Pollutant migration behavior in slurry ponds at Ordos Basin gas well sites
With an acceleration in the rate of gas exploration in Ordos Basin, more and more waste drilling mud has been discharged. After a series of treatment, the waste mud had been buried in some slurry ponds. So a significant number of ponds are scattered in the basin, which give more harm to the fragile ecological environment. But until now, there is little research focusing on real environmental effects of pollutants in slurry ponds. This research chose five slurry ponds used in succession during 2005 and 2009 as targets. The migration behavior of organics, oil and sulfide was studied, and their possible effects on shallow groundwater were forecasted. The results showed that the order of these three pollutants' effects on environment was sulfide>;oil>;organics. According to the migration behavior of mentioned pollutants, it came to conclusion that the sulfide and oil in the slurry ponds used over two years should have brought much influence on shallow groundwater.
The use of 13C-labelled polycyclic aromatic hydrocarbons for the analysis of their transformation in soil.
The formation of non-extractable residues during biodegradation and humification processes in soils and sediments represents a major sink for organic contaminants. The mode of incorporation of polycyclic aromatic hydrocarbons (PAH) and their metabolites into macromolecular organic matter during microbial degradation was studied applying 13C-labelled compounds. Mineralisation rates were determined by measuring the 13CO2 production. An incorporation of 13C-PAH-fragments into humic material could be traced by isotopic analysis of the bulk organic matter. Furthermore, selective chemical degradation reactions were performed to analyse the precise chemical structure of covalently bound 13C-labelled PAH fragments in soil humic substances. Structural assignments by GC-MS combined with isotope measurements on the bulk organic carbon and at the molecular level (Isotope Ratio Monitoring-GC-MS) provided useful information on the fate of xenobiotics within the soil.
Silica in Soils1
Publisher Summary Silica in free and combined forms is a dominant component of the solid material of many soils, and dissolved silica is commonly a major solute of soil solutions. Breakdown of primary silicates, translocation of silica in solution, and deposition of secondary silica-containing substances are involved in the development of soils. Ions essential for the growth of plants are released to the soil solution as silicates weather, and these ions may be held against leaching at exchange sites on other silicates. Silica is absorbed in appreciable quantities by some plants and is returned to the surface of the soil as the plants decay. The nature and transformations of silica and silicates in soil are, thus, fundamental to an understanding of many aspects of soil and plant sciences.