Loch Fad trout farm Isle of Bute

Loch Fad is a freshwater loch, 2.4 km long and 0.3 km wide, situated just inland from the seaside resort of Rothesay on the Isle of Bute, Scotland. It has been used for trout farming since 1976 and, at one time, was the largest trout farm in Europe, producing over 300 tonnes of fish each year. The combination of waste feed and faeces from the large number of fish confined in this small loch has had a marked effect on the water quality. The sediment is very enriched with organic matter and this...

A case history of a eutrophic lake

Strathclyde Park Loch is situated between Hamilton and Motherwell in South Lanarkshire, Scotland. It is an artificial loch and was created from an area of derelict and subsided ground which was a coal mine at one time. The original pond in the subsided ground was extended and contoured to make an attractive amenity lake and became the central feature of Strathclyde Country Park. The loch is very popular in the summer months with anglers, dinghy sailors, canoeists and wind surfers. Unfortunately...

Introduction To Environmental Pollution Global Warming

Water pollution, global warming, poor air quality, acid rain, holes in the ozone layer, etc. - these are issues that are featured regularly in our newspapers, news reports and TV programmes. Ever since we received the first pictures of the earth from outer space, we have become much more aware of how small our world is in the cosmos and how vulnerable it is to destruction by human activities. Concern about the state of our environment is now one of the main issues in people's minds, even higher...

Pesticides

There are 725 pesticides listed in the Pesticides Manual, and of these 450 are approved for use in the UK by the Ministry of Agriculture, Fisheries and Food (MAFF). They are used to control weeds, insects and fungi on crops, animals and fish. In 1993, the amounts of different pesticides used were as follows 10,700 tonnes of herbicides 6,850 tonnes of fungicides 2,670 tonnes of growth regulators 1,140 tonnes of insecticides 635 tonnes of other pesticides.3 Pesticides are usually popularly...

Dissolved oxygen test

The measurement of dissolved oxygen (DO) is a very important test for assessing water quality because oxygen is fundamental to life in water. If the oxygen concentration is reduced by polluting substances such as organic matter or reducing agents (for example, sulphide or ferrous ions), then fish and insect life can die or move to cleaner water. The amount of oxygen present in the water is limited by its solubility and this is affected by the water temperature. At normal winter temperatures of...

Global warming

Carbon Dioxide Pollution Facts

In recent years, the temperature of the earth's atmosphere has been warmer than at any time since measurements were first taken in 1860. Overall, it is estimated that the average overall temperature increase is between 0.3 and 0.6 C. In April 1997, it was announced that satellite measurements of the northern hemisphere of the globe showed that spring was arriving seven days earlier than ten years before and that the leaf fall of autumn was taking place four days later. These were just two...

Gerry Best

Former Head of Chemistry Scottish Environment Protection Agency First published 1999 by LIVERPOOL UNIVERSITY PRESS Liverpool L69 3BX The right of Gerry Best to be identified as the author of this work has been asserted by him in accordance with the Copyright, Design and Patents Act, 1988 All rights reserved. No part of this volume may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without...

Acid rain

Increase Pollution After 1950

Acidification of rain and snow may seem to be a recent environmental pollution problem. However, the phenomenon has been known for over a century since it was first noticed that buildings, trees and plants were damaged if they were downwind of chemical factories discharging acid fumes. The damage was mostly confined to periods of rainfall because of the removal of air-borne pollutants by rain droplets. At that time, the problem was a local one, confined to an area close to the factories. This...

PH value

The pH value of a water sample is a measure of whether it is acidic or alkaline. The pH is defined as 'the logarithm of the reciprical of the hydrogen ion concentration expressed as moles litre'. It has a scale of 0-14, where a value of 7 is neutral. Values less than 7 are acidic whilst those above 7 are alkaline. Pure water has a pH of about 5.6 because carbon dioxide dissolves in it to form a weak solution of carbonic acid. Most river waters are about neutral but, as described below under...

Biological effects of air pollution

Lichens as a measure of air pollution We learned in Chapter 11 about the value of indicator species for monitoring pollution. Just as invertebrate organisms are an important group of indicator organisms for measuring water quality, a useful indicator for air quality is the variety of lichens that are present. Lichens are a group of very slow-growing organisms that you find as encrustations on stonework or as a flaky growth on tree barks. They are unusual organisms because they consist of fungal...

