Related Experiment Video
Updated: Jul 6, 2026
06:42
Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Modelling of phosphorus inputs to rivers from diffuse and point sources
Michael J Bowes1, Jim T Smith, Helen P Jarvie
1Centre for Ecology and Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK. mibo@ceh.ac.uk
The Science of the Total Environment
|March 28, 2008
Summary
A new model quantifies phosphorus (P) sources in rivers by analyzing P concentration and flow relationships. This method helps identify whether point or diffuse P inputs are dominant, aiding in eutrophication risk reduction.
Area of Science:
- Environmental Science
- Water Resource Management
- Ecology
Background:
- Phosphorus (P) delivery to rivers originates from both point and diffuse sources, exhibiting distinct concentration-flow dynamics.
- Point source P concentrations typically decrease with river flow due to dilution, while diffuse source P loads often increase with flow.
- Understanding these differences is crucial for effective management of riverine phosphorus loading and eutrophication.
Purpose of the Study:
- To develop and validate a simple model for quantifying point and diffuse phosphorus (P) inputs into river systems.
- To investigate the relationship between total phosphorus (TP) concentration and river flow in three contrasting UK river catchments.
- To assess the effectiveness of different P source reduction strategies for mitigating eutrophication risk.
Main Methods:
- A power-law function model was developed to quantify P contributions from point and diffuse sources based on their concentration-flow relationships.
- Empirical data on total phosphorus (TP) concentration and river flow were collected from the Swale, Frome, and Avon river catchments in the UK.
- A load apportionment model was applied to the collected data to estimate point and diffuse P load inputs at high temporal resolution.
Main Results:
- The developed model successfully quantified point and diffuse P inputs, yielding TP source apportionments comparable to the export coefficient approach.
- For diffuse-dominated sites, where diffuse sources contributed up to 75% of the annual TP load, the model indicated that reducing point inputs is often most effective for eutrophication control.
- The model demonstrated the dominance of point sources during the plant and algae growing seasons, highlighting their significance for eutrophication risk.
Conclusions:
- The developed modelling approach offers a simple, robust, and rapid method for total phosphorus (TP) source apportionment using concentration-flow datasets.
- This versatile tool does not require complex data like GIS, land use, or population density, making it accessible for catchment managers.
- The findings provide valuable insights for determining effective river mitigation options to reduce phosphorus pollution and eutrophication.
Related Concept Videos
01:21The Phosphorus Cycle
Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, such as phosphate ions (PO43-), found in soil, water, sediment and rocks. Phosphorus is often a limiting nutrient (i.e., in short supply). Consequently, phosphorus is added to most agricultural fertilizers, which can cause environmental problems related to runoff in aquatic ecosystems.
01:30Typical Model Studies
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.
01:30Microbial Wastewater Treatment
Microbial communities in aquatic ecosystems play a key role in the natural breakdown of contaminants introduced through domestic and industrial effluents. Acting as biological catalysts, these microbes change and mineralize a wide range of organic and inorganic pollutants under different redox conditions.In oxygen-rich surface waters, aerobic heterotrophs lead organic matter breakdown, using oxygen as the terminal electron acceptor to efficiently oxidize substrates to carbon dioxide and water.
01:23Linear Approximations
For a differentiable function of two variables, linear approximation estimates values near a known point by replacing the curved surface with its tangent plane. Consider the function\begin{equation*}f(x,y)=x^2+3y^2\end{equation*}near the point (2, 1). The exact value at this point is f(2, 1) = 22 + 3(1)2 = 4 + 3 = 7.The linear approximation of f(x, y)) near (a, b) is\begin{equation*}L(x,y)=f(a,b)+f_x(a,b)(x-a)+f_y(a,b)(y-b)\end{equation*}First, compute the partial derivatives: fx(x, y) = 2x and...
04:01Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
01:15Model Approaches for Pharmacokinetic Data: Physiological Models
Physiological models in pharmacokinetics are instrumental in understanding the distribution and elimination of drugs within the body. These models describe the drug concentration within target organs, influenced by factors such as drug uptake, tissue volume, and blood flow. Drug uptake is governed by the partition coefficient, which signifies the drug concentration ratio in tissue to that in the blood. The blood flow rate to a specific tissue is expressed as Qt, and the rate of change in tissue...