 Welcome to this lecture number 24 in groundwater hydrology and in today's lecture the topics to be covered are the potential evaluation of groundwater pollution followed by physical, chemical, biological analysis of groundwater quality and followed by criteria and measures of groundwater quality. Now, let us go to this potential evaluation of the groundwater pollution. So, whenever we need to evaluate the potential of the groundwater pollution, so this few things are essential there. The first one is the identification of the pollution sources and potential pollutants of these pollutants. So, when we talk of this identification of this pollution sources, whether these pollution sources are they coming from the landfill or are they coming from that is the water supply or are they coming from say some other sources like industrial pollution or municipal agricultural. So, they need to be taken into consideration and here, so the pollutants they may be either physical pollutants, they may be inorganic pollutants, they may be organic pollutants, they may be bacteriological pollutants or they may be radioactive pollutants. And it comes to the physical pollutants of the groundwater pollution. So, here you can say this is the temperature, color, order, turbidity, etcetera. So, these are all can be grouped under the physical pollutants. So, next coming to the inorganic pollutants. So, here we get the this is the heavy metals and various other inorganic there is ions as well as radicals. Coming to this organic pollutants, so here in this organic pollutants we have this carbon, nitrogen, chlorophyll, chemical, oxygen demand, phenolic compounds which are known as phenolics and what are popularly known as MBAS which stands for methylene blue active substances. So, these are all the categorized under these organic pollutants. Next we need to account for the bacteriological pollutants. So, which include the coliform bacteria, the viruses, the pathogens or pathogenic bacteria and then lastly the biochemical oxygen demand. So, these all are grouped under the bacteriological pollutants and last but not the least. So, there is there are what are known as the radioactive pollutants in which tritium is there which is an isotope of hydrogen, then radium, strontium and other radioactive materials. So, here so we need to identify these sources these are the in terms of their category in terms of their origin whether they are originating from landfill or whether they are originating from many industrial source or whether they are originating from municipal source or agricultural source and accordingly we need to take the future this one and next what is required is the assessment of the ground water usage. So, depending upon the usage of ground water we need to that is we need to estimate the potential of pollutants say for example, when we talk of the ground water usage. So, here we need to consider what are the future locations for pumping as well as extraction as well as so the what are the future locations of say the habitation and so on. So, where there is a possibility of more water demand and then so there is a put possibility of ground water not meeting the quality standards and causing pollution and so on. And after this we also need to assess the hydrogeological conditions. So, in this we need to consider the aquifers their depth their aerial extent and other details as well as their hydraulic conductivity and so on as well as the natural ground water recharge and discharge areas the isobarth maps. So, all these hydrogeological conditions need to be assessed properly so that we can get a fair estimate of the potential pollutants the evaluation the potential evaluation of the ground water pollution. And last but not the least so the evaluation of the pollution mechanism. So, whenever there is a pollution taking place so it takes place through the Vado zone. So, that is the basically the unsaturated zone and here the properties of the Vado zone as well as such as the hydraulic conductivity degree of saturation as well as the connectivity of aquifers all these things need to be accounted for in the evaluation of this one. So, once we have the information about all these fact all these items such as the identification of the pollution sources and potential pollutants assessment of the usage of ground water assessment of the hydrogeological conditions as well as the evaluation of the pollution mechanism. So, then we will be in a position to reasonably make a good estimate of the potential evaluation of ground water pollution. So, now let us move over to the physical evaluation of ground water quality and this is taken from the source of the Johnson's Johnson division from the year 1965. Here the physical parameters of which constitutes the physical evaluation of ground water quality include temperature, electric conductivity then the total suspended solids and the total dissolved solids. And here so the temperature for the normal ground water the temperature ranges from say 10 degrees to 20 degrees Celsius and of course it may vary also because these are just normal ranges and they are always and likewise the electrical conductivity of the normal range of variation of electrical conductivity is from 100 to 1000 millimos per centimeter. And coming to this other parameters such as the total dissolved solids so the normal range varies from 100 to 500 ppm and of course in this case so if they so there may also be regions where the total dissolved solids concentration may go even below 100 or may go even above 500 depending upon the hydraulic conductivity. And likewise the total suspended solids concentration also normally varies in the range of say 100 ppm to 500 ppm and of course it can also depending upon the various locations as well as various special specific cases it may even go below 100 or it may even exceed 500. And then so this turbidity also in one of the parameters so in which you can say the normal range of the ground water turbidity is from 1 to 5 which is very much within the permissible range. And so likewise so if the evaluation of all these physical parameters constitute what is known as the physical evaluation of the ground water quality. Now we will go to the chemical analysis of this ground water quality and here in the chemical analysis of ground water quality so the parameters which are analyzed which