Why the noise?

I seem to be having some problems with noise in my photographs; for example, the first one I've posted here shows some evidence of noise in the upper-left corner at 100 percent. Here is the EXIF:
Nikon D70
2006/01/23 18:13:15.9
JPEG (8-bit) Fine
Image Size: 3008 x 1002
Lens: 18-70mm F/3.5-4.5 G
Focal Length: 44mm
Exposure Mode: Manual
Metering Mode: Spot
1/200 sec - F/4.5
Exposure Comp.: -1.3 EV
Sensitivity: ISO 200
Optimize Image: Vivid
White Balance: Auto -1
AF Mode: AF-S
Flash Sync Mode: Not Attached
Auto Flash Comp: 0 EV
Color Mode: Mode IIIa (sRGB)
Tone Comp.: Auto
Hue Adjustment: 0°
Saturation: Normal
Sharpening: Auto
Image Comment:
Long Exposure NR: Off
I don't see anything there that would cause noise unless my using a UV filter (blue by the way...hmmmm, I wonder if that is adding to my blue tint?)
As for the second shot, I just thought I'd throw it in the mix to get your thoughts.
Thanks a million.
dk
Nikon D70
2006/01/23 18:13:15.9
JPEG (8-bit) Fine
Image Size: 3008 x 1002
Lens: 18-70mm F/3.5-4.5 G
Focal Length: 44mm
Exposure Mode: Manual
Metering Mode: Spot
1/200 sec - F/4.5
Exposure Comp.: -1.3 EV
Sensitivity: ISO 200
Optimize Image: Vivid
White Balance: Auto -1
AF Mode: AF-S
Flash Sync Mode: Not Attached
Auto Flash Comp: 0 EV
Color Mode: Mode IIIa (sRGB)
Tone Comp.: Auto
Hue Adjustment: 0°
Saturation: Normal
Sharpening: Auto
Image Comment:
Long Exposure NR: Off

I don't see anything there that would cause noise unless my using a UV filter (blue by the way...hmmmm, I wonder if that is adding to my blue tint?)
As for the second shot, I just thought I'd throw it in the mix to get your thoughts.

Thanks a million.
dk