Evaluation of lead concentration in runoff from painted structures

Urban stormwater runoff is considered to be a major input source of heavy m etals to surface waterways. In this study. lead runoff from painted structu res in an urban setting was assessed. In many cases, high lead concentratio ns were found. Lead concentrations (100 ml over 1600 cm(2)) from 169 differ ent structures followed the order (geometric mean, median. Q10-Q90): wood ( 40, 49, 2.6-380 mu g/ 1)> brick (22, 16, 3.3-240 mu g/l) > block (9.7, 8.0, <2-110 mu g/l). Lead concentration depended strongly on paint age and cond ition. Lead levels from washes of older paints were much higher than from f reshly painted surfaces, which were demonstrated quantitatively as: paint a ge [> 10 y] (77, 88, 6.9-590 mu g/l) much greater than [5-10 y] (22, 16, < 2-240 mu g/l)> [0-5 y] (8.4, 8.1, < 2-64 mu g/l). Lead from surface washes was found to be 70% or greater in particulate lead form, suggesting the rel ease of lead pigments From weathered paints. High intensity washes were fou nd to liberate more particulate lead than lower intensities. ties. Old surf ace paints can contribute high masses of lead into a watershed, targeting t hese structures for source preventive actions to curtail future lead input into the environment: (C) 1999 Elsevier Science Ltd. All rights reserved.