Table 2. Statistics of concentrations from paired water-quality samples collected at eight sites in the upper part of the South-Central Texas study unit
[difference, manual concentration minus autosampler concentration; mS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; --, Wilcoxon signed-rank test not done because fewer than three data pairs with nonzero differences; mg/L, micrograms per liter]
|
|||||||||||||
Specific conductance (µS/cm) |
16 of 16 |
404 |
878 |
0.5 |
0-4 |
0.648 |
|||||||
Alkalinity (as CaCO3) (field) (mg/L) |
16 of 16 |
160 |
280 |
-2.50 |
0-22 |
.633 |
|||||||
Calcium, dissolved (mg/L) |
16 of 16 |
59 |
91 |
-1.25 |
0-7 |
.028 |
|||||||
Magnesium, dissolved (µg/L) |
16 of 16 |
12 |
20 |
.06 |
0-7 | -- | |||||||
Sodium, dissolved (mg/L) |
16 of 16 |
6.1 |
66 |
0 |
0-11 |
.844 |
|||||||
Potassium, dissolved (mg/L) |
16 of 16 |
.77 |
7.3 |
.04 |
0-12 |
.523 |
|||||||
Chloride, dissolved (mg/L) |
16 of 16 |
8.7 |
84 |
.35 |
0-21 |
.275 |
|||||||
Sulfate, dissolved (mg/L) |
16 of 16 |
14 |
71 |
-.25 |
0-16 |
.524 |
|||||||
Fluoride, dissolved (mg/L) |
16 of 16 |
.12 |
.46 |
0 |
0-13 |
.865 |
|||||||
Silica, dissolved (mg/L) |
16 of 16 |
8.1 |
14 |
-.15 |
0-10 |
.124 |
|||||||
Manganese, dissolved (mg/L) |
2 of 16 |
13 |
16 |
-.50 |
0-7 | -- | |||||||
Ammonia nitrogen, dissolved (mg/L) |
14 of 16 |
.02 |
.369 |
.01 |
0-61 |
.866 |
|||||||
Nitrite nitrogen, dissolved (mg/L) |
3 of 16 |
.012 |
.108 |
0 |
0-20 |
.5 |
|||||||
Nitrite plus nitrate nitrogen, dissolved (mg/L) |
15 of 16 |
.292 |
11.3 |
.03 |
1-63 |
.868 |
|||||||
Ammonia plus organic nitrogen, dissolved (mg/L) |
7 of 16 |
.1 |
1 |
-.02 |
2-54 |
.376 |
|||||||
Ammonia plus organic nitrogen, total (mg/L) |
7 of 16 |
.11 |
1.1 |
-.02 |
0-19 |
.188 |
|||||||
Phosphorus, dissolved (mg/L) |
6 of 16 |
.01 |
1.73 |
0 |
1-38 |
.156 |
|||||||
Phosphorus, total (mg/L) |
5 of 16 |
.016 |
1.82 |
-.01 |
0-44 |
.062 |
|||||||
Orthophosphate phosphorus, dissolved (mg/L) |
9 of 16 |
.01 |
1.8 |
.01 |
0-52 |
.875 |
|||||||
Organic carbon, dissolved (mg/L) |
16 of 16 |
.3 |
3.5 |
-.19 |
0-93 |
.02 |
|||||||
Organic carbon, suspended (mg/L) |
8 of 16 |
.2 |
1.1 |
-.16 |
0-120 |
.062 |
|||||||
Suspended sediment (mg/L) |
16 of 16 |
6 |
105 |
-3.06 |
11-105 |
.195 |
|||||||
Atrazine (µg/L) |
6 of 6 |
.01 |
.56 |
-.0080 |
0-90 |
.266 |
|||||||
Benfluralin (µg/L) |
1 of 6 |
.0035 |
.0036 |
.0001 |
3 | -- | |||||||
Carbaryl (µg/L) |
1 of 6 |
.009 |
.01 |
-.0011 |
12 | -- | |||||||
Chlorpyrifos (µg/L) |
3 of 6 |
.0021 |
.0052 |
.0002 |
0-22 | -- | |||||||
Desethyl atrazine (µg/L) |
6 of 6 |
.0044 |
.02 |
-.0004 |
3-28 |
.688 |
|||||||
Diazinon (µg/L) |
5 of 6 |
.001 |
.063 |
-.0008 |
0-300 |
.5 |
|||||||
Diuron (µg/L) |
1 of 6 |
.03 |
.03 |
0 |
0 | -- | |||||||
Lindane (µg/L) |
2 of 6 |
.009 |
.013 |
.001 |
11-23 | -- | |||||||
Malathion (µg/L) |
1 of 6 |
.019 |
.02 |
.001 |
5 | -- | |||||||
Metolachlor (µg/L) |
3 of 6 |
.004 |
.005 |
.0003 |
0-20 | -- | |||||||
p,p'-DDE (µg/L) |
1 of 6 |
.003 |
.0033 |
-.0003 |
10 | -- | |||||||
Prometon (µg/L) |
5 of 6 |
.0037 |
.04 |
0 |
3-36 |
1 |
|||||||
Simazine (µg/L) |
3 of 6 |
.0051 |
.018 |
.0009 |
6-15 |
.25 |
|||||||
Tebuthiuron (µg/L) |
4 of 6 |
.007 |
.15 |
.006 |
0-11 |
.25 |
1 Constituent concentrations less than reporting limits omitted from datasets before computation of statistics and Wilcoxon tests.
2 p-value from exact Wilcoxon signed-rank test for all properties and constituents except suspended sediment because all property and constituent pairs except suspended sediment had fewer than 16 nonzero differences (Helsel and Hirsch, 1992, p. 144). Suspended sediment p-value from large-sample approximation by statistical software.
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