Roof run-off rainwater (Kingston-upon-Thames) filtered through a 0.45 mm membrane filter and then stabilised at pH2 by the addition of concentrated HNO3.Certified valuesCa . 3.5 mg/LK .0.75 mg/LNi . 1.6 mg/LCd . 0.13 mg/LMg .0.40 mg/LPb . 1.0 mg/LCu . 16.
