Tracing terrestrial compounds leaching from two reservoir catchments as input to dissolved organic matter

Abstract

Conventional pyrolysis—GC—MS,thermochemolysis and alkaline CuO oxidation were applied to determine differences between dissolved organic matter (DOM)from terrestrial plants,soil horizons and drinking water reservoirs in two catchments in South Australia.These two reservoir-catchment systems were selected on the basis of contrasting vegetation and land use.Pyrolysis of DOM yielded furans,aliphatic products and N-containing compounds,which are indicative of polysaccharides,lipids and proteins,respectively.Thermo-chemolysis enabled detection of methoxy-benzyl compounds derived from various sources of DOM,indicating that these compounds can be used as bio-markers of vascular plant sources.Vanillic acid was detected from DOM isolates from the vegetation,soils and reservoir waters of the two catchments,using CuO oxidation,and hence this compound also appears to be a suitable bio-marker for tracing allochthonous DOM input into the reservoirs. Each of the three techniques resulted in the formation of different compounds from the DOM isolates,which indicated the type of precursor bio-polymer and/or some of the methoxyphenol structures of lignin.