Geology topics

Leonard I Wassenaar

Publications and source records attributed to Leonard I Wassenaar.

6 recordsLinked to original sources

USGS2016

American woodcock migratory connectivity as indicated by hydrogen isotopes

To identify factors contributing to the long-term decline of American woodcock, a holistic understanding of range-wide population connectivity throughout the annual cycle is needed. We used band recovery data and isotopic composition of primary (P1) and secondary (S13) feathers to estimate population sources and connectivity among natal, early fall, and winter ranges of hunter-harvested juvenile American woodcock. We used P1 feathers from known-origin pre-fledged woodcock ( n  = 43) to create a hydrogen δ 2 H f isoscape by regressing δ 2 H f against expected growing-season precipitation ( δ 2 H p ). Modeled δ 2 H p values explained 79% of the variance in P1 δ 2 H f values, indicating good model fit for estimating woodcock natal origins. However, a poor relationship ( r 2  = 0.23) between known-origin, S13 δ 2 H f values, and expected δ 2 H p values precluded assignment of early fall origins. We applied the δ 2 H f isoscape to assign natal origins using P1 feathers from 494 hunter-harvested juvenile woodcock in the United States and Canada during 2010–2011 and 2011–2012 hunting seasons. Overall, 64% of all woodcock origins were assigned to the northernmost (>44°N) portion of both the Central and Eastern Management Regions. In the Eastern Region, assignments were more uniformly distributed along the Atlantic coast, whereas in the Central Region, most woodcock were assigned to origins within and north of the Great Lakes region. We compared our origin assignments to spatial coverage of the annual American woodcock Singing Ground Survey (SGS) and evaluated whether the survey effectively encompasses the entire breeding range. When we removed the inadequately surveyed Softwood shield Bird Conservation Region (BCR) from the northern portion of the SGS area, only 48% of juvenile woodcock originated in areas currently surveyed by the SGS. Of the individuals assigned to the northernmost portions of the breeding range, several were harvested in the southern extent of the wintering range. Based upon this latitudinal winter stratification, we examined whether woodcock employed a leapfrog migration strategy. Using δ 2 H f values and band-recovery data, we found some support for this migration strategy hypothesis but not as a singular explanation. The large harvest derivation of individuals from the northernmost portions of the breeding range, and the difference in breeding distributions within each Management Region should be considered in future range-wide conservation and harvest management planning for American woodcock.

Journal of Wildlife Management↗

USGS2015

LIMS for Lasers 2015 for achieving long-term accuracy and precision of δ2H, δ17O, and δ18O of waters using laser absorption spectrometry

Rationale Although laser absorption spectrometry (LAS) instrumentation is easy to use, its incorporation into laboratory operations is not easy, owing to extensive offline manipulation of comma-separated-values files for outlier detection, between-sample memory correction, nonlinearity ( δ -variation with water amount) correction, drift correction, normalization to VSMOW-SLAP scales, and difficulty in performing long-term QA/QC audits. Methods A Microsoft Access relational-database application, LIMS (Laboratory Information Management System) for Lasers 2015, was developed. It automates LAS data corrections and manages clients, projects, samples, instrument-sample lists, and triple-isotope ( δ 17 O, δ 18 O, and δ 2 H values) instrumental data for liquid-water samples. It enables users to (1) graphically evaluate sample injections for variable water yields and high isotope-delta variance; (2) correct for between-sample carryover, instrumental drift, and δ nonlinearity; and (3) normalize final results to VSMOW-SLAP scales. Results Cost-free LIMS for Lasers 2015 enables users to obtain improved δ 17 O, δ 18 O, and δ 2 H values with liquid-water LAS instruments, even those with under-performing syringes. For example, LAS δ 2 H VSMOW measurements of USGS50 Lake Kyoga (Uganda) water using an under-performing syringe having ±10 % variation in water concentration gave +31.7 ± 1.6 ‰ (2-σ standard deviation), compared with the reference value of +32.8 ± 0.4 ‰, after correction for variation in δ value with water concentration, between-sample memory, and normalization to the VSMOW-SLAP scale. Conclusions LIMS for Lasers 2015 enables users to create systematic, well-founded instrument templates, import δ 2 H, δ 17 O, and δ 18 O results, evaluate performance with automatic graphical plots, correct for δ nonlinearity due to variable water concentration, correct for between-sample memory, adjust for drift, perform VSMOW-SLAP normalization, and perform long-term QA/QC audits easily. Published in 2015. This article is a U.S. Government work and is in the public domain in the USA.

