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The B2 (B2G) and I4 sediment cores recovered from the centre of the distal mud area of the East China Sea (ECS) were analysed for grain size distribution. Proxies for environmentally sensitive grain size components (ESGSC) retrieved from the composite B2 core, namely, variations in the volumetric content and mean grain size of specific grain size fractions, reveal a detailed history of the East Asia Winter Monsoon (EAWM) including centennial to decadal-scale variations spanning the last 2300 calendar years before present (cal. yr BP). The results indicate that EAWM variations are consistent with temperature changes in eastern China (as inferred from historical documents). Additionally, the sea surface temperature (SST) in the Southern Okinawa Trough, the δ18O of stalagmite from the Sanbao cave and the drift ice indices from the North Atlantic, along with strong or weak EAWMs, corresponding to low or high temperatures, respectively. Four periods of EAWM variations were identified, namely, a weak EAWM stage from 2300 to 2050 cal. yr BP; a comparatively enhanced EAWM between 2050 and 1700 cal. yr BP; a return to a weak EAWM from 1700 to 700 cal. yr BP, including the Roman Warm Period (RWP), the Sui–Tang Dynasty Warm Period (STWP) and the 'Medieval Warm Period' (MWP) and a strongly developed EAWM between 700 and 100 cal. yr BP, corresponding to a 'Little Ice Age'. An important abrupt warm to cold climate change event occurred around 678 cal. yr BP. During this period, the climate change was likely related to global scale changes in atmospheric circulation. Spectral analyses of the ESGSC proxies show high-frequency cycles and a close solar–monsoon connection to the EAWM, suggesting that one of the primary controls for centennial to decadal-scale change in EAWM intensity was the variation in solar radiation during that time. [ABSTRACT FROM AUTHOR]

We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air–sea gas exchange, and gas–particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, air–sea exchange fluxes of gaseous PAHs were estimated to be −54.2–107.4 ng m −2 d −1 , and was indicative of variations of land-based PAH inputs. The logarithmic gas–particle partition coefficient (log K p ) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (log P L 0 ), with a slope of −0.25. This was significantly larger than the theoretical value (−1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH gas–particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH gas–particle partitioning deviated more from the modeling K p for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air–sea exchange. Meanwhile, significant linear regressions between log K p and log K oa (log K sa ) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign. [ABSTRACT FROM AUTHOR]

Seventy-five paired PM2.5 (aerodynamic diameter less than 2.5 μm) and TSP (total suspended particle) samples collected from a pristine island in the East China Sea (ECS) between October 2011 and August 2012 were analyzed for organic carbon (OC), elemental carbon (EC), and n -alkanes. The island lies in the pathway of continental outflow from Mainland China to the northwest Pacific Ocean driven by the East Asian Monsoon. The concentrations of OC, EC (in μg/m 3 ), and n -alkanes (in ng/m 3 ) were highest in winter (means: 4.7, 1.3, 140.1, respectively) and lowest in summer (means: 1.1, 0.3, 17.0, respectively). PM2.5 contained approximately 88% of the OC, 80% of the EC, and 61% of the n -alkanes in TSP. Petroleum residue was the dominant contributor to the n -alkanes. C 12 –C 22 n -alkanes with strong even-to-odd predominance observed in winter were attributed to the microbial contribution from sea spray aerosol (SSA) driven by the higher wind speed. There was a higher secondary organic carbon (SOC)/OC ratio in warm seasons (summer and fall) than that in cold seasons (spring and winter). The dominance of primary organic carbon (POC) and EC in cold seasons was possibly mainly due to the influence of the East Asian continental outflow. Three episodes of high concentrations of carbonaceous aerosols were observed, and we focused on the impact of these pollutants from East Asia on the air quality over the ECS. Carbonaceous pollutants were more concentrated in PM2.5 during the fall episode triggered by biomass burning in East China. The winter haze associated with intensive indoor heating in North China brought substantial carbonaceous pollutants, with a minor influence on their size distribution. The dust episode in spring was related to coarse particles (i.e., TSP–PM2.5), yielding a distinctly different size distribution. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) of sixty-three sediment samples from the coastal East China Sea (ECS), extending ∼1000 km from the Yangtze River Estuary to the south, were measured. The levels of BDE-209 and ∑PBDE7 (sum of BDE-28, 47, 99, 100, 153, 154, 183) were 0.3–44.6 ng/g (dry weight) and nd-8.0 ng/g, respectively. BDE-209 was the predominant congener, followed by BDE-99/100. This was consistent with the historical and current usage of PBDE mixtures in China. The compositions and distribution of PBDEs suggest that the PBDEs in this area could be mainly from the coastal electronic waste dismantling/recycling and Yangtze River input. The poor correlations between TOC, grain size of sediments with PBDEs imply that the PBDE distribution is more related to their land-based inputs rather than the sediment characters in the area. The coastal ECS is an important sink of PBDEs (7.5 t/yr) in the world. [Copyright &y& Elsevier]

