Exercise 1 – Meteoric Water Line Calculations
Meteoric water lines are not essential for every stable isotope study, but they are needed frequently, particularly when comparing surface water or groundwater to precipitation. The calculation of a meteoric water line was covered theoretically in this book, but this exercise provides readers with the opportunity to develop a MWL.
Precipitation and stable isotope data for the University of Cape Town for 2010 are given in the table below. Using the data:
- Calculate the local meteoric water line using the RMA (reduced major axis) regression method and calculate the Pearson’s r correlation coefficient; and,
- Calculate the precipitation-weighted RMA regression line and its Pearson’s r.
Stable isotope data for UCT precipitation
|
Location |
Date |
Precipitation mm |
δ18O ‰ |
δD ‰ |
|
UCT |
Jan 2010 |
9 |
+0.75 |
+9.7 |
|
UCT |
Feb 2010 |
12 |
-0.54 |
-5.8 |
|
UCT |
Mar 2010 |
7 |
-0.83 |
+0.4 |
|
UCT |
Apr 2010 |
44 |
-2.25 |
-12.1 |
|
UCT |
May 2010 |
277 |
-2.78 |
-8.4 |
|
UCT |
Jun 2010 |
222 |
-3.31 |
-17.0 |
|
UCT |
Jul 2010 |
166 |
-3.69 |
-15.0 |
|
UCT |
Aug 2010 |
121 |
-1.74 |
-4.9 |
|
UCT |
Sep 2010 |
100 |
-2.24 |
-3.3 |
|
UCT |
Oct 2010 |
102 |
-2.15 |
-3.3 |
|
UCT |
Nov 2010 |
73 |
-2.39 |
-6.2 |
|
UCT |
Dec 2010 |
17 |
-5.06 |
-39.9 |
Click for solution to Exercise 1