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.

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 July 29, 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 July 29, 2014).

Share This




More Plants & Animals News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
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:
from the past week

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