METHODOLOGY

General methodology adopted for National Water Quality Monitoring Program consisted of establishing network for collection of water sample, monitoring stations, sample size and frequency of sample collection, details of analysis, recording of groundwater level etc. The details of these components are given below:

A uniform site selection criterion was adopted and a grid size of 1 km² (for small cities) 4 and 9 km² (for medium cities) and 16 and 25 km² (for big cities) was established. Preference was given to permanent public points considering the long term monitoring requirement of the project. Geology and depth of aquifers was also considered. A minimum distance of 1 km was maintained between the two monitoring points. Site identification was marked on each city map according to the grid. Sample ID for monitoring purpose was marked on the basis of actual sampling visit sequence of various sites. Following identifications were also marked on every sample of each site:

Cross, field blank and replicate samples for quality control purposes were also collected. Sites for cross samples were selected owing to site number divisible by 10. Sites for Field Blank and Replicates were on the basis of site number divisible by 20. The details regarding grid size and sampling points (number) are shown in Table 4.1.

Table 4.1:  Details of Water Quality Monitoring Network

The national water quality monitoring program covers twenty-one main cities, 11 in Punjab, 3 in Sindh, 4 in Balochistan, and 3 in NWFP. The detail of cities is available in section 1.3. For water quality data collection purposes, the country has been divided into six zones namely Capital Territory Area, Punjab (two zones), Sindh, Balochistan, and NWFP. The field teams of the sub offices were assigned the task in the respective zones of the country and were mobilized for field data collection. Details of the Monitoring Stations (MS) and their areas of responsibility for collection of water samples for water quality monitoring are as under:

• Monitoring Station-I (WRRC, Islamabad)

Rawalpindi, Islamabad and Gujrat cities, Simly, Rawal and Khanpur dams, Tarbela, Mangla and Chashma reservoirs and Jhelum and Chenab Rivers.

• Monitoring Station-II (Regional Office, Lahore)

Lahore, Sialkot, Sheikhupura, Gujranwala, Faisalabad and Kasur cities and Ravi River.

• Monitoring Station-III (Regional Office, Bahawalpur)

Bahawalpur and Multan cities and Sutlaj River.

• Monitoring Station-IV (Drainage Research Centre, Tandojam)

Hyderabad, Karachi and Sukkur cities, Manchar and Hamal lakes, LBOD, RBOD and Hub dam and Indus River.

• Monitoring Station-V (WRRC, Quetta)

Quetta, Khuzdar, Loralai and Ziarat cities and Hanna Lake.

• Monitoring Station-VI (WRRC, Peshawar)

Peshawar, Mardan and Mangora cities and Indus and Kabul Rivers.

Water samples for physico-chemical analysis were collected in polystyrene bottles of 0.5 and 1.5 liter capacities. Before collecting the samples, the bottles were washed properly and rinsed thoroughly several times first with water and then with distilled water. For bacterial analysis, samples were collected in sterilized containers (200 ml). Hydrochloric acid and boric acid were used as preservatives in the sampling bottles for trace elements and nitrate nitrogen respectively before going to field. The first set of water samples was collected after monsoons rains. The sampling team comprised of a Deputy Director as Incharge assisted by a Laboratory Assistant, a supervisor, and a driver.

Following procedure and precautionary measures were followed while collecting samples from the field.

4.3.1    Tap Water

Un-rusted taps were selected for collection of water samples. These taps were properly cleaned and allowed to flow for a few minutes before collecting the sample.

Sample Collection from Tap for Microbiological Analysis

4.3.2    Tubewell Water

The water samples from tube wells were collected after allowing them to flow for at least 10 minutes to get representative sample of the groundwater. Depth of groundwater level and location of the tubewell was properly marked on the topographic survey sheet.

