Tuoji Island Research Articles

Changes in Health Risks and Pollution Sources of Atmospheric PM2.5-bound Metals in a Background Site in North China

To explore the change features of PM2.5-bound metals in a background site of North China in the past ten years, 71 and 160 samples were collected from December 2011 to January 2013 (period Ⅰ) and from September 2019 to November 2021 (period Ⅱ) in Tuoji Island National Atmospheric Monitoring Station, respectively.The concentration of metals sampled was determined using ICP-MS, and the concentrations, sources, and health risks of heavy metals were compared. The results revealed that the average concentration of PM2.5 was (54.06±39.71) μg·m-3during period Ⅱ, which was 3.53 ng·m-3 lower than that during period Ⅰ. The concentrations of Zn, Mn, As, Pb, and V in stage Ⅱ decreased by 54.53, 172.63, 0.8, 79.06, and 3.81 ng·m-3, respectively, whereas the concentrations of Cr, Cu, Cd, and Ni increased by 2.01, 5.42, 3.03, and 3.55 ng·m-3, respectively. The PMF model results indicated that the biggest contributor to PM2.5-bound metal was industrial emissions (32.32%), followed by coal combustion (27.47%), vehicle emissions (23.70%), ship emissions (9.69%), and dust sources (6.83%) during period Ⅱ. The contribution ratio of dust sources and ship emissions decreased by 20.73% and 8.83%, respectively, whereas for coal combustion and industrial emissions it increased by 2.50% and 13.52%, respectively, when compared with that during period Ⅰ. The total carcinogenic risk induced by PM2.5-bound heavy metals of period Ⅱ increased, with the highest contributions by Cr and Cd. The total non-carcinogenic risk decreased, with Mn contributing the most. Therefore, in the process of air pollution control, the control of pollution sources of heavy metals such as Cr and Mn should be reinforced.

Atmospheric Particles Are Major Sources of Aged Anthropogenic Organic Carbon in Marginal Seas.

Deposition of atmospheric particulates is a major pathway for transporting materials from land to the ocean, with important implications for climate and nutrient cycling in the ocean. Here, we report the results of year-round measurements of particulate organic carbon (POC) and black carbon (BC) in atmospheric aerosols collected on Tuoji Island in the coastal Bohai-Yellow Sea of China (2019-2020) and during a cruise in the western North Pacific. Aerosol POC contents ranged from 1.9 to 11.9%; isotope values ranged from -18.8 to -29.0‰ for δ13C and -150 to -892‰ for Δ14C, corresponding to 14C ages of 1,235 to 17,780 years before present (BP). Mass balance calculations indicated that fossil carbon contributed 19-66% of the POC, with highest values in winter. BC produced from fossil fuel combustion accounted for 18-54% of the POC. "Old" BC (mean 6,238 ± 740 yr BP) was the major contributor to POC, and the old ages of aerosol POC were consistent with the 14C ages of total OC preserved in surface sediments of the Bohai-Yellow Sea and East China Sea. We conclude that atmospheric deposition is an important source of aged OC sequestered in marginal sea sediments and thus represents an important sink for carbon dioxide from the atmosphere.

Molecular distributions of dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls in aerosols over Tuoji Island in the Bohai Sea: Effects of East Asian continental outflow

Field measurements of the concentrations of dicarboxylic acids and related compounds (oxocarboxylic acids and α-dicarbonyls) in PM2.5 were conducted on a background island (Tuoji Island, China) over the Bohai Sea to better understand the effects of pollution downwind of the East Asian continental outflow. Air mass backward trajectory calculations demonstrated that the distributions of dicarboxylic acids and related compounds at Tuoji Island depended strongly on the East Asian continental outflow and correlated with the hours spent by an air parcel in the polluted boundary layer. Based on the data analysis, the sampling period was categorized into heavy aerosol pollution periods (HAPPs) and light aerosol pollution periods (LAPPs). The average concentration of dicarboxylic acids and related compounds during HAPPs (1280 ± 503 ng m−3) was approximately seven times higher than that during LAPPs (189 ± 90.8 ng m−3). The order of the major species of dicarboxylic acids and related compounds, ranked by concentrations, was oxalic acid (C2) > glyoxylic acid (ωC2) > succinic acid (C4) > terephthalic acid (tPh) during HAPPs, and C2 > malonic acid (C3) > ωC2 > C4 during LAPPs. Results of positive matrix factorization (PMF) showed that secondary sources were the dominant source of dicarboxylic acids and related compounds, with contributions of 38% and 57% during HAPPs and LAPPs, respectively. Primary sources of biomass burning and plastic waste burning were also significant during HAPPs (contributions: 26% and 20%, respectively) and LAPPs (contributions: 18% and 12%, respectively). The concentration ratios of C3 to C4 (C3/C4), C2 to C4 (C2/C4), fumaric acid to maleic acid (F/M), phthalic acid to azelaic acid (Ph/C9), adipic acid to azelaic acid (C6/C9), and the positive correlations of Ph or tPh with dicarboxylic acids, and levoglucosan with dicarboxylic acids and related compounds further support the PMF results.

