摘要：Conversion of wetlands by drainage for agriculture or other anthropogenic
activities could have a negative or positive feedback to global warming (GWF).
We suggest that a major predictor of the GWF is salinity of the wetland soil (a
proxy for available sulfate), a factor often ignored in other studies. We assess
the radiative balance of two northern salt marshes with average soil salinities > 20 ppt, but with high (macro-) and low (micro-) tidal amplitudes. The flux
of greenhouse gases from soils at the end of the growing season averaged
485 ± 253 mg m − 2 h − 1,
13 ± 30 µg m − 2 h − 1, and
19 ± 58 µg m − 2 h − 1 in the microtidal
marsh and 398 ± 201 mg m − 2 h − 1, 2 ± 26 µg m − 2 h − 1, and
35 ± 77 µg m − 2 h − 1 in the macrotidal
marsh for CO2, N2O,
and CH4,
respectively. High rates of C sequestration mean that loss of these marshes would have a radiative balance
of − 981 CO2_eq. m − 2 yr − 1 in the
microtidal and − 567 CO2_eq. m − 2 yr − 1 in the macrotidal marsh.
