Monday, December 3, 2012

Methylmercury

Long touted as being very healthy, eating seafood may not be quite so.  The article below discusses mercury pollution in ocean surface waters.


Mercury Released Into Air Contaminates Ocean Fish

ScienceDaily (Dec. 3, 2012) — In new research published in a special issue of the journalEnvironmental Health Perspectives and in "Sources to Seafood: Mercury Pollution in the Marine Environment" -- a companion report by the Dartmouth-led Coastal and Marine Mercury Ecosystem Research Collaborative (C-MERC), scientists report that mercury released into the air and then deposited into oceans contaminates seafood commonly eaten by people in the U.S. and globally.
Over the past century, mercury pollution in the surface ocean has more than doubled, as a result of past and present human activities such as coal burning, mining, and other industrial processes. The research findings by C-MERC published December 3 also examine the effects of local mercury inputs that dominate some near-shore coastal waters.
C-MERC's research is presented through nine scientific papers inEnvironmental Health Perspectivesand is the culmination of two years of work by approximately 70 mercury and marine scientists from multiple disciplines including biology, ecotoxicology, engineering, environmental geochemistry, and epidemiology. The research provides a synthesis of the science on the sources, fate, and human exposure to mercury in marine systems by tracing the pathways and transformation of mercury to methylmercury from sources to seafood to consumers.
Two other papers focusing on the health effects of methylmercury were published earlier this year inEnvironmental Health Perspectives. Methylmercury has long been known as a potent neurotoxicant, particularly as a result of acute and high level human exposures primarily through seafood consumption, but more recent research has revealed health effects at increasingly lower levels of exposure.
The companion report, "Sources to Seafood: Mercury Pollution in the Marine Environment," looks at the pathways and consequences of mercury pollution across marine systems by drawing on findings from the C-MERC papers, scientific literature, and data from a range of marine systems and coastal basins. Specifically, the report examines mercury sources, pathways, and inputs for the Hudson River Estuary, San Francisco Bay, Gulf of Mexico, Long Island Sound, Chesapeake Bay, Gulf of Maine, Arctic Ocean, and the open ocean.
C-MERC's research findings are especially timely, as the U.S. and other nations prepare for the fifth session of the United Nations Environment Programme's Intergovernmental Negotiating Committee (INC5) on January 13-18, 2013 in Geneva, Switzerland, which is working to prepare a legally binding instrument to control mercury releases to the environment.
"Despite the fact that most people's mercury exposure is through the consumption of marine fish, this is the first time that scientists have worked together to synthesize what is known about how mercury moves from its various sources to different areas of the ocean and then up the food chain to the seafood most people eat," said Celia Y. Chen, Ph.D., Research Professor of Biological Sciences at Dartmouth. She is a co-author of the new Environmental Health Perspectivespapers on nutrient supply and mercury dynamics, and mercury sources in the Gulf of Maine, and authored an editorial on the subject in the journal, and is also a lead author of "Sources to Seafood." Chen will represent Dartmouth as an accredited non-governmental organization at INC5 in an observer status. Copies of C-MERC's Sources to Seafood report will be made available to INC5 attendees.
C-MERC research suggests that mercury deposited from the atmosphere ranges from 56% of the mercury loading to several large gulfs to approximately 90% in the open ocean.
"Oceans are home to large tuna and swordfish, which together account for more than half of the mercury intake from seafood for the overall U.S. population," said Elsie M. Sunderland, Assistant Professor of Aquatic Science at Harvard University. She is a lead author of an Environmental Health Perspectivespaper on mercury sources in the Gulf of Maine and a lead author of "Sources to Seafood."
Model estimates from the report indicate that methylmercury concentrations in marine fish will decline roughly in proportion to decreases in mercury inputs, though the timing of the response will vary.
"Our model estimates show that for the North Atlantic Ocean, a 20% cut in the amount of mercury deposited to the ocean from the atmosphere would lead to about a 16% decline in mercury levels in fish… But it is important to realize that achieving a 20% decrease in mercury deposition will require substantial cuts in current anthropogenic emissions, given the already very sizeable build-up of mercury in terrestrial environments and ocean waters," said Robert P. Mason, Ph.D., Professor of Marine Sciences at the University of Connecticut. Mason is a lead author of the Environmental Health Perspectives paper on mercury biogeochemical cycling in the ocean and a lead author of "Sources to Seafood."
The C-MERC team also evaluated the fate of mercury in nearshore coastal waters and found a contrasting pattern to the oceans. "For some nearshore coastal waterbodies, like San Francisco Bay and the Hudson River Estuary, where there are large mercury sources such as historically contaminated sites, ongoing releases from wastewater or industrial waste and atmospheric mercury deposition in the watershed, mercury loading can be dominated by river inputs," said Charles T. Driscoll, Ph.D., University Professor of Environmental Systems Engineering at Syracuse University. He is a lead author on anEnvironmental Health Perspectives paper on nutrient supply and mercury dynamics, and a lead author of "Sources to Seafood."
The C-MERC team estimates that river inputs can be as much as 80% of the total mercury inputs to some estuaries. "The impact of mercury released to coastal waters from watersheds via rivers has been a somewhat underappreciated aspect of the problem. Yet, these bays and estuaries can be important sources of fish for local anglers, thus controls on these sources can have substantial local benefits," explained Driscoll.
"C-MERC's synthesis of research identifies the most important drivers of mercury pollution to different oceans and coastal waters, and can help policymakers understand the links between environmental processes, methylmercury levels in marine ecosystems, human exposure, and the human health effects -- all of which are critical to the discussion of how local, regional and global mercury pollution affects the world's supply of seafood," said Chen.
Approximately one-third of all mercury emissions are associated with current industrial sources and other human activities that can be controlled. "The good news is that the science suggests that if mercury inputs are curtailed, mercury levels in ocean fish will decline and decrease the need for warnings to limit consumption of this globally important food source," added Chen.
Share this story on Facebook, Twitter, and Google:
Other social bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided byDartmouth College, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
 APA

