යාපනයේ භූගත ජල සම්පත අහිමි වේද?

අවිධිමත් සංවර්ධන ව්‍යාපෘති හේතුවෙන් යාපනය අර්ධද්වීපයේ භූගත ජල සම්පතට වී ඇති විනාශය පිලිබඳ ලියැවුනු මෙම විමර්ශනාත්මක ලිපිය කේ. සංජීව විසින් රාවය පුවත්පතේ 2015 පෙබරවාරි 22 කලාපයට ලියන ලද්දකි..

Water resources that cannot be neglected ..!

Water pollution is now becoming a national issue in the country through some high profile incidents, since the concern of people on deterioration of water specially due to industries is now alerted. However the biggest issue in people’s concern is the lack of awareness on some technical and scientific parameters used in scientific explanations and their correlations. Hence it is noted that there is a debatable dispute on correlation between pH of water and water pollution arisen in recent past of Sri Lanka. If it is further simplified, it is questioned as pH is an indicator of water pollution..? The answer is “YES” and followed again by “NO” due to some reasons too. The author focuses here on surface and groundwater from which the entire nation is depended.

What is pH of water..? It denotes the acidity and basicity of the water or it can be said that amount of available hydrogen ions in water. pH of pure water is 7 at temperature of 25 ⁰C. If the pH is below 7 it is called that water is acidic and when it is above 7 it is called that water is basic. The truth is that pH of surface and groundwater totally depends on characteristics of geological formations (rocks and soil) in natural conditions. Mostly pH of natural water is slightly acidic (in between 7 and 6). In addition temperature of water can change its pH and it is well noted that pH is decreased with increase of water temperature.

In natural conditions, surface water includes the water in streams, rivers, natural lakes, water pools etc. Mostly surface water is resulted by rains and natural springs. Hence it is clearly concluded that surface water runs on surface and through shallow underground geological formations collecting geochemical substances readily available. Groundwater is the water stored and trapped in shallow and deep underground formations. Whereas dynamic surface water they travel very slowly within the geological formations and in some cases it can be stagnated for a long time allowing sufficient time to contact with ambient rocks/soil. Groundwater is continuously recharged by mainly surface runoff during rainy seasons and surface water storage.

Drinking water extracted directly from springs, streams, rivers, dug wells and tube wells contains dissolved ions added from particular geological formation during the course of movement and time. Hence those waters give us some essential minerals that are vital for our existence. Though those essential mineral matters are supplemented, in extreme conditions some unwanted and poisonous ions can also enter into the body. Such cases have been well documented.. One of the best examples is given by Arsenic poisoning in Bangladesh. Arsenic in water of Bangladesh has been derived from naturally occurring mineral matter of the rocks. The long term intake of such contaminated water causes chronic health problems. Such health problems have also been recorded in dry zone of Sri Lanka and well known health problems of dental epidemiology and goiter have been caused by long term exposure to fluoride derived from rocks and soils in dry zone of the country. Therefore it is well documented and understood that water chemistry is strongly influenced by chemical nature of geological formations in particular area. Hence it is no doubt that geology, water and health are interconnected and health is highly influenced.

Most of the dissolved ions are susceptible to pH of water. Some elements especially metal (cations) ions can easily be dissolved in low pH water. With the increase of pH they tend to be insoluble and removed from water system by precipitating. Hence pH of water is an important factor that decides the fate of ions in water system.

pH of water can also be modified by adding of naturally occurring chemical substances such as sulfur, sulfur containing minerals, peat, calcite (lime) etc. Such various minerals and chemicals can be listed but simply what we can understand here again is the chemical nature of ambient geological formation may modify pH of water. Hence pH of the water is not the same consistence across the country. For example, water in Muthurajawela area is considerably acidic due to the peat formation, water in Jaffna area is slightly basic due to the limestone formation and water in Kalpitiya is more or less neutral due to the quartz sandy formation. Similar local variations too could occur.

