Southeastern Coastal Region Research Articles

Epidemiological characteristics of dengue in mainland China from 1990 to 2019: A descriptive analysis.

In the past 30 years, dengue has undergone dramatic changes in China every year. This study explores the epidemiological trend of dengue in China during this period to identify high-risk seasons, regions, ages, susceptible populations, and provide information for dengue prevention and control activities.Dengue data from 1990 to 2019 were derived from the Public Health Science Data Center, Web of Science, China National Knowledge Infrastructure, PubMed, and Centers for Disease Control and Prevention of the corresponding province. GraphPad Prism 7 was conducted to generate disease evolution maps, occupational heat maps, and monthly heat maps of dengue cases and deaths in mainland China and Guangdong Province. Excel 2016 was used to create a cyclone map of age and gender distribution. Powerpoint 2016 was performed to create geographic maps.From 1990 to 2019, the annual number of dengue cases showed an increasing trend and reaching a peak in 2014, with 46,864 dengue cases (incidence rate: 3.4582/100,000), mainly contributed by Guangdong Province (45,189 cases, accounting for 96.43%). Dengue pandemics occurred every 4 to 6 years. The prevalence of dengue fever was Autumn, which was generally prevalent from June to December and reached its peak from September to November. The provinces reporting dengue cases each year have expanded from the southeastern coastal region to the southwest, central, northeast, and northwest regions, and the provinces with a high incidence were Guangdong, Guangxi, Yunnan, Fujian, and Zhejiang. People aged 25 to 44 years were more susceptible to dengue virus infection. And most of them were male patients. Dengue mainly occurs in the following groups: students, business service staffs, workers, farmers, retired staffs, housewives, and the unemployed. Four provinces reported deaths from dengue, namely Guangdong Province, Zhejiang Province, Henan Province, and Hunan Province.The dengue fever epidemic occurred every 4 to 6 years, mostly in autumn. The endemic areas were Guangdong, Guangxi, Yunnan, Fujian, and Zhejiang provinces. People aged 25 to 44 years, men, students, business service staffs, workers, farmers, retired staffs, housewives, and the unemployed were more susceptible to dengue fever. These findings help to develop targeted public health prevention and control measures.

Climatic yield potential of Japonica‐type rice in the Korean Peninsula under RCP scenarios using the ensemble of multi‐GCM and multi‐RCM chains

AbstractRice production in the Korean Peninsula (KP) in the near future (2021–2050) is analysed in terms of the climatic yield potential (CYP) index for Japonica‐type rice. Data obtained from the dynamically downscaled daily temperature and sunshine duration for the Historical period (1981–2010) and near future under two Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios are utilized. To reduce uncertainties that might be induced by using a Coupled General Circulation Model (CGCM)—a Regional Climate Model (RCM) chain in dynamical downscaling, two CGCM—three RCM chains are used to estimate the CYP index. The results show that the mean rice production decreases, mainly due to the increase of the temperature during the grain‐filling period (40 days after the heading date). According to multi model ensemble, the optimum heading date in the near future will be approximately 12 days later and the maximum CYP will be even higher than in the Historical. This implies that the rice production is projected to decrease if the heading date is selected based on the optimum heading date of Historical, but to increase if based on that of near future. The mean rice production during the period of ripening is projected to decrease (to about 95% (RCP4.5) and 93% (RCP8.5) of the Historical) in the western and southern regions of the KP, but to increase (to about 104% (RCP4.5) and 106% (RCP8.5) of the Historical) in the northeastern coastal regions of the KP. However, if the optimum heading date is selected in the near future climate, the peak rice production is projected to increase (to about 105% (RCP4.5) and 104% (RCP8.5) of the Historical) in the western, southern and northeastern coastal regions of the KP, but to decrease (to about 98% (RCP4.5) and 96% (RCP8.5) of the Historical) in the southeastern coastal regions of the KP.

Analysis of Wave Characteristics along the Coast of Bangladesh Using a Coupled Wave-Hydrodynamic Delft3D Model of the Bay of Bengal

Bangladesh has a unique geophysical location at the northern apex of the Bay of Bengal. Waves originating in the Indian Ocean, are constantly travelling up the bay area and interacting with the Bangladesh coastlands. In order to estimate the major wave properties required for coastal engineering purposes, a 2D coupled Wave-Hydrodynamic model of the greater bay area was developed in this study, using the Delft3D modeling suite. The model was simulated for a year and from the model outputs, significant wave height was primarily assessed at multiple locations along the Bangladesh coastline. Considerable spatial variation was observed in the wave parameters, along the whole coast at different locations, with the south-eastern coastal region showing high trends of wave height; whereas in the deltaic south-western, and south-central zones, wave heights were rather moderate. Strong seasonal variation was also observed for the different parameters, as both wave heights and depth-average current velocity were very high during the wet monsoon season, compared to the lean winter period. The results of this study is expected to provide a reasonably sound characterization of the wave spectrum along the coastline of Bangladesh.

