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Algal susceptivity to inorganic arsenate As(V) is linked to the plant nutrient phosphate due to their similar uptake processes. This study determines the response of Sarcodia suae to three phosphate concentrations (1, 10 and 20 mg l–1) when exposed to As(V) (0, 250 µg l–1) for 7 days. The parameters measured include growth, pigments (Chlorophyll a (Chl a), allophycocyanin (APC), phycocyanin (PC), phycoerythrin (PE), total phycobiliproteins (TPBP) and carotenoids), inorganic arsenic (iAs), and total arsenic (TAs) uptake behaviour and bioaccumulation capacity. The growth rate showed significant differences among treatments. Significantly higher levels of pigments including Chl a and carotenoids were observed with an increase in external phosphate concentrations. On the other hand, APC, PC, PE and TPBP showed no significant differences among treatments. The trend of iAs and TAs uptake when phosphate is high suggests competition between phosphate and As(V) as is evident from the reduction of uptake with increased phosphate. The depletion of phosphate and As(V) in the medium also suggests accumulation by the algae. In addition, S. suae was considered an As accumulator but not a hyperaccumulator as defined on its bioaccumulation capacity of 48 and 97 mg kg–1 of iAs and TAs, respectively. Overall, these findings suggest that environmental factors including levels of phosphate have a key role in developing effective As bioremediation in the environment. Highlights Phosphate in Sarcodia suae probably regulates arsenic uptake. Photosynthetic pigments can be linked to competitive mechanisms of As(V). The red alga Sarcodia suae is a candidate for As wastewater treatments by Bioconcentration Factor analysis. [ABSTRACT FROM AUTHOR]

Climate change due to an increasing concentration of carbon dioxide in the atmosphere is a global issue. It can impact aquatic environments by affecting water flow, pollutant transformation and migration, and other toxicant-related effects. We assessed the interactive effects of temperature warming and pH changes on variations in accumulation of total arsenic (AsT) in the red alga Sarcodia suae at different levels of arsenite (AsIII). Result showed that AsT variations in the alga were moderated by significant joint effects of warming temperature and/or increasing pH levels and their interactions with increasing AsIII concentrations. Our study suggests possible deleterious impacts on macroalgal populations due to toxicological effects associated with prevailing environmental conditions. Therefore, improved pollution management, climate change adaptation, and mitigation strategies are needed to deal with current environmental issues and As aggravation. [ABSTRACT FROM AUTHOR]

Little is known about the effects of environmental factors on total arsenic (TAs) accumulation in marine Rhodophyta. The effects of five environmental factors (temperature, light intensity, pH, exposure duration, and phosphate) at various As(III) concentrations were investigated in Sarcodia suiae. The highest TAs accumulations were recorded at 25°C, a luminance of 80 µmol photons m−2 s−1, and a pH of 8. TAs uptake increased significantly over time. However, a higher phosphate concentration reduced TAs accumulation. These data show that the extent of TAs accumulation depends on various environmental factors. Hence, our results suggest a potential in arsenic recovery process in wastewater treatments. S. suiae may provide a new means of reducing levels of arsenic in contaminated water and may be used as a potential Rhodophyta model for investigating other types of heavy metal pollution in future. [ABSTRACT FROM AUTHOR]

Temperature, light intensity (LI), adsorbent source and concentrations are key external factors affecting algal metabolism and thus metal–accumulation mechanisms. In this study, the alga Sarcodia suiae was exposed individually to a range of temperature (15, 20, and 25 °C), and LI (30, 55, and 80 μmol photons m−2 s−1) at initial arsenate [As(V)] concentration (i conc: 0, 62.5, 125, 250, and 500 μg L−1) conditions, to investigate the variations of total arsenic (TAs) and inorganic arsenic (iAs) accumulation mechanisms in the algal body. Temperature significantly affected TAs and arsenite [As(III)] production and maximum absorption were obtained at 15 °C, which was significantly stimulated by increasing i conc. However, the temperature did not affect As(V) production. LI had no significant effect on TAs or iAs production, although maximum absorption was estimated in 80 μmol photons m−2 s−1. The iAs component of TAs was much greater in the temperature experiment particularly under 250–500 μg L−1 i conc than in the LI experiment, is witnessed. Overall, temperature and i conc strongly affected As accumulation. The predominant iAs produced was As(III), regardless of temperature or LI, suggesting that the alga favored As(III) biosorption. Also, visible effects on the morphology of this alga were adverse with increased concentration and environmental factors did affect the difference somewhat. Our results contribute to improving our understanding of the effects of the tested factors on As cycling, which is necessary for maximizing biosorption of algae if utilized for bioremediation studies as well as in the wastewater treatment implementation approach in the environment. Image 1 • Temperature impacts the total arsenic (TAs) and As(III) accumulation. • Light intensity condition did not affect TAs and inorganic arsenic (iAs) accumulation. • Arsenite[As(III)] produced was comparatively higher than As(V) regardless of temperature or light conditions. • Increased initial concentration enhanced the biosorption efficiency disregard of temperature or light conditions. [ABSTRACT FROM AUTHOR]