An Investigation into the water quality of the River Banwell in

GCSE Science

Wick St Lawrence

Content

Introduction Pages 3 to 6

Case Study Pages 6 to 10

Introduction Continued Pages 10 to 15

Hypothesis Page 16

Equipment Page 16 to 17

Method Page 17 to 20

Preliminary experiment, results and evaluation Page 20 to 22

Aim:

The aim of the investigation is to test the water quality by working out levels or quantities of indicator species, nitrate, nitrite, phosphate, ammonium, temperature and pH. Samples will be taken down stream to come to a conclusion whether or not the river is polluted. The results will be compared to ones taken by the Environment agency to come to a conclusion.

Introduction:

Why is water quality important?

Approximately 97% of the Earths surface is water, including in the solid state, ice. About 0.06% of this fresh water is found in ground water sources eg, aquifers. Only a small percentage, about 0.01% is contained within our lakes, streams and rivers. This water is so important to many ecosystems on land and life on the planet. We depend on this water for many different purposes for example, to drink, to grow food, generate electricity and to enhance our surroundings. Even our simple necessities eg: cleaning and washing requires water.

The Water Cycle

The hydrological cycle is the basis of this investigation. Without it life on this planet would not exist. In this diagram it illustrates how solar radiation, which is the driving force behind the cycle creates this cycle of water. This includes, precipitation from water in the clouds, infiltration into the ground or surface run off into near by water sources, then followed by evaporation and transpiration back into the atmosphere.

The rate of evaporation/transpiration and precipitation help calculate the base-line quantity for human consumption. Precipitation is all forms of water falling onto the ground, which includes, snow, rain, hail and sleet. There are many ways of measuring this data. Evaporation and transpiration are the movement of water back into the environment from open water bodies and plant respiration. The same metrological factors effect evaporation and transpiration, which are solar radiation, air temperature, humidity and wind speed.

What causes water pollution?

Many human activities have by-products, which have to be disposed of. Potential pollutants can come from, mining, business, housing areas, power plants, agriculture, horticulture, deliberate and accidental pollution. There are many ways these waste products can eventually end up in our water sources. There are two specific ways that pollutants can end up in the river. These are called point sources and non-point sources. Point sources are when pollutants are directly released into the area via a pipe for example from a factory. Non-point sources are indirectly deposited in the river for example, if fertilisers are put down on a field in wet weather the fertiliser will be washed into the water body by a process called run off.

Non-point source

This way of polluting is associated with rain events. When rain reaches the ground, a complex process occurs and the unavoidable effect is that the pollutants run into the water body. Even before human intervention this process of rain bringing pollutants into the rivers existed. Rainfall would pick up soil particles causing local streams and rivers to become muddy and unusable. Now that humans effect the environment on a large scale, these processes include farming, harvesting trees, construction work and disposal of solid wastes.

Run off is a process, which is a non-point source. Chemicals maybe bound to soil particles, which are soluble in water. Increased rain splash may increase the chance of the pollutant being detached from the soil particle. This energy created by rain is defined by droplet size, velocity of fall and intensity of the participating storm. Soil characteristics also determine the detachment of pollutants and transport processes. Size, shape, composition and strength of aggregates are the factors determining how easy chemicals are removed from soil particles into water. Also these factors can effect water infiltration. Slope factors also influence pollutant transport. The gradient along with slope length, influences the rate of runoff. Root penetration help slow down the rate of runoff.

Urban storm run-off occurs in urban areas when rainfall lands on human made paths. Fallen rain does not percolate into the ground but ends up carrying pollutants from the surfaces of its path. The control of this can be simple rubbish control strategies.

Point Sources

These are direct sources of pollution, which are purposely put into the water body. These are identifiable where waste is discharged. Most industrial by-products and waste material are removed in this way. These are regulated by a government body, which tests the water quality. These are easier to measure and identify due to the source being known.

Depending on the type of pollutant some may take effect metres from entering the water body, while others travel miles before taking effect on the local ecosystem for example, acid rain. There are many biological and chemical considerations when looking at water quality. Two or more pollutants may react with each other increasing the effects that just one chemical had by itself. Pollutants may be taken up by plants and then eaten by animals causing a cycle of events, which could lead back to a human.

What are the effects of pollution?