 MLA
Dartmouth College (2012, December 3). Mercury released into air contaminates ocean fish. ScienceDaily. Retrieved December 3, 2012, from http://www.sciencedaily.com­/releases/2012/12/121203150008.htm
Note: If no author is given, the source is cited instead.
Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.
Posted by at

Friday, November 30, 2012

Sometimes the cure is worse than the illness...


Pictured: Rotifer.

 I just finished reading a shocking article on ScienceDaily.com.  It covers a study of the toxicity of oil and chemical dispersants in the Gulf of Mexico during/after the 2010 BP Macondo Spill.

 Read on for the disturbing details...


Gulf of Mexico Clean-Up Makes 2010 Spill 52-Times More Toxic; Mixing Oil With Dispersant Increased Toxicity to Ecosystems

ScienceDaily (Nov. 30, 2012) — If the 4.9 million barrels of oil that spilled into the Gulf of Mexico during the 2010 Deep Water Horizon spill was a ecological disaster, the two million gallons of dispersant used to clean it up apparently made it even worse -- 52-times more toxic. That's according to new research from the Georgia Institute of Technology and Universidad Autonoma de Aguascalientes (UAA), Mexico.
The study found that mixing the dispersant with oil increased toxicity of the mixture up to 52-fold over the oil alone. In toxicity tests in the lab, the mixture's effects increased mortality of rotifers, a microscopic grazing animal at the base of the Gulf's food web. The findings are published online by the journalEnvironmental Pollution and will appear in the February 2013 print edition.
Using oil from the Deep Water Horizon spill and Corexit, the dispersant required by the Environmental Protection Agency for clean up, the researchers tested toxicity of oil, dispersant and mixtures on five strains of rotifers. Rotifers have long been used by ecotoxicologists to assess toxicity in marine waters because of their fast response time, ease of use in tests and sensitivity to toxicants. In addition to causing mortality in adult rotifers, as little as 2.6 percent of the oil-dispersant mixture inhibited rotifer egg hatching by 50 percent. Inhibition of rotifer egg hatching from the sediments is important because these eggs hatch into rotifers each spring, reproduce in the water column, and provide food for baby fish, shrimp and crabs in estuaries.
"Dispersants are preapproved to help clean up oil spills and are widely used during disasters," said UAA's Roberto-Rico Martinez, who led the study. "But we have a poor understanding of their toxicity. Our study indicates the increase in toxicity may have been greatly underestimated following the Macondo well explosion."
Martinez performed the research while he was a Fulbright Fellow at Georgia Tech in the lab of School of Biology Professor Terry Snell. They hope that the study will encourage more scientists to investigate how oil and dispersants impact marine food webs and lead to improved management of future oil spills.
"What remains to be determined is whether the benefits of dispersing the oil by using Corexit are outweighed by the substantial increase in toxicity of the mixture," said Snell, chair of the School of Biology. "Perhaps we should allow the oil to naturally disperse. It might take longer, but it would have less toxic impact on marine ecosystems."
Share this story on Facebook, Twitter, and Google:
Other social bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided byGeorgia Institute of Technology.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. Roberto Rico-Martínez, Terry W. Snell, Tonya L. Shearer.Synergistic toxicity of Macondo crude oil and dispersant Corexit 9500A® to the Brachionus plicatilis species complex (Rotifera). Environmental Pollution, 2013; 173: 5 DOI: 10.1016/j.envpol.2012.09.024
 APA

