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River Water Pollution At Langkawi Island Environmental Sciences Essay

Paper Type: Free Essay Subject: Environmental Sciences
Wordcount: 4669 words Published: 1st Jan 2015

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Increasing dearth of water in developing countries has made river water quality evaluation a relevant issue in recent years (Ongley, 1998). The surface water quality is a matter of serious concern today. Rivers due to their role in carrying off the municipal and industrial wastewater and run-off from agricultural land in their vast drainage basins are among the most vulnerable water bodies to pollution. The surface water quality in a region is largely determined both by the natural processes (precipitation rate, weathering processes, and soil erosion) and the anthropogenic influences viz. urban, industrial and agricultural activities and increasing exploitation of water resources (Carpenter et al., 1998 and Jarvie et al., 1998). Pollution of surface water with toxic chemicals and excess nutrients, resulting from storm water runoff, vadose zone leaching, and groundwater discharges, has been an issue of worldwide environmental concern. With an increased understanding of the importance of drinking water quality to public health and raw water quality to aquatic life, there is a great need to assess surface water quality (Campbell et al., 1993).

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APHA (1985), state that the use of water increases with growing population putting increasing strain in the water resources. In 1975, total global use of water was just under 4000 km3 per year, and this is expected to increase about 6000 km3 per year by the year 2000. Averaged on a global scaled, about 70% of this water is used in the agricultural sector, 20% by industry, and 10% for domestic purposes. Nowadays, there become a problem in finding adequate supplies of freshwater to meet our needs and maintaining its quality. Eventhough water availability is not a problem on a global scale, it may be a problem in finding high quality of freshwater at that required place in the required quantity.

In Malaysia, 97% of water resources came from river. River can be defined as any natural stream of water that flows in a channel with defined banks. Malaysia is situated in between longitude 100° and 119° East and latitude 1° and 7° North covers a region on the subject of 329.733 km2 of land which include West Malaysia and the states of Sabah and Sarawak. The annual typical rainfall is 3000mm that contributes to a projected annual water resource of about 900 billion m3 (UNEP, 2002; FAO, 2005). Those rainfalls are stored in river, lake or either other water storage as water resources. The major water demand comes from irrigation for agricultural purposes as well as domestic and industry use (UNDP, 2005).

Problem Statement

As the important channel of substance cycle in biosphere, a whole river eco-system should have the functions of providing the food and water for living, industry and agriculture, amusement, shipping and commerce. Over the past century, it have been being seriously destroyed by various human activities including contaminant discharge, damming, solidifying riverside, destroying vegetation in the riparian zone and etc., resulting in deterioration of water environment, degradation of biological communities and riverbed atrophying. Therefore, the restoration and maintenance of “healthy” river ecosystems have become important objective of river management (Norris and Thoms, 1999).

The development in Malaysia has lead to various kinds of environmental problems. Human activities such as industrialization, aquaculture activities, and urbanization caused a lot of pollution and damage the environment silently. According to the Department of Environment, Ministry of Natural Resources and Environment Malaysia, these activities can produce the anthropogenic pollutants and would be endangered the coastal environment (Chester and Stoner 1974; Ismail et al. 1993, 1995; Ismail and Idris 1996; Law and Singh 1991; Yap et al. 2002, 2003).

The seriousness of heavy metals leads the marine environmental pollution to be recognized as a serious matter to human health concern. Industrial and agricultural activities were reported to be the leading potential source of the accumulation of pollutants in the aquatic environment including the sea (Freedman, 1989; Gümgüm et al., 1994; Nimmo et al., 1998; Barlas, 1999; Tarra-Wahlberg et al., 2001; Akif et al., 2002; Jordao et al., 2002).

The significance of Study

Langkawi Island is one of the most attractive ecotourism spot in Malaysia with well diverse marine lives hence attracting thousands of tourists every year. To support the increasing number of tourist visiting the Langkawi Island, more development were made along the shore line such as hotels, resorts, jetties, shopping mall, and marine recreational facilities. This extensive type of development contributes to the direct impact on the productivity of the marine environment ecosystem and would cause pollution such as heavy metals pollution into the coastal and adjacent area (White, 1988).

