Effect of sewage-sludge application on concentrations of higher-brominated diphenyl ethers in soils and earthworms

Polybrominated diphenyl ethers (PBDEs), including octa-decaBDEs, were found in soil and earthworm samples collected in 2000 from three research stations (reference plots and sewage-sludge-amended plots) and two farms (reference and amended/flooded soils) in Sweden. Sewage-sludge amendment at the research stations increased concentrations of all BDE congeners 2- to 13-fold, with the highest increases for BDE-209. Concentrations 100-to 1000-fold higher were seen in contaminated soils at both farms. BDE-209 was the predominant congener in all soils. sigmaPBDE concentrations in worms ranged from 3.1 to 38 000 ng/g lipid weight and were correlated to soil concentrations, including the octa-decaBDEs. Biota-soil accumulation factors declined in the following order: TeBDE > PeBDE > HxBDE > OcBDE > NoBDE > DeBDE, and ranged from 0.3 to 2 for the octa-decaBDEs. Thus, higher-brominated PBDEs, including BDE-209, are bioavailable from soils and accumulate in earthworms, presenting an exposure pathway into the terrestrial food web. High levels found at one farm 20 years after the last use of PBDEs indicate high persistence of PBDEs in soils, including BDE-209. No evidence of photolytic debromination of BDE-209 in soils was seen.     

Earthworm sublethal responses to titanium dioxide nanomaterial in soil detected by ¹H NMR metabolomics

1H NMR-based metabolomics was used to examine the response of Eisenia fetida earthworms raised from juveniles for 20-23 weeks in soil spiked with either 20 or 200 mg/kg of a commercially available uncoated titanium dioxide (TiO(2)) nanomaterial (nominal diameter of 5 nm). To distinguish responses specific to particle size, soil treatments spiked with a micrometer-sized TiO(2) material (nominal diameter, <45 μm) at the same concentrations (20 and 200 mg/kg) were also included in addition to an unspiked control soil. Multivariate statistical analysis of the (1)H NMR spectra for aqueous extracts of E. fetida tissue suggested that earthworms exhibited significant changes in their metabolic profile following TiO(2) exposure for both particle sizes. The observed earthworm metabolic changes appeared to be consistent with oxidative stress, a proposed mechanism of toxicity for nanosized TiO(2). In contrast, a prior study had observed no impairment of E. fetida survival, reproduction, or growth following exposure to the same TiO(2) spiked soils. This suggests that (1)H NMR-based metabolomics provides a more sensitive measure of earthworm response to TiO(2) materials in soil and that further targeted assays to detect specific cellular or molecular level damage to earthworms caused by chronic exposure to TiO(2) are warranted.     

Emerging brominated flame retardants in the sediment of the Great Lakes

The concentrations of 13 currently used brominated flame retardants (BFRs) were analyzed in 16 sediment cores collected from the North American Great Lakes. Among them, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromocyclododecane (HBCD), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), and hexachlorocyclopentadienyl dibromocyclooctane (HCDBCO) were more frequently detected than others. In general, these emerging BFRs have much lower concentrations than polybromodiphenyl ethers (PBDEs) and dechloranes. Inventories of the five BFRs named above, given on a logarithm basis, were found to decrease linearly with the increasing latitude of the sampling locations, but with weaker statistics than those previously reported for the dechloranes. Logarithm of surface fluxes, on the other hand, was found to be a better parameter in correlating with the longitude. With regard to time trends, the exponential increases in concentrations of these BFRs, particularly DBDPE and BTBPE, in recent years are particularly disturbing. The sediment concentration of DBDPE doubles every 3-5 years in Lake Michigan, and approximately every 7 years in Lake Ontario. The corresponding doubling times for BTBPE are about 5 and 7 years in Lakes Ontario and Michigan, respectively, although declines or leveling off were observed in the top sediment layers in Lake Ontario. In contrast to PCBs, PBDEs, and most dechloranes, the correlations between the surface concentration of emerging BFRs and the latitude or longitude of the sampling sites were not strengthened by normalization of the concentration based on the organic matter content of the sediment.     

