Pesticide Fate Research Group (PFRG)

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Pesticides are applied in agricultural and urban areas to control weeds, insects, and other pests.  These chemicals can be transported off-site into streams and ground water where they partition between water and sediment and degrade over time.  Both the parent pesticides and the degradates can potentially cause adverse effects on aquatic organisms and human health.

Understanding the Occurrence, Transport, and Fate of Current-Use Pesticides in the Environment

The Pesticide Fate Research project (a part of the USGS Toxic Substances Hydrology Program - Pesticide Studies project) is a series of studies to assess the occurrence, transport, and fate of current-use pesticides in surface and ground waters throughout California.  Analytical methods are developed to measure pesticide concentrations in water, sediments, and biological tissues at environmentally-relevant levels.  Field studies are conducted to determine the spatial and temporal occurrence of these pesticides and their degradates.  Complimentary laboratory studies are conducted to understand the factors controlling partitioning and degradation rates in the environment.  By collaborating with toxicologists and ecologists, the potential effects on aquatic organisms and human health can be assessed.

 

A map of California of pesticide sampling locations

Map showing approximate sampling locations.

Coordinated Pesticide Reconnaissance Study of Surface Waters in California

Pesticides are used throughout the State of California in both urban and agricultural settings and are routinely detected in surface water. Each year, new pesticides are introduced to the market and often become detected in surface water. It can take several years or more for routine monitoring programs to acquire the capability to detect new and understudied pesticides of concern because established programs are typically slow to adapt and lag times in the development of analytical methods for new pesticides can be lenghtly. This means that it can take a long time to identify if a new or understudied pesticide is present and impacting surface waters.

This study will utilize the unique analytical capabilities of the USGS Pesticide Fate Research Group, Organic Chemistry Research Laboratory to assess the occurrence of a large suite of current-use pesticides and pesticide degradates (including numerous understudied compounds) in surface waters within California. Water and sediment samples will be collected and analyzed from sites undergoing concurrent, routine water chemistry and toxicity monitoring by various State entities. Analyses conducted by the USGS will greatly expand upon the work conducted by these groups and aid in evaluating their toxicity testing data. The results of this study will be used by the cooperator to determine what emerging pesticides are present in surface water and if any are present above known toxicity values, to prioritize which pesticides, if any, warrant further investigation, and to evaluate models and monitoring protocols.

The proposed study will be a two year reconnaissance of current-use pesticides and pesticide degradates in surface-water and suspended sediment samples collected from 12 sites located throughout California. Samples will be collected from six urban runoff influenced sites and 6 sites primarily influenced by agricultural runoff. Samples will be collected three times per year for two consecutive years at each site and will consist of a combination of wet and dry season events. Samples will be collected by various State entities following State mandated Surface Water Ambient Monitoring Program protocols. Water samples will be analyzed at the USGS PFRG laboratory by two analytical methods (GC/MS and LC/MS/MS) for a suite of 152 pesticides and degradates. Suspended sediments associated with these water samples will be analyzed for 125 pesticides and degradates by GC/MS.

 

Delta Regional Monitoring Program: Current-use Pesticides

The Sacramento-San Joaquin Delta is an area of critical habitat for numerous species of concern, including chinook salmon and the threatened Delta Smelt. In recent years multiple pelagic species within the Delta have been in sharp decline. Previous studies have shown that current-use pesticides associated with agricultural and urban runoff are present in the Delta throughout the year. While studies have suggested that contaminants (including current-use pesticides) may play a role in the decline of pelagic fish species in the Delta, less than half of all pesticides applied in the Delta watershed are analyzed for during routine monitoring. The concentrations and potential ecological effects of these unmonitored pesticides in the Delta ecosystem are unknown.

picture of salmon swimming in a river

Salmon swimming in a river. (Public domain)

This study will utilize the unique analytical capabilities of the USGS Pesticide Fate Research Group (PFRG), Organic Chemistry Research Laboratory (OCRL) to assess the occurrence of a large suite of understudied, current-use pesticides and pesticide degradates in surface waters entering the Sacramento/San Joaquin Delta. Water and suspended sediment samples will be collected and analyzed for these pesticide compounds from sites undergoing concurrent toxicity monitoring by the U.C. Davis Aquatic Health Program (AHP) Laboratory. Analyses conducted by the USGS will greatly aid in evaluating these toxicity testing data. The results of this study will be used by the cooperator to evaluate whether pesticides are present in surface water inflows to the Delta at levels determined to be above toxicity values, to prioritize which pesticides, if any, warrant further investigation, and provide valuable information regarding the health of the Delta ecosystem.

The proposed study will be a an ongoing effort to better understand the occurrence of current-use pesticides and pesticide degradates in surface waters and suspended sediment entering the Sacramento/San Joaquin Delta and the possible effects of exposure to these waters on laboratory-cultured test organisms. Samples will be collected monthly from five baseline sites and five times per year at an additional four sites during specified storm-related and seasonal events. Water samples will be analyzed at the USGS PFRG laboratory by two analytical methods (GC/MS and LC/MS/MS) for a suite over 150 pesticides and degradates. Suspended sediments associated with these water samples will be analyzed for 128 pesticides and degradates by GC/MS. This study will consist of four tasks: (1) project oversight and reporting; (2) sample collection; (3) analyses of environmental and QA/QC samples; (4) preparation of a USGS Data-Series Report.

 

A picture of a river in the neonicotionoid insecticide study

A river in the neonicotionoid insecticide study

Neonicotioniods in Surface Water

Neonicotinoid insecticides are of environmental concern, especially because of potential adverse effects to pollinators, but little is known about their overall occurrence in surface water. Neonicotinoids are commonly used in both agricultural and urban settings. Most current research has focused on their fate near the point of application ("edge of field"). These compounds are water soluble (log Kow <1) and have aqueous half-lives on the order of months, so they have the potential for offsite transport. To better understand the fate and transport of neonicotinoid insecticides, water samples were collected from streams and creeks across the United States for six neonicotinoids. These studies include a nationwide single-point sampling and several regional studies including Iowa, Georgia, and the Chesapeake Bay.

 

Picture of a bee pollinating a flower

Bee pollinating a flower. (Public Domain)

Pesticides in Native Bees

Much attention has been given to the impact of pesticides on honeybees; however, less research has been conducted with native bees. There is little information on the potential exposure of native bees to pesticides in agricultural landscapes. To better understand interactions between native bees and pesticides, native bees are being collected from Conservation Reserve Program (CRP) grasslands located in two different land cover areas (rangeland and cropland) in northeastern Colorado. Habitat quality and quantity are metrics currently being used to better understand the ecosystem services CRP fields provide for native pollinators. However, there is limited information on the effect of pesticide exposure to native bees as they forage in these areas.