Sunday, 16 September 2018

Magnitude 5.6 Earthquake in Western Australia.

Geoscience Australia recorded a Magnitude 5.6 Earthquake at a shallow depth close to Lake Muir in southern Western Australia, slightly before 1.00 pm local time (slightly before 5.00 am GMT) on Sunday 16 September 2018. This is one of the largest Earthquakes ever reported in Western Australia, and was felt over a wide area, but there are no reports of any damage or casualties.

The approximate location of the 16 September 2018 Western Australia Earthquake. USGS.
 
Despite being a long way from any active plate margins, Western Australia is quite prone to Earthquakes, particularly in a zone referred to as the South West Seismic Zone. The cause of these quakes is unclear; the area exists within an area of Archaean Shield known as the Yilgarn Block, which is thought to be between 2.94 and 2.63 billion years old, and which has no internal structures that seem to be related to the quakes.
 
 The South West Seismic Zone (pink). University of Western Australia.
 
Witness statements can help geologists to understand Earthquakes and the geological processes that cause them; if you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to Geoscience Australia here.

See also...

https://sciencythoughts.blogspot.com/2018/07/worker-at-western-australian-gold-mine.htmlhttps://sciencythoughts.blogspot.com/2018/04/western-australian-beach-closed-after.html
https://sciencythoughts.blogspot.com/2018/04/western-australian-teenager-released.htmlhttps://sciencythoughts.blogspot.com/2017/10/landslide-swallows-two-cars-in-perth.html
https://sciencythoughts.blogspot.com/2016/07/car-trapped-by-sinkhole-at-cape-burney.htmlhttps://sciencythoughts.blogspot.com/2016/07/magnitude-35-earthquake-in-northern.html
Follow Sciency Thoughts on Facebook.

Assessing the potential impact of large-scale wind and solar power generation on the Sahara Desert and surrounding regions.

Reducing global emissions of carbon dioxide has been a major international goal since the 1990s, due to the prospect of significant climate change being brought about by rising levels of the gas in the atmosphere. However since this time little progress has been made in developing energy sources not dependant on burning hydrocarbons (the main source of atmospheric carbon dioxide), while demand for energy has grown across the globe. One possible way to counter this that has been suggested is the development of very large scale wind and solar power generation plants in the world's desert regions, though the likely impact of such plants on the climate is itself unclear.

In a paper published in the journal Science on 7 September 2018, Yan Li of the Department of Atmospheric and Oceanic Science at the University of Maryland, the Department of Natural Resources and Environmental Sciences at the University of Illinois at Urbana-Champaign, and the State Key Laboratory of Earth Surface Processes and Resources Ecology at Beijing Normal University, Eugenia Kalnay, also of the Department of Atmospheric and Oceanic Science, and of the Institute for Physical Science and Technology, at the University of Maryland, Safa Motesharrei, again of the Department of Atmospheric and Oceanic Science, and the Institute for Physical Science and Technology, and the Department of Physics, at the University of Maryland, Jorge Rivas of Rockville in Maryland, Fred Kucharski of the Earth System Physics Section at the Abdus Salam International Centre for Theoretical Physics, Daniel Kirk-Davidoff, again of the Department of Atmospheric and Oceanic Science at the University of Maryland, Eviatar Bach, again of the Department of Atmospheric and Oceanic Science and Institute for Physical Science and Technology, at the University of Maryland, and Ning Zeng, once again of the Department of Atmospheric and Oceanic Science at the University of Maryland, and of the Institute of Atmospheric Physics of the Chinese Academy of Science, publish the results of a study which used computer modelling to try to assess the impact of large scale wind and solar power generation on the the Sahara Desert and its surrounding regions.

The Sahara is the word's largest desert, and is in addition very sparsely populated, so that any future large scale wind or solar power projects would face little competition from other forms of Human land use. Li et al. modelled the potential impact of large scale wind and solar projects on both the Sahara and the more populated Sahel, a transition region between desert and wooded savanna to the south, using a model in which wind farms producing three terawatts of power per year and solar plants producing 79 terawatts of power per year were assessed for their impact.