The main consideration of the river Banwell is it is surrounded by agricultural farmed land. When fertilisers for example NPK, are used in wet conditions, these may be washed into the river by surface run off. Eutrophication is the enrichment of fresh water sources by excess nutrients. This is a natural process but due to the nature of humans to domesticate things and grow them under controlled conditions, commercial agriculture especially in MEDC’s is used. This type of agriculture requires large inputs of energy in the form of fertilisers. Lakes start as oligotrophic lakes ever increasing its nutrients naturally into a eutrophic one by erosion and sediments being deposited by streams entering the lake, but if this increase is rapid due to human intervention local ecosystems suffer.

What happens is that these extra nutrients initially increase plant, animal diversity and abundance. Algae also increase in numbers due to this fluctuation of nutrients and begin to photosynthesise releasing oxygen into the water, but they also block light to plant life in lower water levels. Certain plants called cyanobacteria (blue-green algae) release toxins dangerous to the fish and animals. Zooplankton populations fall as macrophytes (large plants) decrease as predators eat more. This leads to less algae being eaten by the zooplankton so the algae increases in numbers once again. Algae death and birth rate are very rapid meaning more algae are broken down after the death by decomposing bacteria using up the oxygen that remains in the water. This rapid decease in oxygen levels lead to the death of many fish and animals leading to population crashes and many food webs collapsing. This process continues to happen and oxygen levels carry on decreasing.

Acidification is also a consideration but occurs naturally. Carbon dioxide dissolves in rainwater to form carbonic acid. Sulphur dioxide and nitrogen IV oxide dissolve to form nitrous and sulphuric acid. Acid rain is a transboundary pollutant as it travels maybe many miles before falling. Humans have also accelerated this process due to the release of nitrogen oxides and sulphur dioxide into the air by the use of cars and certain factories eg power stations.

The major effects that occur due to acid rain being deposited in lakes are that fish have problems regulating salt concentration. Mucus builds up ...

This is a preview of the whole essay

The major effects that occur due to acid rain being deposited in lakes are that fish have problems regulating salt concentration. Mucus builds up in the gills of fish leading to them being unable to breathe. Haemoglobin looses its affinity for oxygen becoming less efficient. Acidification of soil leads to aluminium ions to become leached into the water body killing water creatures directly or increase harmfulness of other chemicals. In high acidic concentrations animals named crustaceans lose their ability to absorb calcium meaning they cannot form their exoskeleton. Aquatic invertebrates decrease and so do the birds that feed on them. Reproduction success decreases as many eggs fail to hatch.

Lead is a heavy metal that was used in petrol and many water pipes are still leaded which is released in water as fine particles. Lead causes disabilities and emotional disturbance in children.

Thermal pollution is also being tested. Waste that is released from power stations, housing areas and industry may change the environment in the water. Toxic effects occur as gas solubility decreases as the temperature increases. Also because of the high temperatures, aerobic organisms use the oxygen at a more rapid rate leading to more species dying due to competition for oxygen.

Pesticides are used by farmers to protect crops from pests. Just with fertilisers they also run off into the river. Even small amounts of pesticides can be lethal as they accumulate in body fat deposits. This is dangerous as these move up the food chain, when these deposits are used they are released inside the body. As these pesticides go up the food chain they become more concentrated causing more harm than at the lower trophic levels. Pesticides are also known to cause eggshell thinning and may reduce fertility in birds. These include herbicides, which are biodegradable and break down rapidly but target specific types of plants for example a grass in a flowerbed.

Sewage is also a problem if it is released without treatment into a water source. With the UK producing annually 400 million tonnes a year, treatment is essential to maintaining water quality. Wastes, which are called controlled wastes, include household waste and industrial waste. This is to be taken into account in this investigation due to the proximity to a sewage treatment center. This can include anything from organic wastes from humans, which could lead to accelerated plant growth to heavy metals from local industry.

Case Study: Sources: Environment agency

The Environment Agency is a statutory department set up by the government to monitor our local environment. They test the biochemical oxygen demand, ammonia and dissolved oxygen along with nutrients nitrate and phosphate. They also look at the biological aspects that affect the life in the river. The lowest grade in any of the three tests becomes its overall grade. The agency tests the river Banwell yearly and produces a report on a scale from A to F. Below is the Environment Agencies official classification chart.

