Southeastern Coastal Area Of China Research Articles

Increased Lateral Transfer of Soil Organic Carbon Induced by Climate and Vegetation Changes Over the Southeast Coastal Region of China

AbstractSoil erosion and the subsequent lateral movement of soil carbon profoundly affect the spatial pattern of carbon sources and sinks in terrestrial ecosystems. The eight river basins of Fujian Province considered in this study are an important part of the southeastern coastal river basin of the ninth largest river system in China. In recent years, the erosion of soil and soil organic carbon in the southeast coastal region of China is not ideal owing to the high and concentrated rainfall, natural vegetation destruction, and other reasons. In this study, the soil organic carbon erosion and deposition rates related to erosion in the eight river basins of Fujian Province are quantified, and their spatial distribution characteristics are extracted. Based on the soil erosion rate from two national soil erosion surveys and topsoil carbon content from the Harmonized World Soil Database, we estimated that the lateral soil organic carbon erosion increased from 7.53 to 26.75 g C m−2 yr−1 in eight river basins of Fujian Province from 1995–1996 to 2010–2012. The soil organic carbon erosion rate in the eight river basins increased by 2.6 times, while the soil organic carbon erosion rate for the whole of China decreased by 44% during the same period. The increase in torrential rain and decrease in vegetation cover in the southeastern coastal areas largely contributed to the erosion of soil and soil organic carbon. The lateral transfer rate of soil organic carbon may be further exacerbated by the increase of torrential rain in the southeastern coastal areas of China.

Risk assessment and source identification of heavy metals in agricultural soil: a case study in the coastal city of Zhejiang Province, China

Heavy metal contamination is a serious environmental problem, especially in developing countries such as China. In this study, we collected 1928 soil samples from the southeastern coastal area of China and analyzed the pollution concentration and potential ecological risk from heavy metals including arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), and mercury (Hg). The mean concentrations of Cr, Hg, and Pb were lower than their corresponding background values, whereas As and Cd were 1.31 and 1.59 times their background values, respectively. The calculation of the mean Pollution Index (PI) for these heavy metals were, in decreasing order Cd (1.59), As (1.31), Cr (0.94), Pb (0.89), and Hg (0.78) and the Nemerow Integrated Pollution Index revealed that almost one-fifth of the soil in the study area was moderately polluted. According to the ecological risk index, about 12% of the soil was at a moderate or high ecological risk, and Cd and Hg presented the highest ecological risk. The GeogDetector software was used to quantitatively assess the potential sources of these metals. The GeogDetector results showed that the soil heavy metals have various sources, including: natural processes had significant impacts on all heavy metals analyzed in this study; farmland types influenced the concentrations of As and Cr significantly; industrial activities significantly increased As, Cr, and Hg; transportation-related activities increased As, Cd, and Hg; and agricultural application of fertilizer and pesticides, had significant impacts on As, Cd, and Pb levels. Based on the results of the interaction detector, natural processes and agricultural activities were determined to be the main sources of heavy metals in the study area.

Overview of the development history of China’s typhoon research and operational work in the past century

Because typhoons are one of the most major natural disasters in the southeastern coastal areas of China, great attention has been paid to the prevention and mitigation of the disasters caused by typhoons. Over the past century, significant progress has been made in typhoon-related scientific research and operational work in China, including the construction of a network of typhoon monitoring stations, the establishment of forecasting operation systems, early warning and prevention of typhoon-related disasters, and the research of basic theories of typhoon behaviors and key forecasting technologies. This paper briefly reviews the milestones in the development history of typhoon research in China over the past century and a half in order to commemorate the predecessors, especially those who made historical contributions to the advancement of typhoon research since the economic and cultural reforms known as the “Opening of China”, who provided historical references which enabled China to become an international leader in the field of typhoon science and technology.