 MLA
Georgia Institute of Technology (2012, November 30). Gulf of Mexico clean-up makes 2010 spill 52-times more toxic; Mixing oil with dispersant increased toxicity to ecosystems.ScienceDaily. Retrieved November 30, 2012, from http://www.sciencedaily.com­/releases/2012/11/121130110518.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Posted by at

Tuesday, November 27, 2012

Antarctic Marine Life

Here's an interesting article from BBC Naturre on Antarctic marine life.  Also below is a link to BBC's Antarctic Ecozone page.
BBC Nature's Antarctic Ecozone Homepage


Antarctic marine wildlife is under threat, study finds

The Southern OceanThe research took place in the Southern Ocean

Related Stories

Marine snails in seas around Antarctica are being affected by ocean acidification, scientists have found.
An international team of researchers found that the snails' shells are being corroded.
Experts says the findings are significant for predicting the future impact of ocean acidification on marine life.
The results of the study are published in the journal Nature Geoscience.
The marine snails, called "pteropods", are an important link in the oceanic food chain as well as a good indicator of ecosystem health.

Ice picks

"They are a major grazer of phytoplankton and... a key prey item of a number of higher predators - larger plankton, fish, seabirds, whales," said Dr Geraint Tarling, Head of Ocean Ecosystems at the British Antarctic Survey (BAS) and co-author of the report.
The study was a combined project involving researchers from the BAS, the National Oceanic and Atmospheric Administration (NOAA), the US Woods Hole Oceanographic Institution and the University of East Anglia's school of Environmental Sciences.
Ocean acidification is a result of burning fossil fuels: some of the additional carbon dioxide in the atmosphere is absorbed into oceans.
This process alters the chemistry of the water, making it more acidic.
Marine snailsPteropods are an important food source for fish and birds
During a research cruise in the Southern Ocean in 2008, scientists assessed the corrosive effects of upwelled water on pteropod shells.
Upwelling occurs when winds push cold layers of deeper seawater from around 1,000m towards the surface layers.
Seawater from these depths is more corrosive to aragonite, the type of calcium carbonate that forms pteropod shells. The point at which this occurs is known as the "saturation horizon".
"Carbonates in shells dissolve more when temperatures are cold and pressure is high, which are the characteristic properties of the deep ocean," Dr Tarling explained.
Scientists found that the combined effect of increased ocean acidity and natural upwelling meant that in some areas of the Southern Ocean the saturation horizon was around just 200m - the upper layer of the ocean where pteropods live.
Dr Tarling explained the significance of these findings: "The snails do not necessarily die as a result of their shells dissolving, however it may increase their vulnerability to predation and infection, consequently having an impact to other parts of the food web."
He said that although upwelling sites are a natural phenomenon in the Southern Ocean, "instances where they bring the saturation horizon above 200m will become more frequent as ocean acidification intensifies in the coming years".
Marine snail shell dissolutionA pteropod (Limacina helicina antarctica) showing acute levels of shell dissolution
Interpreting the results
Dr Tarling said the study is "very much... a pilot study" and that it has provided an important body of work regarding "how pteropods will respond to future oceanic conditions".
To date there have been a number of laboratory studies predicting the effects of ocean acidification on marine organisms, but none assessing the impacts on live specimens in their natural environment.
"It took us several years even to develop a technique sensitive enough to look at the exterior of the shells under high-power scanning electron microscopes, since the shells are very thin and the dissolution pattern, subtle," commented Dr Tarling.
He went on: "We are now undertaking a much more comprehensive programme completely focussed on the effects of ocean acidification, not just on pteropods but to a wider range of organisms."
Join BBC Nature on Facebook and Twitter @BBCNature.
Posted by at

Monday, November 19, 2012

Coral "Forests"



NOAA recently had a recent post on its National Ocean Service website.  The video describes a number of different coral environments.