Langkawi is located in the northern west coast of Peninsular Malaysia, bordering the south of Thailand -off the coast of Kedah and is made up of 99 islands when the tide is high and 104 islands when the tide is low. The largest of the islands is Pulau Langkawi with an area of about 478.5 km2. Research on the geological resources and landscapes of Langkawi Islands has revealed the great geotourism potential of the island system. Comprising the oldest rocks and the most complete Paleozoic – Mesozoic sequence of sedimentary formations, the Langkawi rocks tell the story of the beginning of the Malaysian Land. Diverse scientific records, fossil beds, geological structure and outstanding landforms further make Langkawi a living museum where visitors are able to directly experience a potential natural world heritage site. Conservation of geosites and geotopes are absolutely necessary, in the form of geological park, geological monument, protected site and beautiful landscape, to sustain its ecotourism activities (Ibrahim Komoo & Kadderi Md Desa, 1989).

Langkawi is one of the most beautiful islands group in Malaysia. Apart from having a distinct and unique morphological feature such as Machinchang ridge and karstic morphology in the limestone area, there are a lot of other interesting geological features. Among those are located in the already popular tourist sites, such as Pantai Pasir Hitam, Telaga Tujuh, Pantai Pasir Tengkorak, Telaga Air Hangat, Gunung Raya and Tasik Dayang Bunting. The geological features of those sites are described and is proposed to be made available in the pamphlet forms or placed at sites as geoinformation boards to increase the tourist geological understanding when they visit those sites. Apart from that, there are also many localities with interesting, as well as unique or rare geological features which are not easily found in other parts of Malaysia. All these localities are of very high potential to be promoted as new geotourism spots. Since the Langkawi Islands is very rich in either already popular or potential geotourism localities, a number of geotourism trails is proposed. Each trail could be reach either by land or sea and may be visited in one day trip (Ibrahim Komoo & Hamzah Mohamad, 1993).

According to Ibrahim Komoo & Kadderi Md Desa (1989), the rocks of Setul Formation are commonly found in the eastern part of Langkawi Island. Based on the change in strikes and dips of the bedding plane of the limestone, it is interpreted that the Setul Formation was folded regionally. Field observations indicate that the structures in the detrital members of the formation are more complicated than in the limestone. The limestone of this formation was faulted as well as folded. The well-known Kisap Thrust Fault was interpreted to play very important role in controlling the rock distributions in this area, which separates the Lower Paleozoic from the Upper Paleozoic rocks.

Therefore, these study should be done as well as many human activities, directly or indirectly, lead to modification of the river and its basin which produce changes in the aquatic environment of the river water. Increased access to improved water sources has been a powerful factor in improving health and also in attracting the tourists visiting the Langkawi Island. On the other hand, it also may maintain the geological resources and landscapes of Langkawi Islands.


The aims of this study are:

To determine the concentration of selected ions for selected river water at Langkawi Island.

To classify the water quality status at Langkawi Island based on water quality index (WQI).

To evaluated the origin of pollution sources at Langkawi Island.

Scope of Study

This study involves the determination of selected ions (Na, K, Mg, Ca and Cl) by using Atomic Absorption Spectroscopy (AAS) at selected river in Langkawi Island. The research scope also extensive the classification of Langkawi river water status based on Water Quality Index (WQI) Formula by Department of Environment.



2.1 The Hydrology

Water is a vital element in human life and it is a renewable resource. According to Wan Ruslan (1994), water is essential for physiological existence, very much the same as every other living organism does and for many other purposes such as agricultural, recreational, industrial, hydroelectric power, navigational, propagation of fish and other aquatic life, irrigation, etc.

Generally, water quality means the standards of water body especially river for any beneficial uses. Water quality with a better index value indicates cleaner water body. High water quality is suitable for man and animals consumption compared to the low water quality. Water quality refers to the characteristics of a water supply that will influence its suitability for a specific use, i.e. how well the water quality meets the needs of the consumer. Water quality status indicates the level of pollutant composition and thus relates to human activities (Anhar et al.1998; Mohd Kamil et al. 1997a; 1997b). Water quality for various types of water body varies with input loads, flow rate and quantity of water (Mohd Kamil1991; Wan Nor Azmin et al.1997). River is one of the important water sources and is classified polluted when there are changes in their chemical and physical characteristics that make it unsuitable for any objective and function (Azizi et al. 1997). Pollution standards for each water body usually evaluated by measuring the value of selected water quality parameters. These parameters can be categorized as physical, chemical and biological.

2.2 Water Scarcity

Water has been dubbed the “oil of the 21st century” as its scarcity is increasingly felt globally. Over the last 50 years, the world’s population had risen by more than two-and-a-half times to about 6.4 billion. At the same time, however, the demand for fresh water went up by four times (UNEP, 2002). The United Nations predicted that at this rate, up to 7 billion people in 60 countries may possibly face water scarcity by the year 2050. Without access to clean water, not only would public health suffer because of poor hygiene and sanitation, agricultural and industrial activities could also get disrupted.

