Staff Profile:Professor Penny Johnes

Name:

Professor Penny Johnes

Job Title:

Professor of Freshwater Science

Responsibilities:

• Director of the  Aquatic Environments Research Centre
• Executive Director of  HYDRA
• Undergraduate Teaching: Aquatic Environments: Problems and Management

Areas of Interest:

• Nutrient cycling and retention in wetlands.
• Evaluation of the potential for management of riparian land as a nutrient sink.
• Investigation of the patterns, processes and controls of N speciation and P fractionation along transport pathways linking land to stream and within freshwater systems.
• Investigation of the impacts of increases in nutrient loading on the biodiversity of nutrient-poor lakes.
• Statistical robustness, error calculation and representativity in water quality monitoring programmes.
• Development of classification and monitoring schemes to assess the baseline, current and attainable state of standing freshwaters in England and Wales.
• Export coefficient modelling of the impact of land use change on the nutrient load delivered to surface freshwaters, and the ecological implications of such loading.
• Evaluation of management strategies to reduce nutrient loading on, and to improve the chemical and ecological quality of surface freshwaters.

Research groups / Centres:

Earth Systems Science Research Group

Publications:

Qualifications:

BSc (Plymouth) DPhil (Oxford)

Penny has spent the past 23 years researching biogeochemical cycling (specifically nutrient hydrochemistry dynamics) in wetland and surface freshwater systems, and more recent the rates of nutrient flux to estuaries and coastal waters. Throughout, my research has sought to determine:

• the biogeochemical cycling of the major nutrients in a range of agricultural and aquatic ecosystems;
• the environmental characteristics which can best explain the patterns of nutrient flux to waters in complex rural landscapes and the key characteristics of importance when upscaling from field to global scale;
• the relative importance of N, P and Si as nutrients limiting primary production in rivers, lakes, estuaries and coastal waters
• the processes controlling the transport and transformation of N species and P fractions as they move along the pollutant transport pathways linking land with water;
• the role of fine sediments in the transport of nutrient species from land to stream and within riparian wetlands, the hyporheic zone and river reaches;
• the processes of significance in modelling nutrient flux from land to coastal waters at regional to global scale

Key findings from this work have highlighted the importance of dissolved and particulate organic N and particulate P fractions in the total nutrient load transported to and within fluvial systems; the importance of short-term, extreme flow conditions in controlling the nutrient source/sink function in aquatic ecosystems; and the necessity, when upscaling from plot to catchment or national scale, of defining as the base unit for modelling quasi-homogenous geoclimatic units exerting broadly similar controls on the rate of diffuse nutrient flux from land to water.