solution

Use the water quality monitoring data from Heidelberg University (Chapter 2, Exercise 4) to

• plot TP (total phosphorus) against sampling dates to visualize the changes of TP over time and compare the temporal pattern of SRP to that of river discharge (flow). Describe the seasonal patterns in both.

• plot TP against flow, both in the original and log scales to examine the correlation between TP and flow.

Chapter 2, Exercise 4

The Heidelberg University in Tiffin, Ohio, U.S.A., maintains a long-term monitoring program of several Lake Erie tributaries. The water quality and flow data from the Maumee River station near Waterville, Ohio, can be found at http://www.heidelberg.edu/sites/default/files/ dsmith/files/MaumeeData.xlsx.

(a) Convert the date column into R dates.

(b) Summarize flow and total phosphorus by year and by month.

(c) Plot flow and TP over time.