pH
pH indicates the sample's acidity but is actually a measurement of the potential activity of hydrogen ions (H+) in the sample. pH measurements run on a scale from 0 to 14, with 7.0 considered neutral. Solutions with a pH below 7.0 are considered acids. Solutions with a pH above 7.0, up to 14.0 are considered bases. All organisms are subject to the amount of acidity of stream water and function best within a given range.
The pH of a body of water is affected by several factors.
1. Bedrock and soil composition through which the water moves. Some rock types such as limestone can, to an extent, neutralize the acid while others, such as granite, have virtually no effect on pH.
2. Amount of plant growth and organic material within a body of water. When this material decomposes carbon dioxide is released. The carbon dioxide combines with water to form carbonic acid. Although this is a weak acid, large amounts of it will lower the pH.
3. Dumping of chemicals into the water by individuals, industries, and communities. Remember - something as "harmless" as shampoo rinse water is actually a chemical brew and can affect the pH along with other chemical parameters of water. Many industrial processes require water of exact pH readings and thus add chemicals to change the pH to meet their needs. After use, this altered pH water is discharged as an effluent, either directly into a body of water or through the local sewage treatment plant.
4. Amount of acid precipitation that falls in the watershed. Acid rain is caused by nitrogen oxides (NOx) and sulfur dioxide (SO2) in the air combining with water vapor. These pollutants are primarily from automobile and coal-fired power plant emissions. Acid rain is responsible for many of our first order streams becoming acidic.
Changes in pH do have affects on aquatic life as the river flows was their habitat.
Most organisms have adapted to life in water of a specific pH and may die if it changes even slightly. This is especially true of aquatic macroinvertebrates and fish eggs.
The pH is a critical factor determining the health of a waterway. The factors that control it are obviously complicated. As with many environmental concerns, we need to be aware of the implications of any impacts we have upon the environment.
Conductivity
Conductivity is a measure of water’s capability to pass electrical flow. This ability is directly related to the concentration of ions in the water. These conductive ions come from dissolved salts and inorganic materials such as alkalis, chlorides, sulfides and carbonate compound. Compounds that dissolve into ions are also known as electrolytes. The more ions that are present, the higher the conductivity of water. Likewise, the fewer ions that are in the water, the less conductive it is. Distilled or deionized water can act as an insulator due to its very low conductivity value. Sea water, on the other hand, has a very high conductivity.
Ions conduct electricity due to their positive and negative charges. When electrolytes dissolve in water, they split into positively charged (cation) and negatively charged (anion) particles. As the dissolved substances split in water, the concentrations of each positive and negative charge remain equal. This means that even though the conductivity of water increases with added ions, it remains electrically neutral.
Conductivity can be affected by many factors.
1. The addition of fresh water (rain) lowers conductivity because rainwater has low conductivity and
the increase in water levels dilutes mineral concentrations.
2. Conductivity is affected by temperature. The warmer the water, the higher the conductivity.
3. Soil and rocks release dissolved solids into the waters that flow through or over them. Therefore,
the geology of a certain area will determine the conductivity.
A sudden increase or decrease in conductivity in a body of water can indicate pollution. Agricultural runoff or a sewage leak will increase conductivity due to the additional chloride, phosphate and nitrate ions. An oil spill or addition of other organic compounds would decrease conductivity as these elements do not break down into ions.
Turbidity
Turbidity is commonly used as an indicator for the general condition of the drinking water, but is an easy field water quality parameter to measure. Turbidity in water is caused by suspended matter such as clay, silt, and organic matter and by plankton and other microscopic organisms that interfere with the passage of light through the water (American Public Health Association, 1998). Turbidity is closely related to total suspended solids (TSS), but also includes plankton and other organisms. Turbidity of natural waters tends to increase during runoff events as a result of increased overland flow, stream flow, and erosion.
Turbidity itself is not a major health concern, but high turbidity can interfere with disinfection and provide a medium for microbial growth. It also may indicate the presence of microbes (U.S. EPA Office of Water, Current Drinking Water Standards).
There are also a few factors that will affect the turbidity content in water.
1. Total suspended solids, the factors affecting TSS will also affect turbidity. In addition, organic matter contributes to turbidity.
