Methane and Acetylene Pore Gas Mixture Influence On Water Infiltration.

We compared water infiltration rates when the initial pore gas consisted of methane and acetylene in various proportions.  Hecla loamy fine-sand and Glyndon loam were packed in columns with a soil depth of 15 cm.  Infiltration columns were designed to initiate ponded infiltration conditions nearly instantaneously.  Falling head conditions were used for this study.  Prior to infiltration runs the dry columns were flooded with dry gas.  Three gas compositions were used:  methane, half methane/acetylene, acetylene.  Columns were packed in blocks of three.  That is, three columns were packed at one time, alternating additions of soil and attempting to pack all three identically.  The three columns were then assigned randomly to the three gas compositions.  The results showed infiltration to be about twice as fast for the acetylene treated columns versus the methane treated columns.  With the half and half mixture the infiltration rate was intermediate.  While the infiltration rates with the half/half gas were mostly near the mean of the whole gas rates, some were nearer the acetylene rate.  A linear relationship between fractional gas composition and infiltration rate may be justified, but the instances where half/half  composition resulted in infiltration rates near the acetylene rate are a bothersome inconsistency.  Investigation is continuing.