Deviation of Boron Concentration From Predictions Using Salinity in Coastal Environments

Abstract

To test whether the established B/Cl ratio (0.2414 mg·kg–1·‰–1) derived for the open ocean is applicable to coastal systems globally, we measured the B concentration and salinity of seawater samples (n = 245) collected from the coastal waters of the Yellow, East China, and East Seas. We also measured the B concentration of freshwater samples (n = 10) from six rivers discharging into these seas and analyzed along with the B concentrations of other rivers globally, obtained from literatures. Our results show that the supply of riverine B (2–6 μmol B/kg) did not discernably alter the B/Cl ratio in most estuarine systems. The impact of this riverine B input on the interconversion between total alkalinity ([HCO3–] + 2[CO32–] + [B (OH)4–] + others) and carbonate alkalinity ([HCO3–] + 2[CO32–]) is less than a few micromoles per kilogram for most estuarine and coastal systems, although exceptions in the Baltic Sea do occur.

Boron Isotope Analysis Reveals Borate Selectivity in Seaweeds

“…Boron has two stable isotopes, 10 B and 11 B, and with a large mass difference, there is a substantial range in boron isotope ratio values (δ 11 B) of natural waters, plants, and soils . The δ 11 B of seawater is 39.61 ± 0.04‰; its boron concentration is tied to salinity and is about 0.4 mM at normal salinity . At the pH of seawater, boric acid (B­(OH) 3 ) dominates over borate (B­(OH) 4 – ) by approximately 4:1 (Figure A) .…”

“…27 δ 11 B of seawater is 39.61 ± 0.04‰; 28 its boron concentration is tied to salinity and is about 0.4 mM at normal salinity. 29 At the pH of seawater, boric acid (B(OH) 3 ) dominates over borate (B(OH) 4 − ) by approximately 4:1 (Figure 1A). 30 Due to the preference of 10 B for borate, and 11 B for boric acid, with a measured fractionation of 1.0272 ± 0.0006, 31 there is a predictable offset of these species from the seawater reservoir (Figure 1B).…”

Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

“…The agreement was compelling evidence for insignificant biases in A T derived from organic acids (Cai et al, 1998;Kim and Lee, 2009;Ko et al, 2016) and phytoplankton and bacteria cells (Lee et al, 2021). The B:Cl ratio of 0.2414 confirmed for the open ocean (Lee et al, 2010) was shown to be accurate in the study area and in experiments designed to predict the borate contribution to A T (Lee et al, 2019).…”

Anthropogenic Nitrogen‐Induced Changes in Seasonal Carbonate Dynamics in a Productive Coastal Environment

“…The good internal consistency further indicated minor biases in A T arising from organic acids (Cai et al, 1998; Kim & Lee, 2009; Ko et al, 2016) and phytoplankton cells (Kim et al, 2006) in the Yellow Sea. The B:Cl ratio of 0.2414 derived for the open ocean (Lee et al, 2010) has been shown to be accurate in the study area and in experiments designed to predict the borate contribution to A T (Lee et al, 2019).…”