Featured Research

from universities, journals, and other organizations

Pesticides Persist In Ground Water

Date:
July 2, 2008
Source:
American Society of Agronomy
Summary:
Numerous studies over the past four decades have established that pesticides, which are typically applied at the land surface, can move downward to reach the water table at detectable concentrations. The downward movement of pesticide degradation products can also contribute to the contamination of ground water. This study found that the pesticides and degradation products detected most frequently in shallow ground-water samples were predominantly from two classes of herbicides -- triazines and chloroacetanilides.

Numerous studies over the past four decades have established that pesticides, which are typically applied at the land surface, can move downward through the unsaturated zone to reach the water table at detectable concentrations.

The downward movement of pesticide degradation products, formed in situ, can also contribute to the contamination of ground water. Once in ground water, pesticides and their degradation products can persist for years, depending upon the chemical structure of the compounds and the environmental conditions.

Scientists at the U.S. Geological Survey (USGS) investigated the occurrence of selected pesticides and their degradation products in ground water during a study funded by the USGS National Water-Quality Assessment (NAWQA) Program.

Specifically, the authors examined several of the factors that can influence the likelihood with which pesticides and their degradation products are detected in shallow ground water—including oxidation-reduction (redox) conditions and ground-water residence times—at four study sites across the United States.

The study revealed that the pesticides and degradation products detected most frequently in shallow ground-water samples from all four areas were predominantly from two classes of herbicides—triazines and chloroacetanilides. None of the insecticides or fungicides examined were detected in ground-water samples. In most samples, the concentrations of the pesticide degradation products greatly exceeded those of their parent compounds.

Pesticides or their degradation products were detected most commonly in ground water that recharged between 1949 and 2004, and in monitoring wells spanning the full depth range (about 2 to 52 m) examined—from the shallowest to the deepest wells—in all four study areas. Comparisons of pesticide concentrations with a variety of environmental variables indicated that redox conditions, ground-water residence times, and the concentrations of dissolved oxygen and excess nitrogen gas from denitrification (the breaking down of nitrogen compounds such as nitrate) were all important factors affecting the concentrations of pesticides and their degradation products in all four ground-water systems.

The four sites selected for this study were located in agricultural landscapes in Maryland, Nebraska, California, and Washington. They were also selected for variability in overall land use, crops grown, climate, agricultural practices, irrigation, geohydrologic settings, and redox conditions. During the spring of 2004, water samples were collected from a network of 59 shallow single or clustered monitoring wells and analyzed for the occurrence of 45 pesticides and 40 pesticide degradation products, including herbicide, insecticides, and fungicides.

Greg Steele, senior author for this study, stated “Atrazine and its degradation product deethylatrazine both persisted in similar amounts at the Nebraska site, but in water samples from the other three study sites, there was little change with apparent age of water as the fraction as deethylatrazine generally exceeded 80% of the sum of atrazine and deethylatrazine. On the other hand, in three of the four areas studied (Washington excluded because it did not have any detections of metolachlor or its degradation products), the proportion of metolachlor in ground water was far less than that for its degradation products.”


Story Source:

The above story is based on materials provided by American Society of Agronomy. Note: Materials may be edited for content and length.


Journal Reference:

  1. Steele et al. Occurrence and Fate of Pesticides in Four Contrasting Agricultural Settings in the United States. Journal of Environmental Quality, 2008; 37 (3): 1116 DOI: 10.2134/jeq2007.0166

Cite This Page:

American Society of Agronomy. "Pesticides Persist In Ground Water." ScienceDaily. ScienceDaily, 2 July 2008. <www.sciencedaily.com/releases/2008/07/080701110412.htm>.
American Society of Agronomy. (2008, July 2). Pesticides Persist In Ground Water. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2008/07/080701110412.htm
American Society of Agronomy. "Pesticides Persist In Ground Water." ScienceDaily. www.sciencedaily.com/releases/2008/07/080701110412.htm (accessed September 17, 2014).

Share This



More Earth & Climate News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Isolated N. Korea Asks For International Help With Volcano

Isolated N. Korea Asks For International Help With Volcano

Newsy (Sep. 16, 2014) Mount Paektu volcano in North Korea is showing signs of life and there's not much known about it. 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:
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