In 2020, the Environment Agency announced that only 16% of surface waters were classified as achieving good ecological status according to the EU Water Framework Directive classification. In addition, zero rivers achieved a good chemical status (EA, 2020). The aim of the Water Framework Directive and equivalent recently transposed legislation in the UK (Water Environment Regulations, 2017) is to prevent the deterioration of ground and surface waters. Yet, Water Framework Directive programmes of measures have struggled to improve the overall status of rivers. A key consideration in ecological and chemical water status is the transportation of chemical contaminants to water courses, including pesticides. The use of pesticides is important in maintaining crop yield and quality. However, pesticides can be transported to surface waters in runoff and through inefficient application (spray drift that enters water courses directly).
Pesticides have the potential to cause ecological damage. Recent studies show that invertebrate declines are widespread in aquatic ecosystems, and pesticide use is often cited as a causal factor. Many biological (species, size, reproduction) and environmental factors (physico-chemical properties of contaminants, seasonal hydrographical changes, primary production, land input, sediment resuspension and precipitation) may influence the accumulation of pesticides in aquatic organisms, several order of magnitude higher than the levels present in the environment. Also, the synergistic interactions between contaminants usually lead to a greater toxicity than the sum of their individual parts. The effects then cascade to higher trophic levels by altering food web structure and dynamics, affecting higher-level consumers.
The European Union Drinking Water Directive (Council Directive 98/83/EC) sets regulatory standards for individual and total pesticides at 0.1mg/l and 0.5mg/l, respectively (European Commission, 1998). Many of the compounds are difficult to remove by conventional water treatment technology. Examples of compounds with low removal fractions include clopyralid, propyzamide, carbetamide and metaldehyde. Whist legislation has driven regulatory assessments of individual pesticides, it does not consider the potential impact of the long-term loading of pesticides from diffuse sources. This PhD offers the exciting opportunity for a successful candidate to work with a supervisory/advisory team comprising of internationally respected research leaders and water industry experts with a proven track record for collaboration in ecology, marine biology, water quality, contaminant monitoring, and catchment management. Working collaboratively with South East Water, in South East England catchments the successful candidate will investigate how long-term pesticide loading to surface waters is impacting river ecology and the health of aquatic organisms capable of bioaccumulation. This collaborative initiative has the potential to provide evidence that can be used to reduce environmental degradation of surface waters in South East England. This research will be transferable to the national and international level and is likely to generate considerable interest within the scientific fields of ecology, water quality and management, as well as the water industry.
We therefore seek a PhD candidate to lead and shape this research project under the guidance and direction of the pre-established supervisory/advisory team. The candidate will undertake a blend of desk-based, catchment-based (fieldwork) and laboratory-based research.