Potential Risks of PM2.5-Bound Polycyclic Aromatic Hydrocarbons and Heavy Metals from Inland and Marine Directions for a Marine Background Site in North China.

Ambient PM2.5-bound ions, OC, EC, heavy metals (HMs), 18 polycyclic aromatic hydrocarbons (PAHs), 7 hopanes, and 29 n-alkanes were detected at Tuoji Island (TI), the only marine background atmospheric monitoring station in North China. The annual PM2.5 average concentration was 47 ± 31 μg m−3, and the average concentrations of the compositions in PM2.5 were higher in cold seasons than in warm seasons. The cancer and non-cancer risks of HMs and PAHs in cold seasons were also higher than in warm seasons. BaP, Ni, and As dominated the ∑HQ (hazard quotient) in cold seasons, while the non-carcinogenic risk in warm seasons was mainly dominated by Ni, Mn, and As. The ILCR (incremental lifetime cancer risk) values associated with Cr and As were higher in the cold season, while ILCR-Ni values were higher in the warm season. The backward trajectory was calculated to identify the potential directions of air mass at TI. Through the diagnostic ratios of organic and inorganic tracers, the sources of particulate matter in different directions were judged. It was found that ship emissions and sea salt were the main sources from marine directions, while coal combustion, vehicles emissions, industrial process, and secondary aerosols were the main source categories for inland directions. In addition, potential HM and PAH risks from inland and marine directions were explored. The non-cancerous effects of TI were mainly affected by inland transport, especially from the southeast, northwest, and west-northwest. The cancerous effects of TI were mainly simultaneously affected by the inland direction and marine direction of transport.

Design and performance evaluation of a submerged floating tidal current power generation device

Due to the difficulty and high cost of offshore power supply, there are still many remote islands which have not been fully developed and utilized. In order to solve this kind of problem, a new type of marine current turbine (MCT) power generation device was designed for Tuoji Island, Changdao County, Shandong Province, which is convenient for installation and maintenance. This paper presents both the prototype design and model test verification work. Limited by the size of circulating water channel, the test model was modeled and manufactured under the scale of 3:100, which means the turbine model is not able to meet the small scale geometry similarity and gravity equivalent at the same time. A light circular plate was designed to replace the resistance of the turbine as equal by means of CFD. Then it combines the main body and the equivalent disc to complete the mooring test, observing the attitude response of the device under different angles of current. On the basis, the hydrodynamic performance of the whole device model was observed under different inflow speeds and angles. The results of the model tests indicated that the prototype is relatively stable under the design condition.

Degradation of PAHs during long range transport based on simultaneous measurements at Tuoji Island, China, and at Fukue Island and Cape Hedo, Japan