2. High flow rates. The flow rate of a water body is a primary factor influencing turbidity concentrations. Fast running water can carry more particles and larger-sized sediment. Heavy rains can pick up sand, silt, clay, and organic particles from the land and carry it to surface water. A change in flow rate also can affect turbidity; if the speed or direction of the water current increases, particulate matter from bottom sediments may be resuspended.
3. Soil erosion. Soil erosion is caused by disturbance of a land surface. Soil erosion can be caused by road construction and logging. The eroded soil particles can be carried to surface water. This will increase the turbidity of the water body.
4. Urban runoff. During storm events, soil particles and debris from streets and industrial, commerical, and residential areas can be washed into streams. Because of the large amount of pavement in urban areas, natural settling areas have been removed, and sediment is carried through storm drains to creeks and rivers.
5. Decaying plants and animals. As plants and animals present in a water body die and decay, suspended organic particles are released and can contribute to turbidity.
6. Flooding. As flood waters recede, they will bring along inorganic and organic particles from the land surface, and contribute this to the stream.
There are a few ways that fine particles can have a harmful impact on freshwater fish.
1. Acting directly on fish, killing them or reducing their growth rate, resistance to disease.
2. Preventing successful development of fish eggs and larvae.
3. Modifying natural movements and migrations.
4. Reducing the amount of food available and affecting the efficiency of methods for catching fish.
Total Dissolved Solid (TDS)
Total dissolved solids (TDS) combine the sum of all ion particles that are smaller than 2 microns (0.0002 cm). This includes all of the disassociated electrolytes that make up salinity concentrations, as well as other compounds such as dissolved organic matter. In “clean” water, TDS is approximately equal to salinity. In wastewater or polluted areas, TDS can include organic solutes (such as hydrocarbons and urea) in addition to the salt ions.
At most, freshwater can have 2000 mg/L of total dissolved solids, and most sources should have much less than that. Depending on the ionic properties, excessive total dissolved solids can produce toxic effects on fish and fish eggs. Salmonids exposed to higher than average levels of CaSO4 at various life stages experienced reduced survival and reproduction rates. When total dissolved solids ranged above 2200-3600 mg/L, salmonids, perch and pike all showed reduced hatching and egg survival rates.
Total Dissolved Solids (TDS) are also affected by a few following factors.
1. Some dissolved solids come from organic sources such as leaves, silt, plankton, and industrial waste and sewage. Other sources come from runoff from urban areas, road salts used on street during the winter, and fertilizers and pesticides used on lawns and farms.
2. Some dissolved solids come from inorganic materials such as rocks and air that may contain calcium bicarbonate, nitrogen, iron phosphorous, sulfur, and other minerals. Many of these materials form salts, which are compounds that contain both a metal and a nonmetal. Salts usually dissolve in water forming ions. Ions are particles that have a positive or negative charge.
3. Since rain water contributes to most of the water in a watershed, it contributes to the amount of TDS in a watershed. Rain water is almost pure with less than 10 mg/L of TDS.
Total Suspended Solid (TSS)
Total Suspended Solids (TSS) are solids in water that can be trapped by a filter. TSS can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended solids can cause many problems for stream health and aquatic life.
High TSS can block light from reaching submerged vegetation. As the amount of light passing through the water is reduced, photosynthesis slows down. Reduced rates of photosynthesis causes less dissolved oxygen to be released into the water by plants. If light is completely blocked from bottom dwelling plants, the plants will stop producing oxygen and will die. As the plants are decomposed, bacteria will use up even more oxygen from the water. Low dissolved oxygen can lead to fish kills. High TSS can also cause an increase in surface water temperature, because the suspended particles absorb heat from sunlight. This can cause dissolved oxygen levels to fall even further (because warmer waters can hold less DO), and can harm aquatic life in many other ways, as discussed in the temperature section.
There are a few factors that can affect Total Suspended Solids (TSS).
- The flow rate of the water body is a primary factor in TSS concentrations. Fast running water can carry more particles and larger-sized sediment. Heavy rains can pick up sand, silt, clay, and organic particles (such as leaves, soil, tire particles) from the land and carry it to surface water. A change in flow rate can also affect TSS; if the speed or direction of the water current increases, particulate matter from bottom sediments may be resuspended.
Soil erosion is caused by disturbance of a land surface. Soil erosion can be caused by Building and Road Construction, Forest Fires, Logging, and Mining. The eroded soil particles can be carried by stormwater to surface water. This will increase the TSS of the water body.