Extracting Typhoon Disaster Information from VGI Based on Machine Learning

The southeastern coast of China suffers many typhoon disasters every year, causing huge casualties and economic losses. In addition, collecting statistics on typhoon disaster situations is hard work for the government. At the same time, near-real-time disaster-related information can be obtained on developed social media platforms like Twitter and Weibo. Many cases have proved that citizens are able to organize themselves promptly on the spot, and begin to share disaster information when a disaster strikes, producing massive VGI (volunteered geographic information) about the disaster situation, which could be valuable for disaster response if this VGI could be exploited efficiently and properly. However, this social media information has features such as large quantity, high noise, and unofficial modes of expression that make it difficult to obtain useful information. In order to solve this problem, we first designed a new classification system based on the characteristics of social medial data like Sina Weibo data, and made a microblogging dataset of typhoon damage with according category labels. Secondly, we used this social medial dataset to train the deep learning model, and constructed a typhoon disaster mining model based on a deep learning network, which could automatically extract information about the disaster situation. The model is different from the general classification system in that it automatically selected microblogs related to disasters from a large number of microblog data, and further subdivided them into different types of disasters to facilitate subsequent emergency response and loss estimation. The advantages of the model included a wide application range, high reliability, strong pertinence and fast speed. The research results of this thesis provide a new approach to typhoon disaster assessment in the southeastern coastal areas of China, and provide the necessary information for the authoritative information acquisition channel.

Investigation of the Microcharacteristics of Asphalt Mastics under Dry-Wet and Freeze-Thaw Cycles in a Coastal Salt Environment.

In the coastal areas of southeastern China, high temperatures and humidity in the summer and microfreezing in the winter, as well as a high concentration of salt spray in the environment, seriously deteriorate the durability of asphalt mixtures. Therefore, the microcharacteristics of asphalt mastics (asphalt mixed with mineral filler) under the effect of chlorine salt and “dry–wet and freeze–thaw” (DW-FT) cycles were investigated by Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and atomic force microscopy (AFM) techniques. Two factors, including asphalt mastic types (base and styrene-butadiene-styrene (SBS)-modified mastics) and numbers of DW-FT cycles, were considered based on the natural environment. Regression functions were established to explore the relationship between the FTIR, GPC, and AFM indexes. The results indicate that there were no chemical reactions between the asphalt and filler because the infrared spectrum of the base and SBS-modified mastics were similar. With the increase of the salt “DW-FT” cycle numbers, the sulfoxide index and large molecular size ratios () increased, and the surface roughness ( and ) of the morphology decreased, as illustrated by a flatting mastics surface phenomenon in the AFM test. Regression analysis confirmed that there was a high correlation between the FTIR, GPC, and AFM indexes, and formation of the bee structures was closely related to the long chain index. The SBS-modified mastics had a better antiaging performance with a lower increase in the sulfoxide index after the salt “DW-FT” cycles in the coastal environment.

Multiple sources of Cretaceous granitoids in northeastern Fujian, coastal area of southeastern China

The major elemental and oxygen isotopic features of Cretaceous granitoids in the coastal area of southeastern China cannot be adequately explained by existing Sr-Nd isotopic models of two-component crust-mantle mixing. In this paper, we report the whole-rock elemental, and Sr-, Nd-, and Hf-isotopes, and the zircon U-Pb age and Hf-O isotopic compositions for the Puqian, Danyang, Qingliangshan, Nanyu, and Qishan plutons in northeastern Fujian of this area to further investigate their petrogenesis. The examined rocks included pyroxene diorite, monzodiorite, granodioritic enclave, monzogranite and alkali-feldspar granite. Zircon U-Pb dating gave crystallization ages of 115 Ma for the Puqian monzogranite and granodioritic enclave, 97–109 Ma for the Danyang monzogranite, 99 Ma for the Nanyu pyroxene diorite, 97 Ma for the Qishan alkali-feldspar granite, and 97–103 Ma for the Qingliangshan alkali-feldspar granite. Our new Sr-Nd-Hf-O isotopic and petrogenetic studies of these granitoids showed that, aside from the ancient crustal component (δ18O = 7.5‰, εHf(t) = −10) and the mantle-derived magma (δ18O = 5.3‰, εHf(t) = 2), a separate juvenile low δ18O crustal source (δ18O = 4.2‰, εHf(t) = 2) must be involved. Since the emplacement of the diorite-monzodiorite-granodiorite-monzogranite suite and the A-type granite was coeval with pull-apart basins and bimodal volcanic rocks, the Cretaceous granitoids in northeastern Fujian, coastal area of southeastern China, were emplaced in an extensional setting, possibly due to the backarc extension and the changing drifting direction of the paleo-Pacific plate.

