Heavy metals in the soil environment Titel på præsentation

Heavy metal and effect on plants grown in substrate solution. Metal Deficiency Normal growth Toxicity Heavy metal and effect on plants grown in substrate solution. The concentration is mg/L in the substrate solution.

Non-point: atmospheric depos. (smoke), fertilizer and sewage sludge ( )1 Sources: Point: metal plating industries, wood creosoting, gasworks, industries in general…. Non-point: atmospheric depos. (smoke), fertilizer and sewage sludge From: McLean & Bledsoe, USEPA (1992) 1) Aluminum density 2,7 g/cm3

Risk: toxcicity + mobility Indoor climate (vapours: Hg, As, Se) Water – solubility (pH, Redox, complex agents..) Plant uptake (root zone) Soil ingestion (topsoil - ½ m)

Solubility Key mechanisms that control the distribution of metals between soil water and particle phases. From McLean & Bledsoe (1992).

Sorption and soil pH pH dependant reaction: Me(OH)x ↔ Mex+ + x OH- Mex+ compete with H3O+ on soil particles (cation exchange)

Metal solubility pH – pC diagrams

pC = -Log([Cd])

In EU. From: EEA – 3rd env. assessment, 2003. http://reports.eea.eu.int/environmental_assessment_report_2003_10/en/kiev_chapt_09.pdf

Heavy metal atmospheric deposits in Denmark Data from Danish EPA (Miljøstyrelsen). Miljøprojekt 663 “kortlægning af diffuse jordforurening I byområder” (2002) 1984: Unleaded gasoline introduced. 1994: Lead is removed from gasoline Atm. dep. of lead in the 60’ties approx 50.000 – 60.000 μg/m2/year

Heavy metal non-point source deposits in Denmark: “Kunstgødning” : mineral fertiliser “Spildevandsslam” : Sludge from wastewater treatment plants Quality criteria DK. Lead (Pb): 40. Arsenic (As) 20. Cadmium (Cd): 0.5 [ mg / Kg DW] With the present deposition rate it take from 14 to 70 year to increase the 30 cm topsoil metal content with 1 % compared to the present level.

Arsenic (As) in Danish soils: Red: 10 mg/kg Yellow: 5 mg/kg Dark green: 0 mg/kg From DMU, 1992 survey: http://www.dmu.dk/Jord/Tungmetaller+i+danske+jorde/Kort+over+tungmetaller+i+Danmark/Arsen/

Lead in humuslayer of Norwegian natural soils. Data from www. http://www.grida.no/soeno98/contam/press2.htm

dk Legislation and approach: Sensitive areas: top ½ m soil to be clean* GW areas: no significant leaching *CF: danish quality criteria for contaminated soil

The Usual Suspects… Substances Problem Sources Heavy metals Pb PCE The Usual Suspects… BTX PAH Cr Substances Problem Sources Heavy metals (Hg, Pb, Cd…) Toxic & chronic effects Bio accumulation (strong sorption - Kd) Industry Non-point deposition: smoke, sludge and fertilizer Mineral oil products (BTX, MTBE, PAH...) Health. Taste + smell (indoor climate, water + skin contact) Gasoline stations + tanks for oil heating Chlorinated solvents (PCE, TCE..) Cancer, toxicity. Bioaccumulation (indoor climate + water) Dry cleaning Metal processing Graphic industry