Comparison of Floods Driven by Tropical Cyclones and Monsoons in the Southeastern Coastal Region of China

AbstractIncreasing evidence indicates that changes have occurred in heavy precipitation associated with tropical cyclone (TC) and local monsoon (non-TC) systems in the southeastern coastal region of China over recent decades. This leads to the following questions: what are the differences between TC and non-TC flooding, and how do TC and non-TC flooding events change over time? We applied an identification procedure for TC and non-TC floods by linking flooding to rainfall. This method identified TC and non-TC rainfall–flood events by the TC rainfall ratio (percentage of TC rainfall to total rainfall for rainfall–flood events). Our results indicated that 1) the TC rainfall–flood events presented a faster runoff generation process associated with larger flood peaks and rainfall intensities but smaller rainfall volumes, compared to that of non-TC rainfall–flood events, and 2) the magnitude of TC floods exhibited a decreasing trend, similar to the trend in the amount and frequency of TC extreme precipitation. However, the frequency of TC floods did not present obvious changes. In addition, non-TC floods decreased in magnitude and frequency while non-TC extreme precipitation showed an increase. Our results identified significantly different characteristics between TC and non-TC flood events, thus emphasizing the importance of considering different mechanisms of floods to explore the physical drivers of runoff response. Also, our results indicated that significant decreases occurred in the magnitude, but not the frequency, of floods induced by TC from the western North Pacific, which is the most active ocean basin for TC activity, and thus can provide useful information for future studies on the global pattern of TC-induced flooding.

우리나라 영동지역에 부는 양간지풍(襄杆之風)의 기후학적 특성

The purpose of this study is to uncover the climatological characteristics of Yangganjipung, a strong local wind blowing in Yeongdong region, Korea, which has recently attracted attention as an exacerbation factor of wildland fire spread. Analyses of 20-year (2000-2019) surface climate data observed by the Korea Meteorological Administration demonstrate that strong westerly winds exceeding 20 m/s (25m/s in mountainous areas) more frequently occur in the northeastern coastal region (between Yangyang and Goseong) of Gangwon province rather than the southeastern coastal region, evidencing the existence of Yangganjipung. The intensification of Yangganjipung may be associated with the convergence of strong westerly winds along a southwest-northeast directional tectolinement connected to the western flank of the Taebaek Mountain Range. It is also notable that Yangganjipung tends to occur seasonally between late fall and late spring and diurnally between afternoon and nighttime hours. Examinations of the composited maps of NCEP-NCAR reanalysis data for multiple cases reveal that the formation of a low pressure anomaly core around northern East Sea provides the favorable condition for long-lasting, intense Yangganjipung occurrences. These results are expected to be used as the basic data for establishing a gusty wind warning system to prevent regional-scale climate disasters associated with Yangganjipung such as large-scale forest fires in the eastern coast of the Korean Peninsula.

Urease activity and nitrogen dynamics in highly weathered soils with designer biochars under corn cultivation

The application of designer biochar has the potential to impact soil enzyme activity and soil nitrogen dynamics. However, very little is known about the mechanisms responsible for biochar-enzyme-nitrogen interaction in highly weathered soils. The objective of our 3-year (2016–2018) field experiment was to evaluate the effectiveness of designer biochars (DB) in enhancing urease activity (UA), total nitrogen (TN), total inorganic nitrogen (TIN), and nitrogen uptake (NU) at different growth stages (GS) of corn in a highly weathered soil of southeastern Coastal Plain region, USA. Experimental treatments have consisted of the control, 100% pine chips (100PC), 100% poultry litter (100PL), 2:1 blend of PC and PL (PCPL), 100% raw switchgrass (Panicum vaginatum, L; 100RSG), and 2:1 blend of PC and RSG (PCRSG). All the designer biochar treatments were applied at the rate of 30,000 kg ha−1 to a Goldsboro loamy sand in 2016. Urease activity, TN, TIN, and NU varied remarkably with DB (p ≤ 0.0001) at different GS (p ≤ 0.0001) of corn. Soils treated with 100PL had the greatest UA (28.18 µg N g−1 h−1), TN (0.087%), and TIN (14.53 mg kg−1) while the least UA, TN, and TIN of 20.55 µg N g−1 h−1, 0.063%, and 5.42 mg kg−1, respectively, were observed from the control. The three-year TN average increase over the control was in the order: 100PL (36.8%) > 100RSG (25.8%) > PCRSG (25.3%) > PCPL (23.9%) > 100PC (7.1%). The greatest NU of corn of 140.4 kg N ha−1 was from soils treated with 100PL while the least amount of NU was from 100PC. Overall, our results showed promising significance for the treatment of highly weathered soils since the application of DB did enhance UA and improve TN and TIN in the soils.