Spatiotemporal trends of temperature and precipitation extremes across contrasting climatic zones of China during 1956–2015

Spatiotemporal changes of temperature and precipitation extremes from 1956 to 2015 were analyzed at 200 representative weather stations evenly distributed in the temperate continental zone (TCZ), temperate monsoon zone (TMZ), mountain plateau zone (MPZ), and (sub) tropical monsoon zone (SMZ) of China, using 16 extreme temperature and 11 extreme precipitation indexes. The results showed that warm days (TX90p) and warm nights (TN90p) increased significantly, while cool days (TX10p) and cool nights (TN10p) decreased significantly in the whole China. Overall increasing trends were found for maximum and minimum daily maximum temperature (TXx and TXn) and maximum and minimum daily minimum temperature (TNx and TNn). Warm indexes, including summer days (SU25), tropical nights (TR20), warm spell duration indicator (WSDI), and growing season length (GSL), showed increasing trends, whereas cold indexes such as frost days (FD0), ice days (ID0), cold spell duration indicator (CSDI), and diurnal temperature range (DTR) showed decreasing trends. These extreme temperature indexes exhibited high correlations with mean air temperature. MPZ exhibited the most remarkable change magnitudes among the four zones, while the smallest changes occurred in SMZ. An accelerating warming trend was particularly observed since 1986. Nationally, only daily rainfall intensity (SDII) showed significantly increasing trends, while the increasing trends of other precipitation indexes were not significant. Apart from consecutive wet days (CWD), changes of precipitation extremes presented increasing trends. PRCPTOT and R10mm exhibited the highest correlation coefficient across contrasting climatic zones. Regionally averaged precipitation totals were decreasing in TMZ during 1956–1985, but increasing trends were identified after 1985. The upward tendency of precipitation totals in MPZ and the west part of TCZ may alleviate the pressure of water shortage in arid and semi-arid regions of China, but the upward trend in SMZ, especially in the coastal areas of southeastern China, may aggravate the risk of flood-induced disasters in these regions.

Prevalence of human T-cell lymphotropic virus type-1 infection among blood donors in mainland China: a systematic review and meta-analysis of the last 20 years

ABSTRACTBackground: The southeastern coastal area of China has a high prevalence of HTLV-1 infection among blood donors. However, the estimation of HTLV-1 prevalence on a national and regional level is little known. The aim of this study is to understand and explore the estimation of HTLV-1 infection prevalence among blood donors on a national and regional level in mainland China by using a systematic review and meta-analysis.Study design and methods: All relevant publications of the past two decades (1998–2017), which were reported in both English and Chinese languages, were adopted and systematically assessed. The estimation of prevalence and its 95% confidence interval (CI) at the level of provinces/municipalities and overall were estimated using meta-analysis method.Results: From the 327 studies searched, 60 met the inclusion criteria. These were from 18 provinces and four municipalities and included 1,420,079 blood donors. The overall estimation of the HTLV-1 prevalence in blood donors was 0.169‰, and its 95% CI was 0.121‰-0.240‰.Conclusion: A disproportionate distribution of HTLV-1 infection among blood donors in different provinces/municipalities regarding its prevalence has been reported. This study recommends developing appropriate HTLV-1 screening strategies of blood donors in various regions of China considering regional prevalence, and cost-effectiveness.

Redescription of Rhopalopsole hamata Yang amp; Yang, 1995 (Plecoptera: Leuctridae) based on the male, female, and nymph, with notes on the R. dentata group from China.

The male, female, and nymph of the leuctrid Rhopalopsole hamata Yang Yang, 1995, originally known from Zhejiang, an eastern coastal province of China, are redescribed and illustrated. This new material is from Jiangsu, an eastern-central coastal province of China. Brief biological data is also provided for this species. In addition, a species checklist of the Rhopalopsole dentata group from China is provided. The type localities of these group are mainly in the coastal areas of southeastern China.

