Seasonal characterization and quantification of biomolecules from sargassum collected from Mexican Caribbean coast - A preliminary study as a step forward to blue economy

Changes in holopelagic Sargassum spp. biomass composition across an unusual year

The year 2021 marked a decade of holopelagic sargassum (morphotypes Sargassum natans I and VIII, and Sargassum fluitans III) stranding on the Caribbean and West African coasts. Beaching of millions of tons of sargassum negatively impacts coastal ecosystems, economies, and human health. Additionally, the La Soufrière volcano erupted in St. Vincent in April 2021, at the start of the sargassum season. We investigated potential monthly variations in morphotype abundance and biomass composition of sargassum harvested in Jamaica and assessed the influence of processing methods (shade-drying vs. frozen samples) and of volcanic ash exposure on biochemical and elemental components. S. fluitans III was the most abundant morphotype across the year. Limited monthly variations were observed for key brown algal components (phlorotannins, fucoxanthin, and alginate). Shade-drying did not significantly alter the contents of proteins but affected levels of phlorotannins, fucoxanthin, mannitol, and alginate. Simulation of sargassum and volcanic ash drift combined with age statistics suggested that sargassum potentially shared the surface layer with ash for ~50 d, approximately 100 d before stranding in Jamaica. Integrated elemental analysis of volcanic ash, ambient seawater, and sargassum biomass showed that algae harvested from August had accumulated P, Al, Fe, Mn, Zn, and Ni, probably from the ash, and contained less As. This ash fingerprint confirmed the geographical origin and drift timescale of sargassum. Since environmental conditions and processing methods influence biomass composition, efforts should continue to improve understanding, forecasting, monitoring, and valorizing sargassum, particularly as strandings of sargassum show no sign of abating.

Valorization of Rejected Macroalgae Kappaphycopsis cottonii for Bio-Oil and Bio-Char Production via Slow Pyrolysis

Kappaphycopsis cottonii, a prominent macroalgae species cultivated in an Indonesian marine culture, yields significant biomass, a portion of which is often rejected by industry. This study explores the potential valorization of rejected K. cottonii biomass through slow pyrolysis for bio-oil and biochar production, presenting an alternative and sustainable utilization pathway. The study utilizes a batch reactor setup for the thermal decomposition of K. cottonii, conducted at temperatures between 400 and 600 °C and varying time intervals between 10 and 50 min. The study elucidates the temperature-dependent behavior of K. cottonii during slow pyrolysis, emphasizing its impact on product distributions. The results suggest that there is a rise in bio-oil production when the pyrolysis temperature is raised from 400 to 500 °C. This uptick is believed to be due to improved dehydration and greater thermal breakdown of the algal biomass. Conversely, at 600 °C, bio-oil yield diminishes, indicating secondary cracking of liquid products and the generation of noncondensable gases. Chemical analysis of bio-oils reveals substantial quantities of furan derivatives, aliphatic hydrocarbons, and carboxylic acids. Biochar exhibits calorific values within the range of 17.52-19.46 MJ kg-1, and slow pyrolysis enhances its specific surface area, accompanied by the observation of carbon nanostructures. The study not only investigates product yields but also deduces plausible reaction routes for the generation of certain substances throughout the process of slow pyrolysis. Overall, the slow pyrolysis of rejected K. cottonii presents an opportunity to obtain valuable chemicals and biochar. These products hold promise for applications such as biofuels and diverse uses in wastewater treatment, catalysis, and adsorption, contributing to both environmental mitigation and the circular economy.

