Table 1 Methane concentrations, isotopic values and metadata from aqueous samples collected in the Sólheimajökull forefield between 2013 to 2017. Values presented are mean compositions collected from different field locations pre and post emergence of subglacial waters. The range of values is given in parentheses with sample number presented as (n=).
From: Direct isotopic evidence of biogenic methane production and efflux from beneath a temperate glacier
Sampling location | Pre-upwelling (up until DOY 128) | Early post upwelling (immediately post DOY 128) | Late post upwelling (From DOY 185) | ||||||
|---|---|---|---|---|---|---|---|---|---|
CH4 (ppm) | δ13Cch4 | δDch4 | CH4 (ppm) | δ13Cch4 | δDch4 | CH4 (ppm) | δ13Cch4 | δDch4 | |
2013 | |||||||||
Supraglacial | 0.14 (n = 2) (0.12 to 0.15) | n.d | n.d | ||||||
Meltwater outlet, Jökulsá á Sólheimasandi | 15.2 (n = 8) (5.95 to 20.78) | −56.4 (n = 4) (−57.12 to −56.03) | n.d | ||||||
Proglacial lake East | 8.17 (n = 9) (0.80 to 18.14) | −53.8 (n = 9) (−57.13 to −47.58) | n.d | ||||||
Proglacial lake West | 12.2 (n = 2) (11.59 to 12.75) | −56.6 (n = 2) (−56.76 to −56.45) | n.d | ||||||
Catchment outlet (Bridge) | 4.2 (n = 2) (3.88 to 4.62) | −49.5 (n = 2) (−51.58 to −47.35) | n.d | ||||||
Subglacial upwelling | n.d | n.d | n.d | ||||||
Streams of external catchment origin | 0.17 (n = 4) (0.12 to 0.27) | n.d | n.d | ||||||
2014 | |||||||||
Supraglacial | 0.33 (n = 2) (0.27 to 0.40) | n.d | n.d | 0.27 (n = 1) | n.d | n.d | |||
Meltwater outlet, Jökulsá á Sólheimasandi | 0.65 (n = 7) (0.46 to 0.78) | −22.5 (n = 7) (−27.9 to −17.93) | +22.9 (n = 1) | 1.23 (n = 8) (0.47 to 1.95) | −39.6 (n = 6) (−46.38 to −32.27) | −166.9 (n = 4) (−218.3 to −95.9) | 7.51 (n = 2) (3.77 to 6.57) | −55.98 (n = 2) (−55.28 to −56.68) | n.d |
Proglacial lake East | 1.05 (n = 17) (0.36 to 3.21) | −27.8 (n = 8) (−36.98 to −15.91) | −96 (n = 4) (−134.2 to −7.2) | 1.4 (n = 6) (0.28 to 3.82) | −42.9 (n = 6) (−47.84 to −35.82) | −174.1 (n = 2) (−246.4 to −101.7) | |||
Proglacial lake West | 1.91 (n = 3) (1.46 to 2.37) | −25.3 (n = 1) | −59.2 (n = 1) | 2.86 (n = 4) (1.13 to 4.99) | −41.5 (n = 3) (−51.61 to −23.17) | −189.1 (n = 3) (−267.2 to −39.8) | |||
Catchment outlet (Bridge) | 0.32 (n = 3) (0.32 to 0.33) | −34.2 (n = 1) | n.d | 1.74 (n = 3) (0.36 to 3.11) | −37.3 (n = 3) (−40.4 to −34.57) | −141.2 (n = 3) (−174.1 to −86.6) | |||
Subglacial upwelling | n.d | n.d | n.d | 17.57 (n = 6) (11.71 to 21.73) | −59.6 (n = 6) (−60.22 to −58.56) | −323.7 (n = 4) (−324.3 to −322.6) | |||
Streams of external catchment origin | 0.26 (n = 2) (0.26 to 0.27) | n.d | n.d | 0.28 (n = 4) (0.26 to 0.30) | −44.9 (n = 4) (−46.25 to −42.85) | −108.8 (n = 2) (−112.6 to −104.9) | |||
2017 | |||||||||
Supraglacial | |||||||||
Meltwater outlet, Jökulsá á Sólheimasandi | 10.87 (n = 3) (7.66 to 12.75) | n.d | n.d | ||||||
Proglacial lake East | 4.12 (n = 7) (0.14 to 7.46) | n.d | n.d | ||||||
Proglacial lake West | |||||||||
Catchment outlet (Bridge) | 0.25 (n = 1) | n.d | n.d | ||||||
Subglacial upwelling | |||||||||
Streams of external catchment origin | |||||||||