We investigated the degradation of polycyclic aromatic hydrocarbons (PAHs) during long-range transport. Aerosols were collected simultaneously at remote sites on Tuoji Island, China; Fukue Island, Japan; and the Cape Hedo Atmosphere and Aerosol Measurement Station (CHAAMS), Okinawa, Japan in April, October, and December from 2012 to 2013. These remote sites were convenient for investigating the degradation of PAHs during long-range transport. PAHs were analyzed via gas chromatography/mass spectrometry. We identified air masses that passed over all sites and combined our measurements with a chemical transport model. We estimated the relative contributions of the PAHs at the three sites by normalizing the PAH concentrations to elemental carbon. Benzo[a]pyrene persisted in 5–16% of samples. The results of this study are consistent with laboratory studies in which secondary organic aerosol (SOA) coatings protected PAHs from degradation by ozone. We detected an inhibition of the degradation PAHs by SOA coatings by collecting PAHs simultaneously at the three sites. To elucidate the major sources of the SOAs, we carried out a positive matrix factorization analysis to identify the major sources of SOA coating, which controls the lifetime of PAHs. In spring and winter, the contribution of vehicle emissions was higher (46%) at Tuoji Island than at CHAAMS (13%). In contrast, the contribution of coal combustion was higher at CHAAMS (59%) than at Tuoji Island (28%). This result implies that during long-range transport, PAHs derived from coal combustion are more slowly degraded than PAHs derived from vehicle emissions. We found that the viscosity of SOA coatings derived from vehicle emissions in China was low, and the corresponding PAHs were rapidly degraded. In contrast, the viscosity of SOA coatings derived from coal combustion was high, and degradation of the corresponding PAHs was relatively slow. These results imply that PAHs derived from coal combustion have long lifetime.

Nitrous acid in marine boundary layer over eastern Bohai Sea, China: Characteristics, sources, and implications

Nitrous acid (HONO) serves as a key source of hydroxyl radicals and plays important roles in atmospheric photochemistry. In this study, gaseous HONO and related species and parameters were measured in autumn of 2016 at a marine background site on Tuoji Island in eastern Bohai Sea, China. The HONO concentration in marine boundary layer (MBL) was on average 0.20 ± 0.20 ppbv (average ± standard deviation) with a maximum hourly value of 1.38 ppbv. It exhibited distinct diurnal variations featuring with elevated concentrations in the late night and frequent concentration peaks in the early afternoon. During nighttime, the HONO was produced at a fast rate with the NO2-HONO conversion rate ranging from 0.006 to 0.036 h−1. The fast HONO production and the strong dependence of temperature implied the enhancement of nocturnal HONO formation caused by air-sea interactions at high temperature. At daytime, HONO concentration peaks were frequently observed between 13:00–15:00. The observed daytime HONO concentrations were substantially higher than those predicted in the photostationary state in conditions of intensive solar radiation and high temperature. Strong or good correlations between the missing HONO production rate and temperature or photolysis frequency suggest a potential source of HONO from the photochemical conversions of nitrogen-containing compounds in sea microlayer. The source intensity strengthened quickly when the temperature was high. The abnormally high concentrations of daytime HONO contributed a considerable fraction to the primary OH radicals in the MBL.

Diurnal concentrations, sources, and cancer risk assessments of PM2.5-bound PAHs, NPAHs, and OPAHs in urban, marine and mountain environments

Ambient measurements of PM2.5-bounded polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and oxy-PAHs (OPAHs) were conducted during the summer in Jinan, China, an urban site, and at Tuoji island and Mt. Tai, two background locations. 3.5 h and 11.5 h sampling intervals in daytime and nighttime were utilized to research the diurnal variations of PAHs, NPAHs, and OPAHs. The concentrations of PAHs, NPAHs, and OPAHs were highest at the urban site and lowest at the marine site. The diurnal patterns of PAHs and NPAHs at the urban and marine sites were dissimilar to those observed at the mountain site partly due to the influence of the boundary layer. Vehicle emissions at the urban site made a large contribution to high molecular weight PAHs. 1N-PYR and 7N-BaA during morning and night sampling periods in JN were relatively high. Fossil fuel combustion and biomass burning were the main sources for all three sites during the sampling periods. The air masses at the marine and mountain sites were strongly impacted by photo-degradation, and the air masses at the marine site were the most aged. Secondary formation of NPAHs was mainly initiated by OH radicals at all the three sites and was strongest at the marine site. Secondary formation was most efficient during the daytime at the urban and mountain sites and during morning periods at the marine site. The average excess cancer risk from inhalation (ECR) for 70 years' life span at the urban site was much higher than those calculated for the background sites.