Effect of Pelagic Sargassum on In Vitro Dry Matter and Organic Matter Degradation, Gas Production, and Protozoa Population

This study determined the effect of pelagic Sargassum on in vitro dry matter and organic matter degradation, total gas production (TGP), and protozoa population. The treatments were different levels of Sargassum inclusion on a basal substrate (Stargrass hay; Cynodon nlemfuensis) as follows: T0 (control treatment based on Stargrass hay), T10 (90% Stargrass hay + 10% Sargassum), T20 (80% Stargrass hay + 20% Sargassum), and T30 (70% Stargrass hay + 30% Sargassum). Ruminal fermentation kinetics and protozoa population were determined during 72 h of in vitro incubations. Compared to control, dry matter degradability at 48 and 72 h and organic matter degradability at 24 and 48 h were higher in Sargassum treatments. TGP was lower with T20 at 48 h. The total population of protozoa and the concentration of Entodinium spp. were lower at T20 at 48 h and T30 at 72 h. Cl, S, Ca, K, and Zn (103, 5.97, 88.73, 285.70 g/kg, and 15,900 mg/kg) were high in Sargassum, reaching twice or even nine times higher than the contents in Stargrass (11.37, 1.60, 43.53, 87.73 g/kg, and 866.67 mg/kg). Overall, up to 30% pelagic Sargassum could be included in hay-based substrates from tropical grasses without negative effects on in vitro dry matter and organic matter degradability.

Aleppo pine seeds (Pinus halepensis Mill.) as a promising novel green coagulant for the removal of Congo red dye: Optimization via machine learning algorithm

Consideration is now being given to the use of metal coagulants to remove turbidity from drinking water and wastewater. Concerns about the long-term impact of non-biodegradable sludge on human health and the potential contamination of aquatic systems are gaining popularity. Recently, alternative biocoagulants have been suggested to address these concerns. In this study, using a 1 M sodium chloride (NaCl) solution, the active coagulating agent was extracted from Pinus halepensis Mill. Seed, and used for the first time to remove Congo red dye, the influence of numerous factors on dye removal was evaluated in order to make comparisons with conventional coagulants. The application of biocoagulant was shown to be very successful, with coagulant dosages ranging from 3 to 12 mL L^-1 achieving up to 80% dye removal and yielding 28 mL L^-1 of sludge. It was also found that biocoagulant is extremely pH sensitive with an optimum operating pH of 3. Ferric chloride, on the other hand, achieved similar removal rate with higher sludge production (46 mL L^-1) under the same conditions. A Fourier Transform Infrared Spectroscopy and proximate composition analysis were undertaken to determine qualitatively the potential active coagulant ingredient in the seeds and suggested the involvement of proteins in the coagulation-flocculation mechanism. The evaluation criteria of the Support vector machine_Gray wolf optimizer model in terms of statistical coefficients and errors reveals quite interesting results and demonstrates the performance of the model, with statistical coefficients close to 1 (R = 0.9998, R² = 0.9995 and R² adj = 0.9995) and minimal statistical errors (RMSE = 0.5813, MSE = 0.3379, EPM = 0 0.9808, ESP = 0.9677 and MAE = 0.2382). The study findings demonstrate that Pinus halepensis Mill. Seed extract might be a novel, environmentally friendly, and easily available coagulant for water and wastewater treatment.

Methane Production of Sargassum spp. Biomass from the Mexican Caribbean: Solid-Liquid Separation and Component Distribution

In the last decade, Sargassum spp. seaweed species have caused massive flooding on the Caribbean Sea coasts. These seaweed species have a high content of recalcitrant compounds, such as insoluble fibers and polyphenols, which generate low methane yields in anaerobic digestion (AD). This study investigated the effect of solid-liquid separation of Sargassum biomass on biodegradability and methane yield. A biochemical methane potential (BMP) test was conducted with both fractions and raw biomass (RB). A mass balance was developed to assess the distribution of the components. The obtained liquid fraction (LF) showed high biodegradability and a high methane production rate, and it generated a methane yield of 159.7 ± 7.1 N L kg VS-1, a value that corresponds to approximately twice that achieved with RB and the solid fraction (SF). The component distribution analysis showed that about 90% of total solids (TS), volatile solids (VS), ash, carbon, and cellulose were retained in the SF. In conclusion, the LF had high biodegradability and methane yield. This suggests the potential for LFs of Sargassum biomass to be treated in large-scale high-load reactors; however, studies applied to SFs are needed because they retain a large amount of organic matter with low biodegradability.

