Capsella bursa-pastoris (L.) Medic. as a biomonitor of heavy metals

Capsella bursa-pastoris (L.) Medic. (shepherd's purse) has been tested as a possible biomonitor of heavy metals in the city of Bradford, UK and compar ed with Poa annua L. (annual meadow-grass), a species with a similar ecolog y that had previously been studied for biomonitoring potential. Forty-two s ites turban roadside, urban, urban park, suburban and rural in and around B radford were investigated. Concentrations of Pb, Cd, Zn and Cu have been de termined in soils and in washed and unwashed plant leaves. Differences betw een the washed and unwashed samples, reflecting airborne and soil entry rou tes, respectively, varied according to the metal pollutant. There were sign ificant relationships between the heavy metal concentration in samples of s urface soil (depth 0-10 cm) and washed leaves, the concentrations being gre ater with progressively increased urbanisation of the sites. Capsella bursa -pastoris has been found to be a useful biomonitor of the four heavy metals studied, and it may be a particularly useful species since it could monito r short-term changes in pollution in urban areas. (C) 1999 Elsevier Science B.V. All rights reserved.