Rapid Communications in Mass Spectrometry↗

USGS2015

A new isotopic reference material for stable hydrogen and oxygen isotope-ratio measurements of water—USGS50 Lake Kyoga Water

Rationale As a result of the need for isotopic reference waters having high δ 2 H VSMOW-SLAP and δ 18 O VSMOW-SLAP values for daily use, especially for tropical and equatorial-zone freshwaters, a new secondary isotopic reference material for international distribution was prepared from water collected from Lake Kyoga, Uganda. Methods This isotopic reference lakewater was filtered through a membrane with 0.2-µm pore size, homogenized, loaded into glass ampoules that were sealed with a torch and autoclaved to eliminate biological activity, and measured by dual-inlet isotope-ratio mass spectrometry. This reference material is available in a case of 144 glass ampoules each containing 5 mL of water. Results The δ 2 H and δ 18 O values of this reference material are +32.8 ± 0.4 and +4.95 ± 0.02 mUr (milliurey = 0.001 = 1 &permil;), respectively, relative to VSMOW, on scales normalized such that the δ 2 H and δ 18 O values of SLAP reference water are, respectively, −428 and −55.5 mUr. Each uncertainty is an estimated expanded uncertainty ( U  = 2 u c ) about the reference value that provides an interval that has about a 95 % probability of encompassing the true value. Conclusions This isotopic reference material, designated as USGS50, is intended as one of two reference waters for daily normalization of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer, of use especially for isotope-hydrology laboratories analyzing freshwater samples from equatorial and tropical regions.

Lake Kyoga↗

USGS2011

Improved online δ18O measurements of nitrogen‐ and sulfur‐bearing organic materials and a proposed analytical protocol

It is well known that N 2 in the ion source of a mass spectrometer interferes with the CO background during the δ 18 O measurement of carbon monoxide. A similar problem arises with the high‐temperature conversion (HTC) analysis of nitrogenous O‐bearing samples (e.g. nitrates and keratins) to CO for δ 18 O measurement, where the sample introduces a significant N 2 peak before the CO peak, making determination of accurate oxygen isotope ratios difficult. Although using a gas chromatography (GC) column longer than that commonly provided by manufacturers (0.6 m) can improve the efficiency of separation of CO and N 2 and using a valve to divert nitrogen and prevent it from entering the ion source of a mass spectrometer improved measurement results, biased δ 18 O values could still be obtained. A careful evaluation of the performance of the GC separation column was carried out. With optimal GC columns, the δ 18 O reproducibility of human hair keratins and other keratin materials was better than ±0.15 ‰ (n = 5; for the internal analytical reproducibility), and better than ±0.10 ‰ (n = 4; for the external analytical reproducibility).

Rapid Communications in Mass Spectrometry↗

USGS2010

Estimating 14C groundwater ages in a methanogenic aquifer

This paper addresses the problem of 14 C age dating of groundwaters in a confined regional aquifer affected by methanogenesis. Increasing CH 4 concentrations along the groundwater flow system and 13 C and 14 C isotopic data for dissolved inorganic carbon, dissolved organic carbon, and CH 4 clearly show the effect of methanogenesis on groundwater chemistry. Inverse reaction path modeling using NETPATH indicates the predominant geochemical reactions controlling the chemical evolution of groundwater in the aquifer are incongruent dissolution of dolomite, ion exchange, methanogenesis, and oxidation of sedimentary organic matter. Modeling of groundwater 14 C ages using NETPATH indicates that a significant part of groundwater in the Alliston aquifer is less than 13,000 years old; however, older groundwater in the range of 15,000–23,000 years is also present in the aquifer. This paper demonstrates that 14C ages calculated using NETPATH, incorporating the effects of methanogenesis on the carbon pools, provide reasonable groundwater ages that were not possible by other isotopic methods.

Water Resources Research↗

USGS2009

Does a lack of design and repeatability compromise scientific criticism? A Response to Smith et al. (2009)

In a recent paper published in The Auk , Smith et al. (2009) raised serious concerns over an apparent lack of reproducibility in their study of stable hydrogen isotope values (δD f ) in raptor feathers. The authors based their concerns on results obtained from different laboratories to which they submitted original and blind “repeats” over a multiyear period. A regression of the original sample δD versus “repeat” measurements showed an increase in the magnitude of residuals with increasing δD f , especially for values greater than about −80&permil; (Smith et al. 2009: fig. 2). Because of this, the authors “caution against the continued use of δD f for predicting geographic origin, and for addressing important conservation questions” (p. 41) and conclude that “it is counterproductive to move forward [with hydrogen isotopes in avian studies] without first establishing full confidence in the technique that underlies such insights and conservation recommendations” (p. 45). We disagree with these sentiments.

The Auk↗