olelog

On 27 May 2009 I featured the Pacific Garbage Patch. In an article titled “Project Kaisei: voyage to clean up the plastic vortex” CNN has brought some pictures and a video from an August 2009 voyage to the area.

Apart from the CNN text, I think their dreadful images talk for themselves. The most heavily polluted areas of surface water in the gyre contained six times more plastic than plankton biomass.

A further voyage next year hopes to gather more data and move closer to a practical solution to the ever increasing problem.

• http://edition.cnn.com/2009/TECH/science/10/30/trash.vortex.kaisei/index.html
  

PS.
More footage from the Kasei project:

Hat tip “Living the Scientific Life” Blog
http://scienceblogs.com/grrlscientist/2009/10/project_kaisei_2009_intro_from.php

See also: http://scienceblogs.com/grrlscientist/2009/10/project_kaisei_scripps_oceanog.php

The good news is that plastics in Oceans decompose with surprising speed.

The bad news is that during these processes it releases toxic substances into the water.

Reporting - at the 238th National Meeting of the American Chemical Society (ACS) - a first study to look at what happens over the years to the billions of kilos of plastic waste floating in the world’s oceans, researchers came to the “surprising” discovery that plastics — reputed to be virtually indestructible — decompose with surprising speed. Scientists always believed that plastics in the oceans were unsightly, but a hazard mainly to marine animals that eat or become ensnared in plastic objects. Plastic in the ocean decomposes as it is exposed to the rain and sun and other environmental conditions.

The author described a new method to simulate the breakdown of plastic products at low temperatures, such as those found in the oceans. The process involves modeling plastic decomposition at room temperature, removing heat from the plastic and then using a liquid to extract the BPA (potentially toxic bisphenol A ) and PS oligomer. Typically, he said, Styrofoam is crushed into pieces in the ocean and finding these is no problem. But when the study team was able to degrade the plastic, it discovered that three new compounds not found in nature formed. They are styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST). SM is a known carcinogen and SD and ST are suspected in causing cancer. BPA ands PS oligomer are not found naturally and, therefore, must have been created through the decomposition of the plastic, he said. Trimer yields SM and SD when it decomposes from heat, so trimer also threatens living creatures.

• http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_ARTICLEMAIN&node_id=222&content_id=CNBP_022763&use_sec=true&sec_url_var=region1&__uuid=9ca28f0a-5365-44be-9b67-34aa77382260
  
  
• http://www.sciencedaily.com/releases/2009/08/090819234651.htm
  
  
  

Intensive mining of mercury (Hg) began around 1400 BC in the central Peruvian Andes.

Cinnabar (HgS or mercuric sulphide) is the primary natural source of mercury (Hg), and forms a bright red pigment (vermillion) when powdered. In the Andes vermillion was used as either a body paint or a covering on ceremonial gold objects from the first (Chavín) to the last (Inca) Andean empires.

PhD student Colin Cooke’s results from two seasons of field work in Peru have now provided the first unambiguous records of pre-industrial mercury pollution from anywhere in the world. His findings are published in the 18 May 2009 Early Edition of the Proceedings of the National Academy of Sciences (PNAS).

Cooke and his team recovered sediment cores from high elevation lakes located around Huancavelica, which is the New World’s largest mercury deposit. By measuring the amount of mercury preserved in the cores back through time, they were able to reconstruct the history of mercury mining and pollution in the region.

Mining appears to have began before the rise of any complex or highly stratified society (around 1400 BC). The mercury amounts peaked, however, at about 500 BC (the height of the Chavín culture) and again about 1450 AD (the height of the Inca culture, with Inca expansion into the central Andes). In between, by 800 AD, there was a brief renewal in cinnabar mining. Inca mining continued until 1564 AD when the Spanish crown assumed control,

During the Colonial era (1532–1900 AD), large-scale mercury mining began in earnest with the invention of mercury amalgamation in 1554 AD by Bartolomé de Medina in Mexico. For the next 350 years, mercury amalgamation became the dominant silver processing technique because it allowed for the extraction of silver from low-grade ores. Spanish efforts thus concentrated on supplying mercury to Colonial silver mines for use in amalgamation. Cinnabar ores from Huancavelica were smelted in grass-fired, clay-lined retorts, until vaporization yielded mercury gases, a portion of which was trapped in a crude condenser and cooled, yielding liquid mercury. Emissions of mercury thus occurred both during mining, as cinnabar dust, but also during cinnabar smelting, as gaseous mercury.

