Magmatic Signature in Submarine Hydrothermal Fluids Vented Offshore Ventotene and Zannone Islands (Pontine Archipelago, Central Italy)

Table 3

Chemical composition of the dissolved (D) and bubbling gases (B).

Sample ID	Site	Depth (m)	Type	Sampling method	He	H2	O2	N2	CO	CH4	CO2
1	Z1	20	D	Niskin	bdl	bdl	3.53	9.24			0.46
2	Z1	50	D	Niskin	bdl	bdl	3.36	9.66			0.48
3	Z1	80	D	Niskin	bdl		3.79	9.40			0.46
4	Z1	100	D	Niskin	bdl	bdl	3.79	9.82			0.64
5	Z1	134	D	Niskin	bdl		3.56	6.66			0.53
6	Z2	50	D	Niskin	bdl	bdl	3.74	9.56			0.42
7	Z2	80	D	Niskin	bdl	bdl	3.63	9.37			0.45
8	Z2	100	D	Niskin	bdl	bdl	4.38	9.49	bdl		0.42
9	Z2	127	D	Niskin	bdl	bdl	3.55	9.81			0.64
10	ZDA	50	D	Niskin	bdl		4.16	8.06	bdl		0.41
11	ZDA	80	D	Niskin	bdl		4.43	8.93	bdl		0.43
12	ZDA	100	D	Niskin	bdl	bdl	2.61	6.50			0.41
13	ZDA	120	D	Niskin	bdl		4.62	9.10			0.78
14	ZDA	147	D	Niskin	bdl	bdl	4.83	9.84			0.73
	ASSW				4.80E‐05		4.80	9.60		1.0E‐6	0.24
17	Z2	127	B	ROV			0.016	3.410		0.985	94.62
17 Rec	Z2	127	B	ROV			—	3.353		0.986	94.68
18	Z2	125	B	ROV			15.26	77.57		9	0.145
18 Rec	Z2	125	B	ROV			—	69.31		29	0.475
19	VEN	80	B	Two-way glass bottle		bdl	0.18	1.37		0.163	98.17
11-BT1	ZGP	129	B	ROV							50.94
12-BT1	ZGP	129	B	ROV							55.08
13-BT4	ZGP	127	B	ROV		bdl					54.22

Dissolved gas concentrations are given in ccSTP per liter of seawater. Bubbling gas composition is expressed in vol%. Values for ASSW (air-saturated seawaters) are reported as reference. bdl = below detection limits (detection limits for He, H₂, and CO in the ccSTP; detection limits for He and H₂ in the ). Rec = recalculated concentrations; see text for details. Reactive gases and labels after Martorelli et al. [27].