182
Pesticides, Organic Contaminants, and Pathogens in Air
In a later study, air, sediment, and tadpoles were collected from 28 sites
in Sequoia and Kings Canyon National Parks. Residues frequently found in
sediments and tadpoles included current and historic use pesticides, PCBs,
and others. Concentration of all chemicals was very low on the order of 10 pg/
m 3 (Bradford et al., 2010). These studies showed clearly that pesticides from
California’s Central Valley are deposited in the Sierra Nevada Mountains.
Drift studies indicated that pesticides applied in the southern Central
Valley of California (agricultural) are transported through the air to the
Sequoia National Park in the Sierra Nevada Mountains (rural) (Aston and
Seiber, 1996, 1997). It was estimated that up to 16 kg of chlorpyrifos and its
oxon are deposited onto plant foliage over the course of a summer. These
studies revealed that the pines that dominate these forests are a major sink
for pesticides applied during summertime. Pine needles and other foliage work in a similar manner to solid-phase microextraction devices (see
Chapter 6). They are an important endpoint to study due to the relevance to
sensitive wildlife that live in trees.
Yellow-legged frogs (Rana muscosa) in the Tablelands region of the Sequoia
National Forest were thought to be in decline due to the direct winds
from the Central Valley of California. After a failed attempt to reintroduce
yellow-legged frogs, pesticide levels in water and surviving Tablelands frogs
were measured and compared to samples from the Sixty Lakes Basin in
Kings Canyon National Park which had a healthy frog population (Fellers
et al., 2004). γ-Chlordane and trans-nonachlor were detected in higher levels
in Tablelands frogs than in frogs from the Sixty Lakes Basin. OP insecticides,
chlorpyrifos and diazinon, were found in higher levels in water from the
Tablelands than in the Sixty Lakes Basin.
Transect studies of wetlands spanning from the Pacifc coast to the Cascades
or Sierra Nevada Mountains, cutting through Lassen Volcanic National Park,
Lake Tahoe, Yosemite National Park, and Sequoia National Park, revealed the
presence of 23 pesticides in water, sediment, and biota (in this case, Pacifc
chorus frogs) (Fellers et al., 2013). Individual pesticides did not exceed the
known lethal or sublethal concentrations, however, up to six different pesticides, including trifuralin, α-endosulfan, chlordanes, and trans-nonachlor,
were found in adult frog tissues. Chlorpyrifos oxon in sediment and total
endosulfans exceeded safe levels for frogs. β-Endosulfan, banned in 2011
by the Stockholm convention due to its neurotoxic effects to humans and
animals, was present in almost all samples. Lower cholinesterase activities
were measured in areas with the highest population decline. Chlorpyrifos
has been proven to reduce cholinesterase activities in tadpoles by up to 43%
(Widder and Bidwell, 2006). Interestingly, it does not affect tadpole survival
because of pesticide-induced predator mortality.
More than 90 current use pesticides and their degradates were measured
in a transect study at seven different elevations in the mountains of Northern
California, downwind from high pesticide use areas of the Central Valley
(Smalling et al., 2013). The most frequently detected were two fungicides,
Pesticides, Organic Contaminants, and Pathogens in Air
In a later study, air, sediment, and tadpoles were collected from 28 sites
in Sequoia and Kings Canyon National Parks. Residues frequently found in
sediments and tadpoles included current and historic use pesticides, PCBs,
and others. Concentration of all chemicals was very low on the order of 10 pg/
m 3 (Bradford et al., 2010). These studies showed clearly that pesticides from
California’s Central Valley are deposited in the Sierra Nevada Mountains.
Drift studies indicated that pesticides applied in the southern Central
Valley of California (agricultural) are transported through the air to the
Sequoia National Park in the Sierra Nevada Mountains (rural) (Aston and
Seiber, 1996, 1997). It was estimated that up to 16 kg of chlorpyrifos and its
oxon are deposited onto plant foliage over the course of a summer. These
studies revealed that the pines that dominate these forests are a major sink
for pesticides applied during summertime. Pine needles and other foliage work in a similar manner to solid-phase microextraction devices (see
Chapter 6). They are an important endpoint to study due to the relevance to
sensitive wildlife that live in trees.
Yellow-legged frogs (Rana muscosa) in the Tablelands region of the Sequoia
National Forest were thought to be in decline due to the direct winds
from the Central Valley of California. After a failed attempt to reintroduce
yellow-legged frogs, pesticide levels in water and surviving Tablelands frogs
were measured and compared to samples from the Sixty Lakes Basin in
Kings Canyon National Park which had a healthy frog population (Fellers
et al., 2004). γ-Chlordane and trans-nonachlor were detected in higher levels
in Tablelands frogs than in frogs from the Sixty Lakes Basin. OP insecticides,
chlorpyrifos and diazinon, were found in higher levels in water from the
Tablelands than in the Sixty Lakes Basin.
Transect studies of wetlands spanning from the Pacifc coast to the Cascades
or Sierra Nevada Mountains, cutting through Lassen Volcanic National Park,
Lake Tahoe, Yosemite National Park, and Sequoia National Park, revealed the
presence of 23 pesticides in water, sediment, and biota (in this case, Pacifc
chorus frogs) (Fellers et al., 2013). Individual pesticides did not exceed the
known lethal or sublethal concentrations, however, up to six different pesticides, including trifuralin, α-endosulfan, chlordanes, and trans-nonachlor,
were found in adult frog tissues. Chlorpyrifos oxon in sediment and total
endosulfans exceeded safe levels for frogs. β-Endosulfan, banned in 2011
by the Stockholm convention due to its neurotoxic effects to humans and
animals, was present in almost all samples. Lower cholinesterase activities
were measured in areas with the highest population decline. Chlorpyrifos
has been proven to reduce cholinesterase activities in tadpoles by up to 43%
(Widder and Bidwell, 2006). Interestingly, it does not affect tadpole survival
because of pesticide-induced predator mortality.
More than 90 current use pesticides and their degradates were measured
in a transect study at seven different elevations in the mountains of Northern
California, downwind from high pesticide use areas of the Central Valley
(Smalling et al., 2013). The most frequently detected were two fungicides,