Coordinated influences of the tropical and extratropical intraseasonal oscillations on the 10–30-day variability of the summer rainfall over southeastern China

This study explores the spatial variations and physical mechanisms of 10–30-day rainfall anomalies over southeastern China based on daily station-observed rainfall data for the period 1979–2015. Empirical orthogonal function analysis shows that the dominant spatial distribution of 10–30-day rainfall anomalies is a monopole pattern over the south of the middle and lower reaches of the Yangtze River Valley (SMLY). Lead-lag composites reveal that the evolution of such a monopole pattern depends on the coordinated influences of 10–30-day atmospheric intraseasonal oscillations (ISOs) from the tropics and mid-high latitudes. In the upper troposphere, the southeastward-propagating Rossby wave train from the mid-high latitudes, which presents as anomalous anticyclones and cyclones alternating over eastern Europe to southeastern coastal area of China, induces strong ascents (descents) over the SMLY via vorticity advection. Circulation anomalies associated with tropical ISO over East Asia/Western North Pacific trigger a vertical cell with strong updraft (downdraft) over the SMLY and downdraft (updraft) to the south, further enhancing the ascents (descents) over the SMLY, forming the wet (dry) phases of 10–30-day rainfall anomalies. Moreover, due to the meridional non-uniformity of ISO-related diabatic heating along the Indian Ocean longitudes, an anticyclone (cyclone) is generated over the central Indian–northern Bay of Bengal, which tends to anchor the anomalous ascents (descents) over the SMLY through its interaction with the intraseasonal Rossby wave from mid-high latitudes, thus favoring the persistence of wet (dry) phases of the 10–30-day SMLY rainfall anomalies.

On the subsistence types of the Xiantouling Culture

Abstract The Xiantouling Culture featured sand dune sites and shell midden (kitchen midden) sites. Through an analysis of the faunal and floral remains and tools unearthed from these sites, with the relevant unearthed pottery wares and paleo-environmental research results taken into account, it can be evidenced that the subsistence types of these sites were mainly plant gathering supplemented by fishing and hunting, instead of relying on marine resources. The subsistence type of the sand dune sites was mainly plant gathering and occasionally rice gathering or farming; that of the earlier kitchen madden sites was gathering freshwater shells, and that of the later ones was more relying on marine resources. From the late phase of Xiantouling Culture, the archaeological cultures in the coastal areas of southeastern China began to utilize marine resources in a large scale.

Ages and petrogenesis of Jurassic and Cretaceous intrusive rocks in the Matsu Islands: Implications for lower crust modification beneath southeastern China

