Late glacial and Holocene paleoenvironments in the midcontinent United States, inferred from Geneva Lake leaf wax, ostracode valve, and bulk sediment chemistry

Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

“…Submerged aquatic plants may, conversely, represent an important source of C23 alkane (Ficken et al, 2000, Puleo et al, 2020, but that does not appear to be the case at most of our sites. Higher terrestrial plants generate most of the C23 alkane based on isotopic compositions (Figure 5) and εC29/C23 distributions (Figure 6).…”

“…Compound-specific hydrogen isotopic ratios of leaf-wax n-alkanes are increasingly being used as proxies for past precipitation changes (Schefuß et al, 2005;Pagani et al, 2006;Tierney et al, 2008;Aichner et al, 2010a;Tierney et al, 2011;Rach et al, 2014;Curtin et al, 2019;Puleo et al, 2020). Leaf wax n-alkanes are simple, unbranched, long-chain H saturated organic compounds (formula: CnH2n+2) biosynthesized by plants at the leaf surface during leaf formation from alkanoic acids through the decarboxylation pathway (Jetter et al, 2006;Sachse et al, 2010;Tipple et al, 2013).…”

“…The difference in the most common chain lengths between aquatic and terrestrial plants has led to the use of the mid-chain alkane C23 as proxy for lake water δ 2 H and evapotranspiration (Ficken et al, 2000;Seki et al, 2011;Rach et al, 2014;Rach et al, 2017;Curtin et al, 2019;Puleo et al, 2020) and to the use of the long-chain alkane C29 as proxy for precipitation δ 2 H (Sachse et al, 2004;Sachse et al, 2012;McFarlin et al, 2019). A challenge with this approach has been that most plants produce varying amounts of both mid-and long-chain nalkanes (Ficken et al, 2000;Gao et al, 2011;Feakins et al, 2016;Wang et al, 2018;Dion-Kirschner et al, 2020;He et al, 2020), and the high production rates of all n-alkanes by terrestrial plants may dominate over aquatic sources even for mid-chain lengths (Freimuth et al, 2019).…”

Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

“…Compound-specific hydrogen isotopic ratios of leaf wax n-alkanes are increasingly being used as proxies for past precipitation changes (Schefuß et al, 2005;Pagani et al, 2006;Aichner et al, 2010a;Tierney et al, 2011;Rach et al, 2014;Curtin et al, 2019;Puleo et al, 2020). Leaf wax n-alkanes are simple, unbranched, long-chain saturated organic compounds (formula: CnH2n+2) biosynthesized by plants at the leaf surface during leaf formation from alkanoic acids through the decarboxylation pathway (Jetter et al, 2006;Tipple et al, 2013;Sachse et al, 2010).…”

“…Aquatic submerged and floating plants preferentially produce mid-chain homologues (n-C21 -n-C25) (Ficken et al, 2000, Aichner et al, 2010bGao et al, 2011), while terrestrial plants maximally form long-chain homologues (>n-C25) (Bush and McInerney, 2013). The difference in the most common chain lengths between aquatic and terrestrial plants has led to the use of the mid-chain n-C23 as proxy for lake water δ 2 H values and evapotranspiration (Nichols et al, 2006;Seki et al, 2011;Rach et al, 2014;Rach et al, 2017;Curtin et al, 2019;Puleo et al, 2020) and to the use of the long-chain n-C29-alkane as proxy for precipitation δ 2 H values (Schefuß et al, 2005;Pagani et al, 2006;Rach et al, 2014;Curtin et al, 2019;Puleo et al, 2020;Schartman et al, 2020). A challenge with this approach has been that most plants produce varying amounts of both mid-and long-chain n-alkanes (Ficken et al, 2000;Gao et al, 2011;Feakins et al, 2016;Wang et al, 2018;He et al, 2020), and the high production rates of all n-alkanes by terrestrial plants may dominate over aquatic sources even for mid-chain lengths (Freimuth et al, 2019;Dion-Kirschner et al, 2020).…”