Li et al. found that the wind farms would result in an average rise in ground temperature of 2.16 K, though this would be mostly due to a rising minimum temperature, which would go up by an average of 2.36 k, with the average maximum temperature rising only by 1.85 K. This is a previously observed phenomenon around wind farms, which mix air layers vertically, bringing down warmer air from above the surface at night. The wind farms also increased average daily precipitation in the Sahara by 0.25 mm per day (more than doubling the amount of rain in the desert, though this would not be in the form of very small amounts of rain each day), and in the Sahel region by 1.12 mm per day, as the increased ground temperature leads to more air rising above the desert (hot air rises), drawing more moisture laden air from elsewhere. This increases precipitation is predicted to lead to an increased vegetative ground cover, leading to a lower albedo (the ability of the ground to reflect heat and light, vegetation tends to absorb, whereas exposed rock and sand, particularly if light in colour, tends to reflect), increased surface air friction (which might reduce average wind speeds by up to 36%), and increased evaporation through transpiration, leading to more cloud cover and more rain. 

 Impacts of wind and solar farms in the Sahara on mean near-surface air temperature (kelvin) and precipitation (millimetres per day). The impacts of wind farms (A) and (B), solar farms (C) and (D), and wind and solar farms together (E) and (F), respectively, are shown. Only areas where changes are significant at the 95% confidence level (t test) are displayed on the map. Gray dots denote the location of wind and/or solar farms. At the bottom of each plot, the number after Δ represents the changes in climate (in either kelvin or millimetres of precipitation per day) averaged over areas covered by wind and solar farms. Li et al (2018).

Solar power projects were found to have a similar effect, raising average ground temperatures and increasing precipitation, though in this case the main driver was a decreasing albedo due to the solar panels themselves, which absorb rather than reflecting sunlight, leading to an average rise in daytime maximum temperatures of 1.28 K, while the minimum nighttime temperature rose by only 0.97 K. These solar projects were predicted to raise precipitation in the Sahara by an average of 0.13 mm per day, and in the Sahel by an average of 0.57 mm per day. This model did not produce a notable drop in average wind speeds.

Combining the wind and solar projects resulted in an average temperature rise of 2.65 K, but an average increae of precipitation of 0.35 mm per day in the Sahara and 1.34 mm per day. This is particularly significant as it results in an increase in average rainfall of almost 500  mm per year, significanlty altering the local climate.

 Relative contributions of roughness change (Rough) and vegetation feedback (Veg) in the climate impacts of wind farms in the Sahara. Contributions in the temperature (A), (C), and (E) and the precipitation (B), (D), and (F) impacts are shown. The wind farm impact is produced by the initial roughness of wind turbines and the subsequent albedo changes due to vegetation feedback. At the bottom of each plot, the number after Δ represents the changes in climate (in either kelvin or millimeters of precipitation per day) averaged over areas covered by wind farms. Li et al (2018).

These predictions were based upon an average energy conversion rate of 15% for the solar panels, roughly what we would expect with today's technology, however Li et al. also note that we should expect solar panels to become more efficient in the future, and that as they do so the amount of ground-level warming they cause should drop, so that once their average efficiency passes 35% they would be predicted to cause a cooling at ground level, combined with a reduction in rainfall, resulting in a rather different impact on the climate of the Sahara.

See also...

https://sciencythoughts.blogspot.com/2018/06/livestock-killed-and-airport-damaged-as.htmlhttps://sciencythoughts.blogspot.com/2018/06/flooding-kills-at-least-five-in-kumasi.html
https://sciencythoughts.blogspot.com/2018/06/flooding-kills-at-least-eighteen-in.htmlhttps://sciencythoughts.blogspot.com/2018/01/assessing-potential-for-low-enthalpy.html
https://sciencythoughts.blogspot.com/2017/12/evidence-for-carboniferous-glaciation.htmlhttps://sciencythoughts.blogspot.com/2017/10/orange-cloud-covers-much-of-uk.html
Follow Sciency Thoughts on Facebook.