Atmospheric PAHs, NPAHs, and OPAHs at an urban, mountainous, and marine sites in Northern China: Molecular composition, sources, and ageing

18 gaseous and particulate polycyclic aromatic hydrocarbons (PAHs), 16 nitro-derivative (NPAHs), and 7 oxy-derivative (OPAHs) were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) at three locations in Northern China, an urban site (Jinan), a marine site (Tuoji island), and a mountain site (Mt. Tai). The combined gas and particulate concentrations of 18 PAHs, 16 NPAHs, and 7 OPAHs were highest at the urban site (305.91, 2.80, and 9.05 ng/m3, respectively) and lowest at the mountain location (37.83, 0.27, and 1.59 ng/m3, respectively). A noticeable increase in the high molecular weight PAHs was observed during polluted conditions compared to clean conditions. Diagnostic ratios clearly demonstrated that coal/biomass combustion was the major PAH source in Northern China. The particulate PAHs were the most aged at the mountain site due to long-distance atmospheric transport. The formation rate of NPAHs was most efficient at the mountain location and during heavily polluted days at the urban and marine sites. In addition, the main formation pathway for NPAHs was through the OH initiated secondary reaction. NO3 radicals most significantly contributed to the NPAHs formation at night, during clear weather, and at the mountain site. The logKp value was lowest at the urban site for most individual compounds and highest at the mountain site. Higher logKp was found for NPAHs and OPAHs compared with their corresponding parent PAHs. The linear regression of logKp vs logPL0 at the three sites suggested that the gas-particle partitioning of PAHs might be in non-equilibrium.

Assessing on toxic potency of PM2.5-bound polycyclic aromatic hydrocarbons at a national atmospheric background site in North China

A total of 76PM2.5 samples collected at Tuoji Island from November 2011 to January 2013 were used to analyze 15 congeners of polycyclic aromatic hydrocarbons (∑15PAHs) and assess their toxic potency. The average ∑15PAHs was 15.34±8.87ngm−3, ranging from 4.24 to 40.62ngm−3 over the sampling period. BkF, BbF, Phe and BaP were dominant PAH congeners, contributing together 60.64% of the ∑15PAH concentration. The highest monthly ∑15PAHs concentration was in January 2012, followed by the next January, which was closely four times greater than the lowest level occurred in July 2012. Wheat straw burning was responsible for the high PAH concentrations in June 2012. The averaged BaP toxicity equivalent (TEQ-BaP) concentration was 2.70±1.88ngm−3 over the sampling period. BaP and DaA were the largest contributors, which contributed 58.5% and 14.7% of totals, respectively. The high TEQ-BaP and TEQ-BaP value per unit of ∑15PAHs concentration (TEQ-BaP(U)) values occurred in the cold season and the low levels presented in the warm period. The heaviest monthly TEQ-BaP was 5.28±2.84ngm−3, which appeared in January 2012; the lowest value was 0.86±0.33ngm−3, which occurred in July 2012. The potential source contribution function (PSCF) showed the occurrence of the high health risk associated with PAHs in the middle of Liaoning and the south of Shandong Peninsula.

An integrated OSL chronology, sedimentology and geochemical approach to loess deposits from Tuoji Island, Shandong Province: Implications for the late quaternary paleoenvironment in East China

Abstract The Tuoji II (TJII) section on the Miaodao Islands in the Bohai Sea is a representative aeolian section off China’s east coast. This study applied optically stimulated luminescence (OSL) dating, conducted grain size analysis, and examined major and trace element compositions, to investigate the loess–paleosol sequences. The OSL ages at depths of 0.6, 1.8, 2.8, 3.8, and 4.8 m were determined as 14.4 ± 0.4, 16.7 ± 1.3, 20.8 ± 1.0, 40.9 ± 1.5, and 47.9 ± 3.7 ka, respectively. It was projected that the loess started to accumulate at ca. 62.6 ka, according to presumed depositional rates. In this study, typical aeolian deposits elsewhere including the Luochuan (LC), Xiashu (XS), Wushan (WS), and Xifeng (XF) sections were compared with TJII section here. The results showed similarity in the geochemical characteristics of the deposits from the different areas of China and normalized upper continental crust, indicating aeolian origin of this island loess. In comparison with the LC, XS, WS, and XF samples, the aeolian deposits of the TJII section have higher concentrations of TiO2 and Zr and lower concentrations of Al2O3, Rb, and Ni, and they have higher SiO2/Al2O3 and TiO2/Al2O3 ratios and lower Al2O3/Na2O and Ba/Sr ratios. These features indicate the dust materials of the TJII section were derived from local sources of well-mixed sedimentary protoliths. Our results support the suggestion that paleoclimatic change and the evolution of aeolian sediments were controlled primarily by variation of the East Asian summer monsoon and sea level change.