Over the past years from 1988 the river Banwell was issued a grade E and was deemed a poor water quality river. Below are the official results from that year

As you can read from the graph the Biochemical oxygen demand was at 5.73mg/l where the national average was 4.88mg/l a huge difference which was leading to “impoverished ecosystems” and was “Vulnerable to pollution” and was issued an E. Ammonia national average was set at .569mg N/l and the river Banwell was measured at .629 again above average but was issued a C. The final test was for dissolved oxygen, which received a D grade as it was tested and had a low oxygen saturation level. A river needs to have a good level in all three tests to sustain a clean and diverse ecosystem. The environment agency therefore issues the lowest grade out of them.

Below are the test results for the year of 2002; this year was given a grade D.

The Biochemical oxygen demand was issued a B in this year. The average mg/l was 1.93mg/l where the river Banwell was found to have 1.00mg/l a significant improvement from the tests taken in 1988. Ammonia concentration had also improved dramatically to .109mg N/l compared to national average of .173mg N/l also being awarded a grade B. Unfortunately the dissolved oxygen measurement had only improved by 0.21 from the year 1988 so remained at the same grade. Overall the Banwell received a grade D, not much of an improvement from the grade E given in 1988.

(Source: Amy Northern essay 2004)

The test for pH (concentration of hydrogen ions)

This shows that the pH was slightly acidic, just over the boundary of neutral. A pH of around 7 will be a good indication of a not polluted river.

They also test for the nutrients, phosphate and nitrate. There levels are given below in the table and the classification grade given with them.

These are the results for the nitrate in 1998, in which they received a grade 3 overall.

From the following you can see that the River Banwell had slightly over the national mean, hence receiving a grade 3 meaning “moderate”.

Below are the results for the same test but in 2002.

The Banwell was still over the national mean in 2002 but as you can see from the year before there has been a decline in nitrate levels.

Phosphate test results in 1988 are shown below:

Again the phosphate levels are well over the national average at .80mg/l and stands at a grade 5, meaning it is “very high”.

The results for 2002 are worrying as the phosphate levels have increased from 1988 and the national average has declined dramatically.

With a .16mg/l increase since 1988 this shows that on an environmental point of view it’s classed at a level 5 still at a “high” level.

The table below shows the classification of the biological aspects of testing the river Banwell.

Below is data about plant and animal life provided by the environment agency. These are both from different years, one from 1990 and the other 2002.

1990 results:

2002 results:

From both results it can be said that the river reached a B grade in both years. This shows the Banwell in a biological perspective is nearly unpolluted.

Even though some tests received a high grade, life in the river needs all 3, biological, chemical and nutrients to be of a high standard. For example, the nutrients high levels could be affecting the ecosystem in the water. In comparison the Congresbury Yeo a few miles away received much higher grades overall. The ecosystems will be more established and more diverse as you can see by the animal life there, eg herons and the fishing that takes place, unlike the Banwell where little or no fishing now occurs.

From the data collected from the Environment agency I will be able to come to a conclusion after to whether or not the river is polluted or not. I will also be able to comment from this information to the extent of the improvement or to the decline in quality of water.

Introduction Continued

There are many indications that I can look out for which will indicate whether or not that body of water is contaminated. These are talked about below and their limitations.

Indicator species: Different species have been shown to be more or less sensitive to effects of pollution. These species where observed to be more abundant in certain levels of pollutants. Families of organism are given a score from 1 to 10, dependant on their resilience to concentration of pollutants. The lower the score more likely I am to discover this organism in contaminated water. An example of a score 10 organism is an Oligochaeta (worms). If I was to find a greater abundance of this organism I could suspect that the river is polluted. If I was to find a Siphlonuridae in abundance I could expect that the river is not contaminated. I cannot though just use this method as an indication of contamination because it does not give quantitative results of how chemical contaminated the body of water is.

Biochemical oxygen demand: This is a test of the change in oxygen concentration over a period of 5 days from 1 point to another. The difference is measured to gain the demand for oxygen. If the demand is higher this could indicate that the river is more contaminated because more organic matter is present.

Ammonium nitrate: This is part of the nitrogen cycle. In the human process, the Haber process fertilisers are manufactured. Fertilizers are used by farmers to increase productivity of crops. These are then leached by percolating rainwater into a river. This could lead to species of plants or an increase number of a certain plant to become more abundant. This process is called eutrophication. For example more algae will be present on the riverbed. Leading to an indication of a more contaminated water body.

