Fingerprinting generates reliable sediment provenance information which supports devising policy or practical strategies for soil conservation and sediment management,but it remains challenging in areas with fragmente...Fingerprinting generates reliable sediment provenance information which supports devising policy or practical strategies for soil conservation and sediment management,but it remains challenging in areas with fragmented landscapes and diverse land use practices.This study evaluated the seasonality of biomarker signatures and their variability among particle size fractions,and apportioned target time-integrated suspended sediment to land use-based sources in an intensive agricultural watershed with mosaic land use patch configurations and crop-specific farming practices.Source materials(i.e.,topsoil)from dry croplands,paddy fields and citrus orchards were sampled,and target time-integrated sus-pended sediment samples were collected at the watershed outlet.The content and compound-specific δ^(13)C of long-chain saturated n-alkanes(C_(23)-C_(33))were determined for two particle size fractions(i.e.,<25 μm,25-63 μm).The δ^(13)C of monomeric n-alkanes displayed insignificant variabilities between particle size fractions and temporal variability across the sampling period.The MixSIAR Bayesian model was employed to quantify sediment source contributions.Due to land disturbance by tillage and crop plantation,our results revealed that paddy fields act as an important temporary secondary sediment source despite such fields conventionally being recognized as sediment sinks.Regardless,dry farmland remains the largest contributor to watershed sediment loss.A range of measures such as soil virgin-ization,returning straw to fields,and pasture cultures in orchards are recommended for precision sediment management at watershed scale.展开更多
基金supported by the National Key Research and Development Program of China(2023YFF1305203)the National Natural Science Foundation of China(42477340)+1 种基金the Royal Society Newton International Fellowship(NF161415)awarded to Qiang Tang and supervised by Adrian Collins,the Newton International Fellowships Alumni(AL∖231030)the Special Fund for Youth Team of Southwest University(SWU-XDJH-202306).
文摘Fingerprinting generates reliable sediment provenance information which supports devising policy or practical strategies for soil conservation and sediment management,but it remains challenging in areas with fragmented landscapes and diverse land use practices.This study evaluated the seasonality of biomarker signatures and their variability among particle size fractions,and apportioned target time-integrated suspended sediment to land use-based sources in an intensive agricultural watershed with mosaic land use patch configurations and crop-specific farming practices.Source materials(i.e.,topsoil)from dry croplands,paddy fields and citrus orchards were sampled,and target time-integrated sus-pended sediment samples were collected at the watershed outlet.The content and compound-specific δ^(13)C of long-chain saturated n-alkanes(C_(23)-C_(33))were determined for two particle size fractions(i.e.,<25 μm,25-63 μm).The δ^(13)C of monomeric n-alkanes displayed insignificant variabilities between particle size fractions and temporal variability across the sampling period.The MixSIAR Bayesian model was employed to quantify sediment source contributions.Due to land disturbance by tillage and crop plantation,our results revealed that paddy fields act as an important temporary secondary sediment source despite such fields conventionally being recognized as sediment sinks.Regardless,dry farmland remains the largest contributor to watershed sediment loss.A range of measures such as soil virgin-ization,returning straw to fields,and pasture cultures in orchards are recommended for precision sediment management at watershed scale.
