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Year “7” and Year “8” Studies Focusing on Mulch. Mulch – Buffer Materials. Early research has shown that mulches made from recycled dimensional wood can be contaminated with CCA (Townsend et al. 2003).
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Mulch – Buffer Materials • Early research has shown that mulches made from recycled dimensional wood can be contaminated with CCA (Townsend et al. 2003). • Follow-up study -> Year 7 – South Florida Year 8 – Rest of Florida
Mulch Analysis Methods Visual Inspection Size Distribution Sample Ash for total Metals SPLP Analysis
Mulch Ashing Results Ashed Samples: 20 Colored: 14 Not Colored: 6 Positive for Arsenic: 6 Not Positive for Arsenic: 8 Positive for Arsenic: 1 Not Positive for Arsenic: 5 All 6 samples contained plywood indicating that they contained recycled dimensional wood.
Mulch SPLP Results SPLP Samples: 32 Not Colored: 15 Colored: 17 Positive for Arsenic: 5 Positive for Arsenic: 8 Not Positive for Arsenic: 9 Not Positive for Arsenic: 10 All 8 samples contained plywood indicating that they contained recycled dimensional wood.
Conclusion • Engineered wood was found in 28% of consumer mulches • Arsenic was found in 35% consumer mulches • SPLP tested showed that arsenic leached from 37 % of consumer mulches • 26% of these samples leached over 50 μg/L
Mulch Leaching Study Effect of Iron Oxides on Leaching of CCA