6
Sampling and Analysis
6.1 Introduction
Pesticides are being applied in urban and agricultural settings at an annual
rate of almost 3 billion kg worldwide and at greater than 500 million kg in
the United States. Although these materials are applied to specifc targets,
such as soil, water, or plant foliage, pesticide residues can be unintentionally
transported from the target site through the air (atmosphere). Often, half or
more of applied pesticides are emitted to the air (Majewski et al., 1990). Once
airborne, pesticides may move downwind, where they can affect nontarget
organisms such as vegetation, aquatic and terrestrial wildlife, and humans.
Nevertheless, these chemicals are vital for control of pests.
Assessment of nontarget impacts of pesticides requires that pesticide
transport from the source region be accurately quantifed. Applications have
been developed by academic research laboratories and regulatory agencies (see the Glossary for descriptions of U.S. Environmental Protection
Agency (EPA), Occupational Safety and Health Administration (OSHA), and
United States Department of Agriculture (USDA) Animal and Plant Health
Inspection Service (APHIS)) for most volatile and semivolatile pesticides and
related contaminants including fumigants such as methyl bromide ethylene
oxide/propylene oxide, 1,3-D, chloropicrin, and others. Key steps are sampling, extraction, and detection.
6.2 Sampling
The choice of sampling is based on the properties of the analyte, environmental conditions, and the scope and goals of the study. When extracting
samples from ambient air, the vapor pressure is the primary physical property that dictates its distribution as an aerosol or vapor, which are collected
differently. Siting will depend on the topography and the meteorological conditions. Number of receptors and positioning are important considerations
DOI: 10.1201/9781003217602-6
91
Sampling and Analysis
6.1 Introduction
Pesticides are being applied in urban and agricultural settings at an annual
rate of almost 3 billion kg worldwide and at greater than 500 million kg in
the United States. Although these materials are applied to specifc targets,
such as soil, water, or plant foliage, pesticide residues can be unintentionally
transported from the target site through the air (atmosphere). Often, half or
more of applied pesticides are emitted to the air (Majewski et al., 1990). Once
airborne, pesticides may move downwind, where they can affect nontarget
organisms such as vegetation, aquatic and terrestrial wildlife, and humans.
Nevertheless, these chemicals are vital for control of pests.
Assessment of nontarget impacts of pesticides requires that pesticide
transport from the source region be accurately quantifed. Applications have
been developed by academic research laboratories and regulatory agencies (see the Glossary for descriptions of U.S. Environmental Protection
Agency (EPA), Occupational Safety and Health Administration (OSHA), and
United States Department of Agriculture (USDA) Animal and Plant Health
Inspection Service (APHIS)) for most volatile and semivolatile pesticides and
related contaminants including fumigants such as methyl bromide ethylene
oxide/propylene oxide, 1,3-D, chloropicrin, and others. Key steps are sampling, extraction, and detection.
6.2 Sampling
The choice of sampling is based on the properties of the analyte, environmental conditions, and the scope and goals of the study. When extracting
samples from ambient air, the vapor pressure is the primary physical property that dictates its distribution as an aerosol or vapor, which are collected
differently. Siting will depend on the topography and the meteorological conditions. Number of receptors and positioning are important considerations
DOI: 10.1201/9781003217602-6
91