The problem: Answer a question about this article:
The production for sulfidic zinc ores produces large amounts of sulfur dioxide and cadmium vapor. Smelter slag and other residues of process also contain significant amounts of heavy metals. About 1.1 million tonnes of metallic zinc and 130 thousand tonnes of lead were mined and smelted in the Belgian towns of La Calamine and Plombières between 1806 and 1882. The dumps of the past mining operations leach significant amounts of zinc and cadmium, and, as a result, the sediments of the Geul River contain significant amounts of heavy metals. About two thousand years ago emissions of zinc from mining and smelting totaled 10 thousand tonnes a year. After increasing 10-fold from 1850, zinc emissions peaked at 3.4 million tonnes per year in the 1980s and declined to 2.7 million tonnes in the 1990s, although a 2005 study of the Arctic troposphere found that the concentrations there did not reflect the decline. Anthropogenic and natural emissions occur at a ratio of 20 to 1.
Why does the Geul River contain heavy metals in a significant amount?
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The answer: mining operations leach significant amounts of zinc and cadmium


The problem: Answer a question about this article:
In England, one of the few licensed venues The Eclipse attracted people from up and down the country as it was open until the early hours. The Criminal Justice and Public Order Act 1994 was a government attempt to ban large rave dance events featuring music with "repetitive beats". There were a number of abortive "Kill the Bill" demonstrations. The Spiral Tribe at Castle Morten was probably the nail in the coffin for illegal raves, and forced through the bill, which became law, in November 1994. The music continued to grow and change, as typified by Leftfield with "Release the Pressure", which introduced dub and reggae into the house sound, although Leftfield had prior releases, such as "Not Forgotten" released in 1990 on Sheffield's Outer Rhythm records.
what single introduced dub and reggae into the house sound?
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The answer: "Release the Pressure"


The problem: Answer a question about this article:
There are more than 200 thermochemical cycles which can be used for water splitting, around a dozen of these cycles such as the iron oxide cycle, cerium(IV) oxide–cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity. A number of laboratories (including in France, Germany, Greece, Japan, and the USA) are developing thermochemical methods to produce hydrogen from solar energy and water.
What are labs trying to produce hydrogen from?
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The answer: solar energy and water


The problem: Answer a question about this article:
Witherspoon et al. (2007) have argued that even when individuals can be reliably assigned to specific population groups, it may still be possible for two randomly chosen individuals from different populations/clusters to be more similar to each other than to a randomly chosen member of their own cluster. They found that many thousands of genetic markers had to be used in order for the answer to the question "How often is a pair of individuals from one population genetically more dissimilar than two individuals chosen from two different populations?" to be "never". This assumed three population groups separated by large geographic ranges (European, African and East Asian). The entire world population is much more complex and studying an increasing number of groups would require an increasing number of markers for the same answer. The authors conclude that "caution should be used when using geographic or genetic ancestry to make inferences about individual phenotypes." Witherspoon, et al. concluded that, "The fact that, given enough genetic data, individuals can be correctly assigned to their populations of origin is compatible with the observation that most human genetic variation is found within populations, not between them. It is also compatible with our ﬁnding that, even when the most distinct populations are considered and hundreds of loci are used, individuals are frequently more similar to members of other populations than to members of their own population."
People are more frequently similar to members of what populations?
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The answer:
other populations