Saturday, February 18, 2012

Methane emissions from reservoirs behind Dams

“No time to waste” on transition to green energy

Meanwhile, hydropower would produce such large emissions that it could add to global warming more than coal power alone for a good 60 years or so. “Hydropower is often associated with high methane emissions [due to] the decay of organic matter in the flooded land surface,” explained Caldeira. "There may be some niche locations where additional hydropower could be environmentally desirable, but more often environmental considerations weigh in favour of removing dams, not building them."

Friday, February 17, 2012

Pretreatment of water for RO Plants

Algal blooms not created equal

Since the first commercial seawater RO plant was installed in 1974, pretreatment has been the single biggest variable in determining an installation’s success. More than 3,200 SWRO plants are now producing almost 24 million m3/d (6.3 billion GPD) of fresh water, and of all the pretreatment issues, the ability to effectively deal with harmful algal blooms (HABs) remains the most challenging.

Last week, at an expert workshop entitled Red Tides and Harmful Algal Blooms (HAB): Impact on Desalination Plants, public and private sector organizations met in Muscat, Oman to share information and work towards developing a better understanding of HABs. The event was jointly organized by the Middle East Desalination Research Center (MEDRC), Australia’s National Centre of Excellence in Desalination (NCED) and King Abdullah University of Science and Technology (KAUST). The event was held under the patronage of HE Mohammed Al Mahrouqi, Chairman of Oman’s Public Authority for Electricity & Water.

HABs refer to fast-growing algal blooms that make toxic chemical byproducts that can concentrate in the tissues of fish or shellfish. Animals and humans who eat the shellfish may become sick or suffer severe respiratory problems including paralytic shellfish poisoning (PSP).

Certain phytoplankton species contain reddish pigments; when they bloom, the water often appears to be colored red, hence the term ‘red tide’. However, scientists prefer referring to the blooms as HABs and consider the term ‘red tide’ to be a misnomer because the events are not associated with tides and because the phytoplankton species that are harmful may never reach the densities required to discolor the water.

Don Anderson, a senior scientist at Woods Hole Oceanographic Institution, told the workshop attendees that HABs are an expanding threat to public and ecosystem health and coastal aesthetics worldwide. “HABs are diverse phenomena, caused by many different species, producing different toxins and other compounds, in different hydrographic environments. Methods that might mitigate the impacts of one type of HAB may not work for others. The threat from HABs to desalination plants is real, and deserves attention through targeted research,” said Dr Anderson.

HABs have caused several well-publicized desal plant shutdowns in Oman since 2008. Dr Hamed Al Gheilani, with Oman’s Marine Science and Fisheries Center, and Dr. Hamad Al Hasni, with Oman PAEW, outlined the impacts of those events and described the monitoring program initiated to help predict future events and mitigate their impacts on desalination plants.

The workshop concluded with the attendees dividing into three groups to prepare recommended research topics.

According to MEDRC deputy director Shannon McCarthy, “The workshop resulted in some very specific recommendations for research projects that will help identify the onset of HAB events and to develop methods to mitigate their impact on desalination plant performance and water quality. Over the next few weeks, MEDRC, NCED and KAUST will consolidate those recommendations and determine how selected projects might be funded. We have also already begun planning a follow-up event to build on what has been learned at last week’s workshop.”

Wednesday, February 8, 2012

HOT news: Pacific carbon pump speeds up in summer

HOT news: Pacific carbon pump speeds up in summer
February 7, 2012 | Cheryl Ernst

An international team of scientists led by University of Hawaiʻi at Mānoa oceanographer David Karl has documented a regular, significant and unexpected increase in the amount of particulate matter exported to the deep sea in the North Pacific Subtropical Gyre.

They suspect the previously undocumented phenomenon may be a response to day length, a general phenomenon known as photoperiodism.

Measuring the biological carbon pump

Deployment of sediment traps from the R/V Kilo Moana on a 2007 Hawaiʻi Ocean Time-series cruise (photo by Adriana Harlan and Susan Curless)

Using 13 years of Hawaiʻi Ocean Time-series (HOT) data from Station ALOHA (A Long-term Oligotrophic Habitat Assessment) about 100 miles north of Oʻahu, the scientists identified a rapid, predictable summer jump in the amount of total carbon, organic carbon, nitrogen, phosphorus and biogenic silica transferred from sunlit surface waters to the ocean depths through what is called the biological carbon pump.