A report by UNEP (2002) also state that similar stresses have also been felt on the water resources in Southeast Asia. This is because economic development had generated greater demand for water from different sectors such as agriculture, industry and domestic users. The situation is likely to worsen in the future. As the regional population is expected to rise by an additional 250 million by 2025, per capita water will fall from 10,000 m3 to 6,700 m3. These trends pose several important questions that policy-makers would have to address.

2.3 Water Pollution

Commonly, water pollution is defined as physicochemical alteration in water that may gives effect to organisms (Chiras, 2001). These broadly take into account the variety of water sources including lakes, rivers, oceans, streams, and also groundwater. The sources of water pollution can be either natural (e. g. animal waste) or by human activities such as runoff of pesticides, herbicides, and feces from agricultural land (Lerner & Lerner, 2009b).

The majority of tropical islands have limited sources of freshwater, no surface water or streams and fully reliant on rainfall and groundwater recharge (Praveena et al., 2010). The inhabitants of these islands mostly depend on groundwater to meet their needs, particularly for drinking and tourism purposes. The demand for fresh water has been rising in response to the increase of activities and development in tourism sector (Singh and Gupta, 1999; Aris et al., 2007).

Numerous islands are experiencing water anxiety at the current levels of groundwater extraction at an outstripping supply. The freshwater lens on islands may simply be overexploited or polluted and vulnerable to climate change, pressure of island resources and the related impacts to freshwater resources (Griggs and Peterson, 1993; Singh and Gupta, 1999; Climate Change, 2007).

A report by EQR Malaysia in 2009 state that compared to 2008, there was a slight deterioration in river water quality. There was a reduction in a number of clean rivers compared with 2008. There were 306 clean rivers in 2009 as compared with 334 in 2008 while the number of slightly polluted rivers increased from 197 to 217. There was also an increased in the number of polluted rivers from 48 in 2008 to 54 in 2009. However, the quality of the marine environment with respect to coastal and estuarine areas was within normal variations compared with the Malaysian Marine Water Quality Criteria and Standard (MWQCS). Figure 2.1 shows the trend of the river water quality for several years.

Figure 2.1 River water quality trend (DOE, 2009)

2.4 Water Pollution Sources

The sources of water pollution can be categorized as point and non-point sources (DOE, 2009). Point sources include sewage treatment plants, manufacturing and agro-based industries, and animal farms. Non-point sources are mainly diffused sources such as agricultural activities and surface runoffs. EQR Malaysia 2009 by DOE state that in 2009, 20702 water pollution point sources were recorded. These comprise of manufacturing industries (9762:47.15%), sewage treatment plants (9676:46.74% inclusive of 736 Network Pump Stations), animal farms (769:3.72%) and agro-based industries (495:2.39%). Figure 2.2 shows the composition of water pollution sources by sector in 2009.

Figure 2.2 Composition of water pollution sources by sector in 2009 (DOE, 2009).

The decrease in the number of clean rivers were attributed to an increase in the number of polluting sources such as sewage treatment plants, manufacturing industries, and palm oil mills which contributed to high pollution loading. As in previous years, the major pollutants detected were BOD, NH3-N and SS. High BOD can be attributed to untreated or partially treated sewage and discharges from agro-based and manufacturing industries. The main sources of NH3-N were livestock farming and domestic sewage, whilst the sources of SS were from earthworks and land clearing activities (DOE, 2009).

Freshwater resources in island currently have been increase in demand as it may simply be overexploited or polluted and vulnerable to climate change, pressure of island resources and the related impacts to freshwater resources (Griggs and Peterson, 1993; Singh and Gupta, 1999; Climate Change, 2007). The most significant and instantaneous consequences of climate change are increase in air temperature, increase in sea surface temperature, changes in rainfall (precipitation) patterns and more extreme weather conditions (Tompkins et al., 2005). Vulnerable to climate change has become more frequent in various countries in the recent decade and Malaysia is not excluded from this phenomenon. Effects of climate change will alter the global hydrological cycle in terms of distribution and accessibility of regional water capital. A warmer climate with its increased climate variability will increase the risk of floods and droughts (Climate Change, 2007; Intergovernmental Panel on Climate Change, 1997).

