Remote measurements, nitrogen

The nitrogen species enter the atmosphere from a variety of natural and anthropogenic sources (7). The largest sources are concentrated in urban and industrialized areas. The levels of the species in the atmosphere vary from hundreds of parts per billion by volume (ppbv, that is, 10 9 mole fraction) in these source regions to below one part per trillion by volume (pptrv, 10"12 mole fraction) in remote areas. Even at the pptrv level, these species can play significant roles in atmospheric chemistry, and measurements of species at the sub-pptrv level can yield useful information concerning atmospheric photochemistry. 

Special HPGe detection system which can be operated without using liquid nitrogen, large area planar detector. Gamma measurements at remote locations where liquid nitrogen is not available. 

Today, we often use the NO-O3 chemiluminescence nitrogen oxides (NO ) analyzer for determining NO concentration in the atmosphere. In the atmosphere, especially at rural sites, NO dominates the formation of O3 known as a toxic substance. " It is important that we understand atmospheric chemistry including O3 formation and the changes in atmospheric NO concentration. High sensitivity and quick response are required on the NO-O3 chemiluminescence NO analyzer for that purpose. However, commercial NO < analyzers generally have insufficient sensitivity for the measurement of NO concentration at the low levels, which are often observed in remote region such as rural sites. 

Nitrogen can also be used as a remote label the exocyclic amino group of adenine, which is readily inserted into adenosine by reaction of chloropurine riboside with ammonia and easily removed by adenosine deaminase, is being used in our laboratory for measurement of 0 isotope effects in the y-phosphate of ATP. In this case, 0.36% of the N-, 0-labeled species is mixed with 99.6% of the " N-labeled material to restore the natural abundance of in the amino group of adenine. Depleted C and N are commercially available. 

The ARSA system is designed to operate continuously in remote areas with minimal maintenance and consumables limited to replacement bottles of nitrogen carrier gas and CO2 removal traps. Dryers and gas traps were chosen that could be automatically regenerated in the field. The system has many components and a complex path for the analyte gas that traverses the system. The numerous valves ( 100) for controlling the gas flow and trap regeneration processes require a control system about one order of magnitude more complex than that for the RASA system described in the preceding section, if the number of parts is taken as a measure of... 

The pressure at which the combustion rate is to be determined is achieved by pressurising an inert gas, usually nitrogen, into the combustion chamber until the desired pressure is reached. This is made possible by a high-pressure compressor and an electromagnetic valve, wiiich enables remote control. The pressure inside the chamber is measured by a suitable pressure gauge. 

An ozone monitor is an example of a continuous emission sampler based on absorption spectroscopy. A drop in beam intensity is proportional to ozone concentration in the chamber. Absorption spectrometers exist for sulfur and nitrogen oxides. This type of technology is portable and relatively inexpensive to run and can be used under field conditions, for example monitoring in-use emissions of motor vehicles. Absorption spectroscopy is also used in satellite remote sensing and has been adapted to remote sensing devices deployed on the ground to measure vehicular emissions. 

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