Variation of arsenic concentration on surfaces of in-service CCA-treated wood planks in a park and its influencing field factors

Abstract

Wood preservatives can protect wood from dry rot, fungi, mould and insect damage, and chromated copper arsenate (CCA) has been used as an inorganic preservative for many years. However, wood treated with CCA has been restricted from residential uses in the EU from June 30, 2004, due to its potential toxicity. Such a regulation is not in place in China yet, and CCA-treated wood is widely used in public parks. A portable XRF analyser was used to investigate arsenic (As) concentration on surfaces of in-service CCA-treated wood planks in a popular park as well as the influencing field factors of age in-service, immersion and human footfall. With a total of 1207 readings, the observed As concentrations varied from below the detection limit (<10 mg/kg) to 15,746 mg/kg with a median of 1160 mg/kg. Strong variation of As concentrations were observed in different wood planks of the same age, on the surface of the same piece of wood, inside the same piece of wood, and different surfaces of walkway planks, hand rails and poles in the field. The oldest planks exhibited high As concentrations, which was related to its original treatment with high retention of CCA preservative. The effect of immersion in the field for about 4 months was insignificant for As concentration on the surfaces. However, a significant reduction of As was observed for immersion combined with human footfall (wiping by shoes). Human traffic in general caused slightly reduced and more evenly distributed As concentrations on the wood surfaces. The strong variation, slow aging and relatively weak immersion effects found in this study demonstrate that the in-service CCA-treated wood poses potential health risks to the park users, due to easy dermal contact especially when the wood is wet after rainfall. It is suggested that further comprehensive investigations and risk assessments of CCA-treated wood in residential areas in China are needed, and precautionary measures should be considered to reduce the potential risks to residents and visitors, especially children.

Persistent Hazardous Waste and the Quest Toward a Circular Economy: The Example of Arsenic in Chromated Copper Arsenate–Treated Wood

“…This figure is in fair agreement with concentrations reported for aged CCA‐treated wood in the literature. For example, Tang and colleagues () presented an average arsenic value of 2.7 kg/t in CCA‐treated wood that was at least 10 years old in Jiuzhaigou National Park, Southwestern China (N = 110), with the 25th and 75th percentiles corresponding to an interval of 0.51 to 4.0 kg/t. Sundqvist and colleagues () stated that a typical value of arsenic in treated wood is 0.2%, which is approximately 2 kg/t.…”

Electro-removal of copper, chromium, and arsenic from chromated copper arsenate treated waste wood

“…When removed from service life, a large proportion of copper (Cu), chromium (Cr), and arsenic (As) remains in treated wood and can enter the waste stream unless actions are taken to avoid it (FDEP, 2017;TANG et al, 2015;OHGAMI et al, 2015).…”

“…As stated by D' Almeida and Vilhena (2000), the management of solid waste, including its treatment and final disposal, is the responsibility of generators. Therefore, it is important to develop methodologies for the removal of toxic elements in those types of waste, predicting the difficulties related to their use and proposing viable alternatives for reuse or disposal (SANTOS et al, 2018;TANG et al, 2015;FERRANI et al, 2015). Numerous researchers have turned their attention to the efficacy and use of electro-removal processes in CCA-treated wood compounds as well as avoiding the possible contamination of soils and water from the use of discarded CCA-treated wood at the end of its service life (FDEP, 2017;KUMPIENE et al, 2016;OHGAMI et al, 2015;.…”

“…This electric field is capable of mediating an electric force on the ions of the system, which provides electrokinetic movement (MERCER;FROSTICK, 2014;COUDERT et al, 2014;CHRISTENSEN et al, 2006). Thus, the cleaning agent used in the electro-removal process is provided by an electric current that transports the soluble ions (Cu, Cr, and As) that are present in the wood (SANTOS et al, 2018;MOHAJERANI;VAJNA;ELLCOCK, 2018;FERRARINI et al, 2016;TANG et al, 2015;CHRISTENSEN et al, 2006).…”

“…In this sense, the electro-turning technique should not be confused with the process of adsorption of metals in liquid medium by sawdust of wood since it deals precisely with the process of removal of Cu, Cr, and As metals from wood treated with CCA. The metals removed from the wood (solid material) pass into an electrolytic fluid and can be used again in the production of CCA for the preservation of new wood or to be recovered from the medium by different methods (BABAEE; MULLIGAN; RAHAMAN, 2018;FERRARINI et al, 2016;TANG et al, 2015;JANIN et al, 2012).…”