Massive peatland carbon banks vulnerable to rising temperatures.

Peatlands contain one-third of the world's soil carbon (C). If destabilized, decomposition of this vast C bank could accelerate climate warming; however, the likelihood of this outcome remains unknown. Here, we examine peatland C stability through five years of whole-ecosystem warming and two years of elevated atmospheric carbon dioxide concentrations (eCO2). Warming exponentially increased methane (CH4) emissions and enhanced CH4 production rates throughout the entire soil profile; although surface CH4 production rates remain much greater than those at depth. Additionally, older deeper C sources played a larger role in decomposition following prolonged warming. Most troubling, decreases in CO2:CH4 ratios in gas production, porewater concentrations, and emissions, indicate that the peatland is becoming more methanogenic with warming. We observed limited evidence of eCO2 effects. Our results suggest that ecosystem responses are largely driven by surface peat, but that the vast C bank at depth in peatlands is responsive to prolonged warming.

Stability of peatland carbon to rising temperatures.

Peatlands contain one-third of soil carbon (C), mostly buried in deep, saturated anoxic zones (catotelm). The response of catotelm C to climate forcing is uncertain, because prior experiments have focused on surface warming. We show that deep peat heating of a 2 m-thick peat column results in an exponential increase in CH4 emissions. However, this response is due solely to surface processes and not degradation of catotelm peat. Incubations show that only the top 20-30 cm of peat from experimental plots have higher CH4 production rates at elevated temperatures. Radiocarbon analyses demonstrate that CH4 and CO2 are produced primarily from decomposition of surface-derived modern photosynthate, not catotelm C. There are no differences in microbial abundances, dissolved organic matter concentrations or degradative enzyme activities among treatments. These results suggest that although surface peat will respond to increasing temperature, the large reservoir of catotelm C is stable under current anoxic conditions.

Drugs derived from cannabinoids. 1. Nitrogen analogs, benzopyranopyridines and benzopyranopyrroles.

Various nitrogen analogs of delta6a,10a-tetrahydrocannabinol were synthesized by a general procedure described in an earlier communication. Minimum effective doses (MED50's) and lethal doses (LD50's) were determined by a modified Irwin mouse screen after iv administration of compounds in PEG 200. The most potent compounds were the propargyl (5t), allyl (5m), and chloroallyl (5o-q) derivatives. Overt behavioral effects (CNS depression, static ataxia, and hypersensitivity) of 5t and Roger Adams' carbocyclic analog (III) were found to be similar in the mouse, cat, dog, and monkey. Dichloroisoproterenol prevented and reversed many of the depressant effects of both III and 5t but had no effect on the ataxia produced by these compounds. In antinociceptive tests, 5t was active in the phenylquinone and Eddy hot-plate tests but was inactive in the tail-flick test.