Ammonia gets overdue overview

by Biomechanism 

“Rice, University of Houston team studies how ammonia affects city’s air”

Motor vehicles and industry are primary producers of ammonia in Houston’s atmosphere, and cars and trucks appear to boost their output during the winter, according to a new study by researchers at Rice University and the University of Houston (UH).

Ammonia’s role in air quality draws minimal oversight from the Environmental Protection Agency (EPA), but researchers at both Houston institutions are learning what it means to life in and around the metropolis.

The study led by Rice Professors Robert Griffin and Frank Tittel in collaboration with UH researcher James Flynn and Professor Barry Lefer revealed the seasons play a role in ammonia produced by vehicles. Their instruments also measured plumes of airborne ammonia from isolated incidents. The results appeared in a recent research paper in the journal Atmospheric Chemistry and Physics.

The findings are not cause for immediate concern, said Griffin, an associate professor of civil and environmental engineering. “There may not be a health risk from ammonia itself, but the fact that ammonia is a precursor to particles is a big deal. They can get into your lungs and do some damage.”

Ammonia quickly combines with other airborne elements: sulfuric acid to make ammonium sulfate salts or, in cooler conditions, nitric acid to make ammonium nitrate. The particles could impact air quality as well as atmospheric visibility, cloud formation, climate patterns and nutrient cycling, he said.

Ammonia is found throughout the atmosphere in levels ranging from parts per trillion to parts per billion (ppb), he said. People can detect ammonia at five to 50 parts per million (ppm). Concentrations above 100 ppm are uncomfortable to most, according to the EPA.

The sources are many: industry, motor vehicles, agriculture (as a major component of fertilizer) and livestock. Even humans produce ammonia. (Household ammonia is highly diluted with water — but one should still avoid the pungent fumes.)

Wondering how much ammonia is in the atmosphere at any given time, the researchers gathered data 24 hours a day over two weeks in February and six weeks in late summer, 2010.

Readings were taken atop the University of Houston’s tallest building, North Moody Tower. The residence hall is ideally situated to pick up changes in the wind not only from the nearby Houston Ship Channel and its associated industries to the east, but also power generation facilities to the southwest and Houston traffic in every direction.

Tittel, a pioneer in laser sensing and Rice’s J.S. Abercrombie Professor of Electrical and Computer Engineering, and Rafal Lewicki, a co-author and graduate student in Tittel’s laser science group, designed and built an apparatus to collect the data. Their external-cavity quantum cascade laser-based sensor is finely tuned to pick up signs of ammonia from air samples continuously cycled through the closed system. Real-time readings were taken with a resolution of less than five parts per billion and autonomously monitored at Rice via the Internet.

Sampling at a single site produced results that at first seemed contradictory, Griffin said.

For example, while overall levels were highest in the summer, ammonia emissions from vehicles were found to be highest in winter when harder-working car and truck engines reduced the performance of catalytic converters. (Carbon monoxide levels recorded by UH instruments on the tower correlated nicely, the study showed.)

Part of the answer was blowing in the wind. The researchers found the prevailing wind during winter morning rush hours came from the southeast — past several major highways and Houston’s William P. Hobby Airport — and carried a high level of vehicle emissions.

During summer morning rush hours, the wind whistled in from the northeast, passing the ship channel and increasing readings from industrial activity and including occasional spikes, including a nearby traffic accident, that raised the average.

Winter levels of airborne ammonia ranged from 0.1 to 8.7 ppb with a mean of 2.4 ppb. A larger range — 0.2 to 27.1 ppb with a mean of 3.1 ppb — was observed during the summer.

In the Aug. 14 accident, two 18-wheeled tankers collided on Interstate 45 two miles north of the tower. One was carrying fertilizer and pesticide, and the fumes from the resultant chemical fire reached the sensor, which recorded a spike in airborne ammonia to about 21 ppb. “If the wind was blowing the other way, we wouldn’t have captured it,” said Owen Gong, a graduate student in Griffin’s lab and first author of the paper. “There is a bit of luck associated with this kind of field work.”

A similar spike occurred a few weeks later when winds from Hurricane Hermine in the Gulf of Mexico blew emissions from industries in and around Texas City — 40 miles south of downtown Houston — to the tower. The next week, ammonia levels reached 27 ppb, but no source of the emissions was identified.

Griffin appreciated having access to the UH site and Lefer and Flynn’s help. “Without their data to give us wind direction and other chemical information, analysis of the ammonia time series would have been difficult,” he said.

He admitted that, as an environmental scientist, he lives in interesting times — and in an interesting place. The researcher, who came to Rice from the University of New Hampshire three years ago, said few talk about airborne particles in Houston because the city is currently “in attainment with respect to the air quality standard.” The team’s next study will track the source and fate of other components in airborne particulate matter.

