Characterization of urban NOM in a municipal area with disused toxic waste sites

Natural organic matter (NOM) formed under urban conditions exhibits characteristic features reflecting the diversity of anthropogenically influenced soils. These NOM species indicate the state of the urban soil in respect of humification as well as contaminant loads and transport. Humic and fulvic acids isolated at two dump sites in the municipal area of Staßfurt (Germany) are characterized by a high oxygen functionality and a predominance of aliphatic structures. Permanent metal loads of soil humic acids mainly consist of Mg, Al, K and Fe. Soil fulvic acids are additionally loaded with Ca and Zn. The main feature of all humic and fulvic acids from the investigated area is an enrichment of chalcophile elements relative to the elemental distribution in the upper continental crust. Based on the permanent loads and other characteristics of the site-specific humic substances, an input of organic material from a waste dump into the aquifer could be demonstrated. Aquatic fulvic acids are charged along the ground water flow path, correlating with the elemental content of the dumped materials. A long-term observation of the seepage water path is recommended in order to assess the spreading behaviour of organically bound contaminant metals when humification proceeds.