Frequent cave-ins and extensive mercury poisoning throughout Huancavelica’s 450-year Colonial history have made it one of the most sinister examples of human exploitation and disastrous mining environments ever documented, earning it the nickname mina de la muerte (mine of death).

Reference:
Cooke, C., P. Balcom, H. Biester, and A. Wolfe (2009).
Over three millennia of mercury pollution in the Peruvian Andes, Peru.
Proceedings of the National Academy of Sciences USA
doi:10.1073/pnas.0900517106

• http://www.pnas.org/content/early/2009/05/15/0900517106.abstract
• http://www.science.ualberta.ca/news.cfm?story=91226
• http://research.eas.ualberta.ca/cooke/Colin_Cookes_Webpage/Research.html

In a recent post on pollution in the Baltic Sea I wrote about the visible effects (algal bloom and transparency) of the pollution and about cost-efficient phosphorous abatement. Today I will concentrate on the oxygen problem and the question of possible engineered remediation.

Hypoxia, the lack of oxygen in bottom waters often defined as O₂ < 2 ml/l is a growing problem worldwide and dead zones have spread exponentially since the 1960s in coastal marine waters. The Baltic Sea is a brackish inland sea, alleged to be the largest body of brackish water in the world (other possibilities include the Black Sea). It occupies a basin formed by glacial erosion. The Baltic Proper is permanently stratified, consisting of an upper layer of brackish water with salinities around 7−8 and a lower layer of saline waters with salinities around 11−13. It is likely that the interaction between nutrients and climate has enhanced the conditions for hypoxia to occur.


Diagram of hypoxia in the Baltic Sea from Tackling Hypoxia in the Baltic Sea: Is Engineering a Solution? by Conley et al. 2009.
Saltwater enters from the Danish Straits and moves into the Baltic Proper following depth contours. As the water ages it is depleted of O₂, with anoxia occurring in the deepest basins. As a result of hypoxia the amount of sediment removal of nitrogen (N) through denitrification and anaerobic ammonium oxidation (anammox) decreases (smaller arrows) and is essentially zero in anoxic basins. A strong permanent halocline - that is a vertical zone in the water column in which salinity changes rapidly with depth - is formed at the transition zone at depths varying between ca. 60−80 m, and prevents vertical mixing of the water column and transport of more oxygenated waters to the bottom. Nitrogen removal also occurs below the permanent halocline and above the zone of hypoxia. Sediment phosphorous (P) release is highest in hypoxic area (largest arrow), low in oxic areas, and intermediate in anoxic areas. The anoxic areas tend to have low rates of phosphorous release because sediment phosphorous pools are depleted. The abundance, composition, and diversity of benthic (sea bottom) communities are also strongly influenced by O2. The amount of carbon delivered to the bottom waters of the Baltic Sea is an important control mechanism of oxygen consumption.

Significant amounts of phosphorous are currently released from sediments, an order of magnitude larger than man induced inputs. The Baltic Sea is unique for coastal marine ecosystems experiencing nitrogen losses in hypoxic waters below the halocline.

For more information about the Hypoxia-Related Processes in the Baltic Sea I refer to the paper in Environmental Science & Technology.

In short the Baltic Sea contains the largest man induced dead zone in the world, and due to feedback loops/feedback cycles the internal acceleration of eutrophication in the Baltic is a vicious circle - so the big question is, what can we do about it? Are engineering methods possible? Before I go on I would like to stress that virtually all engineering methods proposed to date for the Baltic Sea seem unrealistic and/or not viable, I will however mention some of the methods proposed.

