|
WATER
ANALYSES FOR RIVER GREAT STOUR
June 4th
1999
DOWNSTREAM
CHANGES
|
Sites
downstream |
|
Footnotes
|
Parameter
|
Units
|
Horton
Bridge
|
Vauxhall
Bridge
|
STW
|
Blackmill
Bridge
|
Bretts
Bailey
Bridge
|
|
|
|
|
GR 115553
|
GR 163598
|
GR
165598
|
GR 174599
|
GR 187602
|
|
1
|
Discharge
|
Cumecs
|
|
|
|
|
|
|
|
Temperature
|
o C
|
16.3
|
15.4
|
17
|
15.5
|
15.5
|
|
2
|
pH
|
pH units
|
8.2
|
8.2
|
7.4
|
8.1
|
8.1
|
|
3
|
Dissolved
oxygen
|
%
|
112
|
119
|
n/a
|
114
|
116
|
|
4
|
BOD
|
mg/l
|
2.8
|
1.6
|
3.0
|
1.7
|
3.0
|
|
5
|
Ammonia
|
mg/l
|
<0.03
|
0.05
|
<0.05
|
0.04
|
0.04
|
|
6
|
Nitrate
|
mg/l
|
5.18
|
5.8
|
21
|
9.0
|
7.8
|
|
|
Nitrite
|
mg/l
|
0.03
|
0.04
|
<0.1
|
0.04
|
0.04
|
|
7
|
Phosphate
|
mg/l
|
0.19
|
0.21
|
3.8
|
0.94
|
0.68
|
|
8
|
Chloride
|
mg/l
|
46
|
45
|
94
|
55
|
53
|
|
9
|
Chromium
|
ug/l
|
n/a
|
1.3
|
8.2
|
1.2
|
1.1
|
|
|
Copper
|
ug/l
|
3.2
|
3.1
|
14
|
4.3
|
3.1
|
|
|
Iron
|
ug/l
|
n/a
|
130
|
60
|
n/a
|
110
|
|
|
Zinc
|
ug/l
|
9.0
|
16.6
|
34
|
16.1
|
17.0
|
Source: The Environment
Agency
Footnotes
1.
Consented discharge = 18,000
cubic metres/day
2. pH: reflects background alkalinity
of Chalk river
3. Oxygen % GQA (General Quality
Assessment) grading: >80% very good; 70% good; 60% fairly good;
50% fair; 20% poor.
4. BOD mg/l GQA: <2.5 very
good; 4 good; 6 fairly good; 8 fair; 15 poor.
5. Ammonia consent level 5mg/l.
Low levels are a sign of a successful STW. GQA grading: <0.25 very
good; 0.6 good; 1.3 fairly good; 2.5 fair; 9 poor.
6. Nitrates = main cause of eutrophication.
High nitrates and low nitrites indicate a successful STW, with good
oxygenation.
7. Phosphates = another STW residue.
Consent level = 1mg/l.
8. Chlorides = mainly salt pollution.
9. Low levels of metal contamination
linked to high pH levels; metals will be more mobile in acid water.
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