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An increase in temperature contributes to an increase in the biological activity, and decrease the dissolved oxygen concentration. The increase in solar radiation is favourable for photosynthesis, increasing the concentration of oxygen producing organisms (microalgae and aquatic plants), which is increase the dissolved oxygen concentration during the day but cause the reduction of oxygen concentration at night (Sanchez et al., 2007). Mokhtar et al. (2008) investigated that relationship between temperature and DO is inversed, when temperature increases, the amount of DO will decreases. The high concentrations of DO can be explained by oxygen production processes with photosynthesis mostly by blue and green algae. However, during the night when respiration takes place, DO will decreases. Another reason lowers of DO values could be because of the increased values of ammonical-nitrogen (Mantzafleri et al., 2009). The DO value in water can be maintaining by maintain the water from polluted. The minimum recommended value for DO by the Ministry of Health is 5mg/L (Sulaiman et al., 1997).
2.11.2 Total Dissolved Solid (TDS)
If sampling was conducted during rainy season, turbidity values and TDS variations can increase by the fact that the abrupt changes in rainfall intensity (Mokhtar et al., 2008)
pH is usually measured by using a colorimetric test. The acidity or alkalinity of the water is an important factor to be considered. There is a normal range of pH values for waters which support a good fishery. The toxicity of several common pollutants is markedly affected by pH changes within this range. However, the productivity of the aquatic ecosystem is considerably reduced below a pH value of 5.0, so that the yield from a fishery would also become less (ELFAC, 1969).
Basically, pH is determined by the amount of dissolved carbon dioxide, which forms carbonic acid in water. The main process influencing the acidic conditions of Eucalyptus River water was the decomposition of organic matter from dead leaves and trees (Mokhtar et al., 2008). Yusoff and Al-Hawas (2008), reported that pH value in water may be affected by several factors, such as soil condition or formation of acid rain as a result from fossil fuel combustion.
2.11.4 Electrical Conductivity (EC)
If the river water has an EC value between 50 to 150 ÎÂ¼S/cm, therefore it can be considered low and does not affect the water quality (Suki et al., 1988). High values of conductivity are an indication of the presence of dissolved inorganism material in water. Higher conductivity may effect on water quality (Yusoff and Al-Hawas, 2008).
Turbidity can be high after heavy shower due to silt, clay or other organic particles being washed away from upper catchment through surface runoff (Sulaiman et al., 1997). However, if there is minimum erosion occurring in a particular area, it will reflect in the low turbidity value. Furthermore, if the river flows past developed and developing area, turbidity value is expected to rise (Suki et al., 1988). High turbidity affects submerged plants by preventing sufficient light from reaching them for photosynthesis. High turbidity also has the capacity to significantly increase water temperature.
2.11.6 Total Suspended Solid (TSS)
Mainly area covered by forest has lower suspended solid. As such there is litter erosion occurring. The suspended solid are expected to rise as the river flows past developed and developing area. Land clearing and housing development also included in contributed of higher value of suspended solid. If suspended solids value is less than 26 mg/L, it can categories in the class of good quality water which requires litter or no treatment for potable use (Suki et al., 1988). According to Radojevic et al. (2007), stated that suspended solid can be measure by using the following equation:
SS (mg/L) = 1000 x (Mt ââ‚¬" Mb) / V
Mt = Weight of evaporation dish + dry residual (mg).
Mb= Weight of filter paper (mg).
V = Volume of sample (mL).
2.11.7 Biochemical Oxygen Demand (BOD)
BOD had increased is partially due to developed areas and waste discharge from the mill (Suki et al., 1988). According to Yusoff et al. (2008), BOD5 is a common parameter used for determining the oxygen demand on the receiving water of a municipal or industrial discharge. High concentrations of organic contents in the aquatic environment contribute to river water pollution. The BOD5 was obtained by using the following equations (If the samples give a DOi concentration less than 3mg/L, the samples was diluted to prevent insufficient dissolved oxygen in fifth day).
When dilution water is applied:
When dilution water is not applied:
DOi = Initial dissolved oxygen of the sample, mg/L.
DOf = Dissolved oxygen after five days incubation, mg/L.
F = Fractional dilution of the sample (i.e. the volume of the sample divided by volume of the BOD bottle).
2.11.8 Chemical Oxygen Demand (COD)
According to World Health Organization (WHO) (1978) reported that COD is the amount of oxygen equivalent to most organic material in water. The residues and wastewater generated by the pulp and paper industry; and domestic sewage can causes of high in COD value. Increasing COD should reduce the DO in the water, leaving less oxygen available to support aerobic respiration by microorganisms and promoting anaerobic decomposition (Ma et al., 2009). According to Radojevic et al. (2007), stated that COD can be measure by using the following equation:
COD (mg/L) = 8000 x M x (V1 ââ‚¬" V2) / Vs
V1 = Volume of ferrous ammonium sulfate titration for blank (mL).
V2 = Volume of ferrous ammonium sulfate titration for sample (mL).
Vs = Volume of sample (mL).
M = Concentration of ferrous ammonium sulfate titration (mol/L)
2.11.9 Ammonical-Nitrogen (NH3-N)
Usually natural water contains less than 0.2 mg/L of ammonical-nitrogen. Water containing 0.5 mg/L of ammonical-nitrogen still considered clean with respect to aquatic life. Water bodies containing 0.5-1.0, 1-2.5 and greater than 2.5 mg/L of ammonical-nitrogen have been roughly classified as slightly, moderately and grossly polluted (Suki and Jaffar, 1990). According to Sanchez et al. (2007), value of ammonia concentration decreased while nitrites and nitrate concentrations increased throughout the creek, which is caused by the nitrification process. High values of NH3-N, NO3-N and PO4-P, only assumptions can be expressed that they could be caused by extreme rainfall and flushing of soils or by productive (domestic, agricultural and recreation) activities or by biological processes (Mantzafleri et al., 2009). If concentration of ammonium ions increases therefore, is observed when aquatic organisms are dying off (WHO, 1978).
2.11.10 Nitrate-Nitrogen (NO3-N)
In undisturbed area the nitrate concentration should less than 1 mg/L (Suki and Jaffar, 1990). Nitrogen compounds, they are well soluble in water. However, nitrate and nitrite are mobile compounds and their transport is less markedly associated with erosion. While on the sloping land nutrient appear in the runoff water, in flat areas only nitrogen compound are transported to surface and ground waters (Pinter and Hargitai, 1987). Increased concentrations of nitrates may indicate faecal pollution of the body of water in the preceding period. High nitrate content in potable water is also harmful for children and causes anemia (WHO, 1978)
2.11.11 Phosphorus (PO4)
Phosphorus is one of the elements which are necessary to sustain the growth of algae (Fox et al., 1989). Phosphorus may be find in water by natural process because subsurface and groundwater run-off usually containing concentration of phosphorus (Sharpley et al., 1976). Land use in particular agriculture is a significant diffuse source, which also contributes to overall phosphorus export (Hanrahan et al., 2003). Fine organic particles have high phosphorus and nitrogen content, may be almost continuously resuspended and partly mineralized in water column rather than buried in the sediments (Trolle et al., 2009). Similar to the interpretation for NO3-N, the intense rainfalls which lead to the flushing of soils, sediment transport processes and their inflow to the lake, could explain the higher concentration of PO4-P (Mantzafleri et al., 2009). The main problem associated with increasing phosphorus is eutrophication, population decreases of fish and aquatic plants and also can causes adverse changes in the terrestrial and aquatic environments (Saghravani et al., 2009).