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Investigation of oxygen sensitive elements in sediment microniches with DGT


Mingyue LUO

Microniches are normally generated by physical disturbance or by biogenic structures within the sediment. Oxygen concentration decreases after sedimentation of organic matter and restores very slowly, as a result, the microniches are temporary anoxic. As, Se and Sb can be strongly influenced by oxygen concentration and organic matter degradation, especially in or close to the microniches. This has never been investigated up to now, because of the limitations of methodology. When the sampled sediment volume is much larger than the microniches, the sampling procedure will mask the presence of those reduced species.  
However, DGT is a good technique to solve this problem. Firstly, it can be deployed closely to the microniches. Secondly, the simultaneous measurement of trace elements and other influential parameters such as O2, pH and dissolved are possibly be measured. If the resin gel is thin enough we can combine DGT technique with planar optode together. Now I am trying to test 3 kinds of resin gel: Metsorb, precipitated Zirconia-Based gel and 3-mercaptopropyl-functionalized silica gel. The work now is to test their property in our lab.