Lignocellulosic feedstock supply systems with intermodal and overseas transportation

With growing demand for internationally traded biomass, the logistic operations required to economically move biomass from the field or forest to end- users have become increasingly complex. To design cost effective and sustainable feedstock supply chains, it is important to understand the economics, energy and greenhouse gas (GHG) emissions, their interdependencies, and the related uncertainties of the logistic process operations of international supply chains. This paper presents an approach to assessing lignocellulosic feedstock supply systems at the operational level. For this purpose, the Biomass Logistic Model (BLM) has been linked with the Geographic Information Systems-based Biomass Intermodal Transportation Model (BIT-UU) and extended with inter-continental transport routes. Case studies of herbaceous and woody biomass, produced in the US Midwest and US Southeast, respectively, and shipped to Europe for conversion to Fischer-Tropsch (FT) diesel are included to demonstrate how intermodal transportation and, in particular, overseas shipping integrates with the bioenergy supply chains. For the cases demonstrated, biomass can be supplied at 99 € Mg−1 to 117 € Mg−1 (dry) and converted to FT diesel at 19 € GJ−1 to 24 € GJ−1 depending on the feedstock type and location, intermediate (chips or pellets) and size of the FT diesel production plant. With the flexibility to change the design of supply chains as well as input variables, many alternative supply chain cases can be assessed

Coral reef bleaching: ecological perspectives

Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae residing within the gastrodermal tissues of host animals. Of particular concern are the consequences of bleaching of large numbers of reef-building scleractinian corals and hydrocorals. Published records of coral reef bleaching events from 1870 to the present suggest that the frequency (60 major events from 1979 to 1990), scale (co-occurrence in many coral reef regions and often over the bathymetric depth range of corals) and severity (>95% mortality in some areas) of recent bleaching disturbances are unprecedented in the scientific literature. The causes of small scale, isolated bleaching events can often be explained by particular stressors (e.g., temperature, salinity, light, sedimentation, aerial exposure and pollutants), but attempts to explain large scale bleaching events in terms of possible global change (e.g., greenhouse warming, increased UV radiation flux, deteriorating ecosystem health, or some combination of the above) have not been convincing. Attempts to relate the severity and extent of large scale coral reef bleaching events to particular causes have been hampered by a lack of (a) standardized methods to assess bleaching and (b) continuous, long-term data bases of environmental conditions over the periods of interest. An effort must be made to understand the impact of bleaching on the remainder of the reef community and the long-term effects on competition, predation, symbioses, bioerosion and substrate condition, all factors that can influence coral recruitment and reef recovery. If projected rates of sea warming are realized by mid to late AD 2000, i.e. a 2°C increase in high latitude coral seas, the upper thermal tolerance limits of many reef-building corals could be exceeded. Present evidence suggests that many corals would be unable to adapt physiologically or genetically to such marked and rapid temperature increases