PH indication: Aquatic animals are sensitive to the acidity or alkalinity of water. Water can increase in pH as a result of high photosynthetic rates of algae which links back to fertilisers. The algae use up the CO2 in the water changing the state of equilibrium in the river causing the carbonate to dissociate.

Nitrate and nitrite: When an ammonium-based fertiliser is used on a field nitrification will occur. This process NH4+ → NO2- → NO3- is called nitrification. Caused by bacteria called nitrosomonas and nitrobacter. These will also cause eutrophication to an extent but not as visible as in a lake as the water is moving constantly so the compounds are being diffused at a more constant rate. From initial investigations the rate at which water is moving is slow at this moment in time.

Nitrogen Cycle

Nitrogen in the air is made available to plants by the process of nitrogen fixation. This conversion of nitrogen into ammonium then dissolves in soil moisture to form ammonium ions. Plants can then use these ammonium ions and take them up through the root hairs or may be converted into nitrite or nitrate by nitrifying bacteria. Nitrate ions can be absorbed by plants or turned back into nitrogen gas by denitrifying bacteria.

Only certain types of plants can carry out the process of nitrogen fixation. Rhizobium is in particular special because of its symbiotic relationship with leguminous plants eg peas. They are present in modules that are formed on the roots of the plant. The bacteria contained provide the plant with ammonia and in return the plant provides sugars from the phloem that it needs to sustain life.

Nitrogen fixation is not the only way nitrogen compounds enter the soil. Lightening and deposition by acid rain can also achieve this. The decomposition in acid rain is achieved by the breakdown of plants and animals and the release of manufactured fertilisers.

Dead organisms that are broken down by bacteria and fungi release ammonia into the soil. The ammonia is converted into ammonium ions, and plant roots can absorb these ions. These ions go on to create proteins in the plant. Animals therefore gain their nitrogen source by consuming these green plants or a trophic level, which feeds on the green plants. Nitrification is the conversion of these ammonium ions back into nitrate ions by this process;

NH4+→NO2-→NO3-

Denitrification is when nitrates in the soil are converted back into nitrogen gas, which returns to the atmosphere.

Phosphate is mined by humans and is then used as a fertiliser. This increases plant output. When these are released eutrophication occurs (see description above).

Phosphate cycle

A source of phosphorus is vital for all organisms. It is needed to manufacture DNA, ATP and protein. Therefore the more phosphate there is the more productivity occurs. In the above diagram it shows inorganic phosphates being leached from the mountain. Plants then absorb these phosphate compounds. Animals gain their phosphorus by consuming plants or trophic levels that feed on the plants. Inorganic phosphate is lost through excretion. If the plants are harvested the phosphate is also removed from the soil hence the need to replenish these sources. This cycle has no gaseous state.

A few details to be taken into account about this cycle in the investigation are how humans effect the cycle. Phosphate deposits are being mined rapidly, and many of these deposits are on the ocean floor. Inappropriate use of these fertilisers in farming practices has lead to great loses from the farmed land. Phosphate is often the limiting factor in water ecosystems; hence the input of phosphate causes eutrophication.

A combination of these different polluting factors will provide a valid conclusion about the state of pollution in the river.

The Banwell River and the Surrounding area:

(Source: multimap.com)

Location and river direction:

The River Banwell runs parallel with Wick St Lawrence and with Worle. It originates at an area south of Weston Super Mare and ends at its delta at Woodspring leading out to the Severn. From this you can see that the river is both surrounded by one side being housing development and the other agricultural.

The test sites- location and choices for test location

Test site: 1

Reason for location: Evidence of animals possibly being able to enter water source. (See picture below.)

Test Site 1

Test Site: 2

Reason for location: I am able to sample the water, and if there is a input of pollution from site 1 I will be able to confirm that that is the source as in theory the pollutants by the time they reach site 2 should of started to diffuse.

Test site: 3

Reason for location: I can make a comparison to test site 1 and 2. If there are pollutants entering at site 1 we should see a gradual decrease in concentration the further away from the source.

