Sulfate concentrations (ppm) collected over several years.
The date of collection is simply indicated by month and year of collection.
Date is a Date object where the day of the month has been arbitrarily set to 1.
A data frame with 23 observations on the following 6 variables.
a numeric vector indicating the sample number
a numeric vector indicating the year of collection
a numeric vector indicating the month of collection
a numeric vector indicating the year and month of collection
a Date object indicating the date of collection, where the day of the month is arbitrarily set to 1
a numeric vector of sulfate concentrations (ppm)
USEPA. (2009). Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Unified Guidance. EPA 530/R-09-007, March 2009. Office of Resource Conservation and Recovery Program Implementation and Information Division. U.S. Environmental Protection Agency, Washington, D.C. p.17-33.
USEPA. (2010). Errata Sheet - March 2009 Unified Guidance. EPA 530/R-09-007a, August 9, 2010. Office of Resource Conservation and Recovery, Program Information and Implementation Division. U.S. Environmental Protection Agency, Washington, D.C.