Description

The rise in abundance of algae in coastal waters is thought to be due to increases in nutrients such as nitrate and other forms of nitrogen. Researchers gathered data to gauge the evidence that nitrates in the discharges of rivers around the world are associated with human population density.

Usage

Format

A data frame with 42 observations on the following 11 variables.

River

a character vector indicating the river

Country

a factor variable with 26 levels

Discharge

the estimated annual average discharge of the river into an ocean (m^3 per second)

Runoff

estimated annual average runoff from the watershed (liters/(sec x km^2))

Area

watershed area (km^2)

Density

density of people (people/km^2)

NO3

nitrate concentration (muM/l)

Export

nitrate export (product of runoff times nitrate concentration)

Dep

deposition (proportional to product of nitratrate precipitation times precipitation)

NPrec

nitrate precipitation (mumol NO_3/(sec x km^2))

Prec

precipitation (cm/year)

Source

Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.

References

Cole, J.L., Peierls, B.L., Caraco, N.F. and Pace, M.L. (1993). Nitrogen Loading of Rivers as a Human-driven Process, in McDonnell, M.J. and Pickett, S.T.A. (eds.) Humans as Components of Ecosystems: The Ecology of Subtle Human Effects and Populated Areas, Springer-Verlag.

Examples