Ocean Service coral video
Posted by at

Wednesday, November 14, 2012

Hurricane Sandy's Size

Check out the fascinating article by Dr. Jeff Masters, of Weather Undergound, regarding Hurricane Sandy's enormous size.

Hurricane Sandy's huge size: freak of nature or climate change?


Published: 1:10 PM GMT on November 13, 2012
Hurricane Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Since detailed records of hurricane size began in 1988, only one tropical storm (Olga of 2001) has had a larger area of tropical storm-force winds, and no hurricanes has. Sandy's area of ocean with twelve-foot seas peaked at 1.4 million square miles--nearly one-half the area of the contiguous United States, or 1% of Earth's total ocean area. Most incredibly, ten hours before landfall (9:30 am EDT October 30), the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969. This is 2.7 times higher than Katrina's peak energy, and is equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been wider; the previous record holder was Hurricane Igor of 2010, which was 863 miles in diameter. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lakeshore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart!

Largest Atlantic tropical cyclones for area covered by tropical storm-force winds:

Olga, 2001: 780,000 square miles
Sandy, 2012: 560,000 square miles
Lili, 1996: 550,000 square miles
Igor, 2010: 550,000 square miles
Karl, 2004: 430,000 square miles



Figure 1. Hurricane Sandy’s winds (top), on October 28, 2012, when Sandy was a Category 1 hurricane with top winds of 75 mph (this ocean surface wind data is from a radar scatterometer on the Indian Space Research Organization’s (ISRO) Oceansat-2.) Hurricane Katrina’s winds (bottom) on August 28, 2005, when Katrina was a Category 5 hurricane with top winds of 175 mph (data taken by a radar scatterometer on NASA’s defunct QuickSCAT satellite.) In both maps, wind speeds above 65 kilometers (40 miles) per hour are yellow; above 80 kph (50 mph) are orange; and above 95 kph (60 mph) are dark red. The most noticeable difference is the extent of the strong wind fields. For Katrina, winds over 65 kilometers per hour stretched about 500 kilometers (300 miles) from edge to edge. For Sandy, winds of that intensity spanned an region of ocean three times as great--1,500 kilometers (900 miles). Katrina was able to generate a record-height storm surge over a small area of the Mississippi coast. Sandy generated a lower but highly destructive storm surge over a much larger area, due to the storm's weaker winds but much larger size. Image credit: NASA.

How did Sandy get so big?
We understand fairly well what controls the peak strength of a hurricane's winds, but have a poor understanding of why some hurricanes get large and others stay small. A number of factors probably worked together to create a "prefect storm" situation that allowed Sandy to grow so large, and we also must acknowledge that climate change could have played a role. Here are some possible reasons why Sandy grew so large:

1) Initial size of the disturbance that became Sandy was large
Sandy formed from an African tropical wave that interacted with a large area of low pressure that covered most of the Central Caribbean. Rotunno and Emanuel (1987) found that hurricanes that form from large initial tropical disturbances like Sandy did tend to end up large in size.


Figure 2. The initial disturbance that spawned Sandy, seen here on October 20, 2012, was quite large.

2) High relative humidity in Sandy's genesis region
The amount of moisture in the atmosphere may play an important role in how large a hurricane gets (Hill and Lackmann, 2009.) Sandy was spawned in the Caribbean in a region where the relative humidity was near 70%. This is the highest humidity we saw during 2012 during the formation of any Atlantic hurricane.

3) Passage over Cuba
Sandy struck Cuba as an intensifying Category 2 hurricane with 110 mph winds. While the core of the storm was over Cuba, it was cut off from the warm ocean waters surrounding Cuba. Most of Sandy's large circulation was still over the ocean, though, and the energy the storm was able to extract from the ocean went into intensifying the spiral bands over water. When Sandy's core re-emerged over water, the hurricane now had spiral bands with heavier thunderstorm activity as a result of the extra energy pumped into the outer portion of the storm during the eye's passage over land. This extra energy in the outer portions of Sandy may have enabled it to expand in size later.

