Bromine as indicator of source of lacustrine sedimentary organic matter in paleolimnological studies

Abstract

Bromine (Br) to organic matter (OM) concentration ratio is studied in lake sediment sequences to provide information on environmental changes modifying OM production. The sequences studied were extracted from shallow lakes Morenito, El Trébol, Escondido, and Portezuelo; and deep lakes Futalaufquen, Moreno, and Traful (North Patagonia Andean range). Lake Morenito, a former Lake Moreno bay until its closure in AD 1960, showed a decrease in Br:OM ratios from 1.38 to 0.74 after lake closure, associated with an increase of primary autochthonous productivity attributable to the development of submerged and emerging macrophytes. Sedimentary sequences from Lakes Escondido, Portezuelo, and El Trébol (with large participation of macrophytes in primary productivity), and from Lakes Moreno, Futalaufquen, and Traful (with little development of littoral macrophytes), showed Br:OM ratios consistent with the Lake Morenito pattern. Consistently, the morphometric parameters mean depth and shoreline development correlate with Br:OM ratios. Therefore, Br:OM ratios can be associated with the composition of primary autochthonous productivity, with values of about 0.7 associated to significant macrophyte contributions, and higher values associated with more pelagic contributions. Accordingly, Br:OM variations along a sedimentary sequence can be associated with modifications on the composition of the primary autochthonous productivity of the water body, providing information on environmental changes.

1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

“…Linear regression tests on the Br and LOI550 results show a significant relationship with a R of 0.53 and pvalue < 0.05 (0.01342). This suggests that Br XRF peak areas can probably be used as a proxy for organic matter content, since Br is known to have a strong affinity for organic matter (e.g., Chagué-Goff and Fyfe, 1996;Ribeiro Guevara et al, 2019). A strong relation between S and Br, in association with organic matter, has been previously reported using PCA, explaining 61% of the variance (Chagué et al, 2018).…”

A 1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

“…Linear regression tests on the Br and LOI550 results show a significant relationship with a R of 0.53 and pvalue < 0.05 (0.01342). This suggests that Br XRF peak areas can probably be used as a proxy for organic matter content, since Br is known to have a strong affinity for organic matter (e.g., Chagué-Goff and Fyfe, 1996;Ribeiro Guevara et al, 2019). A strong relation between S and Br, in association with organic matter, has been previously reported using PCA, explaining 61% of the variance (Chagué et al, 2018).…”

Climate-driven fluxes of organic-bound uranium to an alpine lake over the Holocene

“…Because of the high affinity of bromine (Br) to organic matter (Leri et al, 2010;Leri and Myneni, 2012) and to diatoms in particular (Kerfoot et al, 1999;Phedorin et al, 2000), it has been shown that sedimentary Br amounts are closely related to OM accumulation, the Br/OM ratio being dependent on OM sources (Gilfedder et al, 2011;Guevara et al, 2019;Mayer et al, 2007Mayer et al, , 1981Ziegler et al, 2008). We therefore calculated semi-quantitative Br/TOC ratios by dividing Br obtained by XRF analysis (in fluorescence counts) by TOC contents (in wt%).…”