Griffin did not foresee the EPA monitoring ammonia for the sake of establishing a standard. “But because it can be such a significant precursor to particulate matter, the EPA needs to keep an eye on it,” he said.

View a short video about the research below:

A story in a small USA town

It is raining, and the little town looks totally deserted. It is tough times, everybody is in debt, and everybody lives on credit. 
Suddenly, a rich tourist comes to town. He enters the only hotel, lays a 100 Euro note on the reception counter, and goes to inspect the rooms upstairs in order to choose one. 
The hotel proprietor takes the 100 Euro note and runs to pay his debt to the butcher. 
The butcher takes the 100 Euro note, and runs to pay his debt to the pig grower. 
The pig grower takes the 100 Euro note, and runs to pay his debt to the supplier of his feed and fuel. 
The supplier of feed and fuel takes the 100 Euro note and runs to pay his debt to the town's prostitute that in these hard times, gave her "services" on credit. 
The hooker runs to the hotel, and pays off her debt with the 100 Euro note to the hotel proprietor to pay for the rooms that she rented when she brought her clients there. 
The hotel proprietor then lays the 100 Euro note back on the counter so that the rich tourist will not suspect anything.
At that moment, the tourist comes down after inspecting the rooms, and takes his 100 Euro note, after saying that he did not like any of the rooms, and leaves town. 
No one earned anything. However, the whole town is now without debt, and looks to the future with a lot of optimism. And that, ladies and gentlemen, is how the United States is doing business today.

Health benefits of broccoli require the whole food, not supplements

 by Biomechanism 

New research has found that if you want some of the many health benefits associated with eating broccoli or other cruciferous vegetables, you need to eat the real thing – a key phytochemical in these vegetables is poorly absorbed and of far less value if taken as a supplement.

New studies have found that the health benefits of broccoli depend on consumption of the whole food, rather than supplements. (Photo courtesy U.S. Department of Agriculture)

The study, published by scientists in the Linus Pauling Institute at Oregon State University, is one of the first of its type to determine whether some of the healthy compounds found in cruciferous vegetables can be just as easily obtained through supplements.

The answer is no.

And not only do you need to eat the whole foods, you have to go easy on cooking them.

“The issue of whether important nutrients can be obtained through whole foods or with supplements is never simple,” said Emily Ho, an OSU associate professor in the OSU School of Biological and Population Health Sciences, and principal investigator with the Linus Pauling Institute.

“Some vitamins and nutrients, like the folic acid often recommended for pregnant women, are actually better-absorbed as a supplement than through food,” Ho said. “Adequate levels of nutrients like vitamin D are often difficult to obtain in most diets. But the particular compounds that we believe give broccoli and related vegetables their health value need to come from the complete food.”

The reason, researchers concluded, is that a necessary enzyme called myrosinase is missing from most of the supplement forms of glucosinolates, a valuable phytochemical in cruciferous vegetables. Without this enzyme found in the whole food, the study found that the body actually absorbs five times less of one important compound and eight times less of another.

Intensive cooking does pretty much the same thing, Ho said. If broccoli is cooked until it’s soft and mushy, its health value plummets. However, it can still be lightly cooked for two or three minutes, or steamed until it’s still a little crunchy, and retain adequate levels of the necessary enzyme.

The new study was published in the Journal of Agricultural and Food Chemistry. It was supported by the National Institutes of Health.

Broccoli has been of particular interest to scientists because it contains the highest levels of certain glucosinolates, a class of phytochemicals that many believe may reduce the risk of prostate, breast, lung and colorectal cancer. When eaten as a raw or lightly-cooked food, enzymes in the broccoli help to break down the glucosinolates into two valuable compounds of intensive research interest – sulforaphane and erucin.

Studies have indicated that sulforaphane, in particular, may help to detoxify carcinogens, and also activate tumor suppressor genes so they can perform their proper function.

Most supplements designed to provide these glucosinolates have the enzyme inactivated, so the sulforaphane is not released as efficiently. There are a few supplements available with active myrosinase, and whose function more closely resembles that of the whole food, but they are still being tested and not widely available, Ho said.

Small amounts of the myrosinase enzyme needed to break down glucosinolates are found in the human gut, but the new research showed they accomplish that task far less effectively than does whole food consumption.

Although broccoli has the highest levels of glucosinolates, they are also found in cauliflower, cabbage, kale and other cruciferous vegetables. The same cooking recommendations would apply to those foods to best retain their health benefits, Ho said.

Many people take a variety of vitamins, minerals and phytochemicals as supplements, and many of them are efficacious in that form, researchers say. Higher and optimal levels of popular supplements such as vitamins C, E, and fish oil, for instance, can be difficult to obtain through diet alone. Some researchers believe that millions of people around the world have deficient levels of vitamin D, because they don’t get enough in their diet or through sun exposure.

But for now, if people want the real health benefits of broccoli, there’s a simple guideline.

Eat your vegetables.