Abstract: Forty-two surface sediment samples collected from the southern coastal East China Sea (ECS) were analyzed for organochlorine pesticides (OCPs). The results showed high concentrations of DDTs and parent DDT fractions in the nearshore area, suggesting that there is still a fresh input of these species from non-point sources, probably due to the recent usage of relevant products. However, for HCHs, the high concentrations with elevated β-HCH fraction were focused at the local major river estuaries, indicating that soils-released HCH input was mainly from the major river runoffs. The distribution and composition of OCPs in the coastal ECS could be more prominently controlled by the direct regional inputs rather than the general natural sorption process on particulate organic carbon. DDTs and chlordane are more important for their potential ecotoxicological risk on neighboring benthic community in the nearshore region and the local major river estuaries. [Copyright &y& Elsevier]

Polycyclic aromatic hydrocarbons (PAHs) in two 210Pb dated sediment cores from the coastal East China Sea, strongly influenced by the discharge from the Yangtze River, were determined to help to reconstruct the economic development over the past century in East China. The variations in PAH concentrations and fluxes in the sediment cores were primarily due to energy structure change, severe floods and dam construction activities. The impact on PAHs by the river discharge overwhelmed the atmospheric depositions. The profiles of PAH fluxes and concentrations as well as compositions in the cores revealed the transformation from an agricultural economy to an industrial one especially after the 1990s'' in the region. PAHs in the study area were dominated by pyrolytic sources. [Copyright &y& Elsevier]

Four sediment cores were collected along the Yangtze-derived sediment transport pathway in the inner shelf of the East China Sea (ECS) for OCP analysis. The sediment records of HCHs and DDTs in estuarine environment reflected remobilization of chemicals from enhanced soil erosion associated to extreme flood events or large scale land use transformation. The sediment records in the open sea, instead, reflected long-term historical trends of OCP application in the source region. Unlike the so-called mud wedge distribution of sediment, inventories of HCHs and DDTs slightly increased from the mouth of Yangtze River alongshore toward south, suggesting the sediment deposition rate was one of factors on the exposure of chemicals within the inner shelf of the ECS. Re-suspension and transport of the Yangtze-derived sediment and consequent fractionation in grain size and TOC were also responsible for the spatial variation of inventories of catchment derived OCPs in a major repository area of the Yangtze suspended sediment. The total burdens of HCHs and DDTs in the inner shelf of the ECS were 35 tons and 110 tons, respectively. After 1983 (year of the official ban in China), those values were 13 tons and 50 tons, respectively. It appears that the Yangtze still delivers relatively high inputs of DDTs more than 30 years after the official ban. High proportions of DDD + DDE and β-HCH suggested those OCPs mainly originated from historical usage in the catchment recent years. [ABSTRACT FROM AUTHOR]

Ship-board air samples were collected during March to May 2015 from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) to explore the atmospheric occurrence and gas–particle partitioning of polychlorinated biphenyls (PCBs) when the westerly East Asian Monsoon prevailed. Total PCB concentrations in the atmosphere ranged from 56.8 to 261 pg m −3 . Higher PCB levels were observed off the coast and minor temperature-induced changes showed that continuous emissions from East Asia remain as an important source to the regional atmosphere. A significant relationship between K oa (octanol–air partition coefficient) and K P (gas–particle partition coefficient) for PCBs was observed under continental air masses, suggesting that land-derived organic aerosols affected the PCB gas–particle partitioning after long-range transport, while an absence of this correlation was identified in marine air masses. The PCB partitioning cannot be fully explained by the absorptive mechanism as the predicted K P were found to be 2–3 orders of magnitude lower than the measured K p , while the prediction was closely matched when soot adsorption was considered. The results suggested the importance of soot carbon as a transport medium for PCBs during their long-range transport and considerable impacts of continental outflows on PCBs across the downwind area. The estimated transport mass of particulate PCBs into the ECS and NWP totals 2333 kg during the spring, constituting ca. 17% of annual emission inventories of unintentionally produced PCB in China. [ABSTRACT FROM AUTHOR]

