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The impact of pharmaceutical pollution on biogeochemical cycles

Dr Laura Carter (SEE), Prof Pippa Chapman (SoG)

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Pharmaceuticals are now considered pollutants of emerging concern, having been detected across the globe in soils, sediments, and water bodies. Conventional wastewater treatment technologies do not remove or degrade these chemicals efficiently and so they leave the treatment process in by-products such as treated effluent and sludges and are subsequently released into the environment. Pharmaceuticals from human origin, such as anti-epileptic medicines, anti-depressants and painkillers are known to accumulate in soils to μg/kg levels after continual application to land via use of sludges as a soil amendment and use of treated wastewater as a source of irrigation. The direct release of veterinary medicines (antibiotics) from livestock also presents route by which pharmaceuticals can enter, and persist in soil environments. As these chemicals are biologically active, their presence in the environment presents a risk to organisms which inhabit these matrices. Numerous studies have documented the uptake and effects of pharmaceuticals in plants, however we know very little about the impact of pharmaceuticals on soil processes and functions, such as nutrient cycling.

Soil plays a vital role in ecosystems, and perform five key functions which are providing a medium for plants and a habitat for organisms, regulating water flows, acting as a filter and store to protect the quality of air and water and nutrient cycling. Soil store, moderate the release of, and cycle nutrients (such as carbon, nitrogen and phosphorus) via a number of biogeochemical processes, many of which are controlled by the microbial community. Recent research has demonstrated that antibiotics can affect soil microbial community structure. Effects on biogeochemical processes have also been discovered (primarily in aquatic and sludge environments) including nitrogen transformations and methanogenesis. Studies of pharmaceutical effects on nutrient cycles are limited, with focus primarily on antibiotics. 

As soils play a pivotal role in major global biogeochemical cycles, while hosting the largest diversity of organisms on land, we need to increase our understanding of the impacts of pharmaceutical pollution on nutrient cycling and in particular the microbial processes that control the transformation of nutrients between different forms (e.g. organic nitrogen to ammonium and ammonium to nitrate). By considering the cycling of nutrients as holistic systems of connected feedback loops and processes this will provide an in-depth understanding of the effects of pharmaceuticals on key biogeochemical processes.

The major aim of this project is to determine the impacts of pharmaceutical pollution on soil biogeochemical cycles using a wider suite of pharmaceuticals than has been used previously. It will also investigate the factors and processes influencing the pharmaceutical induced effects on biogeochemical cycles (e.g. a range of soil types, environmental conditions). The potential for residues of pharmaceuticals to significantly alter the biogeochemical cycle of nitrogen and carbon in soil raises a number of concerns pertaining to sustainable agriculture (carbon sequestration), management of nutrient pollution (e.g. nitrate leaching to aquatic water bodies), and climate change (via losses of nitrous oxide (N2O) and methane (CH4)), and urgently warrants further investigation given the increasing use of treated waste water and sludges in agriculture, especially in areas of the world where water scarcity is increasing (e.g. Australia, California and Middle East).

In this project, you will work with scientists at the University of Leeds to quantify the impact of pharmaceutical pollution on key soil biogeochemical cycles (e.g. carbon, nitrogen) and to understand how these impacts can affect wider ecosystem functioning. This will be achieved using an experimental approach in the laboratory and environmentally controlled cabinets using soil cores collected from the field.

In particular, according to your particular research interests, the studentship could 

1. Determine base-line data on the effect of a wide range of pharmaceuticals on biogeochemical cycles that have previously not been fully investigated. 

2. Evaluate the buffering capability of ecosystems and the recovery of biogeochemical cycles after pharmaceutical removal / degradation in soils.

3. Compare the effects of pharmaceutical exposure on biogeochemical cycles in a range of different soil types to investigate the role of soil parameters in the response.

4. Determine the effects of environmental variables, for example temperature, water availability on pharmaceutical-induced effects on biogeochemical cycles.

Click here for a full project description.

Related undergraduate subjects:

  • Earth science
  • Environmental science
  • Geochemistry
  • Geography
  • Soil science