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Re: UV and aquatic plants

I'm not an expert on ultaviolet (UV) light by any means, but I've done
some reading lately.  UV is divided more-or-less arbitrarily into long
wave UVA and short wave UVB.  If I remember right (not a good bet) UVA is
about 340 nm to 400 nm and UVB is about 280 nm to 340 nm.  UVA is used to
make dayglow posters light up, and not much else.  It has very little
biological effectiveness.  Any UV light (blacklight) that you get for use
in normal lighting fixtures where people can be directly exposed to it
produces mostly UVA.

UVB is biologically effective - it kills things.  The earth's surface is
partially shielded from UVB by ozone in the upper atmosphere.  The effect
of UVB on plant production has been the subject of a lot of study because
of ozone depletion.  According to a couple docs I've seen on the web, even
rather small increases in UVB decreases the productivity of aquatic

Roger Miller