4.3.3    Water from Distribution Network

The water samples from the distribution network were collected from the source of supply (as closely as possible) to minimize the effects of pollution in the distribution system and from consumers end to evaluate the actual quality of water being used. All water sample containers were filled slowly to avoid turbulence and air bubbles after flushing the system for sufficient time.

Measurement of Electrical Conductivity in the Field

pH Determination of Samples in the Field

4.3.4    Hand Pump/Dug Well Water

Water samples were collected from hand pumps or dug wells after purging of the hand pump or well. The purging was carried out by making one stroke for every foot of depth (A hand pump or dug well having 30 feet of depth, needs 30 strokes for its purging).

4.3.5    Stream Water

Water samples were collected from the centre by standing in the middle of the stream. Care was taken to keep the bottle well above the bed of the stream to avoid unwanted bed material going into the sample.

4.3.6    Spring Water

Water samples were collected directly from the spring in sterilized sampling bottles for microbiology and bottles used with or without preservatives for other water quality parameters.

4.3.7    Dams, Rivers and Lakes

It is difficult to obtain a truly representative sample when collecting surface water samples. Sampling point was selected carefully (near to bank in case of river) to avoid any kind of debris in the water. Considerable variations like seasonal stratification, runoff, rainfall and wind were also documented while collecting water sample especially from lake.

4.3.8    Microbiological Samples

The water samples for microbiological contamination were collected in clean, sterile plastic bottles (200 ml). The care was taken to ensure that no accidental contamination occurs during sampling. Samples were not taken from those taps, which were leaking between the spindle and gland to avoid outside contamination. The samples were kept cool and in the dark while transporting to the laboratory.

Inoculation of Water Samples in the Laboratory

4.3.9    Type of Water Samples and Preservatives

Samples were collected for microbiological analysis, for trace elements, for Nitrate (N) and general water quality parameters. The details of these samples and preservative used for each sample are given below:

• Type A – All sites – Sterilized sampling bottles for microbiological analysis;

• Type B – All sites – 2+10 ml/litre HNO₃ as preservative for trace elements;

• Type C – All sites – 1 ml/100 ml, 1 M Boric acid as preservative for Nitrate (N); and

• Type D – All sites – No preservative for other water quality parameters.

Types of Samples (A, B, C, D) from Single Source

4.3.10  Check List of Items/Activities Needed before Going to Field

• Number of bottles required for sampling.

• An appropriate preservative filling in the sampling bottles.

• Calibration of field equipment (if necessary).

• General items required for sampling e.g., sampling forms, equipment, markers, ballpoints, distilled water, paint, pH-meter and EC-meter.

4.3.11  Check List of Items/Activities Needed During Collection of Samples

• City map with grids and identified ID site. During site finalization, ensure that site selection meets the criteria of representative sample. Filling site and sample ID in the form.

• Sample bottle with date and sample ID with indelible ink.

• Sample bottles preserved with appropriate preservative.

• Finalization of method for sample collection.

• Ensuring at four water quality samples.

• Confirm cross, field blanks and replicate samples from suitable sites.

• Marking of (P) on site after collecting sample for future reference and use red paint.

4.3.12  Check List Items/Activities after Collection of Samples

• Samples are transported to the laboratory within the recommended time period.

• That the water samples are not filtered.

• Purpose of water testing to the communities is properly explained.

Quality control measures were started from the filed. Standard sampling methods were adopted to collect the samples. Four types of samples were collected for monitoring purpose where as three kinds of samples were collected for quality control. The detail of these samples is as under:

1.  Samples for Monitoring Purposes

1. Samples for microbiological examination in sterile bottle.

2. Samples for the analysis of trace elements by addition of HNO₃ as preservative.

3. Samples for the analysis of Nitrate (N) by addition of boric acid as preservative.

4. Samples without preservative for the analysis of EC, pH, Hardness, Ca, Mg, Na, K and HCO₃ etc.

2. Samples for Quality Control Purposes.

1. Samples for cross analysis (10%).

2. Samples to check reproducibility (10%).

3. Samples for field blank (10%).

Field blank and replicate samples were planned to be analyzed in the same laboratory to see the quality of distilled water and reproducibility in analytical readings. Cross samples were planned to be sent to some reputable laboratories for comparison. However, due to constraint of time, cross samples could not be carried out in any other laboratory. Therefore, all analysis of field blank, replicate and cross samples for water quality purposes was carried out in PCRWR water quality laboratory at Islamabad by two different teams are shown at Annexure-27.