Changes in rainfall during rainy season reveal the groundwater recharge, as a sensitive function of the climatic factors, local geology, topography and land use (Dragoni and Sukhija, 2008). The islands complex and dynamic system will response dynamically in variable and complex ways to climate change (Watson et al., 1998). Most research on the possible impacts of climate change to the hydrologic cycle has been directed at forecasting the potential impacts to surface water, river discharge and quality.

Nevertheless, according to Mokhtar et al. (2008), to protect valuable water resources, one must understand the natural evolution of water chemistry under natural water circulation processes in mixture with knowledge about the background of the study area. This is crucial for the evaluation and protection of water resources and in the assessment of water quality for creating threshold ions composition in natural water.

2.5 Water Quality Index

Water quality index (WQI) act as a marker of water quality change and be able to indicate the effects of these changes on potential water use. The WQI serves as the basis for environmental assessment of a waterway in relative to pollution load categorization and designation of classes of valuable uses as provided under the National Water Quality Standards (NWQS) (Table 2.1 & Table 2.2).

The Water Quality Index (WQI) consists of six (6) parameters which are Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ammoniacal Nitrogen (NH3-N), Suspended Solids (SS) and pH. Water classes and uses were shown in Table 2.3.







91 – 100

80 – 90

0 – 79


92 – 100

71 – 91

0 – 70


76 – 100

70 – 75

0 – 69


81 – 100

60 – 80

0 – 59

Table 2.1 Water Quality Classification Based On WQI (DOE, 2009)

Table 2.2 DOE Water Quality Index Classification (DOE, 2009)












0.1 – 0.3

0.3 – 0.9

0.9 – 2.7





1 – 3

3 – 6

6 – 12





10 – 25

25 – 50

50 – 100





5 – 7

3 – 5

1 – 3




6.0 – 7.0

5.0 – 6.0






25 – 50

50 – 150

150 – 300




76.5 – 92.7

51.9 – 76.5

31.0 – 51.9


Table 2.3 Water classes and Uses (DOE, 2009)



Class I

Conservation of natural environment.

Water supply I – Practically no treatment necessary.

Fishery I – Very sensitive aquatic species.

Class IIA

Water supply II – Conventional treatment required.

Fishery II – Sensitive aquatic species.

Class IIB

Recreational use with body contact.

Class III

Water supply III – Extensive treatment required.

Fishery III – Common, of economic value and tolerant species; livestock drinking.

Class IV


Class V

None of the above.

2.6 Water Quality Index Parameter

2.6.1 Dissolved Oxygen (DO)

Oxygen is essential to all forms of aquatic life, including those organisms responsible for the self-purification processes in natural waters. Low levels of DO are indicative of greater pollution in the river. Pollution can cause DO concentration to drop below the necessary level to maintain healthy biota (Radojevic & Bashkin, 2006). DO can also be expressed in terms of percentage saturation, and levels less than 80 per cent saturation in drinking water can usually be detected by consumers as a result of poor odour and taste (Chapman, 1996).

According to Laenen and Dunnette (1997), DO is a good indicator of the overall ecological health of a river. Although other indicators also signify general river health, an adequate supply of oxygen is essential for animal life. For many species of fish, DO levels below 6 mg/L for any length if time can be lethal.

2.6.2 Biochemical Oxygen demand (BOD)

Biochemical Oxygen Demand (BOD) is the mass of dissolved molecular oxygen which is needed by microorganisms for the oxidation and conversion of organic substances in a sample (20°C) of water under defined conditions and within a defined period of time (index n in days and hours) (Fresenius & Schneider, 1988). Fresenius & Schneider (1988) also state that standardized laboratory procedures are used to determine BOD by measuring the amount of oxygen consumed after incubating the sample in the dark at a specified temperature, which is usually 20°C, for a specific period of time, usually five days. This gives rise to the commonly used term ‘BOD5’.

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BOD measurements are usually lower than COD measurements. Unpolluted water typically have BOD values of 2 mg/L O2 or less, whereas those receiving wastewaters may have values up to 10 mg/L O2 or more, particularly near to the point of wastewater discharge. Raw sewage has a BOD of about 600 mg/L O2, whereas treated sewage effluents have BOD values ranging from 20 to 100 mg/L O2 depending on the level of treatment applied. Industrial wastes may have BOD values up to 25,000 mg/L O2 (Chapman, 1996).