Major and trace element, whole-rock Sr-, Nd- and Hf-isotope, zircon U-Pb age and Hf-O isotope data are reported for the intrusive rocks from the Matsu Islands in the coastal area of southeastern (SE) China, in order to study the ages, sources and petrogenesis of these rocks and evolution of the lower crust. The rocks include gneissic granite, massive granite, brecciated granite and diabase. Secondary ion mass spectrometer (SIMS) zircon U-Pb dating reveals that the rocks in the Matsu Islands were emplaced at ∼160 Ma, ∼130 Ma and ∼94 Ma. The Jurassic granites (∼160 Ma) have high SiO2 (74.1–74.5 wt%) and K2O+Na2O (8.32–8.33 wt%) contents and high Rb/Sr ratios of 0.6–1.2 and (La/Yb)CN ratios of 12.6–19.4. Their relatively high initial 87Sr/86Sr ratios (0.7074–0.7101), variable and negative εNd(t) values (−9.2 to −5.4), and variable zircon εHf(t) (−17.0 to +5.2) and δ18O (4.7–8.1‰) values indicate they were mainly derived from an ancient lower crustal source, but with involvement of high εHf(t) and low δ18O materials. The Early Cretaceous diabase (∼130 Ma) has SiO2 content of 56.5 wt%, relatively high MgO concentration, low initial 87Sr/86Sr ratio and negative εNd(t) value, similar to geochemical features of other Cretaceous mafic rocks in the coastal area of SE China. Zircons from the diabase have high εHf(t) values (−5.5 to +0.2) and relatively low δ18O values of 4.2–5.0‰. These characteristics indicate that the parental magma of the diabase was generated by partial melting of enriched lithospheric mantle, which have been metasomatised by altered oceanic crust-derived low-δ18O fluids. For the Cretaceous granitoids (∼130 Ma and 94 Ma), they have relatively low SiO2 (68.0–71.3 wt%) and K2O+Na2O (5.30–7.55 wt%) contents and low Rb/Sr ratios and (La/Yb)CN ratios of 5.8–7.1. They have low initial 87Sr/86Sr ratios (0.7071–0.7082), homogeneous εNd(t) (−4.3 to −4.5) and relatively high zircon εHf(t) values (−3.7 to +1.2) and low δ18O values (4.6–5.9‰). Their isotopic compositions are similar to those of the diabases in this study as well as other Cretaceous mafic rocks in the coastal area of SE China, suggesting that the sources of the Cretaceous granitoids might be the newly formed lower crust related to the underplated mafic rocks. Whole-rock geochemical, Sr-Nd and zircon Hf-O isotopic compositions indicate that the Jurassic granitoids are most likely generated by partial melting of relatively ancient basement rocks, whereas the Cretaceous granitoids were generated by partial melting of relatively young lower crustal rocks with addition of mantle-derived magma. This distinction implies that the pre-existing ancient lower crust beneath the coastal area of SE China has been modified by large-scale mafic magma underplating. Therefore, underplating of mantle-derived mafic magma would result in modification of the pre-existing ancient lower crust and formation of the relatively juvenile lower crust.

Spatial-temporal dynamics of soil chloride distribution in a coastal saline plain: implication for ocean and climate influences

Purpose Restoration of saline soil in coastal areas requires detailed understanding of spatial and temporal soil salt distribution and how the distribution is affected by different environmental factors (e.g., precipitation and evaporation), particularly under the influence of salt water intrusion. Because of the high accuracy of chloride measurement, and chloride as a common ion in soil salt, we used soil chloride as a proxy of soil salt in a coastal area of southeastern China.

Built-up land change and its impact on ecological quality in a fast-growing economic zone: Jinjiang County, Fujian Province, China

Since China's reform and opening-up, the rapid growth of China's economy has greatly accelerated the expansion of built-up land, which has affected regional ecological environment to a great extent. Taking Jinjiang County of Fujian Province, one of the fastest economic-developing counties in the coastal areas of southeastern China, as a case study area, this paper focused on analyzing the rapid built-up land expansion process of the county and its impact on county's ecological quality using remote sensing techniques. Based on two Landsat images of 1996 and 2015 of Jinjiang, the built-up land of the county was extracted using the index-based built-up index (IBI) and its change was analyzed. In the meantime, the ecological status of Jinjiang was evaluated with a recently-proposed remote sensing based ecological index (RSEI) and the relationship between the built-up land dynamics and the ecological status changes of the county was quantitatively examined. The results showed that during the period from 1996 to 2015, the area of built-up land of Jinjiang had a net increase of 68.54 km2, a growth of 45%, and the expansion intensity was 0.55. The expansion of the built-up lands has caused overall degradation of the county's ecological quality. The mean value of RSEI of the county had declined from 0.532 in 1996 to 0.460 in 2015, a drop of13.5%. The area proportion of high ecological-quality grades also significantly fell from 39% in 1996 to 21% in 2015. The built-up land expansion intensity was negatively correlated with the ecological quality change.

