Pyrethroid Occurrence in Seawater
Based on the theory mentioned above and in order to ascertain the concentration of
the dissolved fraction of pyrethroids, a study using passive water samplers in the
field was carried out in Southern Chile. Thin-film (~7–10 μm) EVA samplers were
deployed (~4 m distance) around four different salmon farms located in the northern
Chilean Patagonia, as shown in Fig. 4. The study was based on the laboratory
methodology and field deployment strategy previously reported by Tucca et al.
[73]. As a first approach, EVA–water partition coefficients (K EVA-W ) for
cypermethrin and deltamethrin were estimated according to the plot constructed by
St. George et al. [72], as shown in Eq. (10):
Log K EVAÀW ¼ 1:04 Log K OW þ 0:22
ð10Þ
with this plot constructed under laboratory conditions. The EVA sampler presented a
good relationship with the octanol–water partition coefficient (K OW ) using pesticides
and PCBs [72, 75]. The estimation of C W in the field was calculated using the
following Eq. (11):
N ¼ K EVAÀW V EVA C W 1 À exp
R s t
K EVAÀW V EVA
!
ð11Þ
where N is the amount of pyrethroids in the sampler, V EVA is the volume of the EVA
copolymer, and R S is the sampling rate of the EVA for time t deployed in the field
(7 days). Based on laboratory calibration, an R S of 0.72 L d
À1 was used in this study.
More adjustment conditions through in situ calibrations (i.e., flow, salinity, and
temperature conditions) should be considered for future studies to establish sampling
parameters for the EVA sampler [76].
The cypermethrin and deltamethrin concentrations in water detected by passive
samplers in salmon cages are shown in Table 4. Pyrethroid concentrations in
seawater ranged between 0.05 and 13.62 ng L
À1 . Deltamethrin means of 1.11
Table 4 Water concentrations of synthetic pyrethroids after treatments on salmon farms located in
Southern Chile
Salmon farm
Treatment
Water concentration (ng L
À1
)
Mean
SD (n)
Range
SF-1
Deltamethrin
1.11
Æ 0.88 (5)
0.05–2.43
SF-2
Cypermethrin
3.40
Æ 4.75 (7)
0.33–13.62
SF-3
Deltamethrin
2.54
Æ 2.16 (3)
0.12–4.28
SF-4
Cypermethrin
ND
ND
ND
ND not detected, SF salmon farm, n number of passive samplers with detected pyrethroids after
deployment in the field
192
F. Tucca and R. Barra
Based on the theory mentioned above and in order to ascertain the concentration of
the dissolved fraction of pyrethroids, a study using passive water samplers in the
field was carried out in Southern Chile. Thin-film (~7–10 μm) EVA samplers were
deployed (~4 m distance) around four different salmon farms located in the northern
Chilean Patagonia, as shown in Fig. 4. The study was based on the laboratory
methodology and field deployment strategy previously reported by Tucca et al.
[73]. As a first approach, EVA–water partition coefficients (K EVA-W ) for
cypermethrin and deltamethrin were estimated according to the plot constructed by
St. George et al. [72], as shown in Eq. (10):
Log K EVAÀW ¼ 1:04 Log K OW þ 0:22
ð10Þ
with this plot constructed under laboratory conditions. The EVA sampler presented a
good relationship with the octanol–water partition coefficient (K OW ) using pesticides
and PCBs [72, 75]. The estimation of C W in the field was calculated using the
following Eq. (11):
N ¼ K EVAÀW V EVA C W 1 À exp
R s t
K EVAÀW V EVA
!
ð11Þ
where N is the amount of pyrethroids in the sampler, V EVA is the volume of the EVA
copolymer, and R S is the sampling rate of the EVA for time t deployed in the field
(7 days). Based on laboratory calibration, an R S of 0.72 L d
À1 was used in this study.
More adjustment conditions through in situ calibrations (i.e., flow, salinity, and
temperature conditions) should be considered for future studies to establish sampling
parameters for the EVA sampler [76].
The cypermethrin and deltamethrin concentrations in water detected by passive
samplers in salmon cages are shown in Table 4. Pyrethroid concentrations in
seawater ranged between 0.05 and 13.62 ng L
À1 . Deltamethrin means of 1.11
Table 4 Water concentrations of synthetic pyrethroids after treatments on salmon farms located in
Southern Chile
Salmon farm
Treatment
Water concentration (ng L
À1
)
Mean
SD (n)
Range
SF-1
Deltamethrin
1.11
Æ 0.88 (5)
0.05–2.43
SF-2
Cypermethrin
3.40
Æ 4.75 (7)
0.33–13.62
SF-3
Deltamethrin
2.54
Æ 2.16 (3)
0.12–4.28
SF-4
Cypermethrin
ND
ND
ND
ND not detected, SF salmon farm, n number of passive samplers with detected pyrethroids after
deployment in the field
192
F. Tucca and R. Barra