RSS

Atmospheric transport of mineral dust from the Indo-Gangetic Plain: Temporal variability, acid processing, and iron solubility

Abstract

Atmospheric transport of chemical constituents from the Indo-Gangetic Plain (IGP) to the Bay of Bengal is a conspicuous seasonal feature that occurs during the late NE-monsoon (December-March). With this perspective, aerosol composition and abundance of mineral dust have been studied during November 2009 - March 2010 from a sampling site (Kharagpur: 22.3 N, 87.3E) in the IGP, representing the atmospheric outflow to the Bay of Bengal. The chemical composition of PM2.5 suggests the dominance of nss-SO42- (6.9 – 24.3 µg m-3); whereas the abundance of mineral dust varied from 3 to 18 µg m-3. The concentration of aerosol iron (FeTot) and its fractional solubility (Fews % = Fews/FeTot *100, where Fews is the water-soluble fraction of FeTot) varied from 60 to 1144 ng m-3 and from 6.7 to 26.5 %, respectively. A striking similarity in the temporal variability of total inorganic acidity (TIA = NO3- + nss-SO42-) and Fews (%) provides evidence for acid processing of mineral dust (alluvium) during atmospheric transport from the IGP. The contribution of TIA to water-soluble inorganic species [(nss-SO42- + NO3-)/ΣWSIS], mass ratios of Ca/Al and Fe/Al, abundance of dust (%) and Fews (%) in the IGP-outflow are similar to the aerosol composition over the Bay of Bengal. With the rapid increase in anthropogenic activities over south and south-east Asia, the enhanced fractional solubility of aerosol iron (attributed to acid processing of mineral dust) has implications to further increase the air-sea deposition of Fe to the surface ocean.

 
Comments Off

Posted by on July 22, 2014 in Blog

 

Evolution of stress and fault patterns in oblique rift systems: 3-D numerical lithospheric-scale experiments from rift to breakup

Abstract

Rifting involves complex normal fault systems that are controlled by extension direction, reactivation of pre-rift structures, sedimentation, and dyke dynamics. The relative impact of these factors on the observed fault pattern, however, is difficult to deduce from field-based studies alone. This study provides insight in crustal stress patterns and fault orientations by employing a laterally homogeneous, 3D rift setup with constant extension velocity. The presented numerical forward experiments cover the whole spectrum of oblique extension. They are conducted using an elasto-visco-plastic finite element model and involve crustal and mantle layers accounting for self-consistent necking of the lithosphere. Despite recent advances, 3D numerical experiments still require relatively coarse resolution so that individual faults are poorly resolved. This issue is addressed by applying a post-processing method that identifies the stress regime and preferred fault azimuth at each surface element. The simple model setup results in a surprising variety of fault orientations that are solely caused by the three-dimensionality of oblique rift systems. Depending on rift obliquity, these orientations can be grouped in terms of rift-parallel, extension-orthogonal, and intermediate normal fault directions as well as strike-slip faults. While results compare well with analog rift models of low to moderate obliquity, new insight is gained in advanced rift stages and highly oblique settings. Individual fault populations are activated in a characteristic multi-phase evolution driven by lateral density variations of the evolving rift system. In natural rift systems this pattern might be modified by additional heterogeneities, surface processes and dyke dynamics.

 
Comments Off

Posted by on July 22, 2014 in Blog

 

Understanding graphene’s electrical properties on an atomic level

For the first time, researchers have used a cutting-edge microscope to study the relationship between the atomic geometry of a ribbon of graphene and its electrical properties.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Chemists eye improved thin films with metal substitution

The yield so far is small, but chemists have developed a low-energy, solution-based mineral substitution process to make a precursor to transparent thin films that could find use in electronics and alternative energy devices.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Carbyne morphs when stretched: Calculations show carbon-atom chain would go metal to semiconductor

Applying just the right amount of tension to a chain of carbon atoms can turn it from a metallic conductor to an insulator. The research has implications for mechanically activated nanoscale electronics and optics.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Climate: Meat turns up the heat as livestock emit greenhouse gases

Eating meat contributes to climate change, due to greenhouse gasses emitted by livestock. New research finds that livestock emissions are on the rise and that beef cattle are responsible for far more greenhouse gas emissions than other types of animals. "That tasty hamburger is the real culprit," the lead researcher said. "It might be better for the environment if we all became vegetarians, but a lot of improvement could come from eating pork or chicken instead of beef."
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Storm-triggered landslides: Examining causes of devastating debris flow

Storm-triggered landslides cause loss of life, property damage, and landscape alterations. For instance, the remnants of Hurricane Camille in 1969 caused 109 deaths in central Virginia, after 600 mm of rain fell in mountainous terrain in 6 hours. More recently, on 8 August 2010, a rainstorm-induced landslide devastated the Chinese county of Zhouqu, causing more than 1000 deaths. A new modeling study examines the multiple factors, both natural and human caused, that came together to produce this event.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Replacing coal, oil with natural gas will not help fight global warming, expert argues

Both shale gas and conventional natural gas have a larger greenhouse gas footprint than do coal or oil, especially for the primary uses of residential and commercial heating. "While emissions of carbon dioxide are less from natural gas than from coal and oil, methane emissions are far greater. Methane is such a potent greenhouse gas that these emissions make natural gas a dangerous fuel from the standpoint of global warming over the next several decades," said the author of a new article.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

Process to purify water using seed extracts now simplified

Researchers have streamlined and simplified a process that uses extracts from seeds of Moringa oleifa trees to purify water, reducing levels of harmful bacteria by 90 percent to 99 percent. The hardy trees that are drought resistant are cultivated widely throughout many countries of Africa, Asia, and Latin America.
 
Comments Off

Posted by on July 21, 2014 in Blog

 

New meteorological insight into mid-level clouds

At medium altitudes ranging from 6,000 feet to 20,000 feet above mean sea level, water droplets in altocumulus clouds can remain in a supercooled liquid phase that cannot be reasonably resolved in current atmospheric models. New meteorological research characterizes mid-level, mixed phase altocumulus clouds in unprecedented detail.
 
Comments Off

Posted by on July 21, 2014 in Blog