Lead contaminated soil is a persistent global threat to the health of animal populations. Nevertheless, links between soil lead and its adverse effects on exposed wildlife remain poorly understood. Here, we explore local geographic patterns of exposure in urban birds along a gradient of lead contamination in Broken Hill, an Australian mining city. Soil lead concentrations are linked to co-located blood lead measurements in rock pigeons (Columba livia), house sparrows (Passer domesticus), crested pigeons (Ocyphaps lophotes) and white-plumed honeyeaters (Lichenostomus ornatus). Median blood lead levels were highest in crested pigeons (59.6 µg/dL), followed by house sparrows (35.2 µg/dL), rock pigeons (35.1 µg/dL), and white-plumed honeyeaters (27.4 µg/dL). Blood lead levels in all species declined away from mining areas, the primary source of lead contamination in Broken Hill. Blood lead increased significantly and at the greatest rate relative to soil lead in the three ground foraging species (crested pigeons, house sparrows, rock pigeons). For these species, soil lead concentrations below 200 mg/kg and 900 mg/kg were needed to maintain a median blood lead concentration under the lower threshold of the subtoxic (20–50 µg/dL) and toxic (≥ 50 µg/dL) effect ranges previously identified for some bird species. We also investigated the effects of lead exposure on blood haemoglobin levels as a general measure of physiological condition in birds exposed to different levels of soil lead contamination. Overall, for every 1 µg/dL increase in blood lead, haemoglobin decreased by 0.11 g/L. The rate of this decrease was not significantly different between species, which supports the measurement of haemoglobin as a robust though insensitive measure of physiological condition in chronically lead exposed birds. Our findings reflect the importance of lead contaminated soil as a widespread source of elevated blood lead and supressed haemoglobin levels in birds inhabiting urbanised and mining impacted environments.

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Blood lead increases and haemoglobin decreases in urban birds along a soil contamination gradient in a mining city
Blood lead increases and haemoglobin decreases in urban birds along a soil contamination gradient in a mining city

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.envres.2024.119236. This is version 2 of this Preprint.

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Authors

Max M Gillings , Riccardo Ton, Tiarne Harris, Mark Patrick Taylor, Simon C. Griffith

Abstract

  Lead contaminated soil is a persistent global threat to the health of animal populations. Nevertheless, links between soil lead and its adverse effects on exposed wildlife remain poorly understood. Here, we explore local geographic patterns of exposure in urban birds along a gradient of lead contamination in Broken Hill, an Australian mining city. Soil lead concentrations are linked to co-located blood lead measurements in rock pigeons (Columba livia), house sparrows (Passer domesticus), crested pigeons (Ocyphaps lophotes) and white-plumed honeyeaters (Lichenostomus ornatus). Median blood lead levels were highest in crested pigeons (59.6 µg/dL), followed by house sparrows (35.2 µg/dL), rock pigeons (35.1 µg/dL), and white-plumed honeyeaters (27.4 µg/dL). Blood lead levels in all species declined away from mining areas, the primary source of lead contamination in Broken Hill. Blood lead increased significantly and at the greatest rate relative to soil lead in the three ground foraging species (crested pigeons, house sparrows, rock pigeons). For these species, soil lead concentrations below 200 mg/kg and 900 mg/kg were needed to maintain a median blood lead concentration under the lower threshold of the subtoxic (20–50 µg/dL) and toxic (≥ 50 µg/dL) effect ranges previously identified for some bird species. We also investigated the effects of lead exposure on blood haemoglobin levels as a general measure of physiological condition in birds exposed to different levels of soil lead contamination. Overall, for every 1 µg/dL increase in blood lead, haemoglobin decreased by 0.11 g/L. The rate of this decrease was not significantly different between species, which supports the measurement of haemoglobin as a robust though insensitive measure of physiological condition in chronically lead exposed birds. Our findings reflect the importance of lead contaminated soil as a widespread source of elevated blood lead and supressed haemoglobin levels in birds inhabiting urbanised and mining impacted environments.

DOI

https://doi.org/10.32942/X2Z61R

Subjects

Ecology and Evolutionary Biology, Environmental Health and Protection, Environmental Monitoring, Environmental Sciences, Life Sciences, Terrestrial and Aquatic Ecology

Keywords

lead exposure, urban ecosystems, pigeons, house sparrows, lead exposure, biomonitoring, urban ecosystems, Pigeons, house sparrows

Dates

Published: 2024-03-29 18:45

Last Updated: 2024-06-18 11:52

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License

CC BY Attribution 4.0 International

Additional Metadata

Language:
English

Conflict of interest statement:
Mark Patrick Taylor has undertaken work for, and received funding from, the Broken Hill Environmental Lead Program of the NSW Environment Protection Authority (EPA). He has received funding for lead and other trace metal related work from the Australian Federal Government. He has also prepared commissioned reports and provided expert advice on environmental contamination and human health for a range of bodies, including the Australian Building Codes Board (lead in plumbing fittings and materials), lawyers, governments, union agencies, and private companies. He has also served as an expert in plaintiff cases of childhood lead poisoning relating to Mount Isa, Queensland and Kabwe, Zambia. No other authors declare a competing interest.  

Data and Code Availability Statement:
All data relating to analyses performed in this manuscript will be made available upon final publication. For any additional data related inquiries, please contact the corresponding author.