In addition to enabling vivid color labeling to be printed over nearly the entire disc, oil-based or water-based marker pens can be used to hand-write labels on these discs.

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Near the water stood a gray historic marker that was terse even by New England standards.

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In addition to creating the sill, officials are planning to take 2.5 million gallons of fresh water from farther north in the river -- past mile marker 100 -- then carry it by barge southward "and suck it into our water treatment facilities, " Laigast said.

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Different materials were handled roughly, placed in water, burnt, scoured with an abrasive cleaning pad and covered in black marker pen, but the laser was still able to read the surface fingerprint.

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Caffeine is often used as a marker of wastewater contaminants, so that means there might be other pollutants in the water that also have a human source, Granek said.

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