Blue carbon sinks in South Africa and the need for restoration to enhance carbon sequestration.

Blue carbon ecosystems (mangroves, salt marshes, and seagrasses) contribute towards climate change mitigation because they are efficient at sequestering atmospheric CO2 into long-term total ecosystem carbon stocks. Destruction or disturbance therefore reduces sink capacity and leads to significant CO2 emissions. This study reports the first national estimates of: 1) total carbon storage, 2) CO2 emissions from anthropogenic activities, 3) the potential for restoration to enhance carbon sequestration for blue carbon ecosystems in South Africa. Mangrove ecosystems have the greatest carbon storage per unit area (253-534 Mg C ha-1), followed by salt marshes (100-199 Mg C ha-1) and seagrasses (45-144 Mg C ha-1). Salt marshes are the most extensive and contribute 67 % to the national carbon stock of 4000 Gg C. Since 1930, 6500 ha has been lost across all blue carbon ecosystems (26 % of the natural extent), equivalent to losing 1086 Gg C from the national carbon stock. Historic CO2 emissions were estimated at an average rate of 30,266 t CO2e yr-1. Despite losses, a total of 3998 ha could be restored to increase carbon sequestration and CO2 removals of 14,845 tCO2e.yr-1. Extractive activities have declined rapidly in recent decades, but abiotic pressures on estuarine ecosystems (flow modification, reduced water quality, and artificial breaching) have been increasing. There is an urgent need to quantify the potential impact of these pressures and include them in estuarine management and restoration plans. Blue carbon ecosystems cover a relatively small area in South Africa, but they are valued for their multiple ecosystem services that contribute towards climate change adaptation and biodiversity co-benefits. These ecosystems need to be included in national policies driving climate change response in the Agriculture, Forestry and Other Land-Use (AFOLU) sector, such as incorporating them into the wetland subcategory of the national GHG inventory.

Biological synthesis of platinum nanoparticles: Effect of initial metal concentration.

The unusual and novel properties of metal nanoparticles are highly sought after in a number of new and existing industries. Current chemical methods of nanoparticle synthesis have shown limited success and it is expected that the use of a biological approach may overcome many of these obstacles. The exploitation of microorganisms for the biosynthesis of metal nanoparticles is an area of research that has received increasing interest over the last decade. The use of living microbes as a tool for nanoparticle biosynthesis has been researched extensively, however the use of the cellular extract within the cells, excluding the living organism as a whole, has not received much attention. In this investigation, the cell-free, cell-soluble protein extract from a consortium of sulfate-reducing bacteria was used successfully in the biosynthesis of geometric Pt(0) nanoparticles, where previously, whole cells from the same culture had only resulted in amorphous Pt(0) deposits. It appears that by removing the spatial restrictions imposed by the cell itself, nanoparticles could form. It was also found that by altering the ratio of Pt(IV) to protein concentration in solution, a variety of particle morphologies resulted.

Analysis of the inter- and extracellular formation of platinum nanoparticles by Fusarium oxysporum f. sp. lycopersici using response surface methodology.

Fusarium oxysporum fungal strain was screened and found to be successful for the inter- and extracellular production of platinum nanoparticles. Nanoparticle formation was visually observed, over time, by the colour of the extracellular solution and/or the fungal biomass turning from yellow to dark brown, and their concentration was determined from the amount of residual hexachloroplatinic acid measured from a standard curve at 456 nm. The extracellular nanoparticles were characterized by transmission electron microscopy. Nanoparticles of varying size (10-100 nm) and shape (hexagons, pentagons, circles, squares, rectangles) were produced at both extracellular and intercellular levels by the Fusarium oxysporum. The particles precipitate out of solution and bioaccumulate by nucleation either intercellularly, on the cell wall/membrane, or extracellularly in the surrounding medium. The importance of pH, temperature and hexachloroplatinic acid (H(2)PtCl(6)) concentration in nanoparticle formation was examined through the use of a statistical response surface methodology. Only the extracellular production of nanoparticles proved to be statistically significant, with a concentration yield of 4.85 mg l(-1) estimated by a first-order regression model. From a second-order polynomial regression, the predicted yield of nanoparticles increased to 5.66 mg l(-1) and, after a backward step, regression gave a final model with a yield of 6.59 mg l(-1).