Featured Research

from universities, journals, and other organizations

Reducing Nitrate Discharge To Downstream Ecosystems

Date:
February 11, 2009
Source:
USDA/Agricultural Research Service
Summary:
Scientists are finding ways to stem the flow of nitrates that are washed out of crop fields into regional surface and groundwater sources.

ARS researchers have invented a bioreactor that removes nitrates from swine effluent, allowing the livestock wastewater to be recycled for irrigation.
Credit: Photo by Peggy Greb

Agricultural Research Service (ARS) scientists are finding ways to stem the flow of nitrates that are washed out of crop fields into regional surface and groundwater sources.

Related Articles


These nitrates come primarily from nitrogen fertilizers that are not taken up by crops. After the nitrates are flushed out of the soil, they flow into subsurface tile drains that channel excess water away from crop fields.

But these underground drains can facilitate the eventual passage of nitrate-laden runoff into the Gulf of Mexico, the Chesapeake Bay and other water bodies. When the runoff enters these areas, it can intensify the development of oxygen-deficient "dead zones," a condition called hypoxia.

ARS research leader Patrick Hunt, agricultural engineer Kenneth Stone, and soil scientist Matias Vanotti developed a process for denitrifying nitrate-laden runoff in subsurface drains before the runoff reaches sensitive aquatic ecosystems downstream. They cultured and encapsulated denitrifying bacteria in polymer gels and verified their denitrification rates. The resulting product was called "immobilized denitrification sludge," or IDS.

They then devised a bioreactor by placing the IDS into a small reactor cylinder. The team tested a bioreactor in the field, where nitrate concentrations in runoff averaged 7.8 milligrams per liter.

Hunt and ARS environmental engineer Kyoung Ro determined that the hydraulic retention time (HRT)--how long the field drainage water remained in the bioreactor--was crucial in the denitrification process. With a one-hour HRT, 50 percent of the nitrogen was removed from the runoff. When the HRT was increased to more than 8 hours, the nitrate removal efficiency approached 100 percent.

The team concluded that the daily nitrate removal rate of a one-cubic-meter bioreactor would be approximately 94 grams per square meter of nitrate from field runoff. This is significantly higher than removal rates reported for in-stream wetlands, treatment wetlands, or wood-based bioreactors.

Hunt, Ro, Stone, and Vanotti all work at the ARS Coastal Plains Soil, Water and Plant Research Center in Florence, S.C.


Story Source:

The above story is based on materials provided by USDA/Agricultural Research Service. Note: Materials may be edited for content and length.


Cite This Page:

USDA/Agricultural Research Service. "Reducing Nitrate Discharge To Downstream Ecosystems." ScienceDaily. ScienceDaily, 11 February 2009. <www.sciencedaily.com/releases/2009/01/090131123518.htm>.
USDA/Agricultural Research Service. (2009, February 11). Reducing Nitrate Discharge To Downstream Ecosystems. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2009/01/090131123518.htm
USDA/Agricultural Research Service. "Reducing Nitrate Discharge To Downstream Ecosystems." ScienceDaily. www.sciencedaily.com/releases/2009/01/090131123518.htm (accessed October 25, 2014).

Share This



More Plants & Animals News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins