Publications by authors named "Sara Peek"

River deltas and their diverse array of aquatic environments are increasingly impacted by anthropogenic inputs of nitrogen (N). These inputs can alter the N biogeochemistry of these systems and promote undesirable phenomena including harmful algae blooms and invasive aquatic macrophytes. To examine N sources and biogeochemical processes in the Sacramento-San Joaquin Delta, a river delta located in central California, USA, that is fed primarily by the Sacramento River, we utilized a multi-tracer approach that measured N species concentrations and stable isotope values monthly from April 2011 to November 2012 in samples collected from the channelized mainstem of the Sacramento River, two channelized distributaries of the Sacramento River, and the Cache Slough Complex, a network of Sacramento River tributaries and shallow water wetland habitat.

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Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δN) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources.

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Article Synopsis
  • Despite reductions in external phosphorus loads since the 1980s, Lake Erie's water quality has worsened over the last decade, marked by increased harmful algal blooms and hypoxic conditions.
  • Researchers are investigating phosphorus cycling in the lake by studying pore-water phosphorus concentrations and sediment cores to quantify phosphorus flux from sediments.
  • Estimates indicate that the phosphorus sediment flux to Lake Erie’s central basin ranges from 300 to 2400 metric tons per year, suggesting that sediments are a significant internal source of phosphorus, contributing 8-20% of the total external phosphorus input.
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