The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014–2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V

Catchment productivity controls CO2 emissions from lakes

Most lakes are oversaturated with CO2 and are net CO2 sources to the atmosphere, yet their contribution to the global carbon cycle is poorly constrained1, 2, 3, 4. Their CO2 excess is widely attributed to in-lake oxidation of terrestrially produced dissolved organic carbon5. Here we use data collected over 26 years to show that the CO2 in 20 lakes is primarily delivered directly through inflowing streams rather than being produced in situ by degradation of terrestrial carbon. This implies that high CO2 concentrations and atmospheric emissions are not necessarily symptoms of heterotrophic lake ecosystems. Instead, the annual mean CO2 concentration increased with lake productivity and was proportional to the estimated net primary productivity of the catchment. Overall, about 1.6% of net primary productivity (range 1.2–2.2%) was lost to the atmosphere. Extrapolating globally, this is equivalent to CO2 losses of ~0.9 Pg C yr−1 (range 0.7–1.3), consistent with existing estimates. These data and our catchment productivity hypothesis re-enforce the high connectivity found between lakes, their catchment and the global C cycle6. They indicate that future concentrations of CO2 in lakes, and losses to the atmosphere, will be highly sensitive to altered catchment management and concomitant effects of climate change that modify catchment productivity