Badgers as a proxy for environmental exposure to potentially toxic elements and ecosystem level interactions in soils

  • Shay Mullineaux

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Since the industrial revolution in the 18th century, the Earth’s natural environment has seen unprecedented levels of environmental change. Steadily, but ever rapidly, the levels of environmental pollution, have continued to increase across the globe. Additionally, through industrial activity, agriculture, urbanisation and habitat destruction, the Earth has been increasingly anthropised, decreasing spatial complexity, creating fewer natural barriers in the environment, and changing the geochemistry of soils. This has led to increased levels of pollutants from anthropogenic sources, and ever higher levels have accumulated in environmental sinks, which are continually reaching new record-breaking levels. Such events are more nuanced at local scales. Northern Ireland, located on the island of Ireland is a location with a complex history. Previously a world centre of heavy-industry, it has in recent decades seen a decline in these highly polluting anthropogenic activities but has continued to modernise in-line with the rest of the developed world. A group of pollutants of note for this region are potentially toxic elements (PTEs) otherwise known as heavy metals or trace metals. These PTEs occur at both naturally and anthropogenically elevated levels in Northern Ireland and have become a subject of interest for scientific investigation. Most research has focused on the geographic distribution, bioaccessibility or public health implications of these elements. This research has demonstrated in detail how Northern Irelands geology, industrial past and ongoing anthropogenic activity have all acted as PTE sources and how soils and by extension living organisms have become sinks for these elements. However, a gap in this research has been an ecotoxicological investigation of these elements, and how they move from soils into the natural ecosystem. In ecotoxicological studies, living organisms are chosen based on their ecology and the demonstratable pathways through which environmental pollutants will move through the environment and accumulate in the living organism’s tissues. The species chosen for this thesis and the research therein, is the European Badger (Meles meles), an omnivorous carnivore which lives in relatively constant territorial units, feeds primarily on Earthworms, arthropods and other soil invertebrates, lives in setts below ground, and spends most of its life interacting with or living within soil. This species is also ubiquitous throughout Northern Ireland, and is therefore, the ideal system, for investigating ecological-soil processes. Within this thesis, the effects of soil PTEs on badgers have been considered, a novel compositional approach has been tested and verified, the effects of land-use and other environmental factors have also been assessed through a novel technique by deducting isotopic ratios in tissues from ratios in interpolated soil isoscapes. In turn, Badgers were shown to accumulate PTEs readily and accumulate them in their tissues readily through both bioaccumulative (accumulation through the food chain) and bioaccessible (accumulation from the environment) pathways, the compositional approach used has also been verified with a number of methods that may be of use to researchers and effects of land-use and other environmental phenomena have been assessed through the novel use of soil isoscapes. Overall, this thesis has developed several approaches of use to scientists interested in studying macroscale terrestrial processes. The use of compositional statistics for studying patterns of PTE accumulation and isoscapes to understand ecological trends across macroscales will be important for future terrestrial research, and these approaches will be needed especially in the context of a changing world.

Thesis embargoed until 31 July 2023.
Date of AwardJul 2022
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorRory Doherty (Supervisor), Michael Scantlebury (Supervisor) & Nikki Marks (Supervisor)

Keywords

  • Bioaccumulation
  • boaccessibility
  • potentially toxic element
  • compositional analysis
  • stable isotopes
  • isoscapes
  • badgers
  • soil baseline

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