Solid-phase microextraction to predict bioavailability and accumulation of organic micropollutants in terrestrial organisms after exposure to a field-contaminated soil

The risk posed by soil contaminants strongly depends on their bioavailability. In this study, a partition-based sampling method was applied as a tool to estimate bioavailability in soil. The accumulation of organic micropollutants was measured in two earthworm species (Eisenia andrei and Aporrectodea caliginosa) and in 30-microm poly(dimethylsiloxane) (PDMS)-coated solid-phase micro extraction (SPME) fibers after exposure to two field-contaminated soils. Within 10 days, steady state in earthworms was reached, and within 20 days in the SPME fibers. Steady-state concentrations in both earthworm species were linearly related to concentrations in fibers over a 10,000-fold range of concentrations. Measured concentrations in earthworms were compared to levels calculated via equilibrium partitioning theory and total concentrations of contaminants in soil. In addition, freely dissolved concentrations of contaminants in pore water, derived from SPME measurements, were used to calculate concentrations in earthworms. Measured concentrations in earthworms were close to estimated concentrations from the SPME fiber measurements. Freely dissolved concentrations of contaminants in pore water, derived from SPME measurements, were used to calculate bioconcentration factors (BCF) in earthworms. A plot of log BCFs against the octanol-water partition coefficient (log Kow) was linear up to a log Kow of 8. These results show that measuring concentrations of hydrophobic chemicals in a PDMS-coated fiber represents a simple tool to estimate internal concentrations of chemicals in biota exposed to soil.     

Polybrominated diphenyl ethers vs alternate brominated flame retardants and Dechloranes from East Asia to the Arctic

Marine boundary layer air and seawater samples taken during a polar expedition cruise from East China Sea to the Arctic were analyzed in order to compare the occurrence, distribution, and fate of the banned polybrominated diphenyl ethers (PBDEs) with their brominated alternatives as well as the chlorinated Dechloranes. The sum of PBDEs (∑(10)PBDEs) in the atmosphere ranged from 0.07 to 8.1 pg m(-3) with BDE-209 being the dominating congener and from not detected (n.d.) to 0.6 pg L(-1) in seawater. Alternate brominated flame retardants (BFRs), especially hexabromobenzene (HBB), (2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), pentabromotoluene (PBT), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EHTBB), bis-(2-ethylhexyl)-tetrabromophthalate (TBPH), were detected in higher concentrations than PBDEs, even in the high Arctic (0.6 to 15.4 pg m(-3) for sum of alternate BFRs), indicating the change of PBDEs toward alternate BFRs in the environmental predominance. In addition, Dechlorane Plus (DP) as well as Dechlorane 602, 603, and 604 were detected both in the atmosphere and in seawater. The highest concentrations as well as the highest compound variability were observed in East Asian samples suggesting the Asian continent as source of these compounds in the marine environment. The air-seawater exchange indicates strong deposition, especially of alternate BFRs, as well as dry particle-bound deposition of BDE-209 into the ocean.     

Fate of brominated flame retardants and organochlorine pesticides in urban soil: volatility and degradation

As the uses of polybrominated diphenyl ethers (BDEs) are being phased out in many countries, soils could become a secondary emission source to the atmosphere. It is also anticipated that the demand for alternative brominated flame retardants (BFRs) will grow, but little is known about their environmental fate in soils. In this study, the volatility and degradation of BFRs and organochlorine pesticides (OCPs) in soil was investigated. A low organic carbon (5.6%) urban soil was spiked with a suite of BFRs and OCPs, followed by incubation under laboratory condition for 360 days. These included BDE- 17, -28, -47, -99; α- and β-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), β-1,2,5,6-tetrabromocyclooctane (TBCO), and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), OCPs: α-hexachlorocyclohexane (α-HCH) and (13)C(6)-α-HCH, trans-chlordane (TC), and (13)C(10)-TC. The volatility of spiked chemicals was investigated using a fugacity meter to measure the soil-air partition coefficient (K(SA)). K(SA) of some spiked BFRs and OCPs increased from Day 10 to 60 or 90 and leveled off afterward. This suggests that the volatility of BFRs and OCPs decreases over time as the chemicals become more strongly bound to the soil. Degradation of alternative BFRs (α- and β-TBECH, β-TBCO, DPTE), BDE-17, and α-HCH ((13)C-labeled and nonlabeled) was evident in soils over 360 days, but no degradation was observed for the BDE-28, -47, -99, and TC ((13)C-labeled and nonlabeled). A method to separate the enantiomers of α-TBECH and β-TBCO was developed and their degradation, along with α-HCH ((13)C-labeled and nonlabeled) was enantioselective. This is the first study which reports the enantioselective degradation of chiral BFRs in soils. Discrepancies between the enantiomer fraction (EF) of chemicals extracted from the soil by dichloromethane (DCM) and air were found. It is suggested that DCM removes both the sequestered and loosely bound fractions of chemicals in soil, whereas air accesses only the loosely bound fraction, and these two pools are subject to different degrees of enantioselective degradation. This calls for caution when interpreting EFs obtained from DCM extraction of soil with EFs in ambient air.     

Passive samplers provide a better prediction of PAH bioaccumulation in earthworms and plant roots than exhaustive, mild solvent, and cyclodextrin extractions

A number of extraction methods have been developed to assess polycyclic aromatic hydrocarbon (PAH) bioavailability in soils. As these methods are rarely tested in a comparative manner, against different test organisms, and using field-contaminated soils, it is unclear which method gives the most accurate measure of the actual soil ecosystem exposure. In this study, PAH bioavailability was assessed in ten field-contaminated soils by using exhaustive acetone/hexane extractions, mild solvent (butanol) extractions, cyclodextrin extractions, and two passive sampling methods; solid phase micro extraction (SPME) and polyoxymethylene solid phase extraction (POM-SPE). Results were compared to actual PAH bioaccumulation in earthworms (Eisenia fetida) and rye grass (Lolium multiflorum) roots. Exhaustive, mild solvent and cyclodextrin extractions consistently overpredicted biotic concentrations by a factor of 10-10?000 and therefore seem inappropriate for predicting PAH bioaccumulation in field contaminated soils. In contrast, passive samplers generally predicted PAH concentrations in earthworms within a factor of 10, although correlations between predicted and measured concentrations were considerably scattered. The same applied to the plant data, where passive samplers also tended to underpredict root concentrations. These results indicate the potential of passive samplers to predict PAH bioaccumulation, yet call for comparative studies between passive samplers and further research on plant bioavailability.     

Brominated flame retardants in glaucous gulls from the Norwegian Arctic: more than just an issue of polybrominated diphenyl ethers

Several, unregulated, current-use brominated flame retardants (BFRs), including hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), and hexabromocyclododecane (as total-(alpha)-HBCD), were examined in egg yolk and plasma of male and female glaucous gulls (Larus hyperboreus) from the Norwegian Arctic. Also examined were BDE209 and 38 tri- to nona-BDE congeners and brominated biphenyl (BB) 101. The HBB, BTBPE, PBEB, and PBT had high detection frequencies and variability in male and female plasma and egg yolk samples, and their concentrations ranged from nondetectable (< 0.02-0.27 ng/g wet wt) to 2.64 ng/g wet wt. The detection frequencies and range of concentrations of non-BDE BFRs were generally highest in plasma of males relative to females. Total-(alpha)-HBCD concentrations were highest among the non-PBDE BFRs (up to 6.12 and 63.9 ng/g wet wt in plasma and egg yolk, respectively). Next highest was HBB with concentrations within a range comparable to the minor PBDEs monitored (e.g., BDE28, 116 and 155). Sum (sigma)38PBDE concentrations ranged from 2.49 to 54.5 ng/g wet wt in plasma and 81.2 to 321 ng/g wet wt in egg yolk. The BDE209 was virtually nondetectable, whereas six octa-BDEs (i.e., BDE196, 197, 201, 202, 203, and 205), as well as three nona-BDEs (i.e., BDE206, 207, and 208, and potential BDE209 debromination products) were found sporadically in plasma and egg yolk. The results from this study suggestthat in addition to PBDEs, several current-use, non-BDE BFRs undergo long-range atmospheric transport and bioaccumulate at low levels in and are maternally transferred (to eggs) in glaucous gulls from the Norwegian Arctic.     

