Year “7” and Year “8” Studies Focusing on Mulch

• 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 – mulches from stores

Year 8 – Rest of Florida – mulches from stores Study to evaluate impact of colorants

Mulch – Buffer Materials

Gary’s Focus Shiba’s Focus

Playground Mulch

Mulch made from C&D Wood

Mulch Analysis Methods

Sample

Visual Inspection

Size Distribution

Ash for Total Metals

SPLP Analysis

Chemical Analysis

Physical Analysis

Visual Inspection

Objects Found in Mulch

Nails Plastic Rubber Glass String Rocks Etc.

Size Distribution

Uniformity Coefficient (UC): The UC will approach 1 if the pieces of sample

are the same size

d50: The size in inches that 50% of the sample is finer than

UC d60

d10

Sieve Analysis

Results: Visual Inspection

52% are colored mulches

17% mulches contained plywood

73% mulches with plywood are colored

Results: Size Distribution

Average d50 of samples is 0.29 in.

Average Uniformity Coefficient is 5.0

D50 Histogram

5

37

49

46

0

10

20

30

40

50

60

0 - 0.1 0.1 - 0.2 0.2 - 0.5 0.5 - 1 1 - 1.5

D50 (in)

Fre

qu

en

cy (

%)

Fre

quen

cy %

Results: Size DistributionUniformity Coefficient

15

28

34

18

4

0

5

10

15

20

25

30

35

40

1 - 3 3 - 4 4 - 5 6 - 8 > 8

UC

Fre

quency (

%)

Chemical Analysis

Sample

Visual Inspection

Size Distribution

Ash for Total Metals

SPLP Analysis

Chemical Analysis

Physical Analysis

Analysis Procedure Total MetalsResults

LeachableResults

Methods: Ash for Total Metals

Ashed Samples: 58

30

20 10 3 25

28

Results: Ash for Total Metals

As > 3.7 mg/kg

Colored Not Colored

As < 3.7 mg/kg As > 3.7 mg/kg As < 3.7 mg/kg

Colored Plywood

Number of

Samples

> 3.7 mg/kgArseni

c

> 10 mg/kg Arseni

c

> 50 mg/kg Arseni

c

> 100 mg/kg Arseni

c

25 12 % 12 % 4 % 0 %

√ 20 15 % 15 % 5 % 0 %

√ 3 0 % 0 % 0 % 0 %

√ √ 10 70 % 70 % 70 % 30 %

Open Bin 3 67 % 67 % 67 % 67 %

Pine Bark 27 7 % 7 % 4 % 0 %

Results: Ash for Total Metals

Metals in Wood (South Florida)

0.01

0.10

1.00

10.00

100.00

1000.00

10000.00

11 15 32 12 13 14 26 1 4 6 7 10 2 3 5 24 8 9 17 18 19 20 22 23 25 16 21 28 30 31

Sample

Co

nce

ntr

atio

n (

mg

/kg

)

AsCuCr

Pla

ygro

und

No

Col

or

No

Ply

woo

d

Woo

d S

oil B

lend

RD

F F

ine

Soi

l

RD

F

Res

ide

ntia

l, no

co

lor,

no

plyw

ood

Out

of

Sta

te

Pla

ygro

und

No

Col

or

No

Ply

woo

d

No

Col

or

No

Ply

woo

d

Col

ored

No

Ply

woo

d

Col

ored

Ply

woo

d

Pla

ygro

und

Col

ored

Ply

woo

d

0.25

pcf

Unt

rea

ted

Metals in Wood (Rest of Florida)

0.01

0.10

1.00

10.00

100.00

1000.00

81 89 91 45 34 35 78 33 41 42 44 48 50 52 54 55 56 57 59 60 61 63 64 65 67 69 71 72 76 84 86 92 94 43 46 47 49 51 53 58 62 66 68 70 36 73 74 75 77 79 80 82 83 85 87 88 90 93 95 96 97

Sample

Co

nce

ntr

atio

n (

mg

/kg

)

AsCuCr

Ply

woo

d

Col

ored

Ply

woo

d

No

Col

or

No

Ply

woo

d

Col

ored

No

Ply

woo

d

No

Col

or

Concentration Range of Arsenic Samples

80

60

95

0

10

20

30

40

50

60

70

80

90

0 - 10 11 - 25 26 - 50 51 - 100 > 100

Concentration Range (mg/kg)

Fre

qu

en

cy (

%)

Fre

quen

cy %

Arsenic vs. ChromiumAsh

0

10

20

30

40

50

60

70

80

90

100

0 50 100

Chromium (mg/ kg)

Ars

enic

(m

g/kg)

SPLP Results

Methods: SPLP Analysis

SPLP Samples: 86

45

29 16 7 34

41

Mulch SPLP Results

Positive for Arsenic

Colored Not Colored

Not Positive for Arsenic Positive for Arsenic Not Positive for Arsenic

SPLP Table

Colored Plywood

Number of

Samples

> 12 g/L

Arsenic

> 50 g/L

Arsenic

> 100 g/L

Arsenic

37 16 % 5 % 3 %

√ 34 21 % 3 % 3 %

√ 4 25 % 0 % 0 %

√ √ 11 82 % 73 % 45 %

Open Bin 4 75 % 75 % 50 %

Pine Bark 45 22 % 4 % 0 %

SPLP (South Florida)

1

10

100

1000

10000

11 15 32 12 13 14 26 1 4 6 7 10 2 3 5 24 8 9 17 18 19 20 22 23 25 16 21 28 30 31

Sample

Co

nce

ntr

atio

n (

mg

/kg

)

AsCuCr

Pla

ygro

und

No

Col

or

No

Ply

woo

d

Woo

d S

oil B

lend

RD

F F

ine

Soi

l

RD

F

Res

ide

ntia

l, no

co

lor,

no

plyw

ood

Out

of

Sta

te

Pla

ygro

und

No

Col

or

No

Ply

woo

d

No

Col

or

No

Ply

woo

d

Col

ored

No

Ply

woo

d

Col

ored

Ply

woo

d

Pla

ygro

und

Col

ored

Ply

woo

d

0.25

pcf

Unt

rea

ted

Concentration Range of Arsenic Samples

76

12

05

8

0

10

20

30

40

50

60

70

80

0 - 12 13 - 25 26 - 50 51 - 100 100 - 200

Concentration Range (ug/L)

Fre

qu

en

cy (

%)

Fre

quen

cy %

SPLP

0

20

40

60

80

100

120

140

160

180

200

0 100 200 300 400 500 600

Chromium (ug/ L)

Ars

enic

(ug/L)

Arsenic vs. Chromium

Arsenic vs. Chromium

0

20

40

60

80

100

120

140

160

180

200

0 20 40 60 80 100 120 140

Chromium (ug/ L)

Ars

enic

(ug/L)

Conclusion

52% are colored mulches 36% colored mulches positive for arsenic

17% mulches contained plywood 67% mulches with plywood positive for arsenic

73% mulches with plywood were colored 82 % of colored mulches with plywood contained arsenic

44 % of South Florida samples detected positive for arsenic in SPLP analysis

75 % of open bin mulches contained high concentrations of arsenic

Conclusion Engineered wood was found in 21% of

consumer mulches Arsenic was found in 28% consumer

mulches SPLP tested showed that arsenic leached

from 27 % of consumer mulches 48% of these samples leached over 50 μg/L

Questions?

Report will be available in the next couple of months