Organic Matter Influence on the Persistent Organic Pollutants (POPs) and other Semivolatile Organic Compounds (SVOCs) Occurrence and Cycling in the Water Column

FONDECYT 11150548

Knowledge on biogeochemistry of persistent organic pollutants (POPs) and semivolatile organic compounds (SVOCs) has increased in the last decade specially in the field of the aquatic environments (fresh and salty). Recent advances showed that the organic matter production in the surface favours the transport of POPs/SVOCs trough the water column by means of the “biological pump”. However, the mass balance among the air-water-sediments-bioconcentration did not explain correctly the fate of POPs/SVOCs in the lower layers in the water column. So there is still some missing points that are unresolved yet. The most important is the role that organic matter (POC+DOC) remineralization plays in the fate of POPs/SVOCs in the watercolumn. Biological pump, is the process trough the sinking particles export POPs/SVOCs associated due to the high hydrophobicity of these organic compounds. Is important to note that the main source of POC in the waters usually comes from the biological acitvities performed by phytoplankton. Thus if the POC is well remineralized it is expected that POPs/SVOCs could follow two ways. First POPs/SVOCs could be redissolved and become associated to the dissolved phase (DOC) or in the other hand POPs/SVOCs could be a part of the more recalcitrant POC like (humic substances that could not be degraded easily) and be transported to sediments where some degradation for POPs/SVOCs had been revealed under anaerobic conditions. In consequence final destiny could be found for POPs/SVOCs first POPs/SVOCs redissolved could be transported to the surface due to internal water mixing and possible changing the surface from sink to source and finally transforming the surface waters in secondary sources; or in the hand there the biological pump works efficiently and exports a big amount of POPs from surface waters to deep waters and finally sediments. These two phenomenons never had been tackled directly as far as we know, however the changing from sink to source has been demonstrated without any conclusive explanation far from speculations of the different causes. On the other hand published works reported that surface water could be source of POPs/SVOCs under oligotrophic and/or low productive copnditions. Thus our hypothesis “The phytoplankton biological pump driving to the sink of POPs/SVOCs from surface water is a largely reversible process under oligotrophic conditions”. This hypothesis will be tested by means of two main goals that consist in the estimation the POPs/SVOCs source and fate in relation to the organic carbon in the water column (POC+DOC) followed by the study how POPs in the water column behave during their vertical transport associated to sinking organic particles and during organic carbon ageing. By achieving these two goals are adequate enough to clarify and test the hypothesis. The methodology proposed for the research perfomance is quite multidiscipliner since these objectives exceeds the environmental anallytical chemistry field. In fact, the state of the art of analytical techniques will be used for POPs/SVOCs, DOC, POC analysis as well as direct designed sampling plan for each objective. Besides these the collsboration with experts in the field is granted and is an important issue for the consecution of the project.

FONDECYT 11150548