Test site: 4

Reason for location: After preliminary scouting an output was discovered. It looks like it could be draining of water from a local housing estate. The area is built on a marshy area so drainage is vital. (See below)

Test site 4

Test site: 5

Reason for location: Again this is so I can compare concentrations and see if there is an increase between test sites 3, which is before the output and this site where I can see if there is an increase after.

Test site: 6

Reason for location: This location was picked so that if data was present at test site 4 and 5 I could see if the concentrations of pollutants had decreased.

Test site: 7

Reason for location: There is another output, maybe from the local water pump. A temperature difference could affect local ecosystems. (See below)

Test Site 7

Test site: 8

Reason for location: This is the final test site where this will confirm or not confirm whether test site 7 is polluting the river.

Hypothesis

I hypothesize that my investigation will encounter some, but not highly concentrated traces of pollutants in the river Banwell. From previous investigations I theorise that while certain pollutants are not found others will be but in pockets of high concentrations.

At test site one, if animals are present I believe that ammonia will be found from the waste the animals are excreting. In test sites 2 and 3 these levels will decrease, as they will dilate in the water over the time it takes to reach these test sites. At test site 4 there is a pipe, which I believe releases water from the local housing area. This could contain metals, household waste even household chemicals. Sites 5 and 6 are also positioned to prove that is the source of pollution, as they should so that there is a decrease as these pollutants disperse over a distance. Test site 7 is a pipe coming from a local pumping station, which I believe will pump higher temperature water into the water body effecting indicator species and their ecosystems.

Equipment

Method

Methods for specific tests

Ph Test:

Method 1

Using a large beaker place a large sample of water into the beaker.
Also have a beaker with distilled water on hand.
Place electronic monitor into the solution of pH 7, which acts as a buffer and set the equipment.
Now place the monitor into distilled water until needed.
Now use the monitor and place into the test sample, wait for 20 seconds when the pH levels seem to be steady.
Do this for each sample using a different beaker and returning the monitor to the distilled water to keep a fair test.
Record on raw data sheet the information given on the device.

Method 2

Place each sample of water into separate beakers and keep them separate avoiding contamination.
Place a pair of tweezers into distilled water to avoid contamination and wear a pair of gloves to avoid contamination.
When ready with the tweezers and wearing gloves pick up a piece of pH paper and place into the water sample. Hold in place for 20 seconds and remove.
Compare with the chart provided and pick the nearest colour and record the pH given along side.
Record on raw data sheet the information given on the device.

Temperature test:

Method 1

On Site place the thermometer into the water.
Wait 20 seconds and remove.
Record on raw data sheet the information given on the device.

Method 2

On Site place the digital thermometer into the water and turn on once submerged in water.
Wait 20 seconds and press the button hold.
Record on raw data sheet the information given on the device.

Indicator Species:

Method 1

Use the net provided and place down stream.
Disturb the floor using an object into the direction of the net and collect the sediment sample.
Remove the net and place collection into a bag, which is labelled. Repeat until enough is collected to get a good sense of the species living in the river.
Place a bit at a time a selection of the collected sediment into a white tray and search for species.
Any species that are found are removed and placed into a beaker.
Compare the species found to charts and books.
Identify and record on data sheet the species found and the frequency.

Method 2

Remove items/habitats from the bottom of the bed, for example a rock. The species will be caught into the current and directed into your net.
Disturb the floor using an object into the direction of the net and collect the sediment sample.
Remove the net and place collection into a bag, which is labelled. Repeat until enough is collected to get a good sense of the species living in the river.
Place a bit at a time a selection of the collected sediment into a white tray and search for species.
Any species that are found are removed and placed into a beaker.
Compare the species found to charts and books.
Identify and record on data sheet the species found and the frequency.

Nitrate test:

Method 1

Using a strip place into the sample of water and wait 20 seconds.
Remove the strip and if there is a colour change record it as a positive reading. If no colour change is observed record as negative.

Method 2

Use a pipette and collect 10ml of the sample and place into the collection pots provided with the test kit.
Insert the tablet labelled number 1 into the sample and crush the tablet to have effect.
Leave standing for ten minutes.
Using the chart provided compare the colour and record the measurement viewed.

Method 3

Use sample stick place in sample for 2 seconds.
Remove stick and wait one minute.
Now compare to colours indicated on the box within one minute.
Record the mg/l stated on bottle.

