Pesticide impact: Comparing lab, field-scale results

Jun 15, 2011

Assessing the environmental risk of pesticide use is an important, complex task that requires knowledge of the equilibrium sorption parameter. This helps researchers assess the risk of pesticides leaching into groundwater. For cost-effective assessments, this is usually determined through batch experiments that find the amount of pesticide in test soils as a function of concentration at a constant temperature. These experimental conditions differ considerably from real-world conditions. Thus, the validity of the data collected using this method is widely debated.

Recently, scientists from Germany and New Zealand evaluated parameters from different experiments that used the same pesticides and soils. Using this data, scientists analyzed the relationships between flow velocities of water, the residence time of the pesticides in the soil and the sorption parameters. Results from the study were published in the May-June 2011 issue of the .

Scientists found that the range of sorption constants increased with increasing water velocity. Only for water velocity values lower than 35 mm/day, the range of sorption constants was between zero and one. Typically, these values have been obtained in field-scale experiments run under unsaturated flow conditions using undisturbed soil columns. The scientists showed that replacing equilibrium constants obtained from standard measurement protocols for pesticide registration purposes would lead to misinterpretation of the data. Experiment operation times greater than one day, with a typical duration of several days to weeks, yield the most realistic results.

According to the authors, it is also important to consider sorption and desorption kinetics. The movement of pesticides into a soil matrix was found to depend strongly on the amount of accessible sorption sites, which is determined by soil water content and . An understanding of this movement will require experimental protocols that take soil structure and soil moisture content into account when researching the impact of .

Explore further: Obama readies climate change push at UN summit

More information: www.agronomy.org/publications/… q/abstracts/40/3/879

Provided by American Society of Agronomy

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Phosphate sorption characteristics of European alpine soils

Jun 14, 2011

Soil chemistry plays an important role in the composition of surface waters. In areas with limited human activities, properties of catchment soils directly relate to the exported nutrients to surface waters. Phosphate sorption ...

Where is your soil water? Crop yield has the answer

Jul 01, 2008

Crop yield is highly dependent on soil plant-available water, the portion of soil water that can be taken up by plant roots. Quantitative determination of the maximum amount of plant-available water in soil using traditional ...

Estimate soil texture-by-feel

Oct 15, 2008

The ability to estimate soil texture-by-feel is an important skill that students and registered soil scientists should learn.

Pesticides persist in ground water

Jul 01, 2008

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. ...

Recommended for you

Obama readies climate change push at UN summit

2 hours ago

President Barack Obama will seek to galvanize international support in the fight against climate change on Tuesday when he addresses the United Nations, with time running out on his hopes of leaving a lasting ...

New toxic spill traced to Mexico mine

3 hours ago

Civil protection authorities have confirmed new toxic spills in northwestern Mexico, where a massive acid spill from a copper mine contaminated waterways.

World greenhouse emissions threaten warming goal

17 hours ago

Emissions of greenhouse gases are rising so fast that within one generation the world will have used up its margin of safety for limiting global warming to 2°C (3.6°F), an international team of scientists ...

Tens of thousands join London climate march

18 hours ago

Tens of thousands of people in London joined a global day of protest Sunday to demand action on climate change, among them British actress Emma Thompson who said the challenge to save the planet was like ...

User comments : 0