Budget of organic and inorganic pollutants in the Doñana National Park (Spain)

We report here an assessment of sources and inputs of organic and inorganic pollutants to the Doñana National Park (SW Spain), one of the finest wetlands in Europe. In the absence of local pollution sources, the occurrence and distribution of heavy metals (Zn, Cu, Pb), organochlorine compounds (DDT and PCBs) and hydrocarbons (both natural and anthropogenic) in different biotic and abiotic compartments of the park are explained in terms of transport processes related to geographical, hydrological and biological factors. In this respect, it has been recognised that drainage waters from the northern opencast-worked polymetallic sulphide deposits constitute a chronic input of heavy metals into the park. Waste waters from olive-oil manufacturing mills in the area may also contribute to the mobilisation of metals towards the park. However, the resulting relative distributions of Zn, Cu and Pb within the park differ from those of mine effluents, indicating a differential transport of these metals through the water systems. Zinc seems to be the best indicator of input from the mining area. Petroleum hydrocarbons enter the park from the SE via the main rivers and tidal sea movements, whereas PAHs, PCBs and DDTs are uniformly distributed at very low levels in surface sediments, indicating a contribution by aeolian transport. Evidence of inefficient recycling of organic matter in the shallow ponds is obtained by the identification of well preserved natural products from local plants and chemical markers of denitrifying bacteria (cyanobacterial markers).

Financial support of CAICYT and CSIC is greatfully acknowledged .

Peer Reviewed