Ammonium test:

Method 1

Using a strip place into the sample of water and wait 20 seconds.
Remove the strip and if there is a colour change record it as a positive reading. If no colour change is observed record as negative.

Method 2

Use a pipette and collect 10ml of the sample and place into the collection pots provided with the test kit.
Insert the tablet labelled number 1 into the sample and crush the tablet to have effect.
Then place tablet number 2 into the solution and crush.
Leave standing for ten minutes.
Using the chart provided compare the colour and record the measurement viewed.

Nitrite test:

Method 1

Using a strip place into the sample of water and wait 20 seconds.
Remove the strip and if there is a colour change record it as a positive reading. If no colour change is observed record as negative.

Method 2

Use a pipette and collect 10ml of the sample and place into the collection pots provided with the test kit.
Insert the tablet labelled number 1 into the sample and crush the tablet to have effect.
Then place tablet number 2 into the solution and crush.
Leave standing for ten minutes.
Using the chart provided compare the colour and record the measurement viewed.

Method 3

Use sample stick place in sample for 2 seconds.
Remove stick and wait one minute.
Now compare to colours indicated on the box within one minute.
Record the mg/l stated on bottle.

Phosphate test:

Method 1

Using a strip place into the sample of water and wait 20 seconds.
Remove the strip and if there is a colour change record it as a positive reading. If no colour change is observed record as negative.

Method 2

Use a pipette and collect 10ml of the sample and place into the collection pots provided with the test kit.
Insert the tablet labelled number 1 into the sample and crush the tablet to have effect.
Then place tablet number 2 into the solution and crush.
Leave standing for ten minutes.
Using the chart provided compare the colour and record the measurement viewed.

*Tests will be conducted three times to gain an average.

Preliminary Experiment

I am conducting a primary experiment to compare the methods stated above and come to a conclusion to which is more accurate and will provide me with the best data to come to a conclusion whether the river Banwell is polluted or not. Each test will be conducted under controlled conditions, as the methods state, but only once, as this test is not to prove my hypothesis but to demonstrate the practicality of the methods.

All tests will be conducted in the laboratory, except temperature where an accurate measurement must be taken on site.

*Test site 8 was not used due to conditions on the day, but was deemed not necessary, as this was not a data collection exercise.

See page 21 and 22 for results

Raw Data 21/09/2005 Primary Experiment

Primary Evaluation:

Testing for the pH provided two different results in terms of accuracy. Method one showed a more accurate measurement. The scale was larger and did not depend on my accuracy of sight, which could leave to human error. The primary experiment using the litmus paper showed a constant result of a neutral 7 pH. While using the digital equipment it was found to pick up even the smallest of changes in hydrogen ion concentration. The digital equipment was also easier to use compare to the litmus paper. For this reason I will choose method 1.

Temperature was also tested with two methods, one with an alcohol thermometer and another, which was a digital thermometer. On a practicality point of view, the water was sometimes out of reach so other means were needed to reach the water. The alcohol thermometer was small in reach compared to the digital thermometer where it had a reach that was suitable. Also the measurements from the digital reader were more accurate, and this is my reason for choosing method 2.

The indicators were both measured in the same way but different measures of capture were used. Method 2 was impractical and a safety issue. Climbing into this river, which no safety equipment available would be dangerous so method one was chosen. Method one was found to be also more efficient as the bed was easily disturbed using the net itself.

Nitrate and Nitrite had 3 methods written. Method one was the test using the strip. Even though this test proved time efficient the results that were presented were not accurate enough for myself to come to a conclusion. Instead of receiving an accurate measurement of how much nitrate/nitrate would be in the sample the sticks only could determine whether they were present. Method 2 and method 3 both produced accurate results, but method 2 was more time consuming than method 3. Method 3 was therefore chosen for this reason.

Ammonia was test with a test kit and a strip measurement test. Again as with the other methods the strip has proven to be an unreliable test showing only a negative or a positive result. For a conclusion to occur the data collected will need to be in more depth. This depth must show the different concentrations within different test sites.

Phosphate was tested using the test kit and a test kit used for testing levels for a fish tank. The test kit for fish tanks also was limited in the sense that only a presence reading was available compared to the test kit was in giving readings to 2dp. Even thought the test kit is more time consuming it is necessary to get this data accurately to come to a fair conclusion.