Will ocean acidification affect marine microbes?

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1-7, doi:10.1038/ismej.2010.79.The pH of the surface ocean is changing as a result of increases in atmospheric carbon dioxide (CO2) and there are concerns about potential impacts of lower pH and associated alterations in seawater carbonate chemistry on the biogeochemical processes in the ocean. However, it is important to place these changes within the context of pH in the present day ocean, which is not constant; it varies systematically with season, depth and along productivity gradients. Yet this natural variability in pH has rarely been considered in assessments of the effect of ocean acidification on marine microbes. Surface pH can change as a consequence of microbial utilisation and production of carbon dioxide, and to a lesser extent other microbiallymediated processes such as nitrification. Useful comparisons can be made with microbes in other aquatic environments that readily accommodate very large and rapid pH change. For example, in many freshwater lakes, pH changes that are orders of magnitude greater than those projected for the 22nd century oceans can occur over periods of hours. Marine and freshwater assemblages have always experienced variable pH conditions. Therefore, an appropriate null hypothesis may be, until evidence is obtained to the contrary, that major biogeochemical processes in the oceans other than calcification will not be fundamentally different under future higher CO2 / lower pH conditions.Funding from the Gordon and Betty Moore Foundation, and logistical support from the Plymouth Marine Laboratory and the Center for Microbial Oceanography: Research and Education (National Science Foundation grant EF-0424599) are gratefully acknowledged

Anaerobic digestion and gasification of seaweed

The potential of algal biomass as a source of liquid and gaseous biofuels is a highly topical theme, with over 70 years of sometimes intensive research and considerable financial investment. A wide range of unit operations can be combined to produce algal biofuel, but as yet there is no successful commercial system producing such biofuel. This suggests that there are major technical and engineering difficulties to be resolved before economically viable algal biofuel production can be achieved. Both gasification and anaerobic digestion have been suggested as promising methods for exploiting bioenergy from biomass, and two major projects have been funded in the UK on the gasification and anaerobic digestion of seaweed, MacroBioCrude and SeaGas. This chapter discusses the use of gasification and anaerobic digestion of seaweed for the production of biofuel

Prisoners of the Capitalist Machine: Captivity and the Corporate Engineer

This chapter will focus on how engineering practice is conditioned by an economic system which promotes production for profit and economic growth as an end in itself. As such it will focus on the notion of the captivity of engineering which emanates from features of the economic system. By drawing on Critical Realism and a Marxist literature, and by focusing on the issues of safety and sustainability (in particular the issue of climate change), it will examine the extent to which disasters and workplace accidents result from the economic imperative for profitable production and how efforts by engineers to address climate change are undermined by an on-going commitment to growth. It will conclude by arguing that the structural constraints on engineering practice require new approaches to teaching engineers about ethics and social responsibility. It will argue that Critical Realism offers a framework for the teaching of engineering ethics which would pay proper attention to the structural context of engineers work without eliminating the possibility of engineers working for radical change

Bioreactor for microalgal cultivation systems: strategy and development

Microalgae are important natural resources that can provide food, medicine, energy and various bioproducts for nutraceutical, cosmeceutical and aquaculture industries. Their production rates are superior compared to those of terrestrial crops. However, microalgae biomass production on a large scale is still a challenging problem in terms of economic and ecological viability. Microalgal cultivation system should be designed to maximize production with the least cost. Energy efficient approaches of using light, dynamic mixing to maximize use of carbon dioxide (CO2) and nutrients and selection of highly productive species are the main considerations in designing an efficient photobioreactor. In general, optimized culture conditions and biological responses are the two overarching attributes to be considered for photobioreactor design strategies. Thus, fundamental aspects of microalgae growth, such as availability of suitable light, CO2 and nutrients to each growing cell, suitable environmental parameters (including temperature and pH) and efficient removal of oxygen which otherwise would negatively impact the algal growth, should be integrated into the photobioreactor design and function. Innovations should be strategized to fully exploit the wastewaters, flue-gas, waves or solar energy to drive large outdoor microalgae cultivation systems. Cultured species should be carefully selected to match the most suitable growth parameters in different reactor systems. Factors that would decrease production such as photoinhibition, self-shading and phosphate flocculation should be nullified using appropriate technical approaches such as flashing light innovation, selective light spectrum, light-CO2 synergy and mixing dynamics. Use of predictive mathematical modelling and adoption of new technologies in novel photobioreactor design will not only increase the photosynthetic and growth rates but will also enhance the quality of microalgae composition. Optimizing the use of natural resources and industrial wastes that would otherwise harm the environment should be given emphasis in strategizing the photobioreactor mass production. To date, more research and innovation are needed since scalability and economics of microalgae cultivation using photobioreactors remain the challenges to be overcome for large-scale microalgae production

National microalgae biofuel production potential and resource

[1] Microalgae are receiving increased global attention as a potential sustainable "energy crop" for biofuel production. An important step to realizing the potential of algae is quantifying the demands commercial-scale algal biofuel production will place on water and land resources. We present a high-resolution spatiotemporal assessment that brings to bear fundamental questions of where production can occur, how many land and water resources are required, and how much energy is produced. Our study suggests that under current technology, microalgae have the potential to generate 220 × 10 9 L yr −1 of oil, equivalent to 48% of current U.S. petroleum imports for transportation. However, this level of production requires 5.5% of the land area in the conterminous United States and nearly three times the water currently used for irrigated agriculture, averaging 1421 L water per liter of oil. Optimizing the locations for microalgae production on the basis of water use efficiency can greatly reduce total water demand. For example, focusing on locations along the Gulf Coast, southeastern seaboard, and Great Lakes shows a 75% reduction in consumptive freshwater use to 350 L per liter of oil produced with a 67% reduction in land use. These optimized locations have the potential to generate an oil volume equivalent to 17% of imports for transportation fuels, equal to the Energy Independence and Security Act year 2022 "advanced biofuels" production target and utilizing some 25% of the current irrigation demand. With proper planning, adequate land and water are available to meet a significant portion of the U.S. renewable fuel goals