In an effort to more fully understand atmospheric outflow of PM 2.5 -associated saccharide species, we investigated primary saccharides (fructose, glucose, sucrose, and trehalose), saccharide alcohols (arabitol and mannitol), and anhydrosaccharides (levoglucosan and mannosan) in atmospheric aerosols at both a megacity site, Shanghai, and a sea background site, Huaniao Island. The results showed that the saccharide species presented pronounced temporal and spatial variability in the outflow from the megacity to the East China Sea, and varied widely with a total concentration range of 8.6–2400 ng m −3 (283 ng m −3 mean) in Shanghai and 0–1050 ng m −3 (51 ng m −3 mean) in Huaniao Island. Both saccharide species (e.g., levoglucosan and sucrose) showed higher concentrations and a noticeable seasonal gradient during the study period ― there was a high level of levoglucosan in the cold season (161 ng m −3 in winter and 229 ng m −3 in autumn) due to elevated biomass burning activities, and a high level of sucrose in the warm seasons (146 ng m −3 in summer and 145 ng m −3 in spring) due to elevated levels of intense biological aerosols including fungal spores and pollen. The calculated levoglucosan/mannosan (L/M) ratio, which may represent the signature of aerosol particles at the two sites, ranged from 5.2 to 10.9 during the cold season. Back-trajectory analysis results indicated that the saccharides originated from regional sources in East and North China before being transported to the sampling site. Emissions due to biomass burning were estimated to correspond to 46% (mass) of the saccharides quantified in the haze particle samples, whereas biogenic emissions corresponded to 18%, indicating that biomass burning was a considerable aerosol source to the regional atmosphere throughout the year. The results presented here support the theory that levoglucosan could be utilized as a molecular marker for East Asian biomass burning outflow, and sucrose as a molecular marker for airborne pollen grains. The results of this study may help future researchers clarify the aerosol sources, as well as their atmospheric transport pathways over East Asia to the western Pacific Ocean. [ABSTRACT FROM AUTHOR]

The East China Seas (ECSs) are the receptors of the land-based persistent organic pollutants (POPs), such as polybrominated diphenyl ethers (PBDEs) mainly from China through atmospheric deposition driven by the East Asian winter monsoon and fluvial discharge (e.g., Yangtze River and Yellow River), making the offshore sediments to be a good proxy to reconstruct history of those pollutants in China. In this work, four well-placed sediment cores were extracted from the mud areas in the ECSs, and the 210 Pb-dated cores were analyzed to yield historical concentration profiles of PBDEs in the area. The results showed that there was a persistent increase from 1970s and almost no clear sign in the decline of PBDEs until recently in China. More importantly, there was a faster increase of PBDEs from 1990s in China; while this period was just shown as gradually leveling off or even declining trends in developed countries. The persistently increasing trend of PBDEs in China since 1990s could be largely due to the booming of the manufacturing industry and unexpectedly transfer of PBDE pollution from developed countries to China. Besides, the relative high concentrations and fluxes of PBDEs in the core from coastal ECS located near a well-known electrical/electronic waste (e-waste) recycling area suggests an important contribution of PBDE emissions from recycling centers of e-waste in China. Although efforts in environmental monitoring of PBDE contamination have been substantially increased over the last decade, China is still lagging behind in terms of nationwide regulation of PBDE usage and treatment of disposal PBDE-containing products. [ABSTRACT FROM AUTHOR]

Eighty paired gaseous phase and PM2.5 (particulate matter < 2.5 μm in diameter) samples, covering four seasons from October 2011 to August 2012 were collected simultaneously from a remote island in the East China Sea (ECS). The samples were analyzed for organochlorine pesticides (OCPs) to determine their seasonal variation and potential sources over the coastal marine environment. The concentrations of individual OCPs in the PM2.5 samples were higher in winter and lower in summer, and the reverse trend was observed for the measured OCP compounds (except hexachlorocyclohexanes, HCHs) in the gaseous phase. Principal component analysis revealed one trend that contributed 40% to PM2.5-bound OCPs characterized by β-HCH, α-HCH, p , p ′-dichlorodiphenyldichloroethane ( p , p ′-DDD), p , p ′-dichlorodiphenyldichloroethylene ( p , p ′-DDE), and chlordanes; whereas two seasonal trends, represented by dichlorodiphenyltrichloroethanes (DDTs) or chlordanes and HCHs, were responsible for 38% and 23% of the gaseous OCPs, respectively. Continental outflow driven by the East Asian monsoon brought large quantities of particulate OCPs to the ECS, especially in winter. Possible fresh sources or net volatilization from the Yangtze River induced by both higher ambient temperature and higher discharge rates caused the higher gaseous DDT and chlordane levels observed in summer. However, the lower concentrations of gaseous HCHs observed in summer suggested that net volatilization had a relatively limited impact on gaseous HCHs due to the long-term prohibition of their use and their low residual levels in the catchment, whereas the elevated concentrations of gaseous HCHs in winter controlled by gas–particle partitioning, resulted from increased particulate HCHs producing a partial shift to gaseous HCHs over ECS. [ABSTRACT FROM AUTHOR]

