Bird urate contamination of atmospheric dust traps

The chemical analysis of atmospheric dust from Niger, West Africa occasionally yielded more water soluble K than could be expected from soil derived dust. The high K values were correlated with samples containing white sand-sized particles. These particles were examined optically and chemically, and by X-ray diffraction and scanning electron microscopy. These white particles were identified as uric acid dihydrate. Their most probable origin was from bird urine by birds perching on the open bucket traps. Bird urine contains soluble cations interspersed with the more insoluble uric acid. We should be cautious in assuming that only atmospheric dust is collected in dust traps. The addition of only a small amount of bird urine may easily invalidate the chemical analysis of atmospheric dust. Dust traps should be designed to prevent the perching of birds.