Large-Scale Engineering to Increase Oxygen in Bottom Waters
The total amount of O2 needed to keep the deep waters above the threshold for hypoxia varies by 2−6 million t of O2 annually. At present there is no known technology that could transfer such an enormous amount of O2 directly into bottom waters and disperse it into large hypoxic volumes. Enhanced ventilation of deep waters through additional inputs of oxygenated saltwater has been suggested as a remediation method. Enhanced saltwater input into bottom waters is, however, expected to increase stratification and thereby increase the area of hypoxia.

Use of windmills to oxygenate the water
This includes windmills. Feasibility, costs, and further consequences for water circulation and fauna and flora so far unknown.

Chemical Removal of Phosphorus
To inactivate phosphorous by the addition of aluminium would require enormous amounts of aluminium. The method has been tried out in (smaller) freshwater lakes, but it is uncertain how aluminium will react in brackish water like that of the Baltic Sea. In the worst case it would be toxic for marine organisms, and anyway dumping of chemicals in the Sea is forbidden by an international convention.

Biomanipulation
Biomanipulation is a method to alter the biological communities by altering the abundance of specific organisms. Although some success has been achieved in freshwaters, the enormous size of the Baltic Sea adds to the uncertainty of the effectiveness of biomanipulation on such a scale.

Stop influx of Marine Water
A drastic solution would be to barricade influx of marine water and thereby change the brackish sea to a large freshwater lake. Although technically possible it would have enormous consequences. It would completely change the aquatic fauna and flora, and species dependent on saltwater, like cod, would completely disappear.

I think it is unnecessary to say that more detailed modeling efforts of the impact on physical mixing process and the response of salinity, temperature, and stratification must be made prior to any large-scale manipulation. So far engineering methods do not look promising, and the countries around the Baltic Sea must increase their efforts to reduce their loading of the Baltic Sea with nutrients like phosphorous and nitrogen. Reductions in hypoxia will not occur until nutrient loads are reduced.

References:
Hypoxia-Related Processes in the Baltic Sea
Conley et al.
Environ. Sci. Technol., 2009, 43 (10), pp 3412–3420
DOI: 10.1021/es802762a
Publication Date (Web): February 18, 2009
• http://pubs.acs.org/doi/abs/10.1021/es802762a

Tackling Hypoxia in the Baltic Sea: Is Engineering a Solution?
Conley et al.
Environ. Sci. Technol., 2009, 43 (10), pp 3407–3411
DOI: 10.1021/es8027633
Publication Date (Web): May 13, 2009
• http://pubs.acs.org/doi/abs/10.1021/es8027633

In Danish:
• http://www.dmu.dk/Udgivelser/DMUNyt/2009/7/biobaltic.htm

Some of my other posts on pollution of the Baltic Sea:
• http://my.opera.com/nielsol/blog/2009/01/15/pollution-of-the-baltic-sea
• http://my.opera.com/nielsol/blog/2009/05/12/baltic-sea-recovering
• http://my.opera.com/nielsol/blog/2009/05/13/baltic-sea-pollution-secchi

The Baltic Sea - sometimes called the “Nordic Dead Sea” because of the high degree of pollution - is slowly recovering and the negative environmental trend has been broken. For the first time discharges of fertilisers have decreased giving the sea a chance to recover.


The improvement is mainly due to the construction of new treatment works in Poland following the country's entry into the EU. Furthermore farmers in Denmark and Sweden have improved fertiliser management.

It has now been shown that levels of phosphates and nitrogen have declined for the first time, by 3,000 tons and 50,000 tons respectively, according to new research compiled by Fredrik Wulff at Stockholm University, who has made the new calculations on commission from the Baltic Marine Environment Protection Commission (HELCOM).

The first significant effects of the change will not be felt for 30-50 years however, according to a report in the Swedish newspaper Svenska Dagbladet (SvD).

• http://www.thelocal.se/19398/20090512/
In Danish:
• http://www.dr.dk/Nyheder/Udland/2009/05/12/082446.htm?rss=true

See also my post on Pollution of the Baltic Sea.