4) Interaction with a trough of low pressure over the Bahamas
As Sandy passed through the Bahamas on October 25, the storm encountered strong upper-level winds associated with a trough of low pressure to the west. These winds created high wind shear that helped weaken Sandy and destroy the eyewall. However, Sandy compensated by spreading out its tropical storm-force winds over a much wider area. Between 15 and 21 UTC on October 25, Sandy's area of tropical storm-force winds increased by more than a factor of two.

5) Leveraging of the Earth's spin
As storms move towards Earth's poles, they acquire more spin, since Earth's rotation works to put more vertical spin into the atmosphere the closer one gets to the pole. This extra spin helps storms grow larger, and we commonly see hurricanes grow in size as they move northwards.

6) Interaction with a trough of low pressure at landfall
As Sandy approached landfall in New Jersey, it encountered an extratropical low pressure system to its west. This extratropical storm began pumping cold air aloft into the hurricane, which converted Sandy into an extratropical low pressure system, or "Nor'easter". The nature of extratropical storms is to have a much larger area with strong winds than a hurricane does, since extratropical storms derive their energy from the atmosphere along a frontal boundary that is typically many hundreds of miles long. Thus, as Sandy made landfall, the hurricane's strongest winds spread out over a larger area, causing damage from Indiana to Nova Scotia.

Are we likely to see more such storms in the future?
Global warming theory (Emanuel, 2005) predicts that a 2°C (3.6°F) increase in ocean temperatures should cause an increase in the peak winds of the strongest hurricanes of about about 10%. Furthermore, warmer ocean temperatures are expected to cause hurricanes to dump 20% more rain in their cores by the year 2100, according to computer modeling studies (Knutson et al., 2010). However, there has been no published work describing how hurricane size may change with warmer oceans in a future climate. We've seen an unusual number of Atlantic hurricanes with large size in recent years, but we currently have no theoretical or computer modeling simulations that can explain why this is so, or if we might see more storms like this in the future. However, we've seen significant and unprecedented changes to our atmosphere in recent decades, due to our emissions of heat-trapping gases like carbon dioxide. The laws of physics demand that the atmosphere must respond. Atmospheric circulation patterns that control extreme weather events must change, and we should expect extreme storms to change in character, frequency, and intensity as a result--and not always in the ways our computer models may predict. We have pushed our climate system to a fundamentally new, higher-energy state where more heat and moisture is available to power stronger storms, and we should be concerned about the possibility that Hurricane Sandy's freak size and power were partially due to human-caused climate change.

References
Emanuel, K. (2005). Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436(7051), 686-688.

Hill, Kevin A., and Gary M. Lackmann (2009), "Influence of environmental humidity on tropical cyclone size," Monthly Weather Review 137.10 (2009): 3294-3315.

Knutson, T. R., McBride, J. L., Chan, J., Emanuel, K., Holland, G., Landsea, C., ... & Sugi, M. (2010). Tropical cyclones and climate change. Nature Geoscience, 3(3), 157-163.

Rotunno, R., & Emanuel, K. A. (1987). An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci, 44(3), 542-561.

The Atlantic is quiet, but a Nor'easter expected next week
The Atlantic is quiet, with no threat areas to discuss. An area of low pressure is predicted to develop just north of Bermuda on Wednesday, and the GFS model predicts that this low could become a subtropical cyclone as moves north-northeastwards out to sea late in the week.

The long-range models are in increasing agreement that a Nor'easter will develop near the North Carolina coast on Sunday, then move north to northeastwards early next week. High winds, heavy rain, and coastal flooding could affect the mid-Atlantic coast and New England coasts next Monday and Tuesday due to this storm, but it appears likely that the Nor'easter will stay farther out to sea than the last Nor'easter and have less of an impact on the region devastated by Sandy. Ocean temperatures off the coast of North Carolina were cooled by about 4°F (2.2°C) due to the churning action of Hurricane Sandy's winds, but are still warm enough at 22 - 24°C to potentially allow the Nor'easter to acquire some subtropical characteristics. I doubt the storm would be able to become a named subtropical storm, but it could have an unusual amount of heavy rain if it does become partially tropical. The Nor'easter is still a long ways in the future, and there is still a lot of uncertainty on where the storm might go.

Jeff Masters
Posted by at
Subscribe to: Posts (Atom)