Symbols
The following symbols have been used throughout the publication
Symbol	Meaning	Symbol	Meaning
..	not available	l	litre
-	nil or negligible	Ml	megalitre
	(less than 1/2 the final digit shown)	Ml/d	megalitre per day
ns	not sampled	l/hd/d	litres per head per day
nd	not detected	mg/l	milligrams per litre
na	not analysed	mg/lO	milligrams per litre of oxygen
		mg/lN	milligrams per litre of nitrogen
<	less than	Gw	Giga watt
>	greater than	Gwh	Giga watt hour
	less than or equal to	ppb	parts per billion
	greater than or equal to	pH	measure of acidity/alkalinity
	(percentage hydrogen ions)
%	per cent	Keq H+	kilo equivalent of hydrogen
		GMT	Greenwich Mean Time
(000)	thousands	0C	degrees celsius
£(000)	thousand pounds
£m	million pounds
mm	millimetre	bcm	billion cubic metres
m	metre	bcf	billion cubic feet
m2	square metres
m3	cubic metre	O	oxygen
m3/sec	cubic metres per second	N	nitrogen
		NO2	nitrogen dioxide
km	kilometre	SO2	sulphur dioxide
km2 or sqkm	square kilometre
ha	hectare	mSv	millisievert
		Bqm-3	bequerels per cubic metre
mg	milligram
g	gram
kg	kilogram
µgm-3	microgrammes per cubic metre
ngm-3	nanogrammes per cubic metre