Saturday, 15 September 2018

Intentionally fragmented stone blades from the Late Pleistocene Kara-Bom Site in the Altai Republic of southern Siberia.

The Initial Upper Palaeolithic of Siberia and Central Asia, from roughly 50 000 to 47 000 years ago, is noted for the appearance of a technology based around long blades unlike anything seen in other parts of the world until the dawn of the Bronze Age. These blades, which could be up to 35 cm in length, and were typically 5-6 cm in width, were not used as a single tool, but rather a source from which smaller blades could be quickly broken off, by either striking them with a rock, breaking them over an anvil such as a stick or rock, or in the case of the very finest examples, possibly simply snapping them by hand. No Human remains have ever been found in association with these tools, but they are generally thought to be associated with the arrival of the first Early Modern Humans in the region.

In a paper published in the journal Archaeological Research in Asia on 24 May 2018, Vyacheslav Slavinsky and Evgeny Rybin of the Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, Arina Khatsenovich, also of the Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, and of the Max Planck Institute for the Science of Human History, and Natalia Belousova, again of the Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, describe the presence of intentionally fragmented long blades at the Late Pleistocene Kara-Bom Site in the Altai Republic of southern Siberia.

The Kara-Bom Site is an open-air multi-layered site situated in an inter mountain depression in the central Russian Altai range, which was excavated by a series of expeditions between 1980 and 1993, and which has been dated to between 48 350 and 45 200 years before the present. The site has yielded an Initial Upper Paleolithic assemblage of chert stone tools, which appear to be consistent with the long blade technology.

Map of Kara-Bom site location in the Russian Altai region. Slavinski et al. (2018).

Slavinski et al. examined 66 artifacts from Kara-Bom which appeared to show affinities with the fragmented long blade technology. From these they were able to reassemble two complete large blades, and a number of partial blades. These appear to have been made by breaking the original blade on a hard anvil with a stone hammer. 

Initial Upper Paleolithic artifacts with traces of intentional fragmentation from the Kara-Bom site: (1), (1a) Reconstructed core on large blade, fragmented by percussion directed toward dorsal ridge; (1b) fragment of core with traces of intentional fragmentation on the two narrow sides; (1c) intermediate “butterfly-like” fragment. Slavinski et al. (2018).

Intentionally fragmented long blade tools have been found at a number of sites in southern Siberia, though most of these lack the accurate dating available at Kara-Bom. Dates are known from the Tolbaga Site in the Transbaikal Region, and the Tolbor 4 Site in northern Mongolia, but these are much younger, between 43 000 and 39 000 years old, so that the Kara-Bom material significantly extends the appearance of the long blade technology, and by extension Modern Humans, into northeastern Asia.

See also...

https://sciencythoughts.blogspot.com/2018/09/stone-tools-from-high-altitude-site-in.htmlhttps://sciencythoughts.blogspot.com/2018/08/deciphering-imput-of-neanderthal-and.html
https://sciencythoughts.blogspot.com/2015/05/rainforest-resources-in-diet-of-late.htmlhttps://sciencythoughts.blogspot.com/2014/10/acheulian-and-levallois-technologies.html
https://sciencythoughts.blogspot.com/2014/04/slash-and-burn-agriculture-in-neolithic.htmlhttp://sciencythoughts.blogspot.com/2011/11/fishermen-targeting-tuna-in-east-t.html
Follow Sciency Thoughts on Facebook.

Callyspongia pedroi & Callyspongia alcoladoi: Two new species of Demosponge from the mesophotic reefs of Cuba.

