Mysteries of DNOM photo-degradation and phosphorus availabilty

Summary

The flux of Dissolved Natural Organic Matter (DNOM) to surface waters has almost doubled over the last 30 years in regions previously suffering from acid rain deposition. Phosphorus is naturally leached from soil to surface water incorporated into this DNOM. It is therefore conceived that there has been a similar doubling in the background flux of P to surface waters. All of this humic material is not readily bio-available, though the UV-rays from solar radiation have the ability to break chemical bonds in the DNOM. This is potentially of significance as the photo-degradation of DNOM may thereby convert relatively inert P-DNOM to bio-available P, and thus have an increased impact on eutrophication. However understanding the effects solar irradiation has on humic matter is far from simple.