In addition to natural conditions, water chemistry including pH can be modified and altered by various anthropogenic activities directly and indirectly. Most anthropogenic inputs behave as pollutants while deteriorating water chemistry. Those can be categorized into two according to the source of derivation as point and non-point source pollutants. In comparison, point source pollutants can simply be managed and controlled while non-point source pollutants are the worst and most difficult to manage. Point source pollution can easily be located and impacted areas can be traced. But in case of non-point pollution discharge points, affected areas and its expansions are not readily available to locate and several investigation attempts have to be carried out. Contamination of water due to chemical fertilizer applications in agriculture is one of the best examples for non-point water pollution.

Discharge of any pollutant/pollutants to the water system in either surface or underground definitely changes its nature and the change can sometimes be physically recognizable by odor, color etc. In some cases it cannot easily be identified and then chemical tests are needed. There are several parameters to be tested since chemical change of water can be any and simple change may cause many changes in water chemistry. Among those parameters, pH is one and sometime most believable and reliable. However, as it depends on the type of pollution and background values of water of particular area. Thus we need to understand, it is very important to compare with background values before results are concluded.

The impacts of industrial discharges can easily be monitored. A plume of discharge can also be traced even though there is no considerable amount of background data on water chemistry of considered area. Several parameters such as nutrition contents, ionic concentrations, biological and chemical oxygen demand, pH, electrical conductivity, salinity, turbidity, temperature are commonly applied in simple water analysis program and data obtained are sufficient enough to have a conclusive decision in most cases. For example if a discharge has a low pH, at the point of discharge, water should definitely get lower pH values and when moving away from it, water should get comparatively higher pH values than the value taken at the point of discharge. When the discharging effluent does not have any pH difference between the water of area, as an indicator, pH cannot be used and some other parameters have to be followed.

In extreme situations special techniques are to be used with regard to the type of industry. If discharged effluents may effect on soil and vegetation, biological indicators can be used in tracing impacted zone of the area.

Though few local incidents became national issues in the country, we are facing a problem of water scarcity mainly due to continuous deterioration of water of the country. It is obviously recorded due to chemical fertilizers and pesticides used in agricultural sector has made the biggest impact and become the major non-point water polluter. The impact of pesticides in water has not been taken into serious consideration so far in the water research sector of the country and hence it is highly questionable about future wellbeing of the people of the country. The industrial sector is growing with a considerable rate hence it should be a must to consider the impact to the water bodies and soil of area before establishment of a particular industry. National guidelines are available for setting an industry as well as allowable environmental norms. Not only that, setting the parameters to evaluate the impact and monitor the recovery should concern back ground values of each parameter. This can be done by reviewing published reports, local and international papers and books etc. Also studying similar case studies provide back ground information and sound knowledge. Variation of climatic conditions of a particular area should also be taken into consideration every time since climate has significant impacts on water chemistry.

Collecting and reviewing all research data on water chemistry of the country will make a platform for future conservation and monitoring programs for the sustainable use of Sri Lankan waters.

Author : Pathmakumara Jayasingha

Deputy Project Manager

Coordinating Secretariat for Science, Technology and Innovation

The author of the article is a graduate in Geology from the department of Geology, University of Peradeniya. He has obtained MSc in Environmental Science and Presently, his PhD in groundwater pollution has been completed and waiting for the final viva conducted by the Postgraduate Institute of Science University of Peradeniya. He has published several international papers on water pollution in reputed and refereed international Science journals.

In addition he is working on Caves of Sri Lanka with a scientific approach and he is one of the pioneering members of the cave research group of Sri Lanka. Also during the last ten years he was working in Archaeology field while popularizing and establishing a new subject area called “GEOARCHAEOLOGY’ in Sri Lanka.

If the publication list is needed to be read, please go to “google scholar” and type the name “Pathmakumara Jayasingha”.

Scientists at ITI develop a simple filter to strain out kidney disease ‘culprits’

Scientists of Material Technology Section at Industrial Technology Institute (ITI) Sri Lanka develop a simple clay based filter to strain out kidney disease “culprits”

(Sunday Times: October 12, 2014)