are to be analyzed are that is the concentration by weight followed by chemical equivalence followed by total dissolved solids by electrical conductance then hardness. So these are the chemical analysis these constitute the chemical analysis of the ground water. And first let us see the concentration by weight so in this concentration by weight so here so this case this milligram per liter so this is replaced by parts per million and this one so this is the ionic concentration or sometimes so it is also expressed in terms of say microgram per liter and this one and it is said that the milligrams per liter so this milligram per liter is equivalent to say 7000 milligram per liter of dissolved solids. And next we will come to the chemical equivalence so in this the various ions the conversion factors for various ions are as under so here so this is to determine or say to estimate the chemical equivalence and here so this is the source is from HEM and in this the chemical constituent and then the conversion factor once we multiply by this conversion factor so it will the equivalent concentration so will be in terms of milli equivalence per liter per liter so if the concentration so basically that is concentration in mg per liter multiplied by this conversion factor C f so that is concentration in mg per liter multiplied by this conversion factor C f so multiplied by C f which is equal to concentration in milli equivalent per liter so this is the equation and here let us consider some of this one like say the aluminum ion Al plus 3 so it has a conversion factor of say 0.11119 likewise the ammonium that is NH 4 plus so it has a concentration of say 0.05544 and among them so these are for some of the cations like so like some more can be listed here like that is the barium so BA plus 2 so it has a conversion factor of 0.01456 and let us go to some of the cations so the chemical constituent then conversion factor like say here this copper so copper has a conversion factor of 0.03148 this potassium say K plus it has a conversion factor of 0.02557 now let us come to some of the anions and here in this anions so this bicarbonate that is HCO3 so it has a conversion factor of say 0.01639 and then carbonate CO3 minus 2 so it has a conversion factor of 0.03333 likewise this hydroxide that is OH minus it has a conversion factor of 0.0588 and here among the cations the highest conversion is factor is for the hydrogen ion so for the hydrogen ion the conversion factor is as high as 0.99209 likewise among the cations the least conversion factor is for iodide so that is 0.00788 and then this nitrate NO3 minus it has a conversion factor of say 0.01613 so this is regarding the this one the chemical equivalence and now we will go to the this total dissolved solids by electrical conductance so here this 1 milli equivalent per liter of cations is equal to 100 micro that is Siemens so this is micro Siemens per centimeter so this is the conversion for the total dissolved solids in terms of this electrical conductance and then lastly we will come to this is the hardness so this hardness which is abbreviated as HT so we can it is expressed as calcium and magnesium hardness and this HT which is equal to calcium multiplied by this calcium carbonate plus the magnesium hardness that is also multiplied by calcium carbonate calcium and so if this is equal to say 2.5 times calcium hardness plus 4.1 times the magnesium hardness so that will give the total hardness and of course so here say some this one that is so the classification based on hardness that is water classification based on hardness is say here this hardness in milligram per liter of CaCO3 and the class are if the hardness is between 0 and 75 milligram per liter then it is called a soft water if it is 75 to 150 it is called moderately hard so 150 to 200 it is called hard and 300 above it is very hard so this is how the water is classified based on the hardness next this coming to this biological analysis of ground water quality so here we know that so this so there is what is called the MPN the most probable number to quantify the microorganisms and also there is what is called what is this BOD so these are biochemical oxygen demand so these are these indicate the two of major parameters based on which the biological analysis of ground water can be done and so accordingly we can classify the ground water as it is good or acceptable or that is requiring treatment and so on. Now let us come to the criteria that is criteria and measures for ground water quality so here we should know that the depending upon the purpose for which the ground water is used to the criteria for ground water quality has to be decided so and we all know that so this drinking water it requires highest quality of ground water highest water quality so therefore this drinking water has most stringent this one so that is say drinking water most stringent water quality standards so next below this is the irrigation water that is somewhat less that is less stringent water quality then other purposes so it may the water quality standards may even be less say if it is used for may be other purposes other than drinking or irrigation so wherein that is one now let us consider this the drinking water quality so the drinking water quality standards now here let us this list the parameters then whether they are desirable or if it is desirable let us write it as D or if it is essential let us write it as E then the unit in which it is the parameter is quantified then the world health organization standards WHO standards as per say 1984 of course they have been revised sometime in the late 2000 and then this Bureau of Indian standards BIS standards so this is the Bureau of Indian standards so this is also 1983 then this upper limit so here in this let me also write this upper limit so now firstly let us consider that is the AL aluminum so it is desirable it is not essential and units are milligram per liter and as per the WHO standards it is 0.2 milligram per liter and as per the this one Bureau of Indian standards so the minimum is so this is lower limit is 0.03 and upper limit is 0.2 next is the MBAS that is methylene blue active substance methylene blue active substance so this is also desirable and this is unit is the mg per liter max and it does this the WHO does not have a standard whereas as per Bureau of