2.6.3 Chemical Oxygen Demand (COD)

Chemical Oxygen Demand (COD) is a measure of the oxygen equivalent of the organic matter in a water sample that is susceptible to oxidation by a strong chemical oxidant (e. g. dichromate). The COD is widely used as a measure of the susceptibility to oxidation of the organic and inorganic materials present in the water bodies and in the effluents from sewage and industrial plants. Correspondingly, it does not indicate the total organic carbon present since some organic compounds are not oxidized by the dichromate method whereas some inorganic compounds are oxidized. However, COD is a useful, rapidly measured, variable for many industrial wastes and has been in use for several decades (Chapman, 1996).

2.6.4 Ammoniacal Nitrogen (NH3-N)

The presence of ammonium ions in water is connected to the process of the biochemical decomposition of protein substances contained in household and industrial sewage (Chan, 2002).

Ammonium ion is in equilibrium with dissolved oxygen in any aqueous solution. All nitrogen that exists either as ion or in equilibrium with NH3 is considered to be ammonia-nitrogen. The relative value for NH3 varies from 0.1 to 5.0% of total sum of ammonium and ammonia at typical pH value of 6-8 and temperature between 5-30°C (Radojevic & Bashkin, 2006). According to report by DOE (2009), the main sources of NH3-N were livestock farming and domestic sewage.

2.6.5 Suspended Solids (SS)

Suspended solids are matter held in suspension in the water or wastewater and retained by a filter (Chan, 2002). The type and concentration of suspended solids controls the turbidity and transparency of the water. Suspended solids consist of silt, clay, fine particles of organic and inorganic matter, soluble organic compounds, plankton and other microscopic organisms. Such particles differ in size from approximately 10nm in diameter to 0.1mm in diameter (Chapman, 1996).

2.6.6 pH

pH is important in natural waters and in water treatment. Aquatic organisms are sensitive to pH changes and require a pH of 6 to 9. The pH is an important variable in water quality assessment as it influences many biological and chemical processes within a water body and all processes associated with water supply and treatment. When measuring the effects of an effluent discharge, it can be used to assist determine the extent of the effluent plume in the water body.

Generally, pH is a measure of the acid balance of a solution and is defined as the negative of the logarithm to the base 10 of hydrogen ion (H+) concentration. The pH scale runs from 1 to 14 (i.e. very acidic to very alkaline), with pH 7 representing a neutral condition. At any given temperature, pH (or the H+ activity) indicates the intensity of the acidic or basic character of a solution and is controlled by the dissolved chemical compounds and biochemical processes in the solution. In unpolluted waters, pH is principally controlled by the balance between the carbon dioxide, carbonate and bicarbonate ions as well as other natural compounds (e. g. humic and fulvic acids). Unpolluted water usually gives the neutral pH value or slightly alkaline. The natural acid-base balance of a water body can be affected by industrial effluents and atmospheric deposition of acid-forming substances. Changes in pH can indicate the presence of certain effluents, particularly when continuously measured and recorded, together with the conductivity of a water body. Variations in pH can be caused by the photosynthesis and respiration cycles of algae in eutrophic waters. The pH of most natural waters is between 6.0 to 8.5, although lower values can occur in dilute waters high in organic content, and higher values in eutrophic waters, groundwater brines and salt lakes (Chapman, 1996; Jonnalagadda et al., 2001).

2.7 Previous Study on River Water Quality Status

Water Quality Index (WQI) value are inconsistent based on the activity and the sources of the impurity. A report by Yusoff & Haron (1999), the study of river water quality status of Ayer Hitam Forest Selangor showed that the upstream water quality was better than the downstream river water quality throughout the phase of sampling. The study shows clearly that as the river flows from uninterrupted (upstream) to the distressed environment (downstream), the physicochemical characteristics vary and thus degrades the water quality status. The value of water quality index based on the DOE-WQI was in the ranged 89.6 – 99.8. Thus indicate that the water quality status within the vicinity fall under Class I and II. It reveals that there is a close relationship between the river water quality and the land use pattern within the vicinity of the sampling stations. Besides development activities, natural factors such as organic matter decomposition may also contribute and hence influence the river water quality in the study area.

Refer to Suratman et al. (2005), river profile status in Ibai River Basin have value of WQI in between 65.0 – 85.4, which have been categorize under Class II with slightly polluted water status. The major activities that contribute to the decline of water quality are the contribution of domestic sewage from residential and from the small workshops. Table 2.4 below shows some previous study done by researchers on river water quality status at different location.

Table 2.4 Previous study of WQI in Malaysia

Study Area

WQI Value


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