A tree-ring chronology spanning 210 years in the coastal area of southeastern China, and its relationship with climate change

A tree-ring chronology spanning 210 years in the coastal area of southeastern China, and its relationship with climate change

Effects of Strong East Asian Cold Surges on Improving the Air Quality over Mainland China

A strong East Asian cold surge (SEACS) is one of the most distinct extreme weather events that can promote an improvement in local air quality. Combining East Asian atmospheric circulation with the air pollution index (API) datasets of 47 major cities throughout mainland China in 11 winter half-years (November–March) during 2001/2002–2011/2012, we investigated the influence of 39 SEACSs in conjunction with air pollution episodes on air quality over mainland China. The results showed that SEACS can cause considerable improvement in air quality and a remarkable decrease in the API over mainland China in up to 4 days after the SEACS outbreak day. The removal efficiency of air pollutants by SEACSs was greater than 30% in north central China, eastern southwest China, and southeast China. The occurrence date of the lowest value of the local API (indicating the best local air quality) can be observed as late day by day from northwest to southeast over mainland China after the SEACS outbreak, indicating a process of gradual improvement in Chinese air quality after the SEACS outbreak. When clean cold air originating from Siberia moves southward into coastal areas of southeastern China, the increase in sea level pressure, the drop in temperature and the enhancement in the northerly wind also tend to progress gradually from north to south over SEACS-affected East Asia. Thus, the “early in the north and late in the south” feature of air quality improvement by SEACSs over mainland China results from the southward movement of cold air masses from high to low latitudes after cold surge outbreaks.

Load estimation and assessment of land-based pollution for Quanzhou Bay and their relevance to the Total Quantity Control of Pollutants Discharged into the Sea (TQCPS) Program in China

The Total Quantity Control of Pollutants Discharged into the Sea (TQCPS) Program belonged to the Public Science and Technology Research Funds Projects of Ocean in China, launched in 2008. As one of the most important and typical demonstration cases of the TQCPS Program, a full investigation of the land-based pollutions discharges around Quanzhou Bay, China developed the total input for three main environmental factors (NH3–N, TP, COD) which were estimated and quantified in 2008 and 2012, respectively. Combined with the trend of seawater quality changes in Quanzhou Bay in the same periods, the effects of the program's implementation were then evaluated. On the whole, by using the basic survey data and export coefficient method, the total amounts of NH3–N, TP and COD discharged into the bay were estimated to be approximately 888.3, 130.6 and 14527.4 t/a in 2008, and 1518.6, 558.8 and 19986.7 t/a in 2012, respectively, where the percentage of the discharge from domestic sources (46.5% in 2008 and 45.2% in 2012) was generally higher than that from the other sources. Based on the characteristic of geography and administrative division, the land areas around the bay were divided into three parts: the south coast region (SCR), the west coast region (WCR), and the north coast region (NCR). The SCR and WCR accounted for 59.2 and 35.4% of the COD loads, and 49.2 and 48.0% of NH3–N loads in 2008. The NCR contributed less of the industrial pollution, but most to domestic pollution (54.1%), followed by 26.2% in the SCR in 2012. The contributions of the discharge from different land areas to the pollution of Quanzhou Bay were found to be differed in 2008 and 2012. Due to the difference in the levels of the economic development among these three areas, the discharge of pollutants from the north coast was much lower than that from the other two parts in 2008; however, following our suggestion of the moderation and optimization of the industrial distribution and the sewage discharge around Quanzhou Bay, the contribution of the west coast decreased while that of the north coast increased significantly in 2012. Furthermore, to a great extent, because of some marine ecological rehabilitation projects, which were also suggested by our TQCPS Program and finally adopted by local government and then developed recently in Quanzhou Bay, the seawater qualities there were improved by in 2012. A longer time and greater efforts are needed to reduce the discharge of land-based pollutants and to improve the marine ecological health and sustainability further. Based on the demonstration results of the research and practice of the TQCPS Program in Quanzhou Bay, some recommendations were suggested. These require further implementation and management and can be transferred to similar estuaries and bays in southeastern coastal areas of China.

Multiple Regression Prediction Model on Economic Loss under Typhoon

China’s southeast coast is one of the regions with most severely influenced by typhoons in the world, which suffers significant casualties and huge economic losses every year. A multiple regression prediction model of the economic losses educed by typhoon disaster in coastal areas of southeastern china was proposed. The principles of multivariate regression analysis were introduced firstly and the Typhoon disaster data over the east coast of China were analyzed. Then, the affected area, deaths and houses collapsed were chose as the variables and a multivariate regression prediction model of the economic losses educed by typhoon disaster was proposed. The results indicate that the factors affecting the economic losses of typhoon disasters randomness were taken into account and the responses of the independent variables and the dependent variable from the statistical data were provided.

