Environmental Time Series Characterization of Sediment and Porewater Mercury, Nitrogen, and Sulfide and Microbial Community Composition at Younger Lagoon Reserve, Santa Cruz, California, USA

The overlying water and porewater analyzed to produce the data provided here was collected at the University of California Natural Reserve System’s Younger Lagoon Reserve, doi: (10.21973/N3894D). Sampling sites included Beach Zone (BZ; 36.949380 N, -122.067624 W), at the southern edge of the lagoon, characterized by sandy sediment and a close connection to the ocean and East Fork (EF; 36.951483 N, -122.066275 W), at the northern boundary of the lagoon, characterized by organic-rich, clay sediment and spatial proximity to agricultural sites. Sampling events to characterize ambient conditions took place in December 2019, April 2020, October 2020. This dataset contains porewater and sediment total mercury (HgT) and methylated mercury (MeHg) concentrations accompanied by acid volatile sulfide (AVS) and chromium reducible sulfide (CRS) concentrations. Other characteristics of overlying and porewater from the same sampling dates also include: pH, oxygen concentration, temperature, and salinity. Nitrate, nitrite, and ammonium concentrations in porewater were determined by quantitative colorimetry method for all sampling events. Sediment organic matter was determined by loss-on-ignition (LOI). Sediment was sampled at both EF and BZ for microbial community characterization via 16s sequencing and the results of genus-level assignments are provided.