PM2.5 aerosol samples were collected from a receptor site in the East China Sea (ECS) to explore the seasonal variation and sources of polybrominated diphenyl ethers (PBDEs). The concentrations of BDE-209 and total 11 PBDEs without BDE-209 (∑ 11 PBDEs) were 7.1 ± 6.8 and 0.97 ± 0.52 pg m −3 , respectively. A distinct seasonal variation was observed for both BDE-209 and ∑ 11 PBDEs, that higher concentrations in winter and spring dominated by the northwesterly winds while lower concentrations in autumn and summer when the southeasterly winds prevailed, suggesting a significant role of continental outflow on the elevated concentrations of PM2.5-bound PBDEs in winter and spring. Besides, the strong dust storm could increase the load of PBDEs in continental outflow to the atmosphere over ECS. Differently, due to the absence of continental outflow in autumn and summer, the good correlations between BDE-209 and ∑ 11 PBDEs implied a potential contribution of the low brominated PBDEs from photoproducts of BDE-209 in high temperature circumstance, while the good correlations of OC with BDE-209 and BDE-99 suggested a significant role of OC in the occurrence of PM2.5-bound PBDEs over ECS. [ABSTRACT FROM AUTHOR]

Knowledge of the fate of sedimentary organic carbon (SOC) in large-river delta-front estuaries (LDEs) is critical for understanding the global carbon cycle. In this study, remineralization of total organic carbon (TOC) in the Changjiang Estuary and adjacent East China Sea (ECS) shelf were investigated by combining sediment and pore water analyses. Distinctively low TOC to sediment surface area (TOC/SSA) loadings (<0.40 mg m −2 ) were observed mainly in the mud deposits comparable to tropical deltaic mobile muds or delta topset, indicating an inefficient SOC preservation. Anaerobic incubations showed that the net reaction rate of ΣCO 2 in pore waters over the whole core (0–24 cm) of sediments in the Changjiang Estuary was 5.1 mmol m −2 d −1 , and over the upper 15 cm was 9.3 mmol m −2 d −1 . ΣCO 2 in pore waters from incubated sediments decreased with time and the consumption rate in the lower layer of sediments was 4.2 mmol m −2 d −1 , close to the consumption rate of major cations, especially calcium, indicating the precipitation of authigenic carbonates. Overall, remineralization of SOC in mobile-mud belts could play a critical role in the biogeochemical cycling and storage of OC, and other important biogenic elements in this highly dynamic LDE. [ABSTRACT FROM AUTHOR]

The Yangtze River Basin, which has a population of 0.4 billion and an economic output accounting for 50% of China׳s Gross Domestic Product (GDP), is one of the most developed regions in China. With dramatic developments in the economy, large quantities of pollutants have entered the Yangtze River and have eventually been discharged into the East China Sea (ECS), and then most of them were preserved in the inner shelf coastal mud areas of the ECS. The inner shelf costal mud areas of the ECS, with sedimentation rate ranging from 0.8 cm/a to 1.2 cm/a, are an ideal place to obtain the high-resolution heavy metal record. In this work, two sediment cores collected in the inner shelf of the coastal mud areas of the ECS in 2009 were used to reconstruct historical records of anthropogenic heavy metal input from the Yangtze River Basin. The temporal distribution of enrichment factors (EFs) is in good accordance with social development of Yangtze River Basin. Before the 1930s, the EFs of Pb and Zn are considered as the background level of study area, according to the agricultural country of China in that time. The much higher EFs of Pb and Zn from the 1930s to 1980s were associated with significant improvement of industry of the Yangtze River Basin. After 1983, the dramatical incensement of EFs of Pb and Zn responded to the remarkable economic development of the Yangtze River Basin. Of particular interest, the construction of the Three Gorges Dam (TGD) in 2003 possibly induced a significant increase in the heavy metal levels in the coastal ECS, and the ban on leaded gasoline in China induced a remarkable decrease in Pb levels. Although heavy metal levels have increased since the 1930s, the coastal mud area of the ECS remains under low ecological risk. [ABSTRACT FROM AUTHOR]