Seasonal variations and source identification of selected organic acids associated with PM10 in the coastal area of Southeastern China

PM10 aerosols from the coastal area of Southeastern China were collected from April 2010 to March 2011 and were measured for C2–C10 dicarboxylic acids, phthalic acids (Ph) and five fatty acids (palmitic, stearic, oleic, linoleic and elaidic acids). For all sites and seasons, molecular distributions of diacids were always characterized by a predominance of oxalic acid (C2), with a relative abundance of 68–87%, followed by malonic acid (C3) and by either succinic acid (C4) or phthalic acid (Ph). This observed molecular composition was different from that in Chinese megacities where Ph was significantly higher than C3 and C4 diacids, which was likely due to the less intensive traffic emissions in the coastal area. Seasonal means of total diacids ranged between 394 and 547ngm−3 at the coastal urban sites and between 163 and 245ngm−3 at off-island sites. These levels were much lower than those reported in Chinese megacities (668–1568ngm−3) and slightly lower than those in Jeju Island, Korea (464–744ngm−3) but higher than those in marine and continental background locations. In all seasons, saturated fatty acids were significantly higher than unsaturated fatty acids due to their greater photochemical stabilities in the atmosphere. Most organic acids showed higher levels in spring and winter and lower levels in summer and fall, which was likely due to the influence of transport and meteorology. The diagnostic ratios of malonic acid to succinic acid (C3/C4), adipic acid to azelaic acid (C6/C9) and phthalic acid to azelaic acid (Ph/C9) were significantly higher in summer than in winter. These diagnostic ratios in the sampled ambient aerosols were completely different from those in primary emissions, suggesting the importance of photochemical production — especially in summer. The diurnal variations of diacids and fatty acid as well as the diagnostic ratios are associated with higher solar radiation and anthropogenic activities during the daytime. Principal component analysis results provide evidence that photochemical oxidation of unsaturated fatty acids and volatile organic compounds is the most important source of diacids. In this analysis, primary sources were found to be minor (traffic and food cooking) or non-existent (biomass burning and crustal dust). Components with high loadings of Ph and unsaturated fatty acids can be regarded as representative of primary traffic emissions.

A thinned lithosphere beneath coastal area of southeastern China as evidenced by seismic receiver functions

During Mesozoic to Cenozoic time, the large-scale tectono-magmatism had strongly modified the lithosphere beneath the southeastern continent of China, leaving the present-day lithosphere as a new one evolving from the ancient lithosphere that was largely removed and replaced. But this model proposed from geochemical and petrological research is urgently in need of support from seismic observational evidence. In this paper, based on the dataset recorded by the dense stations of two NE oriented broadband seismic profiles deployed in the coastal area of southeastern China (SE China), both P-wave (P-RF) and S-wave (S-RF) receiver functions were isolated. We identified Pls phase converted from the Lithosphere-Asthenosphere Boundary (LAB) in P-RFs of individual stations. Migrated Pls phase indicated a depth of 60–70 km for LAB. Inversions/ comparisons of P-RF (Pls phase) and S-RF (Slp phase) waveforms together with Ps and Sp imaging for the crust and upper mantle structure further confirmed this result. P-RF and S-RF migrated images exhibit that a flat LAB is positioned at the depth of 60–70 km spreading along the profile, whereas a distinct structural change of lithospheric base appears at the Min River estuary. Both Ps and PpPs migrated images of P-RFs present an abrupt Moho drop across the Min River fault from south to north, which is consistent with previous result obtained from deep seismic sounding. By taking into consideration other geological and geophysical features such as locally high anomalies of crustal Poisson’s ratios and heat flow at the Min River estuary, we infer that the Min River fault penetrates down to the Moho and may, furthermore, interfere in the deeper lithospheric structure.