Monitoring water quality of the created pool and the reference pools
Water quality testing has been added to the vernal pool monitoring program and will take place once the pools contain water, from September 2008 onwards.
To support a similar habitat to that occuring in the existing vernal pools, the created pool must, at a minimum, replicate the physical aspects of the environment it is attempting to replace. This page will be updated in November at the end of each wet season (earlier in drought years) and will contain a table showing the turbidity of the pools over the entire monitoring period, and a table showing annual nutrient analyses.
Turbidity is measured as NTU (nephelometric turbidity units) with a calibrated Horiba U-10 water meter, when the pools contain sufficent depth of water to allow sampling.
Nutrient analyses are Total N and Total P measured spectrophotmetrically, after thermodigestion.
Turbidity (NTU)
Constructed Pool |
Ref Pool 2 |
Ref Pool 6 |
|
| 15/10/2001 | 83 |
||
| 22/10/2001 | 24 |
7 |
|
| 28/07/2009 | 175 |
4 |
136 |
| 10/08/2009 | 55 |
6 |
108 |
| 20/08/2009 | 87 |
3 |
263 |
| 8/09/2009 | 8 |
||
| 27/09/2009 | 69 |
31 |
|
| 09/08/2010 | 53 |
45 |
|
| 07/09/2010 | 38 |
9 |
12 |
| 20/9/2010 | 98 |
8 |
8 |
| 14/12/2010 | 20 |
Water in the pools was shallow and free water was only available for very short periods during 2011. As a result, no sampling or water quality testing occured.
In wettter years, or after a series of wet years, vernal pool water tends to become very clear as the season progresses, after any dead vegetative material has broken down, with a pH that varies dramatically over a day. Water in the pools in 2009 was generally turbid. In the constructed pool this reflected suspended clay particles, while in the Reference Pool 2 much of the apparent turbidity was actually tea-coloured humic products derived from the breakdown of the annual grasses that had invaded the pool during the previous drought years. As the constructed pool develops a layer of organic material in its base its clay-related turbidity should drop. 2010 showed a typical reduction in turbidiy in the reference pools the longer they held water. This trend is not yet apparent in the constructed pool, but the maturation of vegetation in the pool should see a gradual reduction in overall turbidity in the constructed pool if there are several average to wet seasons in a row.
Nutrients (mg/L)
Constructed Pool |
Ref Pool 2 |
Ref Pool 6 |
||||
| Total N | Total P | Total N | Total P | Total N | Total P | |
| 10/08/2009 | 2.3 |
0.32 |
2.5 |
0.37 |
0.4 |
3.45 |
| 07/09/2010 | 1.8 |
0.35 |
2.3 |
0.66 |
2.7 |
0.59 |
Pool 6 smelt of decomposing vegetative matter on 10/08/2009 when the sample was obtained.
Occasional observations
Constructed Pool |
Ref Pool 2 |
Ref Pool 6 |
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Temp oC |
EC (ms/cm2) |
DO (mg/L) |
pH |
Temp oC |
EC (ms/cm2) |
DO (mg/L) |
pH |
Temp oC |
EC (ms/cm2) |
DO (mg/L) |
pH |
|
| 07/09/2010 | 20.3 |
0.270 |
8.43 |
17.9 |
0.396 |
4.46 |
6.77 |
18.7 |
0.229 |
6.91 |
6.89 |
|
| 14/12/2010 | 25.7 |
0.504 |
3.76 |
8.6 |
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