Analytical Methods

The water samples were analyzed for physical, chemical and bacteriological parameters by using standard methods (Table 4.2). The details of the parameters and methods used for their analysis are given below:

Table 4.2: Water Quality Parameters and Methods used for Analysis

4.5.1    Alkalinity

Alkalinity of water is its acid-neutralizing capacity. The measured value may vary significantly with the end point pH used. The alkalinity is primarily a function of carbonate, bicarbonate and hydroxide contents. The measured values may also include contributions from borates, phosphate, silicates or other bases if present. Alkalinity measurements are used in the interpretation and control of water and waste water treatment processes. Raw domestic waste water has an alkalinity less than or slightly greater than that of the water supply. The method used for this analysis was 2320 Standard Method (1992). The chemicals used for this analysis included:

1. Carbon dioxide free distilled water;

2. Sodium carbonate solution, 0.05 mol/l;

3. HCl 0.02 M;

4. Phenolphthalein indicator; and

5. Methyl orange indicator.

A 100 ml sample was mixed with 2 or 3 drops of phenolphthalein indicator in a conical flask. The phenolphthalein alkalinity of the sample was determined by titrating with standard acid (HCl 0.02 M) until the disappearance of pink colour. The alkalinity to phenolphthalein was considered to be zero in case no colour was produced after addition of few drops of phenolphthalein. The methyl orange alkalinity of the sample was determined by titrating with standard acid (HCl 0.02 M) until the colour changes from yellow to orange.

Total alkalinity as CaCO₃ (m.mol/l)= 1000xBxC

                                                V

where:

B=  ml of standard acid solution to reach the end point of methyl orange;

C=  Concentration of acid in mol/l; and

V=  ml of sample.

Using 100 ml of sample and 0.1 mol/l standard acid solutions, the numerical value of alkalinity is directly expressed in m.mol/l by the number of ml of titrant consumed.

4.5.2 Phosphate

Phosphate occurs in natural waters and waste waters as “Phosphates” classified as following;

• Orthophosphates

• Condensed phosphates (pyro, meta & other polyphosphates)

• Organically bound phosphates

Phosphate occurs in bottom sediments and in biological sludges, both as precipitated inorganic forms and incorporated into organic compounds. Total Phosphorus can be divided analytically into three chemical types such as;

1. Reactive

2. Acid Hydrolyzable

3. Organic phosphorus

Methods to Determine Phosphate are briefed as following;

The method used for phosphate analysis is Molybolovondate Method.

 Following reagents were prepared and used for the analysis;

1. Amino Solution: 3.7 gram sodium sulphite (Na₂So₃). 0.1 g Amino-2-napthol-4 (sulphuric acid). 6.2 g Na metabolisulphurous (Na₂S₂O₅). Dissolved in 100 ml water (stored in Amber colored bottle).

2. Ammonium Molybedate: 4.8 g Ammonium molybedate dissolved in 80 ml. of distill water. 0.25 g or 0.25 ml concentrated ammonium hydroxide added and diluted up to 100 ml distilled water. Heated solution until solution gets cleared.

3. Bismuth Nitrate Solution: 37 ml H₂SO₄ + 63 ml distill water, cool it and dissolve 0.48 g bismuth nitrate.

4. Standard Phosphate Solution: 1.4328 g of potassium dihydrogen phosphate dissolved in one litre of distilled water. This solution equal to 1000 ppm PO₄.

