(Æ0.9) ng L
À1 and 2.54 (Æ2.2) ng L
À1 at salmon farms 1 and 2 were observed, while
a cypermethrin mean of 3.40 (Æ4.8) ng L
À1 was recorded at salmon farm 3. No
cypermethrin concentration in seawater was detected at salmon farm 4. These levels
were within an order of magnitude (ng L
À1 ) of those detected using grab sampling at
several times during cypermethrin and deltamethrin treatments on salmon farms
[8, 34, 35]. It has been reported – and was observed in this study – that pyrethroids
decrease rapidly once released from a cage site after treatment. Due to their low
water persistence and rapid dispersion in seawater, passive samplers may be useful
time-integrative tools to detect the dissolved fraction of organic chemicals bioavailable in seawater after treatment of fish.
2.2.2 Pyrethroid Occurrence in Sediment
The northern Chilean Patagonia (Los Lagos Region, 41
28
0 18
00 S; 72
56
0 18
00 W) is
characterized by the presence of active aquaculture. However, there are few reports
on the environmental occurrence of pyrethroids in the northern Chilean Patagonia
originating in the salmon farming industry [77, 78]. Tucca et al. [77] reported
cypermethrin concentrations in sediment (dry weight, d.w.) based on a sampling
strategy around salmon cages (radius <100 m) in accord with dominant currents
and tidal influences. Cypermethrin concentrations ranged between 18.0 and
1,323.7 ng g
À1 , while deltamethrin was not detected on the sampled salmon farm.
In addition, Placencia et al. [78] reported deltamethrin concentrations in surface
sediment samples collected on a cruise among 12 stations distributed throughout the
continuous waterways of the fjords–Chiloé inner sea. Detected deltamethrin concentrations in sediment (d.w.) proved to be higher than those reported around salmon
farms, with ranges between 390 and 1,020 ng g
À1 . These results suggest that
deltamethrin-accumulating areas are dominated by the hydrodynamics in the study
area, which act as a long-distance transport pathway for this antiparasitic medicine.
Pyrethroids in sediment samples (1 g, d.w.) were extracted using the methodology described by Feo et al. [79]. Briefly, sediment mixed with powdered copper
(0.5 g) was extracted twice with n-hexane/dichloromethane (2:1, 20 mL) in an
ultrasonic bath for 15 min at room temperature. Then, extracts were cleaned using
a Florisil cartridge (2 g/15 mL). Previously, the cartridges were conditioned with
ethyl acetate/dichloromethane (2:1). The cartridges were eluted with 50 mL of ethyl
acetate until reaching full concentration. The samples were concentrated using a
rotary evaporator and reconstituted with 250 μL of ethyl acetate. Pyrethroids were
quantified by GC-NCI-MS [79].
Pyrethroid concentrations detected in the sediment of four salmon farms located
in the northern Chilean Patagonia are shown in Table 5. On salmon farms 1 (SF-1)
and 3 (SF-3), where deltamethrin was used as a treatment of fish, mean levels of 1.55
(Æ1.19, n ¼ 21) ng g
À1 and 1.12 (Æ1.69, n ¼ 24) ng g
À1 , respectively, were found.
Lower levels of cypermethrin were observed, with mean concentrations of 0.70
(Æ1.06, n ¼ 15) and 0.08 (Æ0.09, n ¼ 18) on SF-2 and SF-4, respectively. Higher
concentrations of both pyrethroids were measured within a radius of 500 m, with the
Environmental Risks of Synthetic Pyrethroids Used by the Salmon Industry in. . .
193
À1 and 2.54 (Æ2.2) ng L
À1 at salmon farms 1 and 2 were observed, while
a cypermethrin mean of 3.40 (Æ4.8) ng L
À1 was recorded at salmon farm 3. No
cypermethrin concentration in seawater was detected at salmon farm 4. These levels
were within an order of magnitude (ng L
À1 ) of those detected using grab sampling at
several times during cypermethrin and deltamethrin treatments on salmon farms
[8, 34, 35]. It has been reported – and was observed in this study – that pyrethroids
decrease rapidly once released from a cage site after treatment. Due to their low
water persistence and rapid dispersion in seawater, passive samplers may be useful
time-integrative tools to detect the dissolved fraction of organic chemicals bioavailable in seawater after treatment of fish.
2.2.2 Pyrethroid Occurrence in Sediment
The northern Chilean Patagonia (Los Lagos Region, 41
28
0 18
00 S; 72
56
0 18
00 W) is
characterized by the presence of active aquaculture. However, there are few reports
on the environmental occurrence of pyrethroids in the northern Chilean Patagonia
originating in the salmon farming industry [77, 78]. Tucca et al. [77] reported
cypermethrin concentrations in sediment (dry weight, d.w.) based on a sampling
strategy around salmon cages (radius <100 m) in accord with dominant currents
and tidal influences. Cypermethrin concentrations ranged between 18.0 and
1,323.7 ng g
À1 , while deltamethrin was not detected on the sampled salmon farm.
In addition, Placencia et al. [78] reported deltamethrin concentrations in surface
sediment samples collected on a cruise among 12 stations distributed throughout the
continuous waterways of the fjords–Chiloé inner sea. Detected deltamethrin concentrations in sediment (d.w.) proved to be higher than those reported around salmon
farms, with ranges between 390 and 1,020 ng g
À1 . These results suggest that
deltamethrin-accumulating areas are dominated by the hydrodynamics in the study
area, which act as a long-distance transport pathway for this antiparasitic medicine.
Pyrethroids in sediment samples (1 g, d.w.) were extracted using the methodology described by Feo et al. [79]. Briefly, sediment mixed with powdered copper
(0.5 g) was extracted twice with n-hexane/dichloromethane (2:1, 20 mL) in an
ultrasonic bath for 15 min at room temperature. Then, extracts were cleaned using
a Florisil cartridge (2 g/15 mL). Previously, the cartridges were conditioned with
ethyl acetate/dichloromethane (2:1). The cartridges were eluted with 50 mL of ethyl
acetate until reaching full concentration. The samples were concentrated using a
rotary evaporator and reconstituted with 250 μL of ethyl acetate. Pyrethroids were
quantified by GC-NCI-MS [79].
Pyrethroid concentrations detected in the sediment of four salmon farms located
in the northern Chilean Patagonia are shown in Table 5. On salmon farms 1 (SF-1)
and 3 (SF-3), where deltamethrin was used as a treatment of fish, mean levels of 1.55
(Æ1.19, n ¼ 21) ng g
À1 and 1.12 (Æ1.69, n ¼ 24) ng g
À1 , respectively, were found.
Lower levels of cypermethrin were observed, with mean concentrations of 0.70
(Æ1.06, n ¼ 15) and 0.08 (Æ0.09, n ¼ 18) on SF-2 and SF-4, respectively. Higher
concentrations of both pyrethroids were measured within a radius of 500 m, with the
Environmental Risks of Synthetic Pyrethroids Used by the Salmon Industry in. . .
193