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Slip Statistics

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The following figures are part of the 1998 sampling exercise. I would guess that by 2001 such bad figures are unlikely. The sampling figures are supposed to be displayed at the Slip by the local authority. As far as I'm aware, this is not done. I wonder why?

 

Date

Time

Total Coliforms (colonies/100 ml) Faecal Coliforms (colonies/100 ml) Faecal Streptococci (colonies/100 ml) Salmonella
(0 - Absent)

(1 - Present)
Enteroviruses (plaque forming units/
10 litres)
08/05/1998 09:45 7200 2300 50 - -
14/05/1998 09:05 6100 2800 408 - -
20/05/1998 09:30 164 73 20 - -
25/05/1998 09:30 1145 855 112 - -
01/06/1998 09:30 7300 2700 28 1 3
09/06/1998 10:15 14900 12300 600 - -
18/06/1998 10:05 4500 1800 303 - -
22/06/1998 10:19 3800 800 160 - -
02/07/1998 09:49 2000 360 76 - -
06/07/1998 10:25 73 18 11 - -
14/07/1998 09:20 2200 809 232 - -
24/07/1998 10:15 1500 680 79 - -
29/07/1998 10:00 2200 600 184 - -
03/08/1998 10:00 20200 9400 600 1 0
11/08/1998 01:20 26000 8300 1300 - -
19/08/1998 10:00 1800 720 316 - -
27/08/1998 10:30 2400 640 39 - -
04/09/1998 10:00 1100 200 304 - -
12/09/1998 10:30 1500 760 269 - -
16/09/1998 10:00 1600 855 1400 - -

 

 

Microbiological parameters

G

I

Minimum sampling frequency

Method of analysis and inspection

1

Total coliforms/100 ml

500

10 000

Fortnightly (1)

Fermentation in multiple tubes. Subculturing of the positive tubes on a confirmation medium. Count according to MPN (most probable number) or membrane filtration and culture on an appropriate medium such as Tergitol lactose agar, endo-agar, 0.4% Teepol broth, subculturing and identification of the suspect colonies. In the case of 1 and 2, the incubation temperature is variable according to whether total or faecal coliforms are being investigated.

2

Faecal coliforms/100 ml

100

2 000

Fortnightly (1)

3

Faecal streptococci/100 ml

100

-

(2)

Litsky method. Count according to MPN (most probable number) or filtration on membrane. Culture on an appropriate medium.

4

Salmonella/litre

-

0

(2)

Concentration by membrane filtration. Inoculation on a standard medium. Enrichment - subculturing on isolating agar - identification

5

Enteroviruses PFU/10 litres

-

0

(2)

Concentrating by filtration flocculation or centrifuging and confirmation
 
 

Physico-chemical parameters

G

I

Minimum sampling frequency

Method of analysis and inspection

6

pH

-

6-9 (0)

(2)

Electrometry with calibration at pH 7 and 9.

7

Colour

-

No abnormal change in colour (0)

Fortnightly (1) (2)

Visual inspection or photometry with standards on the Pt.Co scale.

8

Mineral oils mg/litre

0.3

No film visible on the surface of the water and no odour

Fortnightly (1) (2)

Visual and olfactory inspection or extraction using an adequate volume and weighing the dry residue.

9

Surface-active substances reacting with methylene blue mg/l (Lauryl sulphate)

0.3

No lasting foam

Fortnightly (1) (2)

Visual inspection or absorption spectro-photometry with methylene blue.

10

Phenols mg/l (phenol indices) C6 H5 OH

0.005

No specific odour
0.05

Fortnightly (1) (2)

Verification of the absence of specific odour due to phenol or absorption spectro-photometry 4-aminoantipyrine (4 A.A.P.) method.

11

Transparency

2

1 (0)

Fortnightly (1)

Secchi's disc.

12

Dissolved oxygen % saturation O2

80 to 120

-

(2)

Winkler's method or electrometric method (oxygen meter).

13

Tarry residues and floating materials such as wood, plastic articles, bottles, containers of glass, plastic, rubber or any other substance. Waste or splinters

Absence

-

Fortnightly (1)

Visual inspection.

14

Ammonia mg/litre NH4

-

-

(3)

Absorption spectrophotometry, Nessler's method, or indophenol blue method.

15

Nitrogen Kjeldahl mg/litre N

-

-

(3)

Kjeldahl method.
 
 

Other substances regarded as indications of pollution

G

I

Minimum sampling frequency

Method of analysis and inspection

16

Pesticides mg/litre (parathion, HCH, dieldrin)

-

-

(2)

Extraction with appropriate solvents and chromatographic determination.

17

Heavy metals such as: arsenic mg/litre As cadmium Cd chrome VICr VI leadPb mercury Hg

-

-

(2)

Atomic absorption possibly preceded by extraction.

18

Cyanides mg/litre Cn

-

-

(2)

Absorption spectrophotometry using a specific reagent.

19

Nitrates mg/litre NO3 and phosphates PO 4

-

-

(2)

Absorption spectrophotometry using a specific reagent .


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