Surfactants differentially impact p,p'-DDE accumulation by plant and earthworm species

The effect of four surfactants (Triton X-100, Tween-80, rhamnolipids, cyclodextrin) at 100-1000 mg/L on p,p'-DDE phytoextraction by Cucurbita pepo (zucchini) under field conditions and p,p'-DDE bioaccumulation by earthworm species (Eisenia fetida, Lumbricus terrestris) under laboratory conditions was investigated. Abiotically, surfactants (except cyclodextrin) increased contaminant desorption from soil by 4-fold, with higher concentrations generally promoting greater release. Cyclodextrin had no effect on DDE desorption. DDE concentrations in unamended zucchini roots and stems were 30- and 7.8-fold greater than soil levels, respectively, and 1.6% of the contaminant was extracted from the soil. The surfactant effects were cultivar specific. Triton X-100 increased DDE uptake in "Costata" by 2.6-fold, yielding 5% contaminant phytoextraction. In "Goldrush", DDE accumulation decreased by 69% across all surfactants. Surfactants significantly increased DDE bioaccumulation by earthworms. For E. fetida with all surfactants and L. terrestriswith Triton X-100 and cyclodextrin, DDE accumulation increased 2.5-7.2-fold, paralleling abiotic desorption. However, Tween-80 and rhamnolipids increased DDE accumulation in L. terrestris by 74 and 36 fold, respectively. These dramatic increases in contaminant bioaccumulation do not correlate with the increased availability observed abiotically. Surfactant-mediated increases in contaminant bioavailability are an unexpectedly complex process and clearly present unanticipated concerns over pollutant exposure to nontarget organisms.     

Simultaneous immobilization of lead and atrazine in contaminated soils using dairy-manure biochar

Biochar produced from waste biomass is increasingly being recognized as a green, cost-effective amendment for environmental remediation. This work was to determine the ability of biochar to immobilize heavy metal Pb and organic pesticide atrazine in contaminated soils. Biochar prepared from dairy manure was incubated with contaminated soils at rates of 0, 2.5, and 5.0% by weight for 210 d. A commercial activated carbon (AC) was included as a comparison. The AC was effective in immobilizing atrazine, but was ineffective for Pb. However, biochar was effective in immobilizing both atrazine and Pb and the effectiveness was enhanced with increasing incubation time and biochar rates. After 210 d, soils treated with the highest rate of 5.0% biochar showed more than 57% and 66% reduction in Pb and atrazine concentrations in 0.01 M CaCl(2) extraction, respectively. Lead and atrazine concentrations in the toxicity characteristic leaching procedure solutions were reduced by 70-89% and 53-77%, respectively. Uptake of Pb and atrazine by earthworms (Eisenia fetida) was reduced by up to 79% and 73%. Phosphorus originally contained in biochar reacted with soil Pb to form insoluble hydroxypyromorphite Pb(5)(PO(4))(3)(OH), as determined by X-ray diffraction, which was presumably responsible for soil Pb immobilization, whereas atrazine stabilization may result from its adsorption by biochar demonstrated by the significant exponential decrease of extractable atrazine with increasing organic C in biochar (r(2) > 0.97, p < 0.05). The results highlighted the potential of dairy-manure biochar as a unique amendment for immobilization of both heavy metal and organic contaminants in cocontaminated soils.     

