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Dutch Town Lays Air-Purifying Concrete
eldavojohn writes "In an effort to combat air pollution, a Dutch town has paved some of its streets with air-purifying concrete. It contains a titanium dioxide-based additive that utilizes sunlight to turn car exhaust into harmless nitrates. It was shown to do this in a lab and now the scientists are interested in just how much this will affect the air quality around the road. They will sample the air quality by a normal road and by this newly paved one."
The road is here according to a Dutch source.
DNA is the ultimate spaghetti code.
not to mention all the side products that are produced, msot of which i am willing to bet havenot even been identified, much less studied
J Environ Qual. 2008 Feb 11;37(2):291-5. Print 2008 Mar-Apr.Click here to read Links
When does nitrate become a risk for humans?
Powlson DS, Addiscott TM, Benjamin N, Cassman KG, de Kok TM, van Grinsven H, L'Hirondel JL, Avery AA, van Kessel C.
Soil Science Dep, Rothamsted Research, Harpenden, Herts, UK.
Is nitrate harmful to humans? Are the current limits for nitrate concentration in drinking water justified by science? There is substantial disagreement among scientists over the interpretation of evidence on the issue. There are two main health issues: the linkage between nitrate and (i) infant methaemoglobinaemia, also known as blue baby syndrome, and (ii) cancers of the digestive tract. The evidence for nitrate as a cause of these serious diseases remains controversial. On one hand there is evidence that shows there is no clear association between nitrate in drinking water and the two main health issues with which it has been linked, and there is even evidence emerging of a possible benefit of nitrate in cardiovascular health. There is also evidence of nitrate intake giving protection against infections such as gastroenteritis. Some scientists suggest that there is sufficient evidence for increasing the permitted concentration of nitrate in drinking water without increasing risks to human health. However, subgroups within a population may be more susceptible than others to the adverse health effects of nitrate. Moreover, individuals with increased rates of endogenous formation of carcinogenic N-nitroso compounds are likely to be susceptible to the development of cancers in the digestive system. Given the lack of consensus, there is an urgent need for a comprehensive, independent study to determine whether the current nitrate limit for drinking water is scientifically justified or whether it could safely
"One thing I am worried about, though, is the color of these sidewalks. If they're using titanium dioxide, shouldn't they be a nice brown color?"
Actually titanium dioxide is quite white. It is used as pigment for white base paint.
http://en.wikipedia.org/wiki/Photocatalysis
http://en.wikipedia.org/wiki/Titanium_dioxide
TiO2 can catalyze a wide variety of chemical reactions in the presence of ultraviolet light (such as sunlight).
retrorocket.o not found, launch anyway?
Harmless...
In freshwater or estuarine systems close to land, nitrate can reach high levels that can potentially cause the death of fish. While nitrate is much less toxic than ammonia or nitrite, levels over 30 ppm of nitrate can inhibit growth, impair the immune system and cause stress in some aquatic species.[citation needed] However, in light of inherent problems with past protocols on acute nitrate toxicity experiments, the extent of nitrate toxicity has been the subject of recent debate.
In most cases of excess nitrate concentrations in aquatic systems, the primary source is surface runoff from agricultural or landscaped areas which have received excess nitrate fertilizer. These levels of nitrate can also lead to algae blooms, and when nutrients become limiting (such as potassium, phosphate or nitrate) then eutrophication can occur. As well as leading to water anoxia, these blooms may cause other changes to ecosystem function, favouring some groups of organisms over others. Consequently, as nitrates form a component of total dissolved solids, they are widely used as an indicator of water quality.
What could possibly go wrong, though? It's not like roadways are "surfaces" that might "runoff" into storm sewers or waterways.
Alexander Peter Kristopeit bought his basement from his mommy for one dollar.
Because it's a flow restriction and the engine has to work to pump through it. In fact, particulate filters and catalytic converters and mufflers on new US diesel trucks harm the efficiency so much that it can do as much as 4 mpg damage.
The catalytic converter isn't as efficient as a straight pipe. While not legal, cutouts that push exhaust straight outside the engine and bypass the exhaust system do improve horsepower.
It's more like bumping up the speed of your front side bus on your CPU. If you have a slower FSB, you might not ever notice it if you aren't racing your ca... CPU. But when you need that speed, it sure would be nice to remove the FSB limitation.
That said, the amount of good that catalytic converters do means we should probably keep them, as they aren't a huge drain on the power of a vehicle.
a) Not all of Holland is below sea level, 75% of it is above sea level.
b) Nitrates can still pollute the ground water then diffuse into the ocean and rivers
The recent conclusion of a 37 year experiment is it's phosphorus not nitrogen that's the problem:
http://www.canada.com/victoriatimescolonist/news/story.html?id=381d4ce5-89a2-4901-864e-34239419bf67
Schindler's latest series of long-term experiments shows that nitrogen removal completely fails to control blue-green algae blooms. He proved this by manipulating nitrogen and phosphorus levels on Lake 227 for 37 years. Nitrogen control, he found, only encouraged algae blooms.