Environmental impact of Sargassum spp. landings: an evaluation of leachate released from natural decomposition at Mexican Caribbean coast

Large volumes of pelagic Sargassum spp. have stranded periodically on the Mexican Caribbean shoreline. The aim of this research was to study the mobility of metals through the leachates released into the environment during the natural decomposition process of Sargassum spp. Fresh Sargassum samples were placed in cone-bed reactors: under laboratory and local environmental conditions. The leachate generated naturally by decomposition in both conditions was recovered periodically and analyses of pH, volume, and metal content were carried out. Sargassum biomass was monitored by electron microscopy, FT-IR, and CHNS analysis. The Sargassum biomass studied presented a C: N ratio of 24.39, making it a potential raw feedstock for biofuels and other value-added products. Calculations performed on leachate production allowed inferring that each ton of fresh Sargassum that decomposes at a controlled temperature of 27 °C can produce 316 L of leachate. This leachate can contain 5.67 g of As and other potentially toxic metals (e.g., B, Al, Cu). At the end of both experiments, the biomass that was incubated for 30 days presented a C: N ratio of 28.86, so it can still be used as raw material for biofuels; however, the Sargassum biomass that remained 180 days in incubation decreased its C:N ratio at 8.45 at this point, it can be considered a waste. The leachate generated during the natural decomposition process of Sargassum on beaches or disposal sites represents a high risk of contamination of the Yucatan Peninsula water system due to the high content of arsenic and the presence of potentially toxic metals.

Pelagic Sargassum events in Jamaica: Provenance, morphotype abundance, and influence of sample processing on biochemical composition of the biomass

Pelagic Sargassum species have been known for centuries in the Sargasso Sea of the North Atlantic Ocean. In 2011, a new area concentrating high biomass of these brown algae started developing in the Tropical Atlantic Ocean. Since then, massive and recurrent Sargassum influxes have been reported in the Caribbean and off the coast of Western Africa. These Sargassum events have a major negative impact on coastal ecosystems and nearshore marine life, and affect socio-economic sectors, including public health, coastal living, tourism, fisheries, and maritime transport. Despite recent advances in the forecasting of Sargassum events, and elucidation of the seaweed composition, many knowledge gaps remain, including morphotype abundance during Sargassum events, drift of the seaweeds in the months prior to stranding, and influence of sample processing methods on biomass biochemical composition. Using seaweeds harvested on the coasts of Jamaica in summer of 2020, we observed that S. fluitans III was the most abundant morphotype at different times and sampling locations. No clear difference in the geographical origin, or provenance, of the Sargassum mats was observed. The majority of Sargassum backtracked from both north and south of Jamaica experienced ambient temperatures of around 27 °C and salinity in the range of 34-36 psu before stranding. We also showed that cheap (sun) compared to expensive (freeze) drying techniques influence the biochemical composition of biomass. Sun-drying increased the proportion of phenolic compounds, but had a deleterious impact on fucoxanthin content and on the quantities of monosaccharides, except for mannitol. Effects on the content of fucose containing sulfated polysaccharides depended on the method used for their extraction, and limited variation was observed in ash, protein, and fatty acid content within most of the sample locations investigated. These observations are important for the storage and transport of the biomass in the context of its valorisation.

Identifying the Blue Economy Global Epistemic Community

The following article aims to identify the characteristics of the epistemic community of Blue Economy researchers, through the description of its scientific production, its special organization and clustering. The information was examined using bibliometric techniques on 302 research works using the Web of Science databases (JCR) between 2013 and 2021. At the same time, VOSviewer software was used to represent the relationships metrically and visually between the data and metadata. A set of research works is reviewed which relates environmental conservation and its implication in the development of the territory, and the relationship between technology and the improvement of ocean management, to highlight those state interventions where benefits are generated for the population or where there is an important challenge for improvement.