The impact of point source pollution on an urban river, the River Medlock, Greater Manchester A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering 2016 Cecilia Medupin 1 Table of Contents The impact of point source pollution on an urban river, the River Medlock, Greater Manchester ...... 1 A THESIS SUBMITTED TO THE UNIVERSITY OF MANCHESTER FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE ............................................................................................................................................................... 1 FACULTY OF SCIENCE AND ENGINEERING ....................................................................................................... 1 2016 .................................................................................................................................................................. 1 Cecilia Medupin ................................................................................................................................................ 1 Abbreviations ............................................................................................................................................. 5 Words and meanings ................................................................................................................................. 5 Declaration ................................................................................................................................................ 6 Copyright Notice........................................................................................................................................ 6 The Author ................................................................................................................................................ 7 Acknowledgements .................................................................................................................................... 8 Abstract 9 Chapter 1 GENERAL INTRODUCTION ..................................................................................................... 10 1.1 COMBINED SEWER OVERFLOWS (CSOS) .................................................................................................... 12 1.1.1 CSOs and Environmental Regulation ............................................................................................. 14 1.2 PHYSICAL MODIFICATION ......................................................................................................................... 15 1.2.1 Channelisation ............................................................................................................................... 16 1.2.2 Examples of modification to the River Medlock ............................................................................. 17 1.3 RIVER ECOLOGY: IMPACTS OF PRECIPITATION .......................................................................................... 19 1.4 WATER POLLUTION .................................................................................................................................. 21 1.4.1 Physical and chemical characteristics of rivers................................................................................. 21 1.4.2 Biological characteristics of rivers: benthic macroinvertebrates .................................................. 22 1.5 WATER QUALITY IN THE RIVER MEDLOCK ....................................................................................... 25 1.5.1 Why study the impact of combined sewer overflows in the River Medlock? ..................................... 27 1.6 AIMS, OBJECTIVES AND HYPOTHESES ....................................................................................................... 28 1.6.1 Aims ............................................................................................................................................... 28 1.6.2 Objectives ................................................................................................................................... 28 1.6.3 Hypotheses ................................................................................................................................. 29 1.7 OVERVIEW AND STRUCTURE OF THE EXPERIMENTAL RESEARCH CHAPTERS ........................................... 29 Chapter 2 GENERAL METHODOLOGY AND APPROACH .................................................................. 33 2.1 SITE DESCRIPTION OF RIVER MEDLOCK .................................................................................................... 33 2.2 SAMPLING REGIME .................................................................................................................................... 34 2.3 FIELD AND LABORATORY ANALYSIS .......................................................................................................... 38 2.3.1 Benthic invertebrate sampling and analysis................................................................................... 43 2.3.1 Benthic invertebrate sampling ....................................................................................................... 43 2.3.2 Spatial and Statistical analysis ...................................................................................................... 44 2.4 WATER QUALITY STANDARDS .................................................................................................................. 46 2.4.1 WFD Standards .............................................................................................................................. 46 2.4.2 Classification of Invertebrates..................................................................................................... 47 2 Chapter 3 LONG-TERM WATER QUALITY OF A HEAVILY URBANISED RIVER: A CASE STUDY OF RIVER MEDLOCK, GREATER MANCHESTER, UK .......................................................... 51 ABSTRACT ....................................................................................................................................................... 51 3.1 INTRODUCTION ......................................................................................................................................... 52 3.2 METHODOLOGY AND APPROACH ............................................................................................................. 53 3.2.1 Study area ....................................................................................................................................... 53 3.2.2 Study sites and data collection......................................................................................................... 55 3.2.3 Water quality and ecological parameters ......................................................................................... 56 3.3 RESULTS .................................................................................................................................................... 58 3.3.1 Physical and chemical variables ....................................................................................................... 58 3.3.2 Benthic macroinvertebrates ............................................................................................................. 67 3.4 SUMMARY ................................................................................................................................................. 69 3.5 DISCUSSION ............................................................................................................................................... 70 3.6. CONCLUSION ........................................................................................................................................... 72 ACKNOWLEDGEMENTS ................................................................................................................................... 73 3.7 REFERENCES .............................................................................................................................................. 73 Chapter 4 SOURCES OF PO4-P IN AN URBAN RIVER: COMBINED SEWER OVERFLOWS VS WASTEWATER TREATMENT WORKS .................................................................................................... 78 ABSTRACT ....................................................................................................................................................... 78 4.1. INTRODUCTION ........................................................................................................................................ 78 Study area: The River Medlock ................................................................................................................ 80 4.2. METHODS ................................................................................................................................................. 81 4.2.1 Low resolution long term EA data ................................................................................................... 81 4.2.2 Fortnightly spatial data .............................................................................................................. 84 4.2.3 Data collection ........................................................................................................................... 85 4.2.4 High resolution temporal dynamics ............................................................................................... 86 4.2.5 Data analysis..................................................................................................................................