What reasons could there be for different water sample results at four sites along a river?

Background to sampling sites

I visited 4 sites along the River to get my data;

The first site I visited to do my experiments was at a picnic site along
the river, which is about 3km up stream from a reservoir.

The second site I visited to carry out my experiments was immediately
downstream of the canalised out fall from the reservoir.

The third site I visited was another picnic site along the river 2km
upstream from a town.

The fourth site I visited was 3km downstream from the town and 750m down
stream from the town’s sewage treatment works.

Each site is surrounded by rolling green moorlands where sheep graze

RESULTS ARE ON THE NEXT PAGE

Can you please tell me why these results could possibly be different
from one another?

Figure 6.2.1: chart showing the mean pH Figure 6.2.2: chart showing
the mean

levels at each site.
Temperature at each site.



Figure 6.2.3: chart showing the mean Figure 6.2.4: chart
showing the mean

Conductivity µS cm levels at each site. 02 mg lˉ¹ levels at
each site.



ANSWERS HERE

Background to sampling sites

I visited 4 sites along the River to get my data;

The first site I visited to do my experiments was at a picnic site along
the river, which is about 3km up stream from a reservoir.

The second site I visited to carry out my experiments was immediately
downstream of the canalised out fall from the reservoir.

The third site I visited was another picnic site along the river 2km
upstream from a town.

The fourth site I visited was 3km downstream from the town and 750m down
stream from the town’s sewage treatment works.

Each site is surrounded by rolling green moorlands where sheep graze

RESULTS ARE ON THE NEXT PAGE

Can you please tell me why these results could possibly be different
from one another?

Figure 6.3.1: chart showing the mean Figure
6.3.2: chart showing the mean

Nitrate mg lˉ¹ levels at each site
Phosphate mg lˉ¹ levels at each site



Figure 6.3.3: chart showing the mean Figure
6.3.4: chart showing the mean

Turbidity FTU levels at each site
Hardness mg lˉ¹ levels at each site



Figure 6.3.5: chart showing the mean Figure 6.3.6
chart showing the mean

B.0.D mg lˉ¹ levels at each site.
Chloride mg lˉ¹ levels at each site.



Figure 6.3.7: chart showing the mean Alkalinity mg
lˉ¹ levels at each site.

Background to sampling sites

I visited 4 sites along the River to get my data;

The first site I visited to do my experiments was at a picnic site along
the river, which is about 3km up stream from a reservoir.

The second site I visited to carry out my experiments was immediately
downstream of the canalised out fall from the reservoir.

The third site I visited was another picnic site along the river 2km
upstream from a town.

The fourth site I visited was 3km downstream from the town and 750m down
stream from the town’s sewage treatment works.

Each site is surrounded by rolling green moorlands where sheep graze

RESULTS ARE ON THE NEXT PAGE

Can you please tell me why these results could possibly be different
from one another?

Figure 6.4.1: Chart showing the mean BMWP scores from the riffles &
margins at each sampling site.


Figure 6.4.2: Chart showing the mean ASPT scores from the riffles &
margins at each sampling site.

Figure 6.4.3: Chart showing the mean river flow m³ sˉ¹ at each
sampling site.

Figure 6.8.1: Chart showing the number of the microbial population on
each grid square from each sampling site and group along the Derwent
River.