Trend stations

We ended up with a station net containing 110 national monitoring stations in lakes, where some were reference stations and the rest were nominated as trend stations. The geographical distribution of the lakes is shown in Figure 2.1.6. 

In short, tire national surveillance monitoring net consists of 110 annually monitored reference or trend stations. In addition, 800 stations per year are monitored once every sixth year, which adds up to a total of 4910 monitored lakes in the six year monitoring cycle of the Water Framework Directive. 

R. A. Smith and R. B. Alexander, Evidencefor Acid-Precipitation Induced Trends in Stream Chemistry at Hydrologic Bench-Mark Stations, E.S. Geological Survey... 

Many of the faster work stations can provide throughput similar to that observed on a crowded, shared supercomputer, especially for codes that do not benefit greatly from vectorization. The availabihty of such machines for less than 50,000 (much less for academic users) has once again changed concepts of what is computationally feasible. Many more people can perform computations that a few years ago were the sole domain of those with access to large-scale computing faciUties, and this trend is expected to continue. 

Refinements have been made on the source term calculational methods since WASH-1400. The general trend has been toward source term reduction (e.g., the iodine release for the large LOCA) as compared with the RSS results. In cases such as Station Blackout, the RSS underestimated the tellurium and barium compared with results from the BMI-2104 suite. 

A recent trend is the development of park and ride areas for transit passengers to drive to transit. These facilities help make transit accessible to a wide geographic area. Because emissions control devices are ineffective when cold, the auto trip to the transit station may produce nearly as many pollutants as a direct trip to the final destination. Further, park and ride lots occupy a lot of space, making transit stations... 

Carbon Monoxide. The Standard is often exceeded at the Cuitlahuac Station (northwest) during winter,as displayed in Figure 3a. However, a diminishing trend on the number of hours reaching a 26 ppm level can be appreciated in Figure 3b. 

The most recent comprehensive assessment of the quality of rivers in the USA is that of Smith et al. 12), This followed an earlier assessment by Wolman et al. in 1971 (iS). The former 1987 assessment was based on 24 water quality measures from 161-383 stations around the country covering the period 1974-1981. Trends observed included major increases in nitrate, phosphorous, sodium, suspended sediment, fecal bacteria, dissolved oxygen deficit, arsenic and selenium. Major decreases were observed with nitrate, suspended sediment, fecal bacteria, dissolved oxygen deficit and lead. 

In contrast to traditional ambient fixed station "parametric approaches to river quality evaluation for trends determination and water quality standards attainment, data from the Willamette River, Oregon, USA were used to demonstrate the value of quantitative, semi-quantitative and qualitative approaches to mechanistic assessment of river water quality. 

Preliminary results reveal similar trends for Se at station 23. Ongoing analyses will allow us to estimate the flux of Se at the sediment-water interface. 

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