Over the past three decades, Caribbean coral reefs have drastically changed in structure and organization due to anthropogenically driven environmental changes. The prognostic trend indicates a shift from coralto more algal-dominated reefs coupled with a loss in biodiversity and destabilization of reef structure. This study focuses on the composition of the most common algal growth form, the turf, and investigates turf succession within a fringing Caribbean coral reef. In a field study starting October 2007, we followed succession of turf algal assemblages grown on artificial substrata for periods of 15 up to 333 days at different water depths (5, 15 and 25 m). Species composition and abundance, biodiversity, total cover, and biomass were investigated and compared in uniand multivariate analyses. Despite the pronounced change in coral reef structure over the past years, we found little difference from primary succession patterns described 30 years earlier. Succession patterns revealed a high diversity, mainly driven by the filamentous brown algal order Ectocarpales, the crustose green alga Pringsheimiella scutata at early stage, and diverse filamentous Cyanobacteria at later stages. Overall, the study provides insight into the early successional stages of coral reef vegetation by identifying the key species and discussing possible factors determining reef development in relation to environmental change.

Succession patterns in algal turf vegetation on a Caribbean coral reef

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Impact of high hydrostatic pressure on wheat, tapioca, and potato starches

Characterisation of organic coal structure for liquefaction

Crude petroleum and its refined products are principal energy sources driving industrialisation; albeit, the resultant pollution of the natural environment is antithetical to sustainable development. Soil pollution arising from the release of petroleum hydrocarbons causes changes in the soil microbial community structure and functional diversity, which can result in significant impact on soil ecosystem functioning. A number of physical, chemical and biological processes determine hydrocarbon fate in soil, but microbial degradation is generally considered to be the most important loss process. The overall aim of this project was to assess the biodegradation of aliphatic and polycyclic aromatic hydrocarbons in soils contaminated with petroleum oil. The effects of the presence and concentration of co-contaminants, the presence and concentration of HP-beta-CD, and of prescribed fire on microbial catabolic activity in soils were investigated. Selected soils from the UK and the Antarctic (SOM < 1-27% and clay < 0.01---42%) provided a good basis for evaluating the influence of soil physicochemical properties. Levels of hydrocarbons in the background soils reflect their proximity to anthropogenic input sources. Indigenous mineralisation of target hydrocarbons was measured using 14C-radiorespirometry in the background soils and soils amended with increasing diesel oil concentrations analogous to the spatial heterogeneity in contaminant levels common at polluted sites. The 14C-hydrocarbons used were naphthalene, phenanthrene, benzo[a]pyrene, hexadecane and octacosane. Collectively, the results from studies of effect of diesel concentration highlight the need to consider the potential variations in the development of indigenous catabolic activity towards various hydrocarbons when designing bespoke remediation strategies, as contaminant levels varied widely, even on a millimetre/centimetre-scale, in polluted soils. The efficiency of microbial utilisation of labile C-substrate was also influenced by the initial diesel concentration and soil contact time; the use of in-situ derived kEC values is advised to quantify microbial biomass-C in petroleum oil-polluted soils. The failure of HP-beta-CD to promote greater benzo[a]pyrene mineralisation despite a significantly enhanced solubilisation has weighty ecotoxicological implications for cyclodextrin-aided bioremediation of PAH-impacted soil. The negligible long-term effects on overall microbial activity and PAH degradative ability of soils and the substantial reduction of contaminant burdens in soil suggest low-severity prescribed fire as a practicable first-line option for remediation of heavily oil-polluted soils.

Biodegradation of aliphatic and polycyclic aromatic hydrocarbons in petroleum oil-contaminated soils

In a number of contributions to coal liquefaction, gas–liquid mass transfer limitation has been referred by neglecting mass transfer limitation of solvent Into solid coal. Reported apparent activation energies of coal liquefaction reactions are In the range of 10–20 kCal/g–mole, which are too low for thermal reactions, Imply that diffusion Is the rate controlling step. In this study, the solvent diffusion effect on solvolysis of vitrinitic macerals In Alberta subbituminous coal has been studied, by performing petrographlc analyses of original coal and liquefaction residues. Quasi–steady state and transient coal–solvent diffusion-chemical reaction models are developed to Interpret the experimental data. Results indicate that solvent diffusion into the reactive maceral most likely be a rate limiting step In coal liquefaction.

S. Chakrabartty

Papers

Mass transfer limitations in coal liquefaction