Do earthworms mobilize fixed zinc from ingested soil?

A wide range of organisms inhabit the soil and has to deal with soil-bound metals. The bioavailable fraction of metals may be estimated explicitly using the isotopic dilution technique. In the present paper, we evaluated the isotopic exchange technique for assessing the bioavailability of soil Zn (using 65Zn) to earthworms. To validate the technique, the worms were first exposed to various 65Zn levels, and errors due to soil entrained in the gut were evaluated. This exposure indicated no effect of gamma-radiation on growth (wet weight gain) of the organisms and that depuration of the earthworms minimized errors in labile pools determined by isotopic dilution. Our study further showed that the earthworms accessed 55-65% of the total Zn in the soil. The labile pool for the earthworms Eisenia andrei was similar to that for the plant Lactuca sativa, indicating that earthworms and plants to a large extent access the same fraction of soil Zn. Hence, the isotopic dilution technique has the potential to assess biologically available pool of Zn in soils. As lettuce is not known to significantly mobilize nonlabile metals in soil, this study indicates that Zn uptake by E. andrei is predominantly via the exchangeable pools (possibly the soil pore water) rather than dissolution of Zn held within soil particles or within soil organic matter or other food sources.     

Effect of complexation on the accumulation and elimination kinetics of cadmium and ciprofloxacin in the earthworm Eisenia fetida

Land application of solid wastes leads to the accumulation of both metals and antimicrobials in soils. To understand the effects of metal and antibiotic interaction on their accumulation by the earthworm Eisenia fetida, uptake and elimination kinetics and subcellular distribution of cadmium (Cd) and ciprofloxacin (CIP) were determined. The kinetics was accurately described by a one-compartment first-order kinetic model. Bioaccumulation kinetics and subcellular distribution of CIP were not affected by Cd addition. However, Cd exhibited different metabolic and subcellular distribution patterns. With CIP, Cd uptake flux and elimination rate constants were about 2.2 and 9.8 times, respectively, those without CIP. In the presence of CIP, Cd redistributed from fractions D (associated with granules) and E (associated with tissue fragments and cell membranes) to fraction C (associated with cytosol). Without CIP, Cd in fraction C could not be excreted, whereas with CIP, Cd in fraction C was significantly excreted, and the excretion rate constant was consistent with that of CIP. A good relationship was found between CIP and Cd in earthworms during uptake and elimination periods (p < 0.01). Our results indicated that the Cd-CIP complex may be taken up, stored, and eliminated by earthworms.     

Brominated flame retardants in seawater and atmosphere of the Atlantic and the Southern Ocean

Seawater and air samples were collected aboard the FS Polarstern during the cruises ANT-XXV/1 + 2 in the Atlantic and Southern Ocean in 2008. The particulate and dissolved phase in water and particulate and gaseous phase in air were analyzed separately for nine polybrominated diphenyl ethers (PBDEs) and six non-PBDE brominated flame retardants (BFRs). Air concentrations of 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and hexabromobenzene (HBB) in the gaseous and particulate phase (median = 0.56 pg m(-3) for DPTE and 0.92 pg m(-3) for HBB) were comparable to ∑(9)PBDEs (1.0 pg m(-3)). Pentabromotoluene (PBT) was detectable in ～30% of the gaseous phase samples, whereas concentration of 2,4,6-tribromophenyl allylether (ATE), hexachlorocyclopentenyl-dibromocyclooctane (HCDBCO) and 2-ethyl-1-hexyl 2,3,4,5-tetrabromobenzoate (EHTBB) were below their method detection limits. DPTE, and PBDEs were also found in seawater at low pg per liter levels. Elevated seawater concentrations of PBDEs and DPTE were measured in the English Channel and close to South African coast. Concentrations of DPTE, BDE-47, and BDE-99 in the atmosphere generally decreased from Europe toward the Southern Ocean, whereas no latitudinal trend was observed in seawater. Air-water exchange gradients suggested net deposition dominates for all selected substances. The medians of net deposition fluxes for the air-water gas exchange were 83, 21, 69, 20, and 781 pg m(-2) day(-1) for BDE-47, BDE-100, BDE-99, DPTE, and HBB, whereas medians of dry deposition fluxes were 2.0, 0.3, 1.2, 1.0, and 0.5 pg m(-2) day(-1) for BDE-47, BDE-100, BDE-99, DPTE, and HBB. Overall, these results highlight the important role of the long-range atmospheric transport of PBDE and non-PBDE BFRs to remote regions.     

