This book is about the chemical nature of water, clean or dirty, and also what this does to the plants which might – or do – grow in it. There is much chemical variability, so can streams be classed on their nutrients? Yes – by using reference plant communities. The habitat chooses the plants to grow in it from amongst those whose seeds are present. The majestic Thames, the rushing mighty Tweed or (Aberdeen) Dee, the rippling peaty stream or burn, the quiet meandering brook – rivers all over the place. There is an easy but false association in all our minds that clear water is clean. This is not so. Even in a remote place, who can be sure a dead sheep does not lurk behind that far corner? Run-off from roads contains many "nasties". After a week or so with no rain, when it does rain, run-off water is very dark – even near-black – containing rubber, bitumen, other tyre derivatives, heavy metals, petrochemicals and other hydrocarbons from exhaust fumes – a toxic cocktail indeed. But now everyone is so used to it (and it looks just like soil) that hardly any one thinks about it. Aquifer water may be, as in Bath in Somerset, ten thousand years old, or it may be very recent, more accurately termed "flush-water" or "storm-water", running straight to the stream only a little below ground level. Either way the composition of stream water reflects that of the material it has flowed through.
Introduction 1
Where water comes from 12
What is in Water? 13
Rock type, soil type and nutrient status 15
Downstream eutrophication 18
What pollution does 19
River Maps (A different way of understanding rivers) 26
A Case-in-Point 36
Substrate (soil) 44
Research site example: Temple Bridge (TL 7585 7287), River Lark, Suffolk 51
Afterword 59
Tables 1 and 2 59–60
Citations 61
List of Stand-alone Titles in the River Friend Series 62
About the Authors 62