An evaluation of the use of biological indicators in an atmospheric lead survey

Abstract

Atmospheric lead deposition was monitored in the vicinity of a battery factory by an integrated survey of lead levels in indigenous moss and grass samples and by a short-term study of weekly increments in lead deposition at selected sites around the source using the mossbag technique. A highly significant correlation (coeff = 0.95) between the lead content in indigenous mosses and grass can be demonstrated, and the lead levels closely reflect the proximity to the source and the long-term wind pattern. The suspended mossbags adequately monitor the input to ground moss and grass given sufficient exposure time for slow accumulation rates. The spatial variation in mossbag lead content after one month correlates significantly with wind direction and speed and with calculated mean long-term ground level concentrations from stack emissions at each sit; however, only 40 per cent of the temporal (weekly) variation in lead accumulation in the mossbags can be explained by correlation with the wind direction and speed and rainfall at each site.