Figure 4

(Wei) Schematic diagram of the pot for gas sampling. (1) silicon tubes, (2) stainless steel tube, (3) three-way stopcock, (4) gas sampling static chamber, (5) water. A layer was 0–5 cm depth layer; B layer was 5–10 cm depth layer; C layer was 10–15 cm depth layer; and D layer was 15–20 cm depth layer.