Table 1.

Sediment properties during the summer cruises in August 2019

Sample ID	Longitude	Latitude	Sand (%)	Silt (%)	Clay (%)	Total nitrogen (%)	Total nitrogen (µg/g)	Total carbon (%)	Total carbon (µg/g)	δ15N (‰)	C/N
Lena delta
CAC19-Lena 1	126.69564	72.39938	99.7	0.2	0.1	0.01	0.06	0.1	1.1	n.d	18.7
CAC19-Lena 2	126.92899	72.53734	99.6	0.3	0.1	0.01	0.08	0.2	2.2	n.d	27.1
CAC19-Lena 3	127.41932	72.62705	99.6	0.3	0.1	0.01	0.06	0.1	0.8	n.d	13.8
CAC19-Lena 4	127.95918	72.63351	99.5	0.4	0.0	0.01	0.06	0.1	1.1	n.d	18.5
CAC19-Lena 5	128.24466	72.56380	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d
CAC19-Lena 6	128.51548	72.52111	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d
CAC19-Lena 7	128.69504	72.46133	97.8	1.0	1.2	0.01	0.07	0.1	0.8	n.d	11.3
CAC19-Lena 7/8	128.84105	72.45303	99.0	0.4	0.6	0.00	0.04	0.1	1.1	n.d	27.3
CAC19-Lena 8	128.97076	72.47704	98.4	0.8	0.8	0.01	0.07	0.1	1.1	n.d	16.1
CAC19-Lena 8/9	129.09922	72.50168	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d	n.d
CAC19-Lena 9	129.24841	72.50904	98.3	0.8	0.9	0.01	0.06	0.1	0.6	n.d	10.0
Laptev sea
CAC19-S-04	130.12630	72.53012	1.7	83.2	15.0	0.1	1.4	2.3	22.5	3.0	15.7
CAC19-S-05	130.43350	72.53983	10.1	67.5	22.4	0.2	1.6	2.3	23.4	3.3	14.4
CAC19-S-06	130.72248	72.54118	2.9	68.7	28.4	0.2	1.6	2.3	22.9	3.1	14.6
CAC19-S-07	131.01836	72.55056	2.3	66.1	31.6	0.2	1.6	2.2	22.1	3.2	13.9
CAC19-S-08	131.31468	72.55446	5.1	55.4	39.5	0.2	2.0	2.7	26.5	3.6	13.1
CAC19-S-09	131.60606	72.55886	0.6	56.7	42.8	0.2	2.2	2.8	28.0	3.7	12.8
CAC19-S-10	131.91480	72.55320	2.7	58.6	38.7	0.2	1.8	2.2	22.0	3.6	12.0

n.d. not determined. CN ratio of TN and TC