Numerical Modeling of Regional Ground Water Flow in the Deep-Brine Aquifers of the Palo Duro Basin, Texas Panhandle

A conceptual hydrogeologic model of the Palo Duro Basin, Texas Panhandle, subdivides the basin into three hydrogeologic units: the shallow Ogallala and Dockum aquifers, the Permian evaporite aquitard, and the deep confined, underpressured Permian and Pennsylvanian brine aquifer. The first permeable units beneath the thick Permian evaporite section are Wolfcamp strata composed of carbonates, shales, and arkosic sand and gravels (granite wash) with average effective permeability values of 8.9, 0.0001, and 8.6 md, respectively. Groundwaters in the Wolfcamp aquifer flow to the northeast toward the semi-impermeable, granitic Amarillo Uplift. This anomalous hydrologic condition (flow toward a low-transmissivity barrier) may result from the presence of highly permeable granite-wash deposits that flank the uplift and function as "hydrologic sinks." A two-dimensional, vertical-averaging finite-element model, incorporating the different lithologies and their different permeabilities as well as leakage through the overlying evaporite aquitard, has been used to simulate the observed potentiometric surface of the Wolfcamp aquifer. The conditions that best simulate the observed Wolfcamp potentiometric surface are a combination of specified head and no-flow conditions along the uplift, permeability values greater than 260 md for the granite-wash deposits that flank the uplift (in contrast to the average value of 8.6 md), and an increased permeability value of 50 md for the highly porous carbonate zone. The best estimate of the vertical permeability of the evaporite aquitard is 0.00008 md. Treating the whole deep-brine aquifer as a single permeable unit beneath the evaporite aquitard, groundwater flow is to the northeast toward the uplift with a slightly larger west-to-east component than that found when considering only flow in Wolfcamp strata. The conditions that best simulate the averaged potentiometric surface are those from the best simulation of Wolfcamp strata, with increased permeability values of 260 md for the Pennsylvanian granite-wash close to the uplift and 250 md for the high-porosity Pennsylvanian sandstone.Bureau of Economic Geolog

Biological control of lettuce root-knot disease by the used of Pseudomonas aeruginosa, Bacillus subtilis and Paecilomyces lilacinus

The effects of Pseudomonas aeruginosa, Bacillus subtilis and antagonistic fungus Paecilomyces lilacinus (provitan), on the growth and gall development of lettuce infected by root-knot nematodes Meloidogyne spp. was studied both in greenhouse and field environments. In field experiments, lettuce seedlings were cultivated in nematode infested soil, and P. aeruginosa and B. subtilis were applied every week prior to harvesting. Paecilomyces lilacinus was mixed with nematode infested soil two weeks prior to, and again two weeks after planting the lettuce. The results showed that the weight of lettuce planted in nematode infested soil, containing these three tested organisms, was higher than those cultivated in nematode infested soil with no control agents. Bacillus subtilis, P. aeruginosa and P. lilacinus (provitan) also decreased nematode population densities and suppressed nematode infection. As a result fewer galls were developed within the roots. The effects of three tested organisms, B. subtilis, P. aeruginosa and biocontrol agent P. lilacinus, along with bacterial culture supernatants of B. subtilis and P. aeruginosa on root-knot nematodes were examined while being grown in pots. The results show that the average weight of lettuce planted in nematode infested soil and controlled with P. aeruginosa 30 ml was significantly higher (P=0.05) when compared to those treated with other control agents, as well as those grown without control agents. Also shown in this study, B. subtilis, P. aeruginosa and both B. subtilis culture supernatant 50 ml and P. aeruginosa culture supernatant 10 ml, 30 ml and 50 ml significantly suppressed root-gall development within the root system (P=0.05) when compared to those cultivated in nematode infested soil with no control agents. As a result of using these control agents, fewer galls were developed within the roots. Even though, B. subtilis, P. aeruginosa and P. lilacinus (provitan) decreased nematode population densities, the nematode population level was still much higher than the economic threshold level. The supernatants of B. subtilis 50 ml and P. aeruginosa 10 ml, 30 ml and 50 ml significantly decreased nematode population densities (P=0.05). These bacterial supernatants are potentially * Corresponding author: Waraporn Prakob and Jeerapa Nguen-Hom email: [email protected], [email protected] 180 effective agents for controlling root knot nematodes; however further investigation of their use, as well as the development of field application methods for these control agents are needed