TY - JOUR
T1 - A mass balance approach for evaluating leachable arsenic and chromium from an in-service CCA-treated wood structure
AU - Shibata, Tomoyuki
AU - Solo-Gabriele, Helena M.
AU - Fleming, Lora E.
AU - Cai, Yong
AU - Townsend, Timothy G.
N1 - Funding Information:
Funding for this project was received from the National Institute of Environmental Health Science (NIEHS-S11 ES11181, NIEHS-P30 ES05022, and NIEHS-P30 ES05705), Bill Hinkley Center for Solid Hazardous Waste Management (FCSHWM), and the Institute of Hazardous Material Management (IHMM). The research team gratefully acknowledges Gary Jacobi and Dr. Wimal Suaris for assistance with the design and construction of the deck monitoring stations. The team also thanks Tara Fishbain, Caitlin Feikle, Colleen Block, Yuki Sotome, and Alysia Muniz for their assistance with sample collection.
PY - 2007/1/1
Y1 - 2007/1/1
N2 - Many existing residential wood structures, such as playsets and decks, have been treated with chromated copper arsenate (CCA). This preservative chemical can be released from these structures incrementally over time through contact with rainfall. The objective of this study was to evaluate the levels of arsenic and chromium leached from an in-service CCA-treated deck exposed to rainfall, as well as their possible impacts on soils and shallow groundwater. Two monitoring stations, one containing a CCA-treated deck and the other containing an untreated deck as a control, were constructed outside for this study. Rainfall, runoff water from the decks, soils below the decks, and infiltrated water through 0.7-m depth of soil were monitored for arsenic and chromium over a period of 3 years. The concentration of the CCA-treated deck runoff for arsenic (0.114-4.66 mg/L) and chromium (0.008-0.470 mg/L) were significantly (p < 0.001) higher than the untreated deck runoff (≤ 0.002 mg/L for both). During the 3-year monitoring period, 13% of the arsenic and 1.4% of the chromium were leached from the amount initially present in the CCA-treated wood. Arsenic levels (< 0.1-46 mg/kg) in soils under the CCA-treated deck were significantly (p < 0.001) higher than under the untreated deck (< 0.1-2.7 mg/kg), while chromium levels were statistically the same below the two decks (2.4-9.6 mg/kg). Approximately 94% of the arsenic from the runoff was absorbed in the soils below the CCA-treated deck; the upper 2.5 cm of the soils captured 42% of the total. The infiltrated water concentrations for arsenic (< 0.001-0.085 mg/L) and chromium (< 0.001-0.010 mg/L) below the CCA-treated deck were both significantly (p < 0.001) higher than below the untreated deck (≤ 0.006 mg/L). The amounts of arsenic found in the infiltrated water below the CCA-treated deck represented 6% of total arsenic leached and less than 0.7% of the initial mass in the wood. The study demonstrated that exposure of a CCA-treated deck to rainfall resulted in elevated arsenic concentrations in both runoff and soil. Although only a relatively small fraction of the initial arsenic from the wood was found to infiltrate through the soil, these impacts were significant and caused the infiltrated water to exceed drinking water standards. The study suggests that potential exposures to arsenic exist indirectly through an environment that is contaminated with arsenic leached from in-service CCA-treated wood.
AB - Many existing residential wood structures, such as playsets and decks, have been treated with chromated copper arsenate (CCA). This preservative chemical can be released from these structures incrementally over time through contact with rainfall. The objective of this study was to evaluate the levels of arsenic and chromium leached from an in-service CCA-treated deck exposed to rainfall, as well as their possible impacts on soils and shallow groundwater. Two monitoring stations, one containing a CCA-treated deck and the other containing an untreated deck as a control, were constructed outside for this study. Rainfall, runoff water from the decks, soils below the decks, and infiltrated water through 0.7-m depth of soil were monitored for arsenic and chromium over a period of 3 years. The concentration of the CCA-treated deck runoff for arsenic (0.114-4.66 mg/L) and chromium (0.008-0.470 mg/L) were significantly (p < 0.001) higher than the untreated deck runoff (≤ 0.002 mg/L for both). During the 3-year monitoring period, 13% of the arsenic and 1.4% of the chromium were leached from the amount initially present in the CCA-treated wood. Arsenic levels (< 0.1-46 mg/kg) in soils under the CCA-treated deck were significantly (p < 0.001) higher than under the untreated deck (< 0.1-2.7 mg/kg), while chromium levels were statistically the same below the two decks (2.4-9.6 mg/kg). Approximately 94% of the arsenic from the runoff was absorbed in the soils below the CCA-treated deck; the upper 2.5 cm of the soils captured 42% of the total. The infiltrated water concentrations for arsenic (< 0.001-0.085 mg/L) and chromium (< 0.001-0.010 mg/L) below the CCA-treated deck were both significantly (p < 0.001) higher than below the untreated deck (≤ 0.006 mg/L). The amounts of arsenic found in the infiltrated water below the CCA-treated deck represented 6% of total arsenic leached and less than 0.7% of the initial mass in the wood. The study demonstrated that exposure of a CCA-treated deck to rainfall resulted in elevated arsenic concentrations in both runoff and soil. Although only a relatively small fraction of the initial arsenic from the wood was found to infiltrate through the soil, these impacts were significant and caused the infiltrated water to exceed drinking water standards. The study suggests that potential exposures to arsenic exist indirectly through an environment that is contaminated with arsenic leached from in-service CCA-treated wood.
KW - In-service CCA-treated wood
KW - Infiltrated water
KW - Leachable arsenic
KW - Potential exposure
KW - Runoff
KW - Soil
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UR - http://www.scopus.com/inward/citedby.url?scp=33845940941&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2006.10.037
DO - 10.1016/j.scitotenv.2006.10.037
M3 - Article
C2 - 17161449
AN - SCOPUS:33845940941
VL - 372
SP - 624
EP - 635
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
IS - 2-3
ER -