A series of standard phosphate solution ranging from 0 to 10 ppm by diluting the stock solution of phosphate are prepared. 5 ml sample (as standard) + 1 ml amino solution + 1 ml bismuth nitrate + 1 ml ammonium molybedate solution allowed to stand for 10 minute to develop color and measure the color at 650 nm wavelength after setting the spectrophotometer according to instrument instruction manual.

If absorbances are noted, curve between absorbance and concentration is drawn by MS-Excel and regression equation is drawn, which gives the concentration of samples. Then actual samples are taken and added all the reagents, 10 minutes as reaction time is given and absorbance of each sample on spectrophotometer is noted and concentration is drawn from regression equation.

4.5.3    Arsenic

Arsenic is a non-metallic element, present naturally in surface and ground water due to erosion of rocks. It is concentrated in shale, clays, phosphorites, coals, sedimentary iron ore and manganese ores.  Aqueous arsenic in the form of arsenite, arsenate and organic arsenicals may result from mineral dissolution, industrial discharges or the application of herbicides. The chemical form of arsenic depends on its source. Inorganic arsenic may originate from minerals, industrial discharges and insecticides, whereas organic arsenic may come from industrial discharges, insecticides and biological action on inorganic arsenic. The toxicity of arsenic depends on its chemical form. Atomic Absorption Spectrometer (Hydride Generation mode) was used for the analysis of arsenic in water samples. All samples were analysed on HS 55 Mercury/Hydride system, an accessory (AAS, Vario 6 Analytik Jena AG) for the matrix free determination of the hydride forming elements such as As, Bi, Sb, Se, Sn and Te.

The Hydride technique makes use of fact that hydrogen liberated in the reaction of the weakly acidic sample solutions with sodium boro-hydride which combines with metal ions to form gaseous hydrides. These are carried to the hot quartz cell by the carrier gas and decomposed by collision processes in a series of steps, until free As atoms were obtained.

For the analysis of arsenic the Atomic Absorption Spectrophotometer (AAS Vario 6 Analytik Jena AG), Mercury/Hydride System HS55 (Analytik Jena AG), and Argon Gas with 99.99% purity were used. The following common reagents were used for the analysis;

1. Sodium borohydride (NaBH_4, 98% purity)

2. Sodium hydroxide, NaOH

3. Hydrochloric Acid (Concentrated 37% HCl)

4. Arsenic Standard (1007 mg/ml, As in 2% HNO_3, BDH)

In order to make reducing solution (Reductant), 15 g sodium borohydride (NaBH₄) and 5 g of sodium hydroxide were dissolved in 500 ml distilled water. This reagent was used as reducing agent for Arsenic analysis.

The HS 55 Mercury/Hydride system consisting of a basic unit and the cell unit was operated and controlled from PC. Basic unit consists of three accessories. These include batch module, single channel-peristaltic pump and gas valve box. The gas valve box supplied argon gas for scavenging and for transporting the metal hydrides to the system.

Mercury Hydride System of Atomic Absorption Spectrophotometer (AAS)

Pressure of the argon gas cylinder was adjusted at 3-5 bars. After attaining the necessary temperature (950 ^oC) reducing agent was fed by the peristaltic pump. A 10 ml sample was taken into reaction cell and 0.8 ml of concentrated HCl was dispensed into sample and reaction cell was adjusted properly at its place. Calibration standards of arsenic with concentrations (0,10,20,30,40,50 ppb) and (50,60,70,80,90,100 ppb) were prepared. New method of calibration was developed using these standards under the operation of software, and then the method developed was loaded for analysis of actual samples. HS 55 hydride system analyzes the water samples in the following sequences:

• Pre-wash time
• Reaction time
• Rewash time

The detection limit of this method is 0.1 ppb.