The large-scale occurrence of perylene in the surface sediment samples from the estuarine-inner shelf of the East China Sea (ECS) were examined, and for the first time by employing the multiproxies of organic geochemistry to explore the possible sources of perylene and its biogeochemical implication in this river-dominated area. The concentrations of perylene in this area ranged from 7.4 to 141.1 ng g −1 , displaying an apparent decreased trend in an offshore direction and increased alongshore to the south. In addition to the fluvial input, the hydrodynamic sorted fine sediments and associated organic components could also act on the spatial variability of perylene and its varied relationships with the total organic carbon based proxies and PAHs. Higher proportions of perylene towards the 5-ring PAHs indicated a natural diagenetic input. Together with the reported high perylene abundance outside the sediment compartments, the significant relationships between perylene and the terrigenous organic matter (OM) proxies could suggest a combination of the predepositional fluvial input of perylene and in situ formation from its precursors with land-derived OM origins for its appearance in the coastal ECS. The deposition flux of perylene could be likely served as a geochemical imprint to assess the river input influence on the sedimentary environment of the coastal ECS. [ABSTRACT FROM AUTHOR]

A receptor site in the East China Sea (ECS), ∼66 km off the shore of Shanghai, was used to investigate the seasonally atmospheric transport of land-based PAHs. Positive matrix factorization (PMF) modeling and back trajectories were performed to apportion the sources of the 16 USEPA priority PAHs (16 PAHs). In the process, three episodes were observed in all seasons except summer. These episodes provided additional insight to the transport mechanisms of these air pollutants in this most developed region of China. The average concentrations (in ng/m3) of PAHs in PM2.5 in fall, winter, spring and summer were 5.26 ± 5.36, 10.41 ± 8.58, 3.93 ± 2.31 and 0.97 ± 0.25, respectively, and with an annual average of 5.24 ± 5.81. Low molecular weight (LMW) PAHs (i.e., 2 ∼ 3-ring) was a dominant contributor for the 16 PAHs in PM2.5 over the ECS (36.2%), especially in summer (55.6%). The source apportionment by PMF analysis indicated that, based on yearly average, vehicular emission (27.0%) and coal combustion (24.5%) were the two major sources of PAHs, followed by biomass burning (16.5%), petroleum residue (16.3%) and air–surface exchange (15.7%). The highest source contributor for PAHs in fall and winter was coal combustion (30.5%) and vehicular emission (34.5%), respectively; while in spring and summer, the air–surface exchange contributed the most (27.1% and 59.5%, respectively). The specific composition patterns of 16 PAHs and PMF modeling results manifested that the air–sea exchange could be a potential source for the LMW PAHs in PM2.5 over the ECS, especially in warm season. [ABSTRACT FROM AUTHOR]

Abstract: The estuarine-inner shelf region of the East China Sea (ECS) is a major sink of the Yangtze River-derived fine-grained sediments and associated organic materials. In this work, surface sediment samples from a matrix of seventy-three sites that extend from the Yangtze River estuary (YRE) to the southern inner shelf were measured for their elemental, stable isotopic and molecular indices to provide a process-oriented study on the sources, distribution and fate of sedimentary organic matter (SOM) in this region. The results indicated that the re-suspension and alongshore transport of sediments could play a key role on the accumulation of SOM in the area. In addition to the physical reworking, the low C/N ratios and the enriched δ13C values could also be likely related to the presence of microorganism-derived organic matter (OM) and soil-derived OM. The composition and principal component analyses of the n-alkanes indicated that the majority of the riverine terrigenous SOM was primarily restricted within the mud deposits along the coastal ECS. The wide occurrence and southward increasing trend of high molecular weight n-alkanes along the coastal ECS suggest an effective preferential dispersal of the terrigenous organic components. However, the local supply of the marine-derived OM potentially promotes the subsequent degradation of these terrigenous OM, which are likely responsible for the decreasing trend of the carbon preference index (CPI25–33) from the northern YRE to the southern inner shelf. This indicates that the transported SOM from the YRE could become more homogenized as it moved toward the southern inner shelf. The presence of unresolved complex mixtures (UCM), lower Pr/Ph ratios and patterns of more stable geochemical biomarkers (hopanes and steranes) in the nearshore region reveals a petroleum contamination in the coastal environment. [Copyright &y& Elsevier]