Article pubs.acs.org/est
Organophosphorus Flame Retardants and Plasticizers in Airborne Particles over the Northern Pacific and Indian Ocean toward the Polar Regions: Evidence for Global Occurrence Axel Möller,*,† Renate Sturm,† Zhiyong Xie,† Minghong Cai,‡ Jianfeng He,‡ and Ralf Ebinghaus† †
Department for Environmental Chemistry, Institute of Coastal Research, Helmholtz−Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany ‡ SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China S Supporting Information *
ABSTRACT: Organophosphorus compounds (OPs) being applied as flame retardants and plasticizers were investigated in airborne particles over the Pacific, Indian, Arctic, and Southern Ocean. Samples taken during two polar expeditions in 2010/11, one from East Asia to the high Arctic (CHINARE 4) and another from East Asia toward the Indian Ocean to the Antarctic (CHINARE 27), were analyzed for three halogenated OPs (tris(2-chloroethyl) phosphate (TCEP), tris (2-chloroisopropyl) phosphate (TCPP) and tris(1,3-dichloro2-isopropyl) phosphate (TDCP)), four alkylated OPs (tri-nbutyl phosphate (TnBP), tri-iso-butyl phosphate (TiBP), tris(2-butoxyethyl)phosphate (TBEP), and tris(2-ethylhexyl) phosphate (TEHP)), and triphenyl phosphate (TPhP). The sum of the eight investigated OPs ranged from 230 to 2900 pg m−3 and from 120 to 1700 pg m−3 during CHINARE 4 and CHINARE 27, respectively. TCEP and TCPP were the predominating compounds, both over the Asian seas as well as in the polar regions, with concentrations from 19 to 2000 pg m−3 and 22 to 620 pg m−3, respectively. Elevated concentrations were observed in proximity to the Asian continent enhanced by continental air masses. They decreased sharply toward the open oceans where they remained relatively stable. This paper shows the first occurrence of OPs over the global oceans proving that they undergo long-range atmospheric transport over the global oceans toward the Arctic and Antarctica.
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INTRODUCTION Organophosphorus compounds (OPs) are man-made industrial chemicals being applied as flame retardants in various household and industrial products, as plasticizers and in other applications such as antifoaming agents and hydraulic fluids.1 OPs are derivates of phosphoric acid with different substitutes including alkyl chains (e.g., tri-n-butyl phosphate (TnBP)), partly halogenated alkyl chains (e.g., tris(2-chloroethyl) phosphate (TCEP)) as well as aromatic functions (e.g., triphenyl phosphate (TPhP)). Halogenated OPs are mainly used as flame retardants, whereas nonhalogenated OPs are predominantly used as plasticizers and for other applications.1 They have been extensively used worldwide for several decades in large scales with an annual global consumption volume reported of 209,000 tons for 20042 (consumed as flame retardant) and additional unknown consumption volume as plasticizer and for other purposes. In most applications, OPs are used additively in the material allowing them to easily leach out of the material into the environment via volatilization, abrasion, and dissolution.1 However, the scientific research as well as political and public interest on organic flame retardants in the last decades was mainly focused on polybrominated diphenyl ethers (PBDEs) due to their known PBT (persistence, bioaccumulation, toxicity) © 2012 American Chemical Society
properties and their potential to undergo long-range atmospheric transport.3 Their environmental occurrence, even in remote regions has been frequently reported.4 Since PBDEs have been restricted in the early 2000s and the Penta- and OctaBDE mixtures have been finally included in the Stockholm Convention list on Persistent Organic Pollutants (POPs),5 they might be replaced directly by appropriate OP flame retardants in some applications or, at least, the general production and usage of OPs can be expected to increase in the future.6 Regarding possible PBT properties of OPs, several toxic effects are known including skin irritation, carcinogenicity, dermatitis, and neurotoxicity.7−13 They are known to be relatively stable toward biodegradation, especially chlorinated OPs show a high resistance,14 while their potential to bioaccumulate and -magnify is limited due to their relatively low logKOW values (99%32 and 86 ± 25%,27 respectively) allowing to consider the reported particle-bound concentrations as the total concentrations. Thus all presented data are related to airborne particles. Nevertheless, OPs might be distributed in the gaseous phase, which will be also temperature 3128
dx.doi.org/10.1021/es204272v | Environ. Sci. Technol. 2012, 46, 3127−3134
Environmental Science & Technology
Article
depended and might be different for the individual OPs, or airborne particles in the sub-μm range might pass the filter leading to an underestimation of OPs in the atmosphere in the current study. Since some OPs, in particular TPhP and TnBP, are known to be applied in hydraulic fluids,1 the risk of sample contamination by the ship itself is high for these compounds due to possible emissions by the ships exhaust. By sampling in the front of the most upper deck near the bow and sampling during good wind conditions only, which means no sampling during backwinds which might transport exhaust gas to the sampler, the risk of possible contamination by the ship itself (i.e., by sampling of exhaust gases) was limited as good as possible. In addition, sampling was stopped at wind speeds 10 ng m−3 for TnBP and TCEP.35 Data from nonurbanized regions were reported only for Scandinavia and Germany, i.e., Green et al.33 reported OPs for a remote location in southern Norway and for Ny-Ålesund, Spitsbergen, in the European Arctic. They observed mainly TiBP but also the chlorinated OPs as well as TBEP.33 Thereby, they reported TCPP and TCEP concentrations of 330 pg m−3 and 270 pg m−3 which are similar to the concentrations in the Russian/American Arctic found in this 3129
dx.doi.org/10.1021/es204272v | Environ. Sci. Technol. 2012, 46, 3127−3134
No exact concentrations given; ∼few hundred pg m−3 to ∼1 ng m−3, sum of (not specified) OP. Reported as detected but below 1000 pg m . Summer, mean ± SD. Winter, mean ± SD. Tricresyl phosphate. fMedian concentrations are given in brackets. If the detection frequency was
