BIBLIOS

Document type
Journal articles

Document subtype
Full paper

Title
Bromine biogeodynamics in the NE Atlantic: A perspective from natural wetlands of western Portugal

Participants in the publication
F. Moreno (Author)
J. Moreno (Author)
IDL
F. Fatela (Author)
Dep. Geologia
IDL
L. Guise (Author)
C. Vieira (Author)
M. Leira (Author)
IDL

Summary
Bromine (Br) cycling in natural wetlands is highly complex, including abiotic/biotic processes and multiphase inorganic/organic Br compounds. These ecosystems receive Br primarily from the ocean, functioning as sinks/sources of Br, with the overall imbalance mostly depending on the prevailing climate conditions. To trace the present-day transport of the oceanogenic Br (i.e., derived from salt-water spray-droplets) and its uptake and storage in brackish/freshwater wetlands, we surveyed waters, native plants, and soils/sediments from coastal marshes and mountain peatlands in the westernmost fringe of northern Portugal. The calculated enrichment factors of bromide (Br-) relative to chloride in rainfall (EFsea= 16.8–75.3), rivers (EFsea= 1.3–13.9) and wetland waters, superficial (EFsea= 5.8–13.1) and interstitial (EFsea= 2.1–8.9), increase towards the mountainous inland. Our hypothesis is that these results mostly derive from a known Br autocatalytic, heterogeneous, chemical cycle, starting at the seawater-aqueous interface and progressing in altitude. Br-bearing air masses are carried far from the Atlantic by moist westerlies, with Br- rainout from the atmosphere supplying the neighboring mountain peatlands. Bromine concentrations in sampled wetland soils/sediments (111–263 mg/kg) agree with those reported for other coastal regions. They are directly correlated with organic matter, varying irrespective the [Br?] of interstitial waters (129 µg/L–79 mg/L). According to the computed bioconcentration factors, the aqueous component is the major source of Br for all plant species investigated (BFplant/water= 2.1–508.0), as described elsewhere. However, the Br contents in plants (14–173 mg/kg) evidence interspecific differences that suggest a divergence from the acknowledged halophytic-glycophytic “model”. As plants are recognized producers of Br volatile molecules (as methyl bromide, CH3Br), we interpreted translocation factors bellow one in vascular species as explanatory of phytovolatilization rather than restriction of Br- upward movement in plants. Further investigation is needed since considerable intrinsic plant variations in CH3Br emissions are referred in literature.


Where published
Science of The Total Environment

Publication Identifiers
ISSN - 0048-9697

Publisher
Elsevier BV



Document Identifiers
DOI - https://doi.org/10.1016/j.scitotenv.2020.137649
URL - http://dx.doi.org/10.1016/j.scitotenv.2020.137649

Rankings
SCIMAGO Q1 (2018) - 1.536 - Environmental Chemistry

Keywords
Salt marshes Peatlands Autochthonous plants (De)bromination Phytovolatilization Climate