soils is depended of pH level of soil solution. The experiments showed that structural organic matter conformation effects on a sorption of NP which in turn can be influenced by the different solubility of organic matter of treated soils. Sorption on the soil treated by NaCl was less then on other investigated soils.

Mineralization of NP is influenced by the different substrate additions to the soil. Most effective for the mineralization of NP in soil during 3 weeks degradation experiment was the sawdust addition. Mineralization of NP in natural soil with this substrate was 7% of the initial xenobiotics content in the system. The catechol addition had a depressive effect on the microbiological activity and NP degradation in soil.

Conclusion

The differences in NP mineralization in the test soils with substrate additions showed that certain chemical or biological soil properties seem to strongly affect the degradation processes, which still are poorly understood. It is expected that one factor influencing sorption and bioaccessibility of xenobiotics is the structural conformation of soil organic matter that can be altered by different cations.