4.5.4 Lead (Pb)

Natural Water contains more than 5 mg/l. Lead in a water supply may come from industrial, mine and smelter discharges or from the dissolution of old lead piping. Sample was acidified by the addition of 2 ml of concentrated HNO₃ per liter of sample prior to storage in a plastic container. Lead was analysed by Atomic Absorption Spectrometric method using Graphite mode (AAS Vario 6 Analytik Tena AG) using argon gas at a pressure of 3-5 Bars. Graphite tube technique includes steps i.e. Installation of graphite tube furnace unit in the sample chamber; Installation of auto sampler (MPE 50); and Formation of graphite tube. Optical parameters include wavelength adjustment at 217 nm. After ensuring the conditions for lead analysis method was loaded. Conditions were given to auto sampler having Diluents (0.5% HNO₃) at position 41 and stock (lead standard of 100 ppb at position 42) solutions of Pb (NO₃)₂ with 8 ppb concentration and Mg (NO₃)₂ with 5 ppb concentration were used as Analyt modifier. Temperature of instrument was 900 C^o whereas atomization takes place at 1800 C^o. Calibration was performed with number of standards of known concentration using the stock solution of 100 ppb or as required will be given. Working area for samples were at positions 1-40 on auto sampler. Sample name and sample positions were feeded into software and analysis was performed.

Trace and Ultra Trace Elements

Fifty eight different trace and ultra trace elements such as Lead, Arsenic, Iron, Fluoride Beryllium, Cadmium, Cerium, Cesium, cobalt, Chromium, Copper, Niobium, Neodymium, Nickel, Palladium, Praseodymium, Rhodium, Ruthenium, Scandium, Selenium, Samarium, Tin, Strontium, Tantalum, Thallium, Vanadium, Tungsten, Yttrium, Ytterbium, Zinc, Zirconium, Silver, Aluminum, Bismuth, Dysprosium, Erbium, Europium, Gallium, Germanium, Gadolinium, Hafnium, Mercury, Holmium, Indium, Iridium, Lanthanum, Lithium, Lutetium, Manganese and Molybdenum were analyzed. Fifty four of the trace and ultra-trace elements were analyzed on state of art equipment i.e. Inductive Coupled Plasma Spectrometer (ICP Vista Pro). Analytical procedure includes following steps;

1. Torch alignment using standard solution of manganese with concentration of 5 ppm.

2. Wavelength calibration using multielement standard having 50 ppm potassium and 5 ppm other elements i.e. Al, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, Zn.

3. Creation of new worksheet with the selection of required elements.

4. Calibration with various multielement standards solutions having desirable concentrations.

5. Analysis of actual water samples.

Distill-dionized water of high quality (EC<0.3 µS/cm) is used to prepare blank solution. Volume of concentrated Nitric Acid (65%) is added to distill water in a ratio to have blank solution with 2% concentrated HNO₃. This blank solution is used for washing as well as for calibration. Samples to be analyzed are prepared using some concentrated nitric acid to have 2% adjusted ratio of acid in the sample. Reliability and reproducibility of analysis were checked by analyzing, blank, standard and pre-analyzed sample after every ten samples.

4.5.5    Bicarbonates

Bicarbonates are the dominant anion in most surface and ground waters. The weathering of rocks contributes to bicarbonate content in water. Mostly bicarbonates are soluble in water and concentrations in water are related to the pH. Bicarbonates are usually less than 500 mg/l in groundwater. They also influence the hardness and alkalinity of the water. No guidelines values are recommended by WHO. The method used for this analysis was 2320 Standard Method (1992).

Determination of Bicarbonates by Titration Method

The reagent used for this analysis included:

1. Methyl orange indicator; and

2. Standard acid (HCl) 0.02 N.

A 50 ml of sample was taken in flask and added one drop of methyl orange. Then titrated it against the standard acid until the colour changed from yellow to orange and recorded the volume of acid used as “R₂”.

Bicarbonate mg/l= R₂ x20-R₁x20x2

where:

R₁= Volume of acid used for phenolphthalein alkalinity.

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