Developing a method to track oil and gas produced water discharges in estuarine systems using salinity as a conservative tracer.

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge from a point source. The current field method used for fate and effect determinations in open water estuarine systems involves extending a compass oriented transect (COT) from the point source discharge--a method designed for a uniform offshore environment that might be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Research was conducted in a canal and a small, semi-enclosed bay to observe effluent behaviour and to determine if salinity could be used to track the effluent. A salinity/conductivity/temperature (SCT) probe measured water properties within 1 cm of the sediment surface and identified a thin, bottom salinity plume that would have gone undetected by conventional instruments. The plume flowed across the sediment surface and towards greater depths. Plume-affected sampling stations exhibited higher levels of sediment contaminant indicators (SCIs) and indicated that station location could affect impact conclusions.     

Observations on temporal red shift of wheat from multi-date spaceborne MOS-B spectrometer data

High spectral resolution spectroscopy enables to have detailed information on chemical and morphological status of crop. An attempt of using space platform for detecting red edge shift during different growth stages of wheat crop is reported. Study was conducted during rabi 1996–97 season using Modular Opto-Electronic Scanner MOS-B Imaging data onboard IRS-P3 satellite. Inverted Gaussian model was fitted for satellite derived reflectances between 650 and 870 nm to derive inflection wavelength and its subsequent change with crop stages i.e. red shift. Red shift of 10 nm observed from crown root initiation stage (703.8 nm) to peak vegetative stage (714.2 nm). A comparative study on temporal behaviour of vegetative indices like NDVI and ARVI with Red edge showed that latter is more atmospherically stable parameter. It is concluded that red edge shift which hitherto has been observed from ground and airborne sensors, can also be detected from space.     

Comparing methods and sediment contaminant indicators for determining produced water fate in a Louisiana estuary

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge. The current field method used to determine its fate in estuarine systems involves extending a compass oriented transect (COT) from the point source discharge--a method designed for a uniformly dispersing effluent discharged into a uniform offshore environment that may be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Prior research established the viability of the salinity stratification transect (SST) method. Both COT and SST methods were used in a small open bay to determine which more accurately detected effluent dispersion. Determination was based on sediment contaminant indicators (SCIs), including interstitial salinity, hydrocarbons, metals, and radium concentrations. Additionally, SCIs were evaluated for their ability to serve as indicators of effluent dispersion. The data revealed that SST stations exhibited higher contaminant concentrations and that this approach was more accurate in tracking the produced water plume. The data also suggested that SCIs varied in their ability to serve as indicators. Good indicators included interstitial salinity, total targeted aromatic hydrocarbons substantiated with a modified fossil fuel pollution index value, certain metals, and radium-228.     

Fate of petroleum hydrocarbons and toxic organics in Louisiana coastal environments

Numerous potentially toxic compounds are entering Louisiana’s inshore and nearshore coastal environments. To a large degree there is insufficient information for predicting the fate and effect of these materials in aquatic environments. Studies documenting the impact of petroleum hydrocarbons entering Louisiana coastal wetlands are summarized. Also included are research findings on factors affecting the persistence of petroleum hydrocarbons and other toxic organics (pentachlorophenol (PCP), 2,4-dichlorophenoxyacetic acid (2,4-D), creosote, etc.) in sediment-water systems. Sediment pH and redox conditions have been found to play an important role in the microbial degradation of toxic organics. Most of the hydrocarbons investigated degrade more rapidly under high redox (aerobic) conditions although there are exceptions (e.g., 1,1,1-trichloro-2,2-bis(4-chlorophenyl) (DDT) and polychlorobiphenyls (PCBs)). Some of these compounds, due to their slow degradation in anaerobic sediment, may persist in the system for decades.     

电子束CT三维重建技术与颅颌面外科

目的 探讨电子束CT三维重建技术在颅颌面外科的适应症和应用价值。方法 采用美国Imatron公司的电子束CT(electron beam CT,以下简称EBCT)C-150,对76例严重颅颌面病人实行薄层CT容积扫描。将所获CT图象经数字接口传至加拿大ISG公司生产的Allegro工作站进行三维重建。结果EBCT成像技术能立体的、详尽和精确的显示机体组织三维解剖结构极其相互关系。其再现畸形或病体模型的程度可以达到近乎解剖学的精度,为准确了解和掌握病情并制定合理的手术治疗计划提供了极为重要的依据,提高了手术治疗效果。结论EBCT三维重建技术是现代颅颌面外科最主要的诊断方法之一并具有重要的临床应用价值。