Extended Data Fig. 4: DOC aromaticity and pH influence microbial respiration across peatland streams globally.
From: Canal networks regulate aquatic losses of carbon from degraded tropical peatlands
(a) The percentages of DOC oxidized to CO2 during microbial incubations per day were significantly lower in Southeast Asian drainage canals (green) compared to peatland streams or canals at other latitudes (white; p = 0.0003 from a two-tailed paired t-test, n = 20 and 38, respectively; Extended Data Table 2). These differences in microbial DOC lability could only be attributed to the (b) significantly lower water pH (p < 0.0001 from a two-tailed paired t-test, n = 19 and 11, respectively; Extended Data Table 2) and (c) the significantly higher aromaticity of Southeast Asian peat DOC, as measured by the specific ultraviolet absorbance at 254 nm (SUVA254; p < 0.0001 from a two-tailed paired t-test, n = 20 and 38, respectively; Extended Data Table 2). Given that the capacity for microbes to degrade and respire aromatic-containing DOC compounds depends strongly on pH39,40,41, DOC aromaticity and pH are likely major controls on the magnitude of respiration rates. Box plots in (a-c) show the median and interquartile range, with x showing the mean and whiskers showing the upper and lower limits (see Methods).
