I am not sure that this is overly useful except as to draw attention to
the reality of ammonia loss to the atmosphere that is not necessarily
insignificant. Add that to the derived
nitrogen lost annually from the soil through the water system and you merely
complete a dreadful picture that cannot in good conscience be sustained.
Worse of course is that we know how to stop it and so do many others but
that is where it sits. Biochar must
become the new gold standard in a new organic agricultural protocol simply
because it grabs nutrients and holds them until the root arrives to take them.
In practice a thin bed of char at perhaps fifteen percent underlying a
working soil bed should suffice to store all nutrients forever and end any need
for augmentation at all.
Research clarifies health costs of air pollution from
agriculture
34
minutes ago by Kathryn Hansen
(Phys.org) —Ammonia pollution from agricultural sources poses larger
health costs than previously estimated, according to NASA-funded research.
Harvard University researchers Fabien Paulot and Daniel Jacob used
computer models including a NASA model of chemical
reactions in the atmosphere to better represent how ammonia interacts in the
atmosphere to form harmful particulate matter. The improved simulation helped
the scientists narrow in on the estimated health costs from air pollution associated with food produced for export – a growing sector
of agriculture and a source of trade surplus.
"The 'cost' is an economic concept to measure how much people are
willing to pay to avoid a risk," Paulot said. "This is used to
quantify the cost for society but also to evaluate the benefits of
mitigation."
The new research by Paulot and Jacob calculate the health cost
associated with the ammonia emissions from agriculture exports to be $36 billion a year – equal
to about half of the revenue generated by those same exports – or $100 per
kilogram of ammonia. The study was published December 2013 in Environmental
Science & Technology.
The new estimate is about double the current estimate by the U.S.
Environmental Protection Agency, which suggests a cost of $47 per kilogram of
ammonia. The scientists say the new estimate is on the high end of the
spectrum, which reflects the need for more research into characterizing the
relationship between agricultural ammonia emissions and the formation of the
harmful fine particulate matter – a relationship that's not as straightforward
as previous estimates assumed.
"The effect of ammonia on fine particulate is complex, and we
believe that the models previously used in the United States to price ammonia
emissions have not captured this well," Paulot said.
Manure from livestock and fertilizer for crops release ammonia to the
atmosphere. In the air, ammonia mixes with other emissions to form microscopic
airborne particles, or particulates. The particulates that pose the greatest
health risk are those that measure no more than 2.5 micrometers across, or
about 1/30 the width of a human hair, which when inhaled can become lodged deep
within the lungs. Long-term exposure has been linked to heart and lung diseases
and even death. As such, the particles are on the list of six common air
pollutants regulated by EPA's National Ambient Air Quality Standards.
An increase in ammonia, however, does not translate to an equal increase
in particulates. The relationship depends on meteorology as well as the
concentration of other precursors to particulate formation, such as sulfate and
nitric acid.
To clarify the effect of ammonia on fine particulates, Paulot and Jacob
first modeled the agricultural sources of ammonia emissions utilizing a
relatively new ammonia emissions inventory. Next they used the NASA GEOS-Chem
model of atmospheric composition to simulate the complex chemistry that
converts agricultural emissions – in this case ammonia – into fine particulate
matter.
This information was then combined with food export data from the U.S.
Department of Agriculture and the United Nations Food and Agriculture
Organization, averaged from 2000 to 2009. Results show that U.S. food exports
account for 11 percent of the total U.S. emissions of ammonia.
"Our study suggests controls on ammonia emissions from agriculture
could help reduce particulate matter and provide significant societal
benefits," Paulot said.
The impact, however, is not equal everywhere. Areas downwind of large
agricultural regions often set the stage for more mixing of ammonia with
man-made emissions from combustion, such as from traffic and power plants. More
mixing means the formation of more fine particulate matter. For this reason,
the largest health costs are most often carried by the more populated states in the
Northeast and Great Lakes region.
No comments:
Post a Comment