Northeastern TIME Lakes Dragonfly Mercury and supporting lake geochemistry

We sampled lake water and dragonfly larvae in 74 northeastern US lakes (TIME, or Temporally Integrated Monitoring of Ecosystems, lakes) that are part of the US EPA Long-Term Monitoring Network. The lakes are a statistical population of acid-sensitive lakes, a subset of US EPA EMAP lakes originally sampled in the early 1990s (Stoddard et al. 1996). The TIME lakes are 45 lakes in New York, 43 of which are in the Adirondacks, plus 29 lakes in New England. All lakes were sampled in a late-summer index period during 2012; lake water samples were collected manually from the epilimnion via boat, and dragonfly larvae were collected near shore using dip nets. Major ions, acid-base chemistry, total mercury and methylmercury in lake water, and total mercury and methylmercury in dragonfly larvae were analyzed. GIS analysis of lake watersheds and integration of selected EMAP-derived characteristics provides landscape and some morphometry variables for each lake. Additional annual geochemistry data for the lakes beginning in 1992 (with EMAP sampling) and ending in 2016 are available through US EPA.