Industrial water-use efficiency in China: Regional heterogeneity and incentives identification

Progress has been made in improving water-use efficiency (WUE) in China, whereas problems such as unbalanced regional and industrial WUE development still exist. In this study, the WUE of 30 provinces in mainland China at the overall level as well as three industrial (i.e., primary, secondary, and tertiary industrial) levels are investigated. The study covers the time period 2005 to 2015 and is based on the Slacks-based measure approach combined with the Super-efficiency model dealing with undesirable outputs; in addition, a multidimensional analytical framework was developed in this study. Afterwards, the geographical detector model is applied to identify the driving forces of WUE, serving as a reference for policies and strategies needed to improve WUE. Results indicate that China’s overall WUE has been improving since 2005, though further progress is necessary. At the regional level, five regions (i.e., water abundance, vulnerability, stress, scarcity, and absolute scarcity) grouped by the availability of water resources per capita are all the most efficient in terms of water use in the primary industry. The absolute scarcity region performs best in all four dimensions despite the scarcity of water resources per capita, yet the water stress region has the lowest WUE. At the provincial level, provinces in the eastern coastal region, especially the south-eastern coastal region, have the highest WUE, whereas those in the interior south-eastern and south-western region have the lowest. Industrial structure, research and development intensity, and higher education are the main driving forces of WUE. Their mutual interactions and their interactions with other indicators are highly influential.

Threshold of sub-watersheds for SWAT to simulate hillslope sediment generation and its spatial variations

Abstract Exploring the watershed subdivision threshold in Soil and Water Assessment Tool model is crucial for accurate hillslope soil erosion estimation, which has been rarely explored. This study investigated impacts of watershed partitioning on simulation of hillslope sediment generation and its spatial variations, and determined a partition threshold using three newly proposed evaluation indicators (coefficient of spatial variations for hillslope sediment generation, change rate of hillslope sediment generation, and change rate of coefficient of spatial variations for hillslope sediment generation). The Xixi basin in the south-eastern coastal region of China was taken as an example, and was partitioned into eleven different watershed delineations. Effects of watershed subdivision on model parameter aggregation and areal distribution of hydrological response units were analyzed. The results indicated that (1) the previous method revealing the effects of watershed subdivision on hillslope sediment generation, which was only based on watershed outlet data, and the partition threshold determined by the method, were unreliable. (2) Hillslope sediment generation was seriously affected by watershed subdivision levels, increasing the number of sub-watersheds would decrease the modelled amount of hillslope sediment generation and increase its spatial variations. The partition threshold for the average sub-watershed area was 1.6% of the total watershed area and the number of sub-watersheds was 61 as determined from our new indicators, which resulted in stable amount of hillslope sediment generation and its spatial distribution, thus, the hillslope sediment generation could be adequately simulated by this method. (3) The hydrological response unit area, which was strongly related to the change in hillslope sediment generation, was very sensitive to watershed subdivision until the level of watershed subdivision approached the threshold.

Long-Term Trends in the Probability of Different Grades of Haze Days in China from 1960 to 2013

The number of haze days and daily visibility data for 543 stations in China were used to define the probabilities of four grades of haze days: slight haze (SLH) days; light haze (LIH) days; moderate haze (MOH) days; and severe haze (SEH) days. The change trends of the four grades of haze were investigated and the following results were obtained. The highest probability was obtained for SLH days (95.138%), which showed a decreasing trend over the last 54 years with the fastest rate of decrease of?0.903% · (10 years)?1 and a trend coefficient of?0.699, passing the 99.9% confidence level. The probabilities of LIH and MOH days increased steadily, whereas the probability of SEH days showed a slight downward trend during that period. The increasing probability of SLH days was mainly distributed to the east of 105°E and the south of 42°N and the highest value of the trend coefficient was located in the Pearl River Delta and Yangtze River Delta regions. The increasing probability of LIH days was mainly distributed in eastern China and the southeastern coastal region. The probabilities of MOH and SEH days was similar to the probability of LIH days. An analysis of the four grades of haze days