Concentrations of metallic elements in long-range-transported aerosols measured simultaneously at three coastal sites in China and Japan

To determine the effects of long-range transport of aerosols from an upwind area in East Asia to a downwind area in Japan, we chemically analyzed aerosols collected simultaneously on Tuoji Island (Shandong Province, China), Fukue Island (Nagasaki Prefecture, Japan), and Cape Hedo (Okinawa Prefecture, Japan). We focused on changes in the metallic composition of PM2.5 aerosols during long-range transport. The average mass concentrations of PM2.5 at the three sites decreased in the order Tuoji Island > Fukue Island ≈ Cape Hedo (48.3 ± 4.5, 13.9 ± 1.5, and 13.2 ± 0.9 μg/m3, respectively). The fraction of coarse particles in total suspended particles estimated by (1–PM2.5/TSP) was highest on Cape Hedo, indicating that the contribution of sea salts was increased by long-range transport of the aerosols over the ocean. Enrichment factor analysis revealed that at all three sites, Al, K, Ca, Mn, Fe, Co, Sr, and Ba originated from soil; whereas Cr, Ni, Cu, Zn, As, Mo, Ag, Cd, Sn, Sb, Tl, and P appeared to be of anthropogenic origin. Na was the most abundant element on Cape Hedo, indicating the addition of sea salts during aerosol transport. The V concentration was highest at Fukue Island, which was ascribed to V emission from ships. Sixty-one percent of the V on Fukue Island and 62% of the V on Cape Hedo were determined to have originated from ships, implicating of data obtained on dates during which backward trajectory analysis indicated that the same air mass passed over Tuoji Island, Fukue Island, and Cape Hedo in that order.

Aerosol optical properties at urban and coastal sites in Shandong Province, Northern China

In-situ observations of aerosol optical properties were conducted in Jinan, an urban site, from December 2013 to May 2014 and on Tuoji Island, a coastal site, from December 2014 to January 2015; both locations are located in Shandong Province, Northern China. Aerosol optical properties, such as the scattering coefficient (σsp), absorption coefficient (σap) and single-scattering albedo (ω), were obtained using nephelometer and aethalometer. The mean values (±standard deviation) for σsp at 550nm and σap at 532nm, were 204±188Mm−1 and 43±33Mm−1, respectively, in Jinan and 210±246Mm−1 and 8±6Mm−1 on Tuoji Island, respectively. The average ω at 532nm was 0.80±0.09 in Jinan and 0.93±0.04 on Tuoji Island. Pronounced diurnal cycles were observed at both locations for σsp, σap and ω, but the diurnal cycles at the two locations exhibited distinct properties for some of the aerosol optical parameters. The values of σsp and σap peaked between 0800 and 1100 local time (LT) due to traffic emissions and low wind speeds at both locations. And a unimodal ω diurnal cycle, which peaked between 1000 and 1400 LT, was observed in the spring in Jinan. This spring diurnal pattern was mainly related to secondary aerosol formation and aging processes. The high σsp and σap values in Jinan winter were accompanied by calm winds (<2m/s) from 0° to 90°, while the high σsp and σap values on Tuoji Island were observed during the period of stronger wind speeds (>2m/s) from 180° to 270°. This indicates that local emissions were a key source of strongly absorbing and scattering aerosols in Jinan during heating period, whereas, high σsp and σap values on Tuoji Island were mainly influenced by middle- and long-distance transport from Shandong Province and the Jing-Jin-Ji region. Additionally, middle- and long-distance regional transport from direction at 180° to 270° occasionally enhanced the σsp and σap values in the spring at Jinan after heating period. The σsp values in Jinan and Tuoji Island both exhibited relatively profound correlation with the accumulation-mode particle number concentrations.

