Late Holocene climate variability as preserved in high-resolution estuarine and lacustrine sediment archives

• Main Author: Hubeny, Jeremiah Bradford
• Format: Text
• Language: English
• Published: DigitalCommons@URI 2006
• Subjects: Geology; Pacific; North Atlantic; North Atlantic oscillation
• Online Access: https://digitalcommons.uri.edu/dissertations/AAI3239909

Concern regarding human-induced environmental and climate changes is becoming higher-profile. Aquatic sediment that is preserved at the bottom of a lake, estuary, or ocean provide high-quality proxy records of environmental and climate conditions that extend past the instrumental period. This dissertation performs high-resolution proxy analyses from annually resolved sediment records in Rhode Island and central New York State to interpret the natural and anthropogenically induced changes that have occurred over the Late Holocene. The Pettaquamscutt River Estuary's Lower Basin was studied and the post-glacial stratigraphy was interpreted. High-productivity lacustrine sedimentation started at ca. 15,500 cal BP and density-stratified estuarine conditions began about 1000 year ago. Over the last four centuries, the estuary has experienced anthropogenic influence through land clearance associated with European settlers, input of organic and non-organic pollutants, and nitrogen loading associated with domestic septic systems. High-resolution proxy data spanning the last millennium from the Pettaquamscutt River Estuary were used to interpret climate variability in the region. Mass accumulation rates of the photosynthetic fossil pigment bacteriochlorophyll e were linked to climate processes through water temperature limitation of bacterial production. Observed productivity/climatic cycles reveal linkages between the atmospheric-driven North Atlantic Oscillation phenomenon and the oceanic-driven Atlantic Multidecadal Oscillation at subdecadal and multidecadal periodicities. Clastic lamination thicknesses preserved in Pettaquamscutt River Estuary varved sediments record precipitation variability. This relationship was used to reconstruct precipitation variability in Rhode Island over the last millennium and to compare this record to teleconnection climate indices. In addition, a significant positive correlation was calculated between the lamination thicknesses and the Pacific/North American teleconnection pattern at both interannual and decadal time-scales. Finally, a varve record was reconstructed from the sediments of Fayetteville Green Lake, New York in order to compare precipitation variability in Rhode Island and New York. The carbonate laminations were significantly correlated to precipitation conditions in the state. The positive correlation is likely caused by increased precipitation leading to increased groundwater flow. The variability was significantly correlated to the Pacific/North American climate pattern at decadal time scales, suggesting that precipitation variability between Rhode Island and New York are partially driven by the Pacific/North American pattern.