Carcinogenic ptaquiloside in stream water at base flow and during storm events

TY - CONF

T1 - Carcinogenic ptaquiloside in stream water at base flow and during storm events

AU - Strobel, Bjarne W.

AU - Clauson-Kaas, Frederik

AU - Hansen, Hans Chr. Bruun

AU - Ramwell, Carmel

PY - 2017/5/8

Y1 - 2017/5/8

N2 - The globally occurring bracken fern (Pteridium sp.) is widespread in the broadleaf forests of Denmark, and densely populates several vegetation types in the Americas, Australia and on the British Isles. Bracken is toxic to livestock when consumed, and a group of potent carcinogens have been identified, of which the compound ptaquiloside (PTA) is the most abundant. Ptaquiloside has been shown to be highly water soluble, leachable from bracken fronds and litter, and present in the soil below bracken stands. During storm events throughfall from the bracken canopy was collected as well. Stream water samples were taken as grab samples, while throughfall accumulated in glass jars set out below the canopy. Field blanks and fortified lab controls were included to ensure reliability of the analysis. Ptaquiloside concentrations were determined using LC-MS/MS after a clean-up using solid phase extraction. Results showed that PTA levels in the stream were highly dependent on precipitation, and was rising considerably during rain events, peaking at 2.28 μg/L, before quickly (<2 hours) decreasing again to base flow concentrations (ng/L) when this seized. Sampling scheme and sample conservation are crucial to measure these 1-2 hours pulses of natural toxins in the stream. Collected canopy through fall showed high amounts of PTA (up to 169 µg/L) leached from bracken fronds during rainfall, with no apparent deterioration of this source throughout the storm event. The results are important for management of drinking water resources, as this shows the very real potential for PTA leaching to groundwater.

AB - The globally occurring bracken fern (Pteridium sp.) is widespread in the broadleaf forests of Denmark, and densely populates several vegetation types in the Americas, Australia and on the British Isles. Bracken is toxic to livestock when consumed, and a group of potent carcinogens have been identified, of which the compound ptaquiloside (PTA) is the most abundant. Ptaquiloside has been shown to be highly water soluble, leachable from bracken fronds and litter, and present in the soil below bracken stands. During storm events throughfall from the bracken canopy was collected as well. Stream water samples were taken as grab samples, while throughfall accumulated in glass jars set out below the canopy. Field blanks and fortified lab controls were included to ensure reliability of the analysis. Ptaquiloside concentrations were determined using LC-MS/MS after a clean-up using solid phase extraction. Results showed that PTA levels in the stream were highly dependent on precipitation, and was rising considerably during rain events, peaking at 2.28 μg/L, before quickly (<2 hours) decreasing again to base flow concentrations (ng/L) when this seized. Sampling scheme and sample conservation are crucial to measure these 1-2 hours pulses of natural toxins in the stream. Collected canopy through fall showed high amounts of PTA (up to 169 µg/L) leached from bracken fronds during rainfall, with no apparent deterioration of this source throughout the storm event. The results are important for management of drinking water resources, as this shows the very real potential for PTA leaching to groundwater.

M3 - Poster

ER -