Relationship between arsenic content and macroelements, microelements, and polysaccharides in Sargassum horridum (Ochrophyta, Phaeophyceae) in the Gulf of California, Mexico

Sargassum species are known for their capacity to accumulate toxic elements, which may pose environmental risks and limit their use. Arsenic accumulation in Sargassum may vary in response to environmental and physiological conditions. Moreover, interactions between chemical elements may result in synergistic or antagonistic effects. This study determined the variability in the concentration of macroelements (N, P, K) and microelements (As, Cd, Pb, Cu, Zn, and Mn) through time and between growth stages in Sargassum horridum from a site adjacent to a phosphorite deposit in the Gulf of California. A generalized linear model (GLM) was performed to assess the influence of other concurrent elements, polysaccharides (alginate and fucoidan), and their main functional groups (uronic acids and sulfate) on arsenic content. Elemental concentrations showed the following decreasing order: N > K > P > Fe > Mn > Zn > Cd > As > Cu > Pb. Arsenic concentration was 4.33 ± 0.20 mg kg^-1. Significant differences in element concentrations were found by month and growth stage. The main variables associated with arsenic accumulation in S. horridum were potassium, nitrogen, zinc, fucoidan, sulfate from fucoidan, and alginate. The implications of the arsenic, cadmium, and lead concentrations in S. horridum and its potential applications in food, feed, and agricultural contexts are discussed. This research sheds light on the dynamic nature of elements accumulation in Sargassum, emphasizing the need for a comprehensive and context-specific understanding of elemental variations within Sargassum for safe and responsible applications.