140G0321Q0057 STATEMENT OF WORK.pdf

STATEMENT OF WORK

Radiocarbon dating of pika pellets from across the western USA

Introduction and Background

The USGS requires an independent lab to radiocarbon date an initial batch of 150 samples of fecal matter of American pikas. This dating is required because the USGS PI has surveyed areas of current and former American-pika (Ochotona princeps) occupancy since 2012 across the western USA and collected fecal matter samples.

1.0 Scope

The purpose of this contract is to obtain radiocarbon dates (either 1 or 2 date ranges, depending on the antiquity of the given sample) and all 7 measurements listed in Task 4.2 for 200 samples of pika fecal pellets in the base year (FY21), plus three additional years in which radiocarbon dating of additional samples could occur in future years. The ultimate goal is to not only understanding the specific factors that have caused pikas to no longer occupy the patches from which the pellets were collected, but also backcasting what pika distributions were in past decades. In turn, these goals help understand patterns of near- and longer-term vulnerability of American pikas and other wildlife species to changing environmental conditions and forecast where triage efforts should happen. Vendor shall provide consultations in terms of the interpretation of the results.

1) For each sample, which is in a sealed coin envelope, USGS-NOROCK will provide details on the collection location (latitude, longitude [both in decimal degrees], elevation), additional notes, and whether the pellet sample was associated with an old haypile, non-buried pellets, or buried pellets.

2.0 Applicable Documents

3.1 Literature Cited:

Millar, C. I., K. Heckman, C. Swanston, K. Schmidt, R. D. Westfall, and D. L. Delany.

2014. Radiocarbon dating of American pika fecal pellets provides insights into population extirpations and climate refugia. Ecological Applications 24:1748–1768.

{specifically, see the Methods section for the details of the approach}

4.0 Technical Requirements

Specific requirements

4.1 Graphite Measurement: The contractor shall perform radiocarbon measurements on prepared graphitized samples by Accelerator Mass Spectrometry, including primary and secondary samples.

4.1.1 The contractor shall measure samples in batches of roughly 50, measuring each batch within 8 weeks of receipt of graphite.

4.1.2 Given that the antiquity of the pellets is generally from years to a couple centuries old, precision of the estimated year of the sample should be 3‰-4‰ (3- 4 per mil; i.e., 0.3% - 0.4%), for all samples analyzed (Precision)

4.1.2.1 Given the state of the art of radiocarbon dating (Zoppi 2010, Millar et al. 2014), precision may be assessed via standard procedures to estimate analytical precision, using backgrounds, primary standards, and secondary standards (as described in Appendix I)

4.2 Data processing: The contractor shall convert raw data from the Accelerator Mass Spectrometry measurements into isotopic ratios.

4.3 Data reporting: The contractor shall generate radiocarbon data reports reflecting the radiocarbon abundance of samples and standards (Radiocarbon Data Reports). Radiocarbon Data Reports will be delivered to USGS-NOROCK in an Excel file format for each sub-batch of 50 samples, within 10 weeks of the vendor receiving the graphitized samples (Timeliness).

Production of Radiocarbon Data Reports will serve as proof of the satisfactory execution of all required tasks and fulfillment of technical requirements.

4.3.1 Radiocarbon Data Reports will produce, for each sample, all of these 7 Measurements (items 3-7 resemble those of Table 1, below):

1) Radiocarbon age, of each sample

2) Precision in the estimate of Change in the Carbon-14 amount

3) Change in the Carbon-14 amount (expressed in units of per mil): Δ14C

4) Fraction of the sample that is modern

5) Precision of that estimated fraction (expressed as + 2 sigma)

6) Calibrated age of the fecal pellets, on the far (i.e., older) side of the bomb curve

7) Calibrated age of the fecal pellets, on the near (i.e., younger) side of the bomb curve

5.0 Deliverables

From the lab sample analyses, the contractor shall provide to USGS-NOROCK, for each sample (i.e., each envelope of pika fecal pellets), all of the following 7 measurements, in Excel format (Radiocarbon Data Reports), within 10 weeks of the vendor receiving the graphitized samples (Timeliness):

1) Radiocarbon age, of each sample

2) Precision in the estimate of Change in the Carbon-14 amount

3) Change in the Carbon-14 amount (expressed in units of per mil): Δ14C

4) Fraction of the sample that is modern

5) Precision of that estimated fraction (expressed as + 2 sigma)

6) Calibrated age of the fecal pellets, on the far (i.e., older) side of the bomb curve

7) Calibrated age of the fecal pellets, on the near (i.e., younger) side of the bomb curve

The vendor shall achieve a precision of 3-4 per mil.

The contractor shall return the unused fecal pellets from each sample to USGS-NOROCK in individually labeled and simply sealed coin envelopes (in a way that allows easy re-inspection), so that USGS-NOROCK can retain them as evidence and vouchers to corroborate the previous pika occupancy, at each talus patch.

The vendor shall provide consultations to help USGS-NOROCK interpret the results.

6.0 Quality Assurance Plan (QAP)

Given the state of the art of radiocarbon dating, quality of dates is assured by simultaneous analysis of secondary standards of known age with all unknowns, standardized against primary standards. Liberal use of background samples (n = 2 per 50-unknown-sample batch), primary standards (n = 8 per 50-unknown-sample batch), and secondary standards (n = 2 per 50-unknown-sample batch) will guarantee the needed precision.

Task 4.1 The NOROCK PI shall evaluate Precision, as outlined in section 4.1 by discussing with successful vendor and if needed, requesting feedback from peer researchers that are very familiar with radiocarbon dating.

Task 4.3 The NOROCK PI shall assess the completeness (relative to Measurements listed in Section 4, and the state of the discipline outlined in Zoppi 2010 and Millar et al. 2014) and timeliness of the results provision (as a function of the date by which the graphitized samples are received by the vendor), once Radiocarbon Data Reports results are provided to USGS-

NOROCK.

Task 4.3.1 USGS-NOROCK shall assess whether the 7 metrics are provided for each sample as noted in Section 4, once results are provided to the USGS.