The main causes of pollution in rivers are: River Pollution Pollution is an addition to the environment with consequent adverse effects to that environment The main causes of pollution in rivers are: Agricultural Pollution - the effects of excess fertilisers and pesticides and farm slurry Industrial Pollution - inorganic and organic waste that directly contaminates rivers Dumps - spoil heaps and refuse tips release harmful chemicals that may leach into rivers Domestic Pollution - treated effluent from sewage works is discharged into many of our rivers Thermal Pollution - warm waste water from cooling towers and other industrial processes raises the temperature of the water and lowers oxygen solubility Atmospheric Pollution - pollution of the atmosphere with nitrogen and sulphur oxides produces acid rain that modifies the pH of rivers which, in certain conditions, has lethal effects on the river organisms Oil Pollution - can result from river traffic

a hillside from its source is crystal clear and unpolluted Water tumbling down a hillside from its source is crystal clear and unpolluted As rivers flow through towns, agricultural land and industrial areas, various pollutants enter the water body and influence the distribution and composition of aquatic life As pollution loads increase, species diversity declines and the abundance of pollution-tolerant species increases

This river is becoming increasingly polluted as organic and inorganic materials ‘run off’ from the surrounding agricultural land

Acid Rain Industrial Waste Fertiliser run off Farmyard Waste Thermal Pollution from cooling towers Oil Pollution Effluent from sewage works

Methods for detecting and measuring river pollution include: Sampling the populations of river invertebrates; river invertebrates are indicator organisms that serve as indicators of the state of the river by their presence or absence Chemical testing to determine the amount of dissolved oxygen in the water Chemical testing for determining levels of specific chemicals such as ammonia, nitrates and phosphates Physical testing such as measurements of the turbidity of the water and the quantity of suspended solids The amount of dissolved oxygen in the water is a major determinant for the presence and abundance of invertebrates in river ecosystems The discharge of organic material into rivers lowers the oxygen availability and sensitive organisms are unable to survive

Plecoptera Stonefly nymphs Ephemeroptera Mayfly nymphs These invertebrates are intolerant of pollution and low oxygen concentrations; they feed on detritus and other invertebrates and have flattened bodies and claws for crawling over the surface of stones Mayfly and stonefly nymphs are clean water fauna and indicators of well-oxygenated unpolluted water Plecoptera Stonefly nymphs Ephemeroptera Mayfly nymphs

Trichoptera Caddis-fly larva Gammarus pulex Freshwater Shrimp These invertebrates are tolerant of mild pollution and reappear in rivers polluted with organic material as oxygen levels return to normal

Asellus aquaticus water hog-louse Hirudinea Freshwater Leech Limnaea Freshwater Snail These invertebrates are tolerant of moderate pollution and reappear downstream from the polluting source

Bloodworm – midge larva Annelida Tubificid worms in cases Eristalis teneax Larva of bee-fly (rat-tailed maggot) Chironomus thummi Bloodworm – midge larva These invertebrates are tolerant of high pollution and are adapted to survive the low oxygen levels in polluted water Tubificid and Chironomus larvae possess a form of haemoglobin in their blood that exhibits a high affinity for oxygen Rat-tailed maggots possess a breathing tube at their rear end which penetrates the river surface enabling these organisms to obtain oxygen from the atmosphere

intolerant of pollution Clean water organisms intolerant of pollution

Organisms tolerant of mild pollution that reappear as rivers recover from organic pollution

Organisms tolerant of mild pollution that reappear as rivers recover from organic pollution

The bright-red colour of Chironomus is due to the presence of haemoglobin, adapting this organism for survival in conditions of low oxygen concentration

Fresh water fauna return The Effect of Organic Pollution on River Fauna Clean water fauna Fauna tolerant of high pollution Fauna tolerant of moderate pollution Fauna tolerant of slight pollution Fresh water fauna return

http://www.youtube.com/watch?v=UGqZsSuG7ao http://www.youtube.com/watch?v=h-zncNp-X-E (song)

The Effect of Raw Sewage on the Chemical Composition of a River Ecosystem Ammonium ions (NH4+) Dissolved oxygen Biological Oxygen Demand (BOD) Nitrates (NO3) Suspended solids Explain the graph

the river increases the quantity of suspended solids, and light Entry of sewage into the river increases the quantity of suspended solids, and light availability to oxygen- producing aquatic plants is reduced Ammonium ions (NH4+) Dissolved oxygen Biochemical Oxygen Demand (BOD) Nitrates (NO3) Nitrates stimulate the growth of algae Suspended solids Organic material in the discharge provides an abundant source of food for bacteria and other decomposers resulting in a rapid growth of their populations The oxygen level falls dramatically as it is utilised by decomposers for respiration and the BOD is high Organic material is gradually broken down and the river recovers from the polluting effects as it flows downstream The Biochemical Oxygen Demand reflects the demand for oxygen by the decomposers; it is a measure of the dissolved oxygen taken up by microorganisms in decaying the available organic matter Ammonium ions are released as decomposers oxidise the organic matter and these are rapidly oxidised to nitrates by nitrifying bacteria

Species diversity decreases with high pollution and gradually The increased nitrate levels, resulting from microbial decomposition of organic material, stimulates the growth of algae River invertebrates are indicators of the degree of pollution in the river Species diversity decreases with high pollution and gradually increases again as the river recovers

Pollution from Nitrogen Fertilisers Nitrogen based fertilisers have many benefits such as increased productivity in plants/crops but they have had detrimental effects: Reduced species diversity – grass/nettles prefer nitrogen rich soil, so they out compete other species e.g. silage fields Leaching – Rain water removes nitrates from soil and then into streams/rivers. This can be harmful if water is a source of drinking water. High nitrate levels can lead to inefficient oxygen transport in babies and stomach cancer. Eutrophication – Fertilisers leaching into watercourses.

Eutrophication Eutrophication is a natural process but can be made worse by over use of fertilisers (usually inorganic). In most lakes and rivers, nitrates exist in low amounts and are limiting factor for plant and algal growth Over use of fertiliser on agricultural land near watercourses can lead to leaching of nitrates into lakes and rivers, leading to nitrate levels increasing. Algal and plant growth increases exponentially. Algal growth is mainly on surface and upper layers – leads to ‘algal bloom’ This dense layer absorbs most sunlight and prevents it from penetrating lower layers. Light is now limiting factor for lower plant life – starts to die. Dead plants and algae provide food for saprobiotic bacteria, so their population number grows exponentially. These decomposers require more oxygen for respiration, so the concentration of oxygen decreases but nitrates increase due to decomposition. Oxygen levels are now limiting factor for population of aerobic organisms (fish, invertebrates) and these die off. Less competition for anaerobic organisms. These continue to grow in numbers. Dead material is further broken down releasing more nitrates and toxic waste such as Hydrogen Sulphide – Water becomes putrid.

Complete troubled waters activity

Biotic Data Biotic data was used to calculate the Simpson’s Diversity Index and the Trent Biotic Index for each site The Biotic Index is given as a Roman Numeral which describes the quality of the stream, from 0 for very polluted, to X for very clean The index is dependent upon the presence or absence of certain indicator species, as well as the composition of the community Instructions for determining the index are provided in the workbook

(After F. Woodiwiss, Trent River Authority Trent Biotic index (After F. Woodiwiss, Trent River Authority