Tropical and subtropical reefs are noted for their high biodiversity, particularly on their Coral-dominated shallower parts, where photosynthesis is possible, and which are therefore referred to as the ‘photic zone’. Below this photic zone lies an area where some light is present, but not enough to allow much photosynthesis. In this area, known as the mesophotic zone, Sponges, Porifera, are the dominant reef animals, both in terms of number of species and number of individuals. To date a total of 241 Sponge species have been described from the mesophotic zone of the Caribbean, including 141 from the Greater Antilles (Cuba, Jamaica, Puerto Rico and the Cayman Islands). However, a recent survey of the reefs around Cuba identified a total of 296 species of Sponge, suggesting the presence of many species which have either not been described to date, or not previously been recorded in the Caribbean.

In a paper published in the journal Zootaxa on 31 August 2018, Linnet Basutil of the Instituto de Ciencias del Mar, María García-Hernámdez of the Centro Nacional de Áreas Protegidas, and Christina Díaz and Shirley Pomponi of the Harbor Branch Oceanographic Institute at Florida Atlantic University, describe two new species of Sponge from the Cuban mesophotic zone, both of which are placed in the Demosponge genus Callyspongia.

The first new species is named Callyspongia pedroi, in honour of Cuban marine biologist Pedro Alcolado, for a lifetime dedicated to studying the Sponges of the Caribbean. This species forms a series of branching ropey tubes 10-14 mm in length and 6-10 mm in diameter, smooth to the touch and pink or light red in colour. Branching on this species is uncommon, and it has no true holdfast, adhering to the substrate wherever it touches. It has a fibrous skeleton with embedded fusiform spicules, this skeleton comprises a primary mesh with gaps 120–425 μm across, made up of fibres 20–40 μm in diameter, with a secondary mesh with gaps of 50–350 μm, with fibres 10–15 μm in diameter. Callyspongia pedroi was found on reefs around most of the cost of Cuba, at depths of 44.4–102.4 m. 

Callyspongia pedroi. (a) Specimen in live habit, (b) another specimen in live habit, but not collected, (c)-(d) specimen on deck, (e) microconulose surface, and oval flushed osculum. Basutil et al. (2018).

The second species is named Callyspongia alcoladoi, also in honour of Pedro Alcolado. This species forms branching ropey tubes 20-30 cm in length and 3-8 mm in diameter, smooth to the touch, but with occasional spiny projections up to 4 cm in length, and grey-pink in colour. This species also has no true holdfast, adhering to the substrate wherever it touches, though it branches much more frequently than the previous species. It has many subdermal cavities, 0.25–0.8 mm in diameter, which are visible to the naked eye and a skeleton made up of primary, secondary and tertiary meshes of fibres, with the primary mesh having gaps of 80–250 μm, and fibres 30–150 μm in diameter, the secondary mesh having gaps of 70–210 μm, and fibres 15–30 μm in diameter, and the tertiary mesh having gaps of 30-70 μm, and fibres 8-25 μm in diameter. The species was found on the east wall of Bahía de Cochinos on the south coast of Cuba, and at Punta del Fraile northwest of Punta Maisí on the eastern tip of Cuba, at depths of 51.5–73.4 m.

Callyspongia alcoladoi. (a) Specimen in live habit, (b) another specimen in live habit, but not collected, (c)-(d) specimen on deck, (e) Very smooth surface and round osculum, slightly sunken. Basutil et al. (2018). 

See also...

https://sciencythoughts.blogspot.com/2017/12/terpios-hoshinota-tracking-progress-of.htmlhttps://sciencythoughts.blogspot.com/2017/10/plenaster-craigi-new-species-of.html
https://sciencythoughts.blogspot.com/2017/09/looking-for-animals-in-wengan-biota.htmlhttps://sciencythoughts.blogspot.com/2015/03/preservation-of-cellular-structures-in.html
https://sciencythoughts.blogspot.com/2014/12/two-new-species-of-homoscleromorph.htmlhttps://sciencythoughts.blogspot.com/2014/12/thirteen-new-species-of-deepwater.html
Follow Sciency Thoughts on Facebook.

