Figure 10.3: Nutrient trends in rivers in the national monitoring network, 1989–2005
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Nitrate Nitrogen
Total Nitrogen
Ammoniacal Nitrogen
Dissolved Reactive Phosphorus
Note:
mg/L = milligrams per litre.
Source: Adapted from Ministry for the Environment, 2006d.
Text description of figure
Figure showing map of national monitoring network locations and graphs of average nutrient trends across the network. The map shows that 33 of the 77 sites are in the South Island and the remainder in the North Island (that is, there are approximately equal numbers of sites in each island and they are fairly evenly distributed across the landscape).
Nitrate Nitrogen
|
Rivers with lowest concentrations |
Median rivers |
Rivers with highest concentrations |
|---|---|---|---|
1989 |
0.0162 |
0.1400 |
0.6835 |
1990 |
0.0107 |
0.1050 |
0.6478 |
1991 |
0.0080 |
0.0980 |
0.7290 |
1992 |
0.0107 |
0.1000 |
0.7851 |
1993 |
0.0054 |
0.0590 |
0.5838 |
1994 |
0.0087 |
0.0830 |
0.7098 |
1995 |
0.0087 |
0.1275 |
0.8489 |
1996 |
0.0082 |
0.1035 |
0.7303 |
1997 |
0.0069 |
0.0965 |
0.7714 |
1998 |
0.0054 |
0.0935 |
0.7577 |
1999 |
0.0066 |
0.1215 |
0.8985 |
2000 |
0.0051 |
0.1045 |
0.8163 |
2001 |
0.0046 |
0.1440 |
0.7640 |
2002 |
0.0071 |
0.1110 |
0.9673 |
2003 |
0.0059 |
0.1420 |
0.8353 |
2004 |
0.0042 |
0.1145 |
1.0008 |
2005 |
0.0042 |
0.1155 |
0.9486 |
Total Nitrogen
|
Rivers with lowest concentrations (5th) |
Median rivers |
Rivers with highest concentrations (95th) |
|---|---|---|---|
1989 |
0.0609 |
0.2525 |
0.9863 |
1990 |
0.0457 |
0.2500 |
1.0030 |
1991 |
0.0400 |
0.2200 |
1.0390 |
1992 |
0.0518 |
0.2500 |
1.0085 |
1993 |
0.0559 |
0.2250 |
0.7434 |
1994 |
|
|
|
1995 |
0.0424 |
0.2225 |
1.1074 |
1996 |
0.0450 |
0.2225 |
1.0085 |
1997 |
0.0526 |
0.2285 |
1.1241 |
1998 |
0.0595 |
0.2430 |
1.0849 |
1999 |
0.0599 |
0.2730 |
1.0730 |
2000 |
0.0591 |
0.2240 |
1.1626 |
2001 |
0.0617 |
0.2815 |
1.1152 |
2002 |
0.0584 |
0.2670 |
1.1744 |
2003 |
0.0500 |
0.2680 |
1.0044 |
2004 |
0.0647 |
0.2695 |
1.2668 |
2005 |
0.0549 |
0.2795 |
1.1445 |
Ammoniacal nitrogen
|
Rivers with lowest concentrations (5th) |
Median rivers |
Rivers with highest concentrations (95th) |
|---|---|---|---|
1989 |
0.006 |
0.009 |
0.032 |
1990 |
0.004 |
0.007 |
0.033 |
1991 |
0.004 |
0.007 |
0.025 |
1992 |
0.005 |
0.008 |
0.029 |
1993 |
0.004 |
0.007 |
0.028 |
1994 |
|
|
|
1995 |
0.003 |
0.006 |
0.025 |
1996 |
0.003 |
0.006 |
0.043 |
1997 |
0.002 |
0.005 |
0.049 |
1998 |
0.002 |
0.005 |
0.043 |
1999 |
0.002 |
0.006 |
0.037 |
2000 |
0.002 |
0.005 |
0.034 |
2001 |
0.002 |
0.005 |
0.038 |
2002 |
0.002 |
0.005 |
0.041 |
2003 |
0.001 |
0.004 |
0.034 |
2004 |
0.001 |
0.005 |
0.032 |
2005 |
0.001 |
0.004 |
0.041 |
Dissolved reactive phosphorus
|
Rivers with lowest concentrations (5th) |
Median rivers |
Rivers with highest concentrations (95th) |
|---|---|---|---|
1989 |
0.0010 |
0.0045 |
0.0210 |
1990 |
0.0010 |
0.0045 |
0.0237 |
1991 |
0.0010 |
0.0040 |
0.0240 |
1992 |
0.0004 |
0.0040 |
0.0279 |
1993 |
0.0002 |
0.0040 |
0.0293 |
1994 |
0.0005 |
0.0040 |
0.0297 |
1995 |
0.0008 |
0.0053 |
0.0293 |
1996 |
0.0009 |
0.0057 |
0.0275 |
1997 |
0.0006 |
0.0056 |
0.0382 |
1998 |
0.0006 |
0.0048 |
0.0302 |
1999 |
0.0006 |
0.0065 |
0.0279 |
2000 |
0.0009 |
0.0058 |
0.0271 |
2001 |
0.0008 |
0.0062 |
0.0316 |
2002 |
0.0008 |
0.0052 |
0.0267 |
2003 |
0.0005 |
0.0043 |
0.0292 |
2004 |
0.0006 |
0.0047 |
0.0214 |
2005 |
0.0007 |
0.0050 |
0.0221 |
