FIG. 1.

Methanogenesis from [¹²C]acetate and [¹³C]acetate. F1, microcosm with soil from eutrophic site; F4, microcosm with soil from eutrophic site; U3, microcosm with soil from oligotrophic site. Analyses were conducted in duplicate, and the bars indicate mean values after conversion to a gram (dry weight)-of-soil basis; the error bars indicate ±1 standard deviation. After week 4, acetate was added to in all microcosms a second time.