Cassytha filiformis: A Parasitic Plant targetting Insects.

Parasirism is very common in the natural world, with many species of Prokaryotic and single-celled Eukaryotic life-forms relying on the strategy, Fungi frequently parasitising Animals, Plants and other Fungi, Animals parasitising other Animals and Plants, and Plants parasitising both other Plants and Fungi. However, Plants, whilst occasionally directly consuming Animals (carnivory) do not generally parasitise Animals.

In a paper published in the journal Current Biology on 20 August 2018, Scott Egan, Linyi Zhang, Mattheau Comerford, and Glen Hood of the Department of BioSciences at Rice University describe an example of parasitism of Animals by Plants, a trophic interaction which they suspect, while not previously recorded, may in fact be widespread in nature.

Egan et al. were inspecting Sand Live Oaks, Quercus geminata, targetted by the parasitic Love Vine, Cassytha filiformis, in a native scrub habitat in southern Florida, when they observed that the galls (tumors induced by the action of a parasitc Animal on a Plant, in which the Animal, typically a larval Arthropod, lives, protected by the gall tissue and feeding on the fluids of the host Plant) of two parasitic Wasp species, Belonocnema treatae and Callirhytis quercusbatatoides, were penetrated by the haustoria (root like projection from a Parasitic Plant, that penetrates the tissues of the host) of the vine. This was despite the fact that the galls of these Wasps are located on the underside of the leaves, an area not usually targeted by the Vine, suggesting that this food source is actively sought out, rather than being attacked purely by chance.

(A) Cassytha filiformis Vine attaching haustoria to a leaf gall induced by the Wasp Belonocnema treatae on the underside of their host Plant, Quercus geminata. (B) Labeled graphic of Insect gall, parasitic Vine, and Vine haustoria. Egan et al. (2018).

The galls of Belonocnema treatae attacked by the Vine were on average 35% larger than those that were not, though this appeared to be driven by the Vine not attacking smaller galls, with no gall smaller than 3.5 mm in diameter, being attacked, rather than the Vine causing larger galls. Inspection found 45% of parasitised galls contained a dead and mummified Wasp, compared to just 2% of non-parasitised galls, suggesting the interaction had a highly adverse effect on the Wasps. A wider inspection of the area found the Vine was parasitising the galls of a further four species of Wasps, Andricus quercuslanigera, Neuroterus minutissimus, Disholcaspis quercusvirens, and Andricus quercusfoliatus, as well as the Gall Midge Arnoldiola atra.

See also...

https://sciencythoughts.blogspot.com/2017/09/thismia-nigricoronata-new-species-of.htmlhttps://sciencythoughts.blogspot.com/2016/12/lecanorchis-tabugawaensis-new-species.html
https://sciencythoughts.blogspot.com/2016/02/rafflesia-consueloae-dwarf-corpse.htmlhttps://sciencythoughts.blogspot.com/2015/08/gastrodia-madagascariensis-not-so-new.html
https://sciencythoughts.blogspot.com/2015/06/balanophora-coralliformis-new-species.htmlhttps://sciencythoughts.blogspot.com/2015/04/tripius-gyraloura-sphaerularid-nematode.html
Follow Sciency Thoughts on Facebook.

Three known deaths as Typhoon Mangkhut sweeps across northern Luzon Island, the Philippines.

Three people have been confirmed dead after Typhoon Mangkhut (known in the Philippines as Typhoon Ompong) made landfall in Cagayan Province on northen Luzon Island at about 1.40 am local time on Saturday 15 September 2018 (about 5.40 pm on Friday 14 September GMT). brining with it sustained winds of 270 kilomtres per hour, and gusts of up to 325 kilometres per hour. Two of the deaths have been confirmed as female emergency workers caught in one of the many landslides triggered by the storm. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

 
Man caught by a storm surge in Manila Bay associated with Typhoon Magkhut on 15 September 2018. Mark Cristino/EPA/EFE


