Water Quality Monitoring
There are 21 field water quality monitoring stations or sites in 12 river basins in the states of Madhya Pradesh, Maharastra, Rajasthan and Gujarat, where physical parameters such as temperature, colour, odour, specific conductivity, total dissolved solids, pH and dissolved oxygen of river water are observed. There are two Leve-II laboratories to analyse twenty five physico‐chemical and bacteriological parameters of river water. Other parameters like heavy metals / toxic parameters and pesticides etc are also tested.
Water samples are collected at a regular frequency- of once a month or bimonthly, usually on the first working day of the month at all Water Quality Monitoring Stations. Monthly /bimonthly collection of water samples started from August 2004 onwards. These water samples are usually collected from a point, 15 to 20 cm below the water surface having maximum depth of flow along the cross-section of river. Water samples are collected in clean and pre rinsed polythene bottles of 1 liter capacity and bottles are filled up to their full capacity without any air bubble.
The samples, thus collected, are sent to Divisional Laboratories located at Gandhinagar and Surat by special messenger so as to reach within 24 - 48 hours of collection. Their particulars like in-situ temperature, depth, velocity etc. written on paper slip are pasted on the polythene bottles. Five physical parameters are tested either in situ or at the field water quality monitoring station i.e. Level-III lab.
- Discharge by current meter or float method
- Temperature in degree centigrade in situ by thermometer
- Conductivity in micro- mhos/cm measured with the help of Electric conductivity meter
- pH values determined using pH meter
- Titrimetric Method
Parameters determined by this technique are Carbonate, Bicarbonate, Chloride, Calcium and Magnesium. In this procedure, determining the volume of a solution of accurately known concentration, which is required to tract quantitatively with the solution of the substance to be determined, carries out quantitative chemical analysis.
- Spectro- photometric / colorimetric Method
Parameters analysed are Aluminium, Iron, Ammonium, Fluoride, Nitrate, Nitrite Phosphate and Silicate. In this technique, the instruments used are Colorimeter/Spectrophotometer, based on the phenomenon of absorption/ transmission of light. A series of standard solution of known concentrations are prepared and treated with appropriate reagents to produce coloured solution. Then the light of specific wavelength is passed through the standard solution. A calibration curve is drawn with concentration against measured absorbance transmittance. Concentration is then determined from calibration curve.
- Flame photometric method
The parameters estimated through this technique are sodium and potassium. The emission intensity from standard solution is measured by aspirating with the flame and calibration curve of emission intensity against concentration of standard solution is plotted. Then the test samples are aspirated for flame emission. The amount of element present in the sample is determined from the calibration curve drawn with the result of standard solutions.
- Nephelometric Method
The parameter estimated by this instrument is Sulphate. The degree of the light scattered by a series of standard solutions treated with Barium Chloride is measured. A Calibration curve of scattered intensity against concentration of solution is plotted. Then the test samples are allowed for scattering. The concentration of Sulphate in the sample is determined from the calibration curve drawn with the results of standard solutions.
Biological/ Bacteriological Characteristics
- Biochemical Oxygen demand (3days) (BOD3-27 Test)
Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 3 days of incubation at 27 °C and is often used as a surrogate of the degree of organic pollution of water.
- Dissolved Oxygen (DO) The analysis of dissolved oxygen levels for water has been key to the determination of surface water purity and ecological wellness. The term is used to describe the amount of oxygen dissolved in a unit volume of water.