3. Urban Runoff
- During storm events, soil particles and debris from streets and industrial, commerical, and residential areas can be washed into streams. Because of the large amount of pavement in urban areas, infiltration is decreased, velocity increases, and natural settling areas have been removed. Sediment is carried through storm drains directly to creeks and rivers.
4. Wastewater and Septic System Effluent
- The effluent from Wastewater Treatment Plants (WWTPs) can add suspended solids to a stream. The wastewater from our houses contains food residue, human waste, and other solid material that we put down our drains. Most of the solids are removed from the water at the WWTP before being discharged to the stream, but treatment can’t eliminate everything.
5. Decaying Plants and Animals
- As plants and animals decay, suspended organic particles are released and can contribute to the TSS concentration.
6. Bottom-Feeding Fish
- Bottom-feeding fish (such as carp) can stir up sediments as they remove vegetation. These sediments can contribute to TSS.
Total Kjeldahl Nitrogen (TKN)
Total Kjeldahl nitrogen is the sum of organic nitrogen, ammonia, and ammonium in the chemical analysis of soil, water and wastewater. To calculate Total Nitrogen (TN), the concentrations of nitrate-N and nitrite-N are determined and added to the total Kjeldahl nitrogen.
Today, total Kjeldahl nitrogen is a required parameter for regulatory reporting at many treatment plants.
The Kjeldahl analysis may be broken down into three main steps:
- Digestion - the decomposition of nitrogen in organic samples utilizing a concentrated acid solution. This is accomplished by boiling a homogeneous sample in concentrated sulfuric acid. The end result is an ammonium sulfate solution.
- Distillation - adding excess base to the acid digestion mixture to convert NH4+ to NH3, followed by boiling and condensation of the NH3 gas in a receiving solution.
- Titration - to quantify the amount of ammonia in the receiving solution. The amount of nitrogen in a sample can be calculated from the quantified amount of ammonia ions in the receiving solution.
Colour
Testing the colour of any sample of water offers a fast way to determine the level of contamination. Most discolouration results from organic materials through inorganic substances such as various minerals can also be responsible.
The colours of water indicates the presence of a range of chemical and organic pollutants such as copper from plumbing systems, rust from iron pipes, algae, bacteria, and so on. This means that colour testing is an effective way to determine the nature of water pollution.
Water Testing Instruments for Colour Measurement
Colour in water can be measured by eye. This process involves comparing a sample to a series of slides or tubes of various hues. However, this method is cumbersome and not suitable for certain types of contamination such as that resulting from industrial waste.
Nowadays we have access to range of sophisticated colour measurement equipment. Models such as the MD 100 Photometer are equipped with high-quality interference filters.
Fast, easy to use, highly accurate, the MD 100 Photometer is compact, portable and safe. They use LEDs as a light source to test water in a transparent sample chamber. They can also store comprehensive date of past results for ease of recall.
BOD
Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. the BOD value is commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20°C and often used as a surrogate of the degree of organic pollution of water.
The method that used for the BOD was dilution method. This standard method is recognized by U.S. EPA, which is labelled 5210B in the Standard Methods for the Examination of Water and Waste water. In order to obtain BOD5, dissolved oxygen(DO) concentrations in a sample must be measured before and after the incubation period, and appropriately adjusted by the sample corresponding dilution factor. This analysis is performed using 300 ml incubation bottles in which buffered dilution water is dosed with seed microorganisms and stored for 5 days in the dark room to prevent DO production via photosynthesis. In
addition to the various dilutions of BOD samples, this procedure requires
dilution water blanks, glucose
glutamic acid (GGA) controls, and seed controls. The dilution water
blank is used to confirm the quality of the dilution water that is used to
dilute the other samples. This is necessary because impurities in the dilution
water may cause significant alterations in the results.
Most pristine rivers will have a 5-days BOD below 1 mg/L. Moderately polluted rivers may have a BOD value in the range of 2-8 mg/L. rivers considered severely polluted when BOD values exceed 8 mg/L. Municipal sewage that is efficiently treated by a three-stage process would have value about 20 mg/L or less. So, the lower value BOD indicates better quality of water. Based on the result obtained, all the biochemical oxygen demand value for the dilution 25 ml, 50 ml, and dilution 100 ml for the five week below than 1 mg/L. So, the Sungai Lendu does not polluted because the BOD value does not exceed 1 mg/L.
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