TABLE 4.

Percentage of N₂O related to total N gases evolved (N₂O + N₂) for the nitrate concentration assayed

Nitrate concn (μM)	% N2O in samples from:
	Ravenseat	Ivelet Bridge			Catterick Bridge	Thornton Manor	Naburn Weir	R. Wiske
		April	June	August				April	June	August
17.8	21	6	7.5	58		4.3
37.7	38	2	3.4	21	1.0	3.0	<0.0
53.6	19	3	6.4	25
71.4					6.0	5.1	6.0
107.1	2.3					5.3
142.8		4	12	15	17	10	6.4
214.3					15	14	3.2
357.1					17		11	50	68	18
714.3								65	80	20
1,428								71	62	22
2,857								76	73	29
5,714								68	73	33
11,429								72	75	43