Bioaccumulation of organic chemicals in contaminated soils: evaluation of bioassays with earthworms

Earthworms live in close contact with the soil and can thus be considered representative for the bioavailability of chemicals at contaminated sites. Bioavailability can either be assessed by analyzing earthworms from contaminated locations or by exposing laboratory-reared specimens to soil samples from the field (bioassays). In this study, we investigate the relevance of bioassays by using an extended experimental design (to identify signs of depletion of the bioavailable phase by the earthworms) and by using two species of earthworm (the standard test species Eisenia andrei and the field-relevant Aporrectodea caliginosa). Furthermore, bioassay results are compared to body residues of worms collected from the field site: a heavily polluted polder, amended with dredge spoil. We focused on telodrin, dieldrin, hexachlorobenzene, and eight PCBs. With our bioassay design, it was shown that depletion was unlikely, although more subtle effects could have occurred (e.g., changes in sorption during the experiments). E. andrei is a good choice for bioassays because its body residues correlate well to those in A. caliginosa, as well as to those in the field-collected worms. Nevertheless, E. andrei accumulated slightly more than the other species and appeared to be more sensitive to the conditions in soil from one of our sites.     

Comparison of subcellular partitioning, distribution, and internal speciation of Cu between Cu-tolerant and naïve populations of Dendrodrilus rubidus Savigny

When considering contaminated site ecology and ecological risk assessment a key question is whether organisms that appear unaffected by accumulation of contaminants are tolerant or resistant to those contaminants. A population of Dendrodrilus rubidus Savigny earthworms from the Coniston Copper Mines, an area of former Cu mining, exhibit increased tolerance and accumulation of Cu relative to a nearby non-Cu exposed population. Distribution of total Cu between different body parts (posterior, anterior, body wall) of the two populations was determined after a 14 day exposure to 250 mg Cu kg(-1) in Cu-amended soil. Cu concentrations were greater in Coniston earthworms but relative proportions of Cu in different body parts were the same between populations. Cu speciation was determined using extended X-ray absorption fine structure spectroscopy (EXAFS). Cu was coordinated to O atoms in the exposure soil but to S atoms in the earthworms. There was no difference in this speciation between the different earthworm populations. In another experiment earthworms were exposed to a range of Cu concentrations (200-700 mg Cu kg(-1)). Subcellular partitioning of accumulated Cu was determined. Coniston earthworms accumulated more Cu but relative proportions of Cu in the different fractions (cytosol > granular > tissue fragments, cell membranes, and intact cells) were the same between populations. Results suggest that Coniston D. rubidus are able to survive in the Cu-rich Coniston Copper Mines soil through enlargement of the same Cu storage reservoirs that exist in a nearby non-Cu exposed population.     

Brominated flame retardants, polychlorinated biphenyls, and organochlorine pesticides in captive giant panda (ailuropoda melanoleuca) and red panda (Ailurus fulgens) from China

Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and brominated flame retardants (BFRs) were investigated in captive giant and red panda tissues from China. The total concentrations of OCPs, PCBs, and polybrominated diphenyl ethers (PBDEs) in tissues ranged from 16.3 to 888 ng/g lipid weight (lw), 24.8 to 854 ng/g lw, and 16.4 to 2158 ng/g lw, respectively. p,p'-DDE and beta-HCH were major OCP contaminants. PCBs 99, 118, 153/132, 170, 180, and 209 were the major contributing congeners determined. Among PBDEs, congener BDE-209 was the most frequent and abundant, followed by BDE-206, BDE-208, BDE-207, BDE-203, BDE-47, and BDE-153. Decabromodiphenyl ethane (DeBDethane) was detected in 87 and 71% of the giant and red panda samples with concentrations up to 863 ng/g lw, respectively. The remarkable levels and dominance of BDE-209 and DeBDethane may relate to significant production, usage, or disposal of BFRs in China. The positive significant correlation between concentrations of PBDEs and PCBs in captive pandas may suggest that the exposure routes of PBDEs and PCBs to panda are similar. To our knowledge, this is the first report of the occurrence of DeBDethane in captive wildlife samples. Therefore, further studies are warranted to better understand DeBDethane production, transport, uptake, and toxicological effect.     

Brominated flame retardants in the atmosphere of E-waste and rural sites in southern China: seasonal variation, temperature dependence, and gas-particle partitioning

The recycling of electrical and electronic waste(e-waste) in developing countries has attracted much attention as a significant source of brominated flame retardants (BFRs).Gaseous and particle-bound BFRs were measured in the atmosphere at e-waste and rural sites in southern China during 2007-2008. The annual average concentrations in the air were 3260 ± 3370 and 219 ± 192 pg/m3 for polybrominated diphenyl ethers (PBDEs) and were 546 ± 547 and 165 ± 144 pg/m3 for non-PBDE BFRs at the e-waste and rural sites,respectively. PBDEs had unusually high relative concentrations of di- and tribrominated congeners at the e-waste site. The Clausius-Clapeyron (CC) plots showed that the gaseous concentrations of less brominated BFRs (di- through hexa-BFRs) were strongly controlled by temperature-driven evaporation from contaminated surfaces (e.g., e-waste, soils, and recycled e-waste remains) except for winter. However, weak temperature dependence at the rural site suggests that regional or long-range atmospheric transport was largely responsible for the air concentrations. Gas-particle partitioning (KP) of PBDEs correlated well with the subcooled liquid vapor pressure (PL(o)) for most sampling events. The varied slopes of log KP versus log PL(o) plots for the e-waste site (-0.59 to -1.29) indicated an influence of ambient temperature and atmospheric particle properties on the partitioning behavior of BFRs. The flat slopes (-0.23 to -0.80) for the rural site implied an absorption-dominant partitioning. This paper suggests that e-waste recycling in Asian low-latitude regions is a significant source of less brominated BFRs and has important implications for their global transport from warm to colder climate     

Effects of polyethyleneimine-mediated functionalization of multi-walled carbon nanotubes on earthworm bioaccumulation and sorption by soils

Carbon nanotubes (CNTs) are often modified for different intended potential applications to enhance their aqueous stability or change properties such as surface charge. Such changes may also profoundly impact their environmental behaviors. Herein, we report the effects of modifying (14)C-labeled multiwalled carbon nanotubes (MWCNTs) with polyetheyleneimine (PEI) surface coatings to render them more stable in solution and to give them positive, negative, or neutral surface charges. These carbon nanotubes were used to test their sorption by soils and uptake and elimination behaviors by earthworms. Sorption results indicate nearly linear sorption isotherms for regular MWCNTs and nonlinear isotherms for modified MWCNTs, indicating that the PEI coatings influenced MWCNT interactions with soils. Nevertheless, there were minimal differences in the sorption results among the different soils for each type of nanotube despite differences in the soil organic carbon and cation exchange capacities. Differences in uptake behaviors by earthworms were not apparent among different types of PEI-MWCNTs and MWCNTs with limited absorption into organism tissues consistently observed. Elimination patterns were well fit with an exponential decay model suggesting that the worms can readily eliminate any accumulated MWCNTs.