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COI Funded Project: Rationalizing Nutrient Control in the Coastal Ocean: The Importance of Scientific Research

Project Funded: 2001

Proposed Research

A wide variety of human activities result in substantial introductions of macronutrients into rivers, estuaries, and the coastal ocean. These introductions enhance the potential for over-enrichment of coastal water bodies, and, if eutrophic conditions set up, then significant environmental and economic damages may result. At present, the control of nutrient pollution in the United States is haphazard and uncoordinated across media. In order to move toward a more rational nutrient control policy, the characteristics of nutrient loading, including its variability, must be understood more clearly. In particular, it is critical to elucidate the roles that ocean processes play as both a source of and a sink for nutrients.

The overall goal of the proposed project is to enhance the relevance to society of oceanographic research on nutrient fluxes in the coastal ocean. We propose to characterize the usefulness of scientific research about the role of ocean processes in regulating nutrient loads. Further, we propose to estimate the economic impacts of the development of scientific information on nutrient fluxes in the coastal ocean. This research is interdisciplinary, representing an important new area of inquiry for WHOI.

Final Report

A wide variety of human activities result in substantial introductions of macronutrients into rivers, estuaries, and the coastal ocean.   These introductions enhance the potential for the over-enrichment (eutrophication) of coastal water bodies.   If eutrophic conditions become established, significant environmental and economic damages may result.   In recent years, over-enrichment of coastal ecosystems by nutrients, particularly nitrogen, has emerged as the most widespread and measurable effect of pollution on living marine resources and biodiversity in coastal waters.

At present, the control of nutrient pollution in the United States is haphazard and uncoordinated across media ( e.g. , water, atmosphere).   In order to move toward a more rational nutrient control policy, the characteristics of nutrient loading, including its variability, must be understood more clearly.   In particular, it is critical to elucidate the roles that ocean processes play as both a source of and a sink for nutrients.

A burgeoning literature on nutrient pollution and management in coastal waters demonstrate how nutrients enter coastal waters through point sources ( e.g ., wastewater treatment plants) and non-point sources ( e.g ., runoff from agricultural lands and atmospheric depositions).   Sources of nutrients are associated with various economic activities, such as fossil-fuel combustion (NO x ), fertilizer applications, and waste disposal.   Importantly, the ocean may play a significant role in controlling the flow of nutrients through coastal waters, including acting as a net supplier of nutrients to estuaries or coastal embayments.

In this study, we develop an analytical model of nutrient management in a coastal community.   A degree of scientific uncertainty is inevitable and is associated with the sources of nutrients and processes regulating nutrient cycling in coastal waters.   The model may be used to estimate the value of environmental research required to resolve the uncertainty.   We illustrate the model using a numerical simulation of a hypothetical case.

In the model, coastal water pollution may be the consequence of marine processes, economic activities, or some combination of the two. Our results suggest that when nutrient over-enrichment is the result of economic activity, then the optimal level of activity is lower than when nutrient levels are supplied by natural sources.   The results highlight the importance of environmental research on nutrient sources and coastal ocean processes.

The difference between the optimal levels of economic activity both with and without uncertainty results in a difference in net economic benefits.   This difference is a measure of the value of environmental research.   Our simulation results show clearly that, when economic activity has little effect on water quality and the ocean plays the key role in regulating nutrients at a specific location, the benefits of research could be substantial.   Generally speaking, research is more valuable if it leads to unexpected findings.  If, however, the outcome of research is more or less expected, the value of research will be small.   We find that the average value of environmental research, which is a measure of what the community should be willing to pay for improved understanding of nutrient cycling processes, is on the order of 2.5 percent of the total damages from coastal nutrient over-enrichment.   This proportion may be sensitive to the functional forms describing the scientific uncertainty.

In addition to the level of economic activity, we extend our model to examine the optimal levels of investment in pollution control.   We show that uncertainty about the role of the coastal ocean in regulating nutrients may cause either under- or over-investment in controlling nutrients from economic activities.   Although we have focused our analysis on nutrient control in coastal waters, the analytical framework is potentially applicable to many other environmental issues ( e.g ., climate change) in which uncertainty exists with respect to the cause of environmental degradation ( i.e ., natural processes versus economic activities).


Originally published: January 1, 2001