Organic matter compositions and loadings in soils and sediments along the Fly River, Papua New Guinea

摘要: The compositions and loadings of organic matter in soils sediments from a diverse range environments along the Fly River system were determined to investigate carbon transport sequestration this region. Soil horizons highland sites representative upland sources have contents (%OC) that 0.3 25 wt%, carbon:nitrogen ratios (OC/N) 7 25 mol/mol, highly negative stable isotopic (δ13Corg   −25‰) non-woody vegetation biomarkers (cinnamyl phenols cutin acids) more abundant relative upper floodplain sites. Soils developed on relict Pleistocene terraces, which are typically not flooded receive little sediment river, characterized by low %OC ( −21‰) LP concentrations (∼3 mg/100 mg OC). These contain modern reflects primarily local (C3 or C4) sources. Total suspended solids collected river varied widely overall (1 < TSS < 9000 mg/L), (0.1–60 wt%), OC/N (7–17 mol/mol) δ13Corg signatures (−26 −32‰). reflect mixture C3 vascular plants freshwater algae. However, algal production appears be preserved soils. A comparison active (0.2 0.5 mg C/m2) with previous studies actively depositing adjacent delta–clinoform (0.4–0.7 mg C/m2) indicates less effective at sequestering than deltaic sediments. Furthermore, negligible accumulation rates display significantly lower (0.1–0.2 mg C/m2). This deficit likely mineralization sedimentary during long term oxidative weathering, further reducing storage.