This summer export pulse is approximately threefold greater than mean wintertime particle fluxes and fuels more efficient carbon sequestration, according to an article published in the February 7 PNAS, the Proceedings of the National Academy of Sciences. Co-authors are Matthew Church from the University of Hawaiʻi at Mānoa, John Dore from Montana State University, Ricardo M. Letelier from Oregon State University and Claire Mahaffey from the University of Liverpool.

Half of the photosynthesis on Earth is attributable to microscopic, single-celled phytoplankton that inhabit the sea. The vast majority of photosynthetic carbon fixation takes place in low-biomass, low-nutrient open ocean gyres, with about 15 percent of particulate organic matter settling into deep-sea reservoirs to await eventual resurfacing.

The researchers suspect that the unanticipated summer jump in deep-sea sequestration of carbon is due to seasonal increases in the biomass and productivity of symbiotic nitrogen-fixing cyanobacteria in association with diatoms.

This increase in microbial presence and activity is distinct from surface blooms, which don’t necessarily result in transfer of particulate matter, but does have ecological implications, said Karl. Besides identifying the probable mechanism and documenting seasonal variability and efficiency in carbon sequestration, the findings confirm the importance of nitrogen fixation and diatom-cyanobacteria symbiosis in the efficient transfer of carbon and energy to the deep sea.

In the absence of any obvious predictable stimulus or habitat condition, the scientists hypothesize that changes in day length may be an important environmental cue to initiate aggregation and subsequent export of organic matter to the deep sea. Nearly all cyanobacteria and eukaryotic algae studied to date, including marine diatoms, have light-activated molecular switches, they note.

Their conceptual model provides a testable hypothesis for future laboratory and field experimentation.

Becoming a microbial oceanography pioneer

Congratulated by researchers and crew on his last cruise as HOT principal investigator in 2009, David Karl has logged more than 1,000 days at sea (photo by Dan Sadler)

It’s not the first time that Karl has been out front with unexpected findings that spur new science. A three-page profile that accompanies the PNAS article describes the origin and high points of a remarkable oceanographic career.

A baseball-playing, motorcycle-riding youth who served as high school class president and aspired to become a commercial fisherman, Karl was captivated by the sea from his first glimpse of the ocean, viewed from atop a Maine mountain when he was 17.

As a master’s student at Florida State University, he helped improve the assay used to quantify ocean microbes and applied it to marine sediments—the first of many tools and processes he had a hand in developing.

A newly minted PhD just hired by the University of Hawaiʻi, he set off on his first National Science Foundation–funded grant to study newly discovered life forms at hydrothermal vents on the Galapagos Rift. In 1999, he published the first account of microorganisms in another extreme environment, the accreted ice of Antarctica’s Lake Vostok.

Karl conceived of the Hawaiʻi Ocean Time-series program, launched by the National Science Foundation with a $1 million grant in 1988 and is still collecting crucial microbial and biogeochemical data such as that providing the basis for the current paper. (UH Mānoa colleague Roger Lukas leads the companion physical oceanography portion of HOT.)

Along the way, Karl has garnered numerous professional awards and been elected to the National Academy of Sciences. He has published hundreds of papers and helped secure more than $62 million in extramural funds. His proposal of “Southern Ocean” as the name for waters south of the 60° south latitude was formally designated by the U.S. Geographical Board of Names, and he is credited with helping create the discipline of microbial oceanography.

Karl at the blessing of C-MORE Hale on the UH Mānoa campus in November 2010 with, from left, U.S. Senator Daniel Inouye, University of Hawaiʻi President M.R.C. Greenwood and National Science Foundation Director Subra Suresh (UH photo)

As director of the new Center for Microbial Oceanography: Research and Education, a National Science Foundation–sponsored Science and Technology Center with five partner institutions, he continues to advance the understanding of the life of the sea “from genome to biome.”

Reflecting on his first Galapagos Rift dives, Karl says the mesmerizing deep-sea hydrothermal vents “revealed how little we actually knew about our planet.”

With unflagging enthusiasm, he continues to do his best to change that.

About the research

The research was supported by grants from the National Science Foundation and the Gordon and Betty Moore Foundation.

Monday, February 6, 2012

Carbon Sequestration by Diatoms

A report on carbon sequestration by Diatoms -

"After thirteen years of work scientists have determined that diatoms perform a
natural carbon sequestration annually according to a report released at the
Proceedings of the National Academy of the Sciences web site on January 30,
2011 [ should be 2012 ]."

A paper about role of Diatoms in oceans -