Indian standards it has to it needs to be within 0.2 and 1 next is arsenic which is a toxic substance of course however that is also in this one and this is it is also been listed as desirable and this is mg per liter maximum so again this arsenic even the maximum concentration should not exceed 0.01 milligram per liter and so here so this is 0.05 milligram per liter that is upper limit so next is this cadmium and cadmium is also desirable mg per liter max it is 0.003 and here so this is 0.01 next let us so this is the chromium Cr plus 6 so it is also desirable and so this is mg per liter and this chromium needs to be within 0.05 and it is a same as per the next is copper so this copper is also desirable and so again the units are same mg per liter and it is the maximum is 1 as per world health standards so this is world health this is a standard upper limit obviously and in this in case of first one so it has to be the minimum is 0.05 and maximum is 1.5 next is this say colour and colour is it is essential and so it is expressed in terms of hazen units and it is the upper limit as per WHO standards is 15 and as per the Bureau of Indian standards it needs to be between 5 and 25. Next is cyanide that is Cn minus and this is also toxic substance that is however it is also this is desirable and it is this one cyanide is mg per liter max and it needs to be within 0.07 and so here as per the Bureau of Indian standards it has to be within 0.05. So next is the electrical conductivity that is EC so this electrical conductivity is essential it is the unit is I am sorry this DS per meter that is DECA Siemens per meter DC Siemens per meter then it is 1600 the upper limit and as per the Bureau of Indian standards it needs to be between 800 and 4800. So next we will so these are some of the parameters so let me just the parameter then whether it is desirable that is D or essential E then the unit then WHO standard upper limit and Bureau of Indian standards it is lower limit upper limit. So we will go to this hardness as the total hardness as CaCO3 in terms of CaCO3 so this is essential and it has units of mg per liter and it is the upper limit as per WHO standards is 500 as per Indian standards so 300 to 500 and next is IR so it is essential so the same mg per liter 0.3 and here it is in case of Bureau of Indian standards 0.3 to 1. Next is lead so this is desirable so this is mg per liter 0.05 and here also it is 0.05 as per the upper standards of upper limits of this one. Next is magnesium it is also desirable so WHO as per this is also mg per liter and here it is not given so whereas as per the Bureau of Indian standards it is 1983 it is between 30 and 100. And then next we will go to this manganese it is desirable so mg per liter max mg per liter and so this is 0.4 and in this case in case of Bureau of standards it is 0.1 and 0.3. Next is mercury it is also considered poisonous but however it is list and here this is mg per liter max and this one 0.001 and here this is same. Next is this nitrate so it is essential then 6.5 to 8.5 mg per liter 6.5 to 8.5 and here it is 6.5 and then 9.2. Now this sulphate so this sulphate is desirable mg per liter so it is 400 is upper limit and then 200 as per this one 200 to 400. Next is like taste so taste is essential and here it is so in this one so everywhere it is written as it has to be agreeable. Next is TDS total dissolved solids so this is mg per liter max this is desirable mg per liter max and then this has to be upper limit is 1000 and it has in this case it is 200 to 2000 as per the Bureau of Indian standards. So these are some of the standards and now let us discuss the so this water quality for agriculture so here so this the classification of poor quality ground waters for agriculture so this is a source that is Gupta et al that is 1994 so in this classification of poor quality ground waters so this is the water quality then the EC of irrigation water which can be used for irrigation or agricultural water so in terms of deca semen per meter next is this sodium absorption ratio that is say R in terms of irrigation water in terms of mole next is this residual alkalinity so this residual alkalinity in milli equivalent per liter so here say if the water quality has to be good then this electrical conductivity for irrigation water it has to be less than 2 deca semen per meter and the sodium absorption SAR sodium absorption ratio has to be less than 10 mole and the residual alkalinity has to be less than 2.5 milli equivalent per liter so next is if these saline waters so they have an electrical conductivity ranging from say 2 to 4 and again the sodium absorption ratio is less than 10 and this residual alkalinity is again less than 2.5 so this is a marginally saline waters next is saline water so the saline waters the electrical conductivity for of irrigation water is greater than 4 then this but however the sodium absorption ratio is still less than 10 and the residual alkalinity is still less than 2.5 next is a high sodium absorption ratio and saline water in this case the electrical conductivity is greater than 4 and this one is greater than 10 and this is less than 2.5 so these are all these 3 come under saline waters now coming to this alkaline waters so that is marginally alkaline for this the electrical conductivity is less than 4 this SAR is less than 10 and this residual alkalinity is say 2.5 to 4 next is alkaline so there for them the electrical conductivity is less than 4 the SAR sodium absorption ratio is less than 10 and residual alkalinity is greater than 4 milli equivalent per liter and next is highly alkaline so all these 3 come under alkaline water and again this highly alkaline also this electrical conductivity is variable this sodium absorption ratio is greater than 10 and this is greater than 4. So like this the so if the electrical conductivity is less than 2 the sodium absorption is less than 10 and residual alkalinity is less than 2.5 milli equivalent per liter so then that is the ideal and which can be used for all kinds of this agricultural crops. However, if it is either marginally saline or saline or high sodium alkaline so in that case we have to it has depending upon the crop we need to use this one and so this is how regarding this one and in the next lecture we will be discussing about the other aspects of ground water quality thank you.