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College science courses aim to teach students both disciplinary knowledge and scientific literacy skills. Several instruments have been developed to assess students' scientific literacy skills, but few studies have reported how demographic differences may play a role. The goal of this study was to determine whether demographic factors differentially impact students' scientific literacy skills. We assessed more than 700 students using the Test of Scientific Literacy Skills (TOSLS), a validated instrument developed to assess scientific literacy in college science courses. Interestingly, we found that Scholastic Aptitude Test (SAT) reading score was the strongest predictor of TOSLS performance, suggesting that fundamental literacy (reading comprehension) is a critical component of scientific literacy skills. Additionally, we found significant differences in raw scientific literacy skills on the basis of ethnicity (underrepresented minority [URM] vs. non-URM), major (science, technology, engineering, and mathematics [STEM] vs. non-STEM), year of college (e.g., senior vs. freshman), grade point average (GPA), and SAT math scores. However, when using multivariate regression models, we found no difference based on ethnicity. These data suggest that students' aptitude and level of training (based on GPA, SAT scores, STEM or non-STEM major, and year of college) are significantly correlated with scientific literacy skills and thus could be used as predictors for student success in courses that assess scientific literacy skills.

Recently, it has been shown that U-Th dated speleothems may provide a valuable archive of atmospheric radiocarbon (14C), but the reliability of these records is dependent upon the stability of the dead carbon proportion (DCP) derived from the soil and bedrock. In order to assess climatic influences on speleothem DCP, we have investigated DCP variability over the Holocene interval where atmospheric 14C is well known based on dendrochronologically dated tree rings by conducting 14C measurements on a U-Th dated stalagmite (HS4) from Heshang Cave, Hubei Province, China (30°27 'N, 110°25 'E; 294 m) spanning 0.5-9.6 ka. We investigated climatic controls on DCP, and found that DCP in HS4 has an average value over the Holocene of 10.3 ± 1.5%, with an average age offset from atmospheric radiocarbon of 875 ± 130 years, and displays a response to both precipitation increases and decreases. HS4 DCP increases during the wetter mid-Holocene interval (~5.5-7.1 ka), likely reflecting a shift to more closed-system dissolution in response to increased soil moisture. DCP decreases during the 8.2 ka event, a time period of dry conditions at Heshang Cave, though the lower amplitude of this shift indicates that DCP may be less sensitive to dry events. Speleothems are potentially valuable archives of atmospheric radiocarbon, especially in older portions of the 14C calibration curve where knowledge of atmospheric 14C is limited, however minor climatic influences on DCP could introduce uncertainties of several hundred years to calibrated ages. © 2014 Elsevier B.V.

Marine radiocarbon (14C) is a widely used tracer of past ocean circulation, but very few high-resolution records have been obtained. Here, we report a time series of carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from the Newport Beach pier in Orange County, within the Southern California Bight, from 2005 to 2010. Surface seawater was collected bimonthly and analyzed for Δ14C, δ13C, and salinity. Results from May 2005 to November 2010 show no long-term changes in δ13C DIC values and no consistent variability that can be attributed to upwelling. Δ14C DIC values have lowered from ~34‰ to about ~16‰, an 18‰ decrease from the beginning of this project in 2005, and is consistent with the overall 14C depletion from the atmospheric thermonuclear bomb pulse at the end of the 1950s. Δ14C DIC values, paired with salinity, do appear to be suitable indicators of upwelling strength with periods of upwelling characterized by more saline and lower DIC Δ14C values. However, a similar signal was not observed during the strong upwelling event of 2010. These results were obtained in the Southern California Bight where upwelling is fairly weak and there is a complex oceanographic circulation in comparison with the remaining western USA coastline. It is therefore likely that the link between DIC Δ14C, salinity, and upwelling would be even stronger at other sites. These data represent the longest time series of Δ14C data from a coastal Southern California site performed to date.

The seasonal cycle is a fundamental aspect of climate, with a significant influence on mean climate and on human societies. Assessing seasonality in different climate states is therefore important but, outside the tropics, very few palaeoclimate records with seasonal resolution exist and there are currently no glacial-age seasonal-resolution sea-surface-temperature (SST) records at mid to high latitudes. Here we show that both Mg/Ca and oxygen isotope (δ18O) ratios in modern limpet (Patella) shells record the seasonal range of SST in the western Mediterranean - a region particularly susceptible to seasonal change. Analysis of a suite of fossil limpet shells from Gibraltar shows that SST seasonality was greater during the last glacial by ~2°C as a result of greater winter cooling. These extra-tropical seasonal-resolution SST records for the last glacial suggest that the presence of large ice-sheets in the northern hemisphere enhances winter cooling. This result also indicates that seasonality in the Mediterranean is not well-represented in most palaeoclimate models, which typically show little change in seasonal amplitude, and provides a new test for the accuracy of climate models. © 2011 Elsevier B.V.