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<DIV class=formatpublished>Nature</DIV>
<DIV class=formatpublished>Published online <ABBR class=published
title=2011-09-22T18:00:00Z>22 September 2011</ABBR> </DIV>
<DIV class=formatpublished>doi:10.1038/news.2011.552 </DIV>
<DIV class=formatpublished> </DIV>
<DIV class=type-of-article><FONT size=4>Nitrogen pollution disrupts Pacific
Ocean</FONT></DIV>
<DIV class=intro>Surging nitrates in Asian waters could dramatically affect
marine wildlife.</DIV>
<DIV class=byline><SPAN class=vcard><SPAN class="author fn">Susan Moran
</SPAN></SPAN></DIV><SPAN class=cleardiv><!-- --></SPAN>
<DIV class=entry-content sizset="16" sizcache="4">
<P sizset="20" sizcache="1">Nitrate levels in the waters off China, Japan and
the Korean Peninsula are soaring, according to a 30-year study published in
<SPAN class=i>Science </SPAN>today<SUP sizset="20" sizcache="1"><A
href="http://www.nature.com/news/2011/110922/full/news.2011.552.html?WT.ec_id=NEWS-20110927#B1">1</A></SUP>.
Researchers attribute the nitrate spike to rises in nitrogen pollution, and warn
that it could severely affect marine ecology, leading to algal blooms and 'dead
zones' with low oxygen levels.</P>
<P>Researchers from South Korea and the United States have analysed
measurements, taken from the 1980s to the 2000s, of the amount of nitrogen and
phosphorous at various depths in the seas bordering China's east coast — namely
the Yellow Sea, the East China Sea and the Sea of Japan. They compared the
nitrogen levels in the oceans to the amount of nitrogen deposited in the
atmosphere, using measurements taken at four air-monitoring sites.</P>
<P>Over that time span, rapid population growth and industrial activity in the
region, particularly in China, have caused increases in nitrogen pollution,
including nitrogen oxides from fossil-fuel burning and ammonia compounds from
agriculture. This nitrogen reaches the sea from the air, and to some degree from
rivers.</P>
<P>The researchers found that as nitrogen pollution has increased, oceans in the
region have become more enriched with nitrogen relative to phosphorus. They warn
that this shift in nutrients could favour marine organisms that thrive in
conditions of high nitrogen and low phosphorus. </P></DIV>
<DIV class=inlineheading><STRONG>Surprise shift</STRONG></DIV>
<DIV class=entry-content sizset="16" sizcache="4">
<P>Kitack Lee of Pohang University of Science and Technology in South Korea, one
of the authors of the study, says he was surprised to see that nitrogen levels
were affected even in such large, deep bodies of water.</P>
<P>He does not single out any particular country as the primary source of the
nitrogen pollution, but notes that the study areas are located downstream of
China and thus the "contributions of anthropogenic nitrogen from China are
inevitably large".</P>
<P sizset="21" sizcache="1">The study builds on previous research showing the
growing impact of nitrogen pollution on the open ocean<SUP sizset="21"
sizcache="1"><A
href="http://www.nature.com/news/2011/110922/full/news.2011.552.html?WT.ec_id=NEWS-20110927#B2">2</A></SUP>,
and on isolated lakes, streams and estuaries, including Chesapeake and Tokyo
bays and bodies of water in Norway and Sweden. </P>
<P>"The paper takes a large data set to prove the point that has been shown in
other regions, but not here," says Hans Paerl, an oceanographer at the
University of North Carolina in Chapel Hill, who has researched atmospheric
nitrogen deposition and over-enriched coastal waters for decades. He cautions
that increasing nitrate abundance in the ocean could spur a rise in the growth
of algae, including toxic blooms that are harmful to marine life.</P>
<P>In their study, Lee and his colleagues found that nitrate levels rose most in
the Yellow Sea east of China (and southwest of South Korea), where the
Changjiang River reaches the sea.</P>
<P>In one of the blocks of water studied in that area, nitrate concentrations
have surged from 2 micromoles per litre to 8 micromoles per litre over the past
25 years. The current concentration in that area "is 30 times higher than [in]
the Gulf of Mexico," says Ken Johnson, an oceanographer at the Monterey Bay
Aquarium Research Institute in Moss Landing, California. "If you saw 8
micromoles in the Gulf, the dead zones there would ultimately be a lot
bigger."</P><!-- 300x250 ad -->
<DIV class="ad ad300x250">Johnson is leading a group of scientists trying to
launch a global network of sensors that would continuously measure the impact of
climate on nutrient fluxes, including nitrogen, as well as monitoring ocean
acidification and oxygen stocks. "It's embarrassing how little data we have on
oceans worldwide," he says.</DIV>
<P>James Galloway, an environmental scientist at the University of Virginia,
Charlottesville, who co-authored an August 2011 report on nitrogen in the
environment for the US Environmental Protection Agency, says that the Pacific
study demonstrates the need for greater controls on combustion systems and on
nitrogen discharges to waterways from agricultural runoff, sewage and other
sources. "Ultimately, the challenge is how to prevent the environmental
consequences without diminishing the ability to produce food and energy, for
Asia and elsewhere," he says.<SPAN class=end-of-item> </SPAN></P>
<UL id=article-refrences class=xoxo sizset="16" sizcache="4">
<LI sizset="17" sizcache="4">
<H2 class=heading>References</H2>
<OL sizset="17" sizcache="4">
<LI id=B1 sizset="22" sizcache="1"><A name=B1><!-- . --></A>Kim, T.-W., Lee,
K., Najjar, R. G., Jeong, H.-D. & Jeong, H.-J. <SPAN
class=journalname>Science</SPAN> advance online publication <A class=reftxt
href="http://dx.doi.org/10.1126/science.1206583">http://dx.doi.org/10.1126/science.1206583</A>
(<SPAN class=cite-month-year>2011</SPAN>).</LI>
<LI id=B2 sizset="24" sizcache="1"><A name=B2><!-- . --></A>Duce, R. A.
<I>et al. </I><SPAN class=journalname>Science</SPAN> <SPAN
class=journalnumber>320,</SPAN> 893-897 (<SPAN
class=cite-month-year>2008</SPAN>). | <A class=reftxt title=""
href="http://dx.doi.org/10.1126/science.1150369">Article</A> | <A
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href="http://links.isiglobalnet2.com/gateway/Gateway.cgi?&GWVersion=2&SrcAuth=Nature&SrcApp=Nature&DestLinkType=FullRecord&KeyUT=000255868300032&DestApp=WOS_CPL">ISI</A> | <A
class=reftxt title="Article on ChemPort - "
href="http://chemport.cas.org/cgi-bin/sdcgi?APP=ftslink&action=reflink&origin=npg&version=1.0&coi=1:CAS:528:DC%2BD1cXlslygsb0%3D&pissn=1744-7933&pyear=2011&md5=9de0c9b902189a3de670450a8e94a3c1">ChemPort</A> |</LI></OL></LI></UL></DIV></FONT><BR>
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