Arsenic and selected elements in marine angiosperms, south‐east coast, NSW, Australia

Abstract

The leaves of four angiosperm species, the mangrove Avicennia marina, the samphire Sarcocornia quinqueflora, the seablight Suaeda australis and the seagrass Posidonia australis, were sampled from three locations from the south-east coast of NSW. Mean total arsenic concentrations (mean ± SD) in dry mass for all locations were A. marina (0.38 ± 0.18 to 1.2 ± 0.7 µg g −1 ), S. quinqueflora (0.13 ± 0.06 to 0.46 ± 0.22 µg g −1 ), S. australis (0.03 ± 0.06 to 0.05 ± 0.03 µg g −1 ) and P. australis (0.34 ± 0.10 to 0.65 ± 0.26 µg g −1 ). Arsenic concentrations were significantly different between species and locations but were consistently low compared with marine macroalgae species. Significant relationships were found between arsenic and iron concentrations for A. marina, S. quinqueflora and P. australis and a negative relationship between arsenic and zinc concentrations for S. quinqueflora. No relationship between arsenic and phosphorus concentrations was found in this study. Angiosperms contained predominantly inorganic arsenic in the water-extractable and residue fractions with minor concentrations of DMA in the water-soluble fraction. P. australis also contained dimethylated glycerol and phosphate arsenoriboses. The presence of arsenobetaine, arsenocholine, trimethylated glycerol arsonioribose and an unknown cation in P. australis is most likely due to the presence of epiphytes on fronds. There is no evidence to suggest that angiosperms produce arsenobetaine as arsenic is mostly present as inorganic arsenic. In conclusion, marine angiosperms only accumulate low arsenic concentrations and uptake appears to be dependent on iron uptake but not phosphorus uptake. Marine angiosperms mainly cycle inorganic arsenic with little biomethylation of arsenic occurring.

Concentrations and speciation of arsenic in New England seaweed species harvested for food and agriculture

“…Other nutrients, such as N, Fe, Si, are also essential to growth and metabolic processes in algae, and may also influence the uptake and transformation of As (Duncan 2015). There was no correlation between As and Fe in this study, but relationships between As V and Fe have been observed in marine plants, which take up As via their roots (Thomson et al, 2007). The presence of arsenosugar SO 4 in seaweeds of the order Fucales corresponded with significantly higher concentrations of S than in Laminariales, which had higher concentrations of arsenosugar SO 3 (Fig.…”

“…Similar distributions of arsenosugars across taxa have been observed in other studies (Francesconi and Kuehnelt, 2002; Tukai et al, 2002). Low concentrations of arsenosugars were observed in flowering plant samples in this and other studies (Chancho et al, 2010), although these are suggested to be due to algal epiphytes attached to the samples, and not produced in the plants themselves (Thomson et al, 2007). …”

“…(Edmonds et al, 1993; Tukai et al, 2002) The brown algae of the order Laminariales had both the highest As and the largest range of As concentrations (13.9 – 106 mg/kg). Concentrations of As in flowering plants ( Spartina altiflora and Zostera marina ) from the same sites in New Hampshire were low (3.4–5.2 mg/kg) compared to macroalgae, and As uptake in plants is thought to occur by a different mechanism via roots (Thomson et al, 2007), than in macroalgae which are epiphytic. Sample sizes for most species in this study were not sufficient to decipher differences between commercial samples from Maine and those collected in New Hampshire.…”

Measurement of arsenic species in environmental, biological fluids and food samples by HPLC-ICPMS and HPLC-HG-AFS

“…In addition, a range of procedures including brushes and razor blades have been used to remove epiphytes [26], however, rarely are samples checked under a microscope to determine if surface material has been removed. Several studies have reported the presence of AB in seaweeds and seagrass leaves [74,76] an As species not thought to be produced by these organisms and likely to be produced by associated epiphytes. For example, seaweeds contain symbiotic fungi that are part of the plant matrix [75] and cannot be removed by washing or scrapping.…”

Arsenic Speciation, Distribution, and Bioaccessibility in Shrews and Their Food

“…One limitation of this extraction solution is that only arsenic species that solubilize in it can be identified and quantified; this resulted in incomplete extractions with extraction efficiencies for shrews averaging 35 ± 15%. However, research has demonstrated that most, if not all, methylated species of arsenic are extracted with methanol and water (1:1) (Mir et al 2007;Smith et al 2008a;Száková et al 2005;Thomson et al 1993), with the remaining arsenic assumed to be inorganic in nature, based on XAS studies (Mir et al 2007;Smith et al 2008a;Száková et al 2005). The speciation pattern for shrews does not indicate a clear difference between populations living in background or contaminated sites.…”