Boron Isotope Analysis Reveals Borate Selectivity in Seaweeds

Abstract

The role of boron in terrestrial plant physiology is diverse and increasingly well understood, but its role in marine aquatic eukaryotes is less clear. Our research reveals a distinctive and large offset in boron isotopes from seawater, irrespective of seaweed type or season. We show that the offset is consistent with the incorporation of borate from seawater. Boron is a known micronutrient in plants but very few studies have used boron isotopes to investigate boron’s role in plant physiology. Seaweed, as the most primitive multicellular plant, has an important role in investigating wider plant adaptations that use boron to meet functional needs. Furthermore, seaweed and other plants are a key base nutrient provider in food webs, supplying boron to consumers and playing a critical role in boron environmental cycling.

Boron Isotopes in Fresh Surface Waters in a Temperate Coastal Setting

“…A single algae sample (not identified at the species level) collected from the southern pond was −4.6‰, which was 10-20‰ lower than the pond water it was growing in. This fractionation of light B by pond algae is similar to what is observed with marine algae (seaweed) [30]. The algae sample had a [B] of 366 ppb, which is a high enrichment factor relative to the average southern pond water (10-30 ppb).…”

“…The surface water 𝛿 11 B value heterogeneity from south to north on Setauket Pond may also reflect natural processes, as the removal of light boron by algae is the most obvious explanation of the trend to heavier 𝛿 11 B in the flow direction. Biological processes are rarely considered for controlling boron isotope values and fractionation, but research investigating seaweed's boron physiology [30] and garden experiments with seaweed as a fertilizer [31,32] suggest that uptake (algae tissue growth) and release (algae tissue decomposition) of boron could have a recognizable and a profound influence on surface waters. We consider this a rich avenue for future research.…”

Calibration free laser ablation molecular isotopic spectrometry (CF-LAMIS) for boron isotopic composition determination

“…In addition to the elds mentioned above, B-IC is an inevitable factor in hydrology, oceanography, environmental sciences, etc. [12][13][14][15] This increased interest in B-IC demands an accurate and precise isotopic composition calculation method.…”