“…The main focus of research in the past has been the detrimental effects of heavy metals added to soils through the use of sewage sludge for crop production (Chander & Brookes, 1991;Fließbach, Martens, & Reber, 1994), while less attention has been given to other sources of heavy metals (Dai et al, 2004;Kamitani, Oba, & Kaneko, 2006). In Germany, exhaust dust from lead factories is an important source of heavy metal contamination (Chander, Dyckmans, Hoeper, Joergensen, & Raubuch, 2001a;Chander, Dyckmans, Joergensen, Meyer, & Raubuch, 2001b).…”