Typhoon Mangkhut is the most severe storm anywhere in the world of 2018, and the worst storm to hit the Philippines since Typhoon Haiyan in 2013, which killed over 6000 people. A similarly large death toll from Typhoon Magkhut has largely been avoided by large scale evacuations of low lying areas in the path of the storm, triggered by warnings from meteorologists that the storm might cause storm surges of up to nine metres. Similatr evacuations are now underway in Hong Kong, Macau, and parts of South China, which are predicted to be hit by the storm will hit within the next two days. Tropical storms loose energy as they pass over land, eventually disapaiting, and this has been true of Mangkhut as it crossed Luzon island, becoming less severe as it moved westward, however it is still a very powerful storm, and is expected to gain energy again once it clears Luzon and passes over the South China Sea.

The path and strength of Typhoon Mangkhut. Thick line indicates the past path of the storm (till 6.00 am GMT on Saturday 15 September 2018), while the thin line indicates the predicted future path of the storm, and the dotted circles the margin of error at 12, 24, 36 and 72 hours ahead. Colour indicated the severity of the storm. Tropical Storm Risk.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Atlantic being referred to as hurricanes.

 
Damage caused by Typhoon Mangkhaut in Tuguegrao City in Cagayan Province.  Aaron Favila/AP.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

See also...

https://sciencythoughts.blogspot.com/2018/08/three-dead-and-one-missing-as-flash.htmlhttps://sciencythoughts.blogspot.com/2018/07/landslides-kill-four-children-in.html
https://sciencythoughts.blogspot.com/2018/06/magnitude-55-earthquake-off-coast-of.htmlhttps://sciencythoughts.blogspot.com/2018/01/evacuations-ordered-after-eruption-on.html
https://sciencythoughts.blogspot.com/2017/12/flash-flood-destroys-village-on.htmlhttps://sciencythoughts.blogspot.com/2017/11/landslides-kills-two-on-luzon-island.html
Follow Sciency Thoughts on Facebook.

Friday, 14 September 2018

Hurricane Florence kills four in North Carolina.

Four people have been confirmed dead after Hurricane Florence made landfall in North Carolina on Thursday 13 September 2018. The storm made landfall at Wrightsville Beach in New Hanover County, North Carolina early in the morning, brining with it storm surges in excess of three metres. The four people known to have died in the storm include a mother and child killed when a tree fell on their car in Wilmington, a person killed while trying to connect a generator in Lenoir County and a woman in Pender County who died of a pre-existing medical condition when emergency services were unable to reach her due to a road blocked by fallen trees. In addition the storm left around 700 000 people without electricity, and caused a number of buildings collapsed, including a hotel in Jacksonville in  Onslow County, from which a number of people had to be rescued.

Flooding in River Bend, North Carolina, on 13 September 2018, after the Trent River burst its banks during Hurricane Florence. Action News Jacksonville.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Atlantic being referred to as hurricanes.

The path and strength of Hurricane Florence. Thick line indicates the past path of the storm (till 3.00 pm GMT on Friday 14 September 2018), while the thin line indicates the predicted future path of the storm, and the dotted circles the margin of error at six and twelve hours ahead. Colour indicated the severity of the storm. Tropical Storm Risk.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

See also...

https://sciencythoughts.blogspot.com/2018/05/thousands-evacuated-after-landslide.htmlhttps://sciencythoughts.blogspot.com/2018/05/journalists-die-in-north-carolina-as.html
https://sciencythoughts.blogspot.com/2017/08/chemical-spill-at-swimming-pool.htmlhttps://sciencythoughts.blogspot.com/2016/12/tracing-origin-of-hexavalent-chromium.html
https://sciencythoughts.blogspot.com/2016/09/tropical-storm-hermine-makes-landfall.htmlhttps://sciencythoughts.blogspot.com/2014/07/north-carolina-suffers-flooding-but-no.html
Follow Sciency Thoughts on Facebook.