The impact of the Cretaceous–Paleogene (K–Pg) mass extinction event on the global sulfur cycle: Evidence from Seymour Island, Antarctica

The Cretaceous–Paleogene (K–Pg) mass extinction event 66 million years ago led to large changes to the global carbon cycle, primarily via a decrease in primary or export productivity of the oceans. However, the effects of this event and longer-term environmental changes during the Late Cretaceous on the global sulfur cycle are not well understood. We report new carbonate associated sulfate (CAS) sulfur isotope data derived from marine macrofossil shell material from a highly expanded high latitude Maastrichtian to Danian (69–65.5 Ma) succession located on Seymour Island, Antarctica. These data represent the highest resolution seawater sulfate record ever generated for this time interval, and are broadly in agreement with previous low-resolution estimates for the latest Cretaceous and Paleocene. A vigorous assessment of CAS preservation using sulfate oxygen, carbonate carbon and oxygen isotopes and trace element data, suggests factors affecting preservation of primary seawater CAS isotopes in ancient biogenic samples are complex, and not necessarily linked to the preservation of original carbonate mineralogy or chemistry. Primary data indicate a generally stable sulfur cycle in the early-mid Maastrichtian (69 Ma), with some fluctuations that could be related to increased pyrite burial during the ‘mid-Maastrichtian Event’. This is followed by an enigmatic +4‰ increase in δ³⁴SCAS during the late Maastrichtian (68–66 Ma), culminating in a peak in values in the immediate aftermath of the K–Pg extinction which may be related to temporary development of oceanic anoxia in the aftermath of the Chicxulub bolide impact. There is no evidence of the direct influence of Deccan volcanism on the seawater sulfate isotopic record during the late Maastrichtian, nor of a direct influence by the Chicxulub impact itself. During the early Paleocene (magnetochron C29R) a prominent negative excursion in seawater δ³⁴S of 3–4‰ suggests that a global decline in organic carbon burial related to collapse in export productivity, also impacted the sulfur cycle via a significant drop in pyrite burial. Box modelling suggests that to achieve an excursion of this magnitude, pyrite burial must be reduced by >15%, with a possible role for a short term increase in global weathering rates. Recovery of the sulfur cycle to pre-extinction values occurs at the same time (∼320 kyrs) as initial carbon cycle recovery globally. These recoveries are also contemporaneous with an initial increase in local alpha diversity of marine macrofossil faunas, suggesting biosphere-geosphere links during recovery from the mass extinction. Modelling further indicates that concentrations of sulfate in the oceans must have been 2 mM, lower than previous estimates for the Late Cretaceous and Paleocene and an order of magnitude lower than today

Observations of wake characteristics at the Goodnoe Hills MOD-2 array

The array of three MOD-2 wind turbines and two meteorological towers at Goodnoe Hills, Washington, provides an opportunity to evaluate turbine and wake interactions in a real environment. The triangular arrangement of the three turbines provides opportunities to study the effect of wakes on the performance of a downwind turbine at three different distances: 5, 7, and 10 rotor diameters (D), where 1 D is 300 ft. The information obtained from this test configuration is critical to future wind farm activities and is a key objective of the MOD-2 test program. This report describes the analysis of data measured at the turbines and towers from August 29 to November 12, 1982. The data are 2-min averages of 1-s values. Background flow characteristics were also examined to determine if flow variations across the site could mask wake measurements. For this analysis, one year's data gathered at the meteorological towers were analyzed. The results show some differences between characteristics measured at the towers, but these differences were not great enough to consider in evaluating wakes at the towers

Candidate wind turbine generator site: annual data summary, January 1981-December 1981

Summarized hourly meteorological data for 34 candidate and wind turbine generator sites for calendar year 1981 are presented. These data are collected for the purpose of evaluating the wind energy potential at these sites and are used to assist in selection of potential sites for installation and testing of large wind turbines in electric utility systems. For each site, wind speed, direction, and distribution data are given in eight tables. Use of information from these tables, with information about specific wind turbines, should allow the user to estimate the potential for wind energy production at each site

Candidate wind-turbine generator site cumulative meteorological data summary and data for January 1982 through September 1982

Summarized cumulative hourly meteorological data for 20 new sites selected in early 1980 as part of the expanded candidate site program are presented. The reporting period is July 1980 through September 1982. The data collection program at some individual sites may not span this entire period, but will be contained within the reporting period. The purpose of providing the summarized data is to document the data collection program and to provide data that could be considered representative of longer-term meteorological conditions at each site. For each site, data are given in eight tables and in a topographic map showing the approximated location of the meteorological tower and turbine, if applicable. Use of the information from these tables, along with information about specific wind turbines, should allow the user to estimate the potential for longer-term average wind energy production at each site. Two appendices of other data are provided. Appendix A contains summarized data collected at new and original sites during the period January 1982 through September 1982. Appendix B contains cumulative summarized data for those original sites selected in 1976 with data collection programs continuing into 1982