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.
[Environmental impact of oil pollutant on groundwater during oilfield exploitation in Daqing--a modelling analysis].
This paper analyzed the pollution sources and paths of groundwater environment in Longnan of Daqing during oilfield exploitation. Based on the technological characteristics of oilfield exploitation, a mathematical model on the migration and transformation of oil pollutants was developed, in which, the degradability and the adsorption capacity of oil pollutants were taken into account. An analytical formula of oil pollutant migration in groundwater was derived with continuous sources, and a prediction on the migration was made, which provide an important basis for the environmental impact assessment of oilfield exploitation project.
Time and Heritage
As a historian studying what can be considered a form of intellectual history, I have slowly come to adopt Michel de Certeau’s observation made at the end of the 1980s that ‘objectifying the past, for the last three centuries, has undoubtedly left unconsidered time within a discipline that has continued to use it as a taxonomic instrument’. To a certain degree, time has become commonplace for the historian who has preserved or instrumentalized it. It is not considered because it is inconceivable, but because we do not think of it or, more simply, we do not think about it. As a historian attempting to pay attention to the time I’m living in, I have thus, like many others, noticed the swift development of the category of the present until it has become obvious that the present is omnipresent. This is what I refer to here as ‘presentism’.