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Environmental Monitoring


January 2013 Issue

To Get Water Samples, Scientists Drill Through 3 Kilometers of Ice
A British team of scientists and engineers began in December efforts to bore a hole through more than 3 kilometers of solid ice into an ancient lake buried beneath the West Antarctic Ice Sheet using a specially designed high-pressure hot-water drill.

The team hopes to find signs of life in the water and clues to the Earth's past climate in the mud at the floor of Lake Ellsworth. This will also have implications for understanding future sea-level rise.

The hot-water drill, designed by British Antarctic Survey (BAS) engineers, was to take around five days of continuous drilling through the ice to reach the lake. With water at 90° C, the water pressure from the hose will be around 2,000 pounds per square inch.

A titanium probe, designed by a team at the National Oceanography Centre, will collect water samples and data. A sediment corer developed by BAS will capture lake-bed mud samples. The team will have 24 hours to keep access to the 40-centimeter-wide borehole open before it refreezes to an unusable size.

To protect Lake Ellsworth's environment and ensure samples are uncontaminated, space-industry-standard clean technology has been used to sterilize equipment. This included a four-stage chemical wash, followed by full exposure to hydrogen peroxide vapor during the final assembly process. Equipment will be treated again on site. The water used for drilling will undergo a four-stage filtration process, down to 0.1 microns, before being passed under ultraviolet light.

Subsea Dispersants had Little Effect On Gulf Spill, 3D Model Suggests
A 3D model, developed by researchers at the University of Miami, has indicated that the dispersant injected at the wellhead of the 2010 Macondo blowout was not necessary to break up the oil and that it did not have its expected outcome.

The study, published in Environmental Science & Technology, is the first to examine the effects of the use of unprecedented quantities of synthetic dispersants on the distribution of an oil mass in the water column, based on a modeling approach.

The researchers, led by University of Miami associate professor Claire Paris, estimated the distribution of oil droplet sizes with and without injection of dispersant at the wellhead. They then applied an oil-mass tracking model of the Connectivity Modeling System (CMS), which was developed shortly after the incident, and presented a 3D simulation of the spill to examine the effect the synthetic dispersant may have had on the oil transport in the water column.

Injecting chemical dispersant at the wellhead may have had little effect because, with the high pressure at which the oil came from the well, it was already dispersed in small droplets.

'It is impossible to know whether the synthetic dispersant was well mixed with the oil as it was injected,' Paris said. 'Our models treat both scenarios, and regardless of whether you have the dispersant in the water mixture or not, the amount of oil reaching the sea surface remained relatively unchanged.'

These findings expand on a study published in 2012 in which the team studied the role of wind-induced surface drift on the fate of the oil in the Gulf of Mexico. The model will be helpful in assessing the 3D transport of oil in the water column and quantifying the utility of synthetic dispersants for deepwater oil leaks.

Sea Levels Rise 60 Percent Faster Than IPCC Projections
Satellite measurements show that sea levels are rising 60 percent faster than the Intergovernmental Panel on Climate Change's (IPCC) central projections, new research suggests.

While temperature rises appear to be consistent with the projections made in the IPCC's fourth assessment report (0.16° C per decade), satellite measurements show that sea levels are rising at a rate of 3.2 millimeters a year, compared to the best estimate of 2 millimeters a year in the report.

The researchers, from the Potsdam Institute for Climate Impact Research, Tempo Analytics and Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, published their findings in Environmental Research Letters.They state that the findings are important for keeping track of how well past projections match the accumulating observational data, especially as projections made by the IPCC are increasingly being used in decision making.

The study involved an analysis of global temperatures and sea-level data over the past two decades, comparing them both to projections made in the IPCC's third and fourth assessment reports. Results were obtained by taking averages from the five available global land and ocean temperature series.

The study also shows that it is very unlikely that the increased rate is down to internal variability in the climate system and also shows that nonclimatic components of sea-level rise, such as water storage in reservoirs and groundwater extraction, do not have an effect on the comparisons made.

Ship-Based Cameras Record Sea Ice to Recreate 3D Map
A University of Delaware research team has developed a camera system for mapping polar ice floes in 3D, a procedure made difficult by ice's lack of texture and whiteness, UDaily reported in December.

The system is accurate within 10 to 20 centimeters. The work could lead to a database of other information for scientists doing similar work in the polar regions.

The team, led by professor Chandra Kambhamettu, mounted three cameras on the RV Polarstern to capture images of the sea ice as the expedition assessed walrus habitat and record data in real time.

Two of the ship-board cameras worked in a stereo pair, according to UDaily. A third camera for recording structure from motion analysis was positioned between them to gather the same information on its own. The team will compare the results from both systems to determine which provides the best data.

The system's baseline infrastructure can cover various distances with equal accuracy, an advantage that may also allow the technology to become competitive with lidar systems. Development of the camera system is part of a National Science Foundation project with the University of Virginia and University of Alaska, Fairbanks.


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