Monitoring of Pb Exposure in Waterfowl Ten Years after a Mine Spill through the Use of Noninvasive Sampling

Monica Martinez-Haro,Hugues Lefranc,Rafael Mateo,Mark A Taggart,Rosa C Martín-Doimeadiós,Andy J Green,Andrew Iwaniuk

doi:10.1371/journal.pone.0057295

Abstract

Lead exposure in waterfowl was studied using noninvasive fecal sampling in the Guadalquivir Marshes in Spain, an area affected by the 1998 Aznalcóllar mine disaster. Feces of greylag geese (Anser anser, n = 191) and purple gallinule (Porphyrio porphyrio, n = 91) were collected from three different impacted sites (Entremuros, Caracoles and Cerro de los Ánsares) during the winters of 2004 to 2008. Lead and aluminium (an indicator of sediment ingestion) and Pb isotope signatures (to discriminate between sources of Pb exposure) were analyzed in freeze-dried, acid digested samples. The concentrations of fecal porphyrins and biliverdin were determined as noninvasive biomarkers to study Pb exposure effects. Results showed a decrease in Pb exposure over time in wintering greylag geese. In contrast, for purple gallinule resident in the Entremuros a clear trend was not evident. For both species, sediment ingestion appeared to be the main source of exposure to Pb. In the Entremuros, some samples from purple gallinule were detected with higher Pb levels than expected for simple soil ingestion, and these had Pb isotopic profiles compatible with mining sludge or Pb shot. Whilst fecal Pb isotopic profiles were effective in differentiating between samples from sites with different levels and sources of pollution, the combined use of element ratios (such as Pb/Al) and other non-traditional stable isotope signatures may also prove worthwhile. Overall, the fecal Pb levels detected were below those described in feces for waterfowl from other uncontaminated areas(<10 µg/g d.w.). Despite this, for both species fecal Pb levels were positively correlated with porphyrin excretion, and for purple gallinule, with the coproporphyrin III/I ratio, suggesting some subtle effects on heme synthesis in birds. Ten years after the mine spill, Pb contamination in birds by this pollution source was still detectable and subtlethal effects may persist.

Highlights

The Guadalquivir marshes are an extensive mosaic of wetlands of deltaic origin, located in south-western Spain
Ten years after the Aznalcollar mine spill (1998–2008), this study shows that there had been a progressive decrease in exposure to Pb in greylag geese in various parts of the Donana National and Natural Parks
In the Entremuros, the site most affected by the spill, the mean fecal Pb concentration in geese had decreased to 3 mg/g d.w. in 2005/2006, well below the 15 mg/g d.w. previously reported in the 2001/2002 wintering season [24]

Summary

Introduction

The Guadalquivir marshes are an extensive mosaic of wetlands of deltaic origin, located in south-western Spain. In April 1998, the Guadalquivir marshes were severely affected by the Aznalcollar mine accident [3,4], when a tailing pond dike collapsed at the Los Frailes mine (located ,45 km north of Donana National Park). This mine was one of many that exploit the vast Iberian Pyrite Belt, one of the largest sulphide deposits in the world [5,6].

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Results

Conclusion