Trout farming

The artificial rearing of trout has been taking place in the UK and elsewhere for much longer than salmon farming and it is much more widespread. Trout rearing not only produces fish for fishmongers and supermarkets, but also maintains or improves the fish stocks in rivers for anglers. As with salmon farming, the eggs are stripped from a mature female, fertilized by milt from a male and then hatched in a hatchery. After spending their juvenile stages in large tanks through which clean river...

Percolating filter sewage treatment works

Percolating Filter

For many years, the percolating filter system of sewage treatment was the most commonly used although now it is steadily being replaced by the activated sludge process . The incoming sewage, whether it be from a combined or separate sewerage system, is first passed through a 'gate' of parallel iron bars coarse screen which removes the large objects that find their way into the sewers, such as pieces of wood, bottles or cardboard boxes. The grit and stones from roads etc. are allowed to settle...

Tertiary treatment

Tertiary Aquatic Life

The sewage treatment processes described above can purify sewage so that at least 90 per cent of the organic matter is biodegraded and the concentration of nutrients is substantially reduced. The effluent can be discharged into most rivers without any adverse effect on the receiving water quality. There are some rivers though that drain into lakes, and others may be shallow and slow flowing. In these cases, the nutrients present in the purified sewage effluent may encourage the growth of water...

Effluents from poorly operated works

Sewage Eutrophication Downstream

Although there has been a great improvement in the treatment of sewage in the last 10-15 years because of investment in new plant and equipment, there are still some sewage works where the wastewater is not adequately treated. This may be because they are old and the equipment is inefficient, or they may be overloaded, i.e. they are receiving more sewage than they were designed to purify. In these situations, the effluent that enters the receiving water still contains many of the substances...

Investigating acid rain

Acid rain affects the water quality of streams only if there is insufficient neutralizing capacity in the soils and rocks in the catchment. The streams most likely to be affected will be those where the catchment geology is of hard igneous rocks such as granite and these can be checked beforehand by looking at a geological map of the country. It is possible though to check the acidity of rainwater and to see the influence of wind direction on the pH. To carry out such an investigation, a...

Chloride

The amount of chloride in a water sample can give an indication of the amount of sewage effluent in river water. As shown in Tables 3 and 4 in Chapter 2, sewage effluent contains about 50-100 mg l of chloride ion. This originates largely from human urine which typically has 1 per cent chloride ion present. Clean river water on the other hand usually has lt 10 mg l chloride so the measurement of this ion can give an indication of the amount of dilution that an effluent receives in a river. A...

Freshwater eutrophication

Freshwater Pollution

Algal blooms have increased markedly in many freshwater lakes and ponds they also occur in very-slow moving water, in canals and rivers such as the Norfolk Broads. The problem can be attributed to the increasing amount of phosphorus entering the affected waters. We have already seen that phosphates are a major component in modern detergents, but they are also present in human sewage, animal excreta, industrial effluents and agricultural fertilizers. In most freshwater lakes and rivers,...

Eutrophication

The word 'eutrophication' comes from the Greek eutrophos which means well nourished. It is applied to water that is enriched with nutrients, mainly phosphorus and nitrogen compounds, which encourage the growth of abnormally large number of algae and aquatic plants. The extent of nutrient enrichment of water its 'trophic' state is described by different prefixes, graded from ultra-oligotrophic water, which is very deficient in nutrients, through oligotrophic, mesotrophic and eutrophic, to...

Dalquharran minewater pollution a case study

The Dalquharran mine is situated near the village of Dailly in South Ayrshire, Scotland. Coal has been extracted in this area since the fourteenth century, initially from the surface because the layers of coal emerged from the hillside. As time went by, successively deeper layers were mined until there was a honeycomb of workings throughout the area. In the 1950s, the then National Coal Board NCB established the Dalquharran Mine and coal was extracted from six different layers at increasingly...

Sewage treatment in East Kilbride Scotland a case study

East Kilbride is located about 15 km south-east of Glasgow in an area of high ground. It is one of Scotland's 'new towns' and was built to take the overspill of Glasgow's population. Originally it was a small village of a few hundred people, but it expanded very rapidly from 1944. Now it is one of Scotland's largest towns with a population of about 85,000 people. As it was built on a hill, the drainage from the town flows in two directions from the high point. In the west side of the town, the...