Chemical characteristics and influence of continental outflow on PM1.0, PM2.5 and PM10 measured at Tuoji island in the Bohai Sea

To investigate the chemical characteristics and sources of size-segregated particles in the background region, PM1.0, PM2.5 and PM10 samples were collected in Tuoji Island (TI) during the winter of 2014. Water-soluble inorganic ions (WSIIs) including Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3− and SO42−, organic carbon (OC) and elemental carbon (EC) and water-soluble organic carbon (WSOC) were analysed. The average mass concentrations of PM1.0, PM2.5 and PM10 were 44.5μg/m3, 62.0μg/m3 and 94.4μg/m3, respectively, and particles were importantly enriched in PM1.0. Secondary WSIIs (NH4+, NO3− and SO42−) were the most abundant species, and their contribution was highest in PM1.0. The average values of NOR and SOR were more than 0.1 in PM1.0, suggesting that secondary formation of SO42− and NO3− from the gas precursors SO2 and NO2 occurred in PM1.0. Secondary organic carbon accounted for 62.3% in PM1.0, 61.9% in PM1.0–2.5 and 48.9% in PM2.5–10 of OC, formed mainly in the fine mode. The particles concentrations were mainly affected by air mass from the North China Plain, especially the air mass from the southwest of Shandong province, which had low speed and altitude.

Identification and quantification of shipping emissions in Bohai Rim, China

Rapid development of port and shipbuilding industry in China has badly affected the ambient air quality of coastal zone due to shipping emissions. A total of 60 ambient air samples were collected from background site of Tuoji Island in Bohai Sea strait. The air samples were analyzed for PM2.5, organic carbon (OC), element carbon (EC), inorganic elements, and water-soluble ions. The maximum concentration of PM2.5 was observed during spring (73.6μg·m−3) compared to winter (39.0μg·m−3) with mean of 54.6μg·m−3. Back trajectory air mass analysis together with temporal distribution of vanadium (V) showed that V could be the typical tracer of shipping emissions at Tuoji Island. Furthermore, the ratios of vanadium to nickel (V/Ni), vanadium to lead (V/Pb) and vanadium to zinc (V/Zn) also suggest shipping emissions at Tuoji Island. The annual average primary PM2.5 estimate of shipping emissions was 0.65μg·m−3 at Tuoji Island, accounting for 2.94% of the total primary PM2.5, with a maximum of 3.16% in summer and a minimum of 2.39% in autumn.

Impact of agricultural waste burning in the Shandong Peninsula on carbonaceous aerosols in the Bohai Rim, China

A total of 115PM2.5 samples were collected for analyzing organic carbon (OC) and elemental carbon (EC) at Tuoji Island (TI), China from November 2011 to December 2012. The results showed that annual arithmetical means of OC and EC concentrations were 3.8±2.7 and 2.2±2.2μgm−3, which contributed 8% and 4% of PM2.5 mass concentrations, respectively. High EC concentrations occurred in winter, contributed mainly by EC outflow from the northwest source region, while high OC concentrations were found during spring, attributed largely to biofuel burning in the Shandong Peninsula, and short distance and favorable transport from the peninsula to the TI. Agricultural waste open burning in the peninsula caused the largest variability of OC concentration in summer. Eliminating agricultural field burning in the peninsula can reduce at least one-third of concentration levels and half of northward transport fluxes of OC and EC in Bohai Rim in summer.

Comparative Study on the Grain Size Characteristics of Loess Deposit Both on Miaodao Islands and on the Laizhou Bay Plain and Its Implications for Provenance

Abstract The grain size records of loess-paleosol deposit in China are some of the most important terrestrial records of the Quaternary. It systematically carried out fieldwork on loess profile of Tuoji Island on Miaodao Islands and Changyi profile on the Laizhou Bay plain, analyzed grain size of 220 and 86 samples respectively. It shows the grain size of loess in Tuoji Island profile coarser than Changyi profile. The environment-sensitive size fractions of Tuoji Island and Changyi loess section respectively are 89.1-100.0colonm and 70.8-79.4colonm, by analyzing grain-size class vs. standard deviation values method. The changes of grain size characteristics of loess-paleosol recorded in different sections implicated the much plentiful materials in the Changyi profile on Laizhou Bay plain than Tuoji profile on Miaodao Islands.