Guangcai Zhong

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.

Distribution and air-sea exchange of current-use pesticides (CUPs) from East Asia to the high Arctic Ocean.

Surface seawater and marine boundary layer air samples were collected on the ice-breaker R/V Xuelong (Snow Dragon) from the East China Sea to the high Arctic (33.23-84.5° N) in July to September 2010 and have been analyzed for six current-use pesticides (CUPs): trifluralin, endosulfan, chlorothalonil, chlorpyrifos, dacthal, and dicofol. In all oceanic air samples, the six CUPs were detected, showing highest level (>100 pg/m(3)) in the Sea of Japan. Gaseous CUPs basically decreased from East Asia (between 36.6 and 45.1° N) toward Bering and Chukchi Seas. The dissolved CUPs in ocean water ranged widely from <MDL to 111 pg/L. Latitudinal trends of α-endosulfan, chlorpyrifos, and dicofol in seawater were roughly consistent with their latitudinal trends in air. Trifluralin in seawater was relatively high in the Sea of Japan (35.2° N) and evenly distributed between 36.9 and 72.5° N, but it remained below the detection limit at the highest northern latitudes in Chukchi Sea. In contrast with other CUPs, concentrations of chlorothalonil and dacthal were more abundant in Chukchi Sea and in East Asia. The air-sea gas exchange of CUPs was generally dominated by net deposition. Latitudinal trends of fugacity ratios of α-endosulfan, chlorothalonil, and dacthal showed stronger deposition of these compounds in East Asia than in Chukchi Sea, while trifluralin showed stronger deposition in Chukchi Sea (-455 ± 245 pg/m(2)/day) than in the North Pacific (-241 ± 158 pg/m(2)/day). Air-sea gas exchange of chlorpyrifos varied from net volatilizaiton in East Asia (<40° N) to equilibrium or net deposition in the North Pacific and the Arctic.

Perfluoroalkyl acids (PFAAs) in riverine and coastal sediments of Laizhou Bay, North China

This study investigates the concentrations and distributions of perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulphonates (PFSAs), in surface sediments from Laizhou Bay and its adjacent rivers. ∑PFAAs showed much higher levels in the river sediment (with a mean of 5.25 ng/g dw) than in the coastal sediment (with a mean of 0.76 ng/g dw). Perfluorooctanoic acid (PFOA) was the predominant compound, accounting for 50% to 97% of ∑PFAA concentrations in 70% of the samples. The highest concentrations were detected in the Xiaoqing River, possibly due to the rapid development of the nearby fluorochemical industry. Hydrodynamics strongly influenced the distribution of PFAAs in Laizhou Bay. The hydrophilic property of shorter-chained PFAAs (C≤8) allowed them to be transported to the inner bay via currents, to adsorb onto suspended sediment and then to be deposited. The Xiaoqing River showed the highest PFOA concentration (76.9 ng/g dw) among the bodies of sediment that had been studied worldwide, which might pose a potential threat for the benthic organisms of this river.

Polybrominated diphenyl ethers (PBDEs) in the riverine and marine sediments of the Laizhou Bay area, North China

62 riverine and marine sediments were collected from the Laizhou Bay area, where the largest manufacturing base of brominated flame retardants (BFRs) in Asia is located. Eight polybrominated diphenyl ethers (PBDEs) were analyzed to investigate the impact of rapidly-developed bromine industries on the regional aquatic system. PBDE concentrations varied largely in riverine sediments. Σ(7)PBDEs (including BDE 28, 47, 99, 100, 153, 154 and 183) and BDE 209 ranged from 0.01 to 53 ng g(-1) dw and from 0.74 to 285 ng g(-1) dw with a mean value of 4.5 ng g(-1) dw and 54 ng g(-1) dw, respectively, indicating a strong influence of direct pollution discharges from local factories. In marine sediments, Σ(7)PBDEs and BDE 209 ranged from not detected (nd) to 0.66 ng g(-1) dw and from 0.66 to 12 ng g(-1) dw with a mean value of 0.32 ng g(-1) dw and 5.1 ng g(-1) dw, respectively. PBDE concentrations were mostly <10 ng g(-1) dw for Σ(7)PBDEs and <50 ng g(-1) dw for BDE 209, which are at a relatively low level for monitored riverine and coastal sediments around the world. Even at the most contaminated sites in Laizhou Bay area, PBDE concentrations were not among the highest concentrations reported in the literature. Congener compositions were dominated by BDE 209 (57.2-99.9% of the sum of BDE congeners), with minor contributions from penta- and octa-BDE products. Tri- to octa-BDE congeners were well correlated among each other (r > 0.75) and thus sources from similar mixing of penta- and octa-BDE products were suggested in this area. Compared with riverine sediments, a much better correlation between PBDE concentrations with TOC was observed in marine environment. The congener pattern changed and their correlation coefficients among each other were remarkably reduced. Contributions of BDE 28, 47 and 99 to Σ(7)PBDEs were generally the same in almost all the marine sites, while it was distinctively higher for BDE 153. These are probably attributable to several reasons, such as contributions by atmospheric deposition and/or redistribution between particles of various sizes during and/or after fluvial transportation combined with the difference of physiochemical properties of BDE congeners.

Levels and distribution of Dechlorane Plus in coastal sediments of the Yellow Sea, North China.

Dechlorane Plus (DP) has been determined in surface sediments from three Chinese coastal bays, e.g. Jiaozhou, Sishili and Taozi Bay in North China. DP concentrations ranged from <1.2 to 187 pg g(-1) dry weight (dw) (mean: 24.7 pg g(-1)dw) in Jiaozhou Bay, <1.2 to 135 pg g(-1)dw (mean 69.9 pg g(-1)dw) in Sishili Bay and <1.2 to 66.7 pg g(-1)dw (mean: 40.4 pg g(-1)dw) in Taozi Bay, respectively. Additionally, two dechlorinated species were quantified, which accounted for 0.6-5.1% of the ∑DP concentration. The f(syn) values (syn-isomer/(syn-+anti-isomer)) in sediments from Jiaozhou Bay (mean 0.29) were close to the technical DP mixture (0.2-0.4), probably indicating local inputs of DP. In contrast, sediments in Sishili and Taozi Bay showed much lower f(syn) values (mean 0.16). During transportation the DP isomers are subject to stereo selective degradation which partly resulted in the relative enrichment of anti-DP in coastal sediments.

The spatial distribution of organochlorine pesticides and halogenated flame retardants in the surface sediments of an Arctic fjord: the influence of ocean currents vs. glacial runoff.

Selected organochlorine pesticides (OCs) and halogenated flame retardants (HFRs) were analyzed in surficial fjord sediments collected down the length of Kongsfjorden, Svalbard in the Norwegian high Arctic. Hexachlorocyclohexane (α-HCHs) was found to be the most abundant OC in the sediment, followed by BDE-209>chlordane>α-endosulfan>Dechlorane Plus (anti-DP)>trifluralin concentration ranges were high over the relatively small study area of the fjord (e.g. ∑HCH: 7.2-100 pg g(-1) dry weight (dw)), with concentrations broadly similar to, or lower than, measurements conducted in other parts of the Arctic. Concentrations of legacy OCs, including both HCH isomers and chlordane showed a decreasing trend from the outer, seaward end of the fjord to the inner, glacier end of the fjord. Conversely, sediment concentrations of α- and β-endosulfan (0.1-12.5 pg g(-1) dw) increased from the outer fjord to the inner fjord. This contrasting pattern may be attributed to the influence of historical vs. contemporary sources of these chemicals to the fjord area, whereby the North Atlantic/West Spitzbergen oceanic current dominates the transport and input of the legacy OCs, whereas atmospheric deposition and meltwater runoff from the glaciers influence the inner fjord sediments for endosulfan. Interestingly, BDE-209 and Dechlorane Plus did not reveal any clear spatial trend. It is plausible that both glacial runoff and oceanic current end members are playing a role in introducing these chemicals to the fjord sediments. The relatively low fractional abundance of the syn-DP isomer (fsyn), however, indicates the long-range transport of this chemical to this Arctic site.

Selected current-use and historic-use pesticides in air and seawater of the Bohai and Yellow Seas, China

Consumption of pesticides in China has increased rapidly in recent years; however, occurrence and fate of current-use pesticides (CUPs) in China coastal waters are poorly understood. Globally banned pesticides, so-called historic-use pesticides (HUPs), are still commonly observed in the environment. In this work, air and surface seawater samples taken from the Bohai and Yellow Seas in May 2012 were analyzed for CUPs including trifluralin, quintozene, chlorothalonil, dicofol, chlorpyrifos, and dacthal, as well as HUPs (hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and endosulfan). CUP profile in both air and seawater samples generally reflected their consumption patterns in China. HUPs in the air and seawater samples were in comparable levels as those of CUPs with high concentrations. alpha-Endosulfan, dicofol, and chlorothalonil showed strong net deposition likely resulting from their intensive use in recent years, while CUPs with low consumption amount (quintozene and dacthal) were close to equilibrium at most samplings sites. Another CUP with high usage amout (i.e., chlorpyrifos) underwent volatilization possibly due to its longer half-life in seawater than that in air. alpha-HCH and gamma-HCH were close to equilibrium in the Bohai Sea, but mainly underwent net deposition in the Yellow Sea. The net deposition of alpha-HCH could be attributed to polluted air pulses from the East China identified by air mass back trajectories. beta-HCH showed net volatilization in the Bohai Sea, which was driven by its relative enrichment in seawater. HCB either slightly favored net volatilization or was close to equilibrium in the Bohai and Yellow Seas.

Currently used pesticides, hexachlorobenzene and hexachlorocyclohexanes in the air and seawater of the German Bight (North Sea)

Surface seawater and air samples collected from the German Bight (North Sea) in March, May and July 2010 were analysed for hexachlorobenzene (HCB) and hexachlorocyclohexanes (HCHs), five currently used pesticides (CUPs) (trifluralin, endosulfan, chlorpyrifos, dacthal and quintozene) and pentachloroanisole (metabolite). Volatilisation from local surfaces was considered to be the main source of these chemicals to the air (excluding trifluralin). Long-range transport from Western Europe partly contributed to the higher air concentrations observed in July whereas riverine input was the main source for HCHs and pentachloroanisole in seawater in March. Air-sea gas exchange of HCB and alpha-HCH in the German Bight was found to be near equilibrium, probably reflecting the past use of these chemicals, their wide dispersal in the environment and lack of contemporary use. Deposition of target compounds from the air to seawater was observed to be much higher in July compared with depositional fluxes for March and May, except for chlorpyrifos (with volatilisation fluxes in all sampling periods: similar to 25 ngm (2) day (1)). Concentrations of trifluralin in seawater appear to have decreased since its restriction of use in European Union member states, with net volatilisation from seawater observed in March (flux: 6.3 +/- 7.2 ng m(-2) day(-1)). With the exception of chlorpyrifos, our results indicate that volatilisation from local sources combined with long-range transport from Western Europe and subsequent deposition are important pathways for these compounds to German Bight seawater during summer periods.

Perfluoroalkyl and polyfluoroalkyl substances in the lower atmosphere and surface waters of the Chinese Bohai Sea, Yellow Sea, and Yangtze River estuary

Polyfluoroalkyl and perfluoroalkyl substances (PFASs), in the forms of neutral polyfluoroalkyl substances in the gas phase of air and ionic perfluoroalkyl substances in the dissolved phase of surface water, were investigated during a sampling campaign in the Bohai Sea, Yellow Sea, and Yangtze River estuary in May 2012. In the gas phase, the concentrations of neutral ∑PFASs were within the range of 76-551pg/m3. Higher concentrations were observed in the South Yellow Sea. 8:2 fluorotelomer alcohol (FTOH) was the predominant compound as it accounted for 92%-95% of neutral ∑PFASs in all air samples. Air mass backward trajectory analysis indicated that neutral ∑PFASs came mainly from the coast of the Yellow Sea, including the Shandong, Jiangsu, and Zhejiang provinces of China, and the coastal region of South Korea. The fluxes of gas phase dry deposition were simulated for neutral PFASs, and neutral ∑PFASs fluxes varied from 0.37 to 2.3pg/m2/s. In the dissolved phase of the surface water, concentrations of ionic ∑PFASs ranged from 1.6 to 118ng/L, with the Bohai Sea exhibiting higher concentrations than both the Yellow Sea and the Yangtze River estuary. Perfluorooctanoic acid (PFOA) was the predominant compound accounting for 51%-90% of the ionic ∑PFAS concentrations. Releases from industrial and domestic activities as well as the semiclosed geographical conditions increased the level of ionic ∑PFASs in the Bohai Sea. The spatial distributions of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) were different significantly. The Laizhou Bay was the major source region of PFCAs and the Yangtze River estuary was the major source of PFSAs.

Polycyclic aromatic hydrocarbons (PAHs) in Chinese forest soils: profile composition, spatial variations and source apportionment

Previous studies reported that forest ecosystems can play a vital role in scavenging anthropogenic polycyclic aromatic hydrocarbons (PAHs) and act as primary reservoirs of these environmental pollutants. The present study aimed to investigate the occurrence, spatial pattern and source apportionment of PAHs across Chinese background forest soils (O- & A-horizons). The 143 soils collected from 30 mountains showed significantly (p < 0.05) higher levels of ∑15PAHs (ng g−1 dw) in O-horizon (222 ± 182) than A-horizon (168 ± 161). A progressive increase in the levels of lighter PAHs was observed along altitudinal gradient, however heavier PAHs did not show any variations. Carbon contents (TOC & BC) of forest soils were found weakly correlated (p < 0.01) with low molecular weight (LMW)-PAHs but showed no relation with high molecular weight (HMW)-PAHs. Source apportionment results using PMF and PCA revealed that PAHs in forest soils mainly come from local biomass burning and/or coal combustion and attributed that forest soils may become a potential sink for PAHs in the region.