Strontium isotope variation and carbonate versus silicate weathering in rivers from across Alaska: Implications for provenance studies

Fifty years of Cook Inlet beluga whale feeding ecology from isotopes in bone and teeth

“…Because 87 Sr/ 86 Sr ratios are driven by geologic processes, the ratio of 87 Sr/ 86 Sr in a river's water remains relatively unchanged at a specific site through time, but varies along the length of the river as a result of the geologic formation the river flows through. The magnitude of variation in terms of 87 Sr/ 86 Sr in ocean waters is considerably lower compared to the 87 Sr/ 86 Sr variation exhibited by the rivers and estuaries in Alaska (Bataille et al 2014, 2015. Therefore, 87 Sr/ 86 Sr ratios measured in the hard structures of an organism can be compared to the 87 Sr/ 86 Sr ratios of various estuarine and freshwater sources, and used to determine when an organism switches from a marine-influenced prey to a more freshwater-influenced prey.…”

“…It is notable that these changes in foraging ecology occurred while the range of CIBW continued to contract into the upper reaches of Cook Inlet (Rugh et al 2010), where freshwater prey items are available. To determine which freshwater input was most influential, we compared the 87 Sr/ 86 Sr ratio from GLGs to known ratios in river systems flowing into Cook Inlet available from Brennan et al (2014) and from the present study (Fig. 1).…”

“…Freshwater river samples were either collected above tidal influence (Susitna River, Yentna River, and Eagle River), or at low tide when access to areas above tidal influence was more difficult (Bird Creek, 20 Mile River, Portage Creek, and Placer River). Samples were collected for strontium isotope analysis following field collection methods described by Brennan et al (2014), and sent via 2 d FedEx ® to the Geochemistry Laboratory at the University of Utah, Salt Lake.…”

“…87 Sr/ 86 Sr ratios differ by geologic formation and influence the water in the rivers flowing through them (e.g. Brennan et al 2014, 2015, Padilla et al 2015, while marine waters are relatively uniform (Veizer 1989, Brennan et al 2015, thus 87 Sr/ 86 Sr ratios can be used to determine the likely location within an estuarine system where prey or predators spent time. Another explanation to changing δ 13 C and δ 15 N values is a change in the environmental baseline.…”

Potential impacts to perennial springs from tar sand mining, processing, and disposal on the Tavaputs Plateau, Utah, USA

“…For the Sr concentration, the estimated maximum laboratory uncertainty is 5%. The isotopic analysis of strontium was performed using a Thermo Neptune multi-collector ICP-MS with an in-line strontium purification method (Brennan et al, 2014). SRM 987 (Strontium carbonate, National Institute of Standards and Technology, USA) was run together with samples and the measured average value was 0.71029 ± 0.00001 (1 s, N = 8).…”