Total Petroleum Hydrocarbon Degradation and BTEX Leaching in Soils after Application of Oil-Base Drilling Mud: Impact of Application Rate, Rainfall Regime, and Time by Chad J Penn in (MAOPS)-Lupine Publishers
Increases in oil and gas drilling have resulted in large quantities of
oil base "mud" (OBM) to be disposed of. Land application of OBM to
agricultural land is a common disposal technique that presents agronomic
and environmental challenges since the material is rich in total
petroleum hydrocarbons (TPH). Leaching of lower molecular weight
hydrocarbons, mainly benzene, toluene, ethylbenzene, and xylene (BTEX),
is a concern due to their relatively low octanol: water partition
coefficients. The objective of this study was to determine the effect of
rainfall regime and TPH loading rate on TPH degradation and BTEX
leaching after OBM application. An OBM was characterized for TPH, BTEX,
and trace metals. A soil column study was conducted where OBM was
applied at five loading rates (0, 22,000, 45,000, 67,000, and 90,000 kg
TPH ha-1) and was subjected to four moisture regimes. OBM
samples were taken at day 0, 7, 30, 60, and 91 to monitor TPH
degradation. Leachate samples were taken at day 0, 14, 28, 35, 49, 56,
63, 77, and 84 to monitor electrical conductivity (EC), pH, metal
concentrations, and BTEX concentrations. After 60 days, a maximum TPH
degradation of 35% was measured. Leachate BTEX concentrations increased
as TPH application rate increased and was mostly undetectable by day 28.
Leachate EC increased over time and with increasing TPH rates. TPH rate
had no effect on leachate pH. OBM loading rates had the greatest effect
on TPH degradation and BTEX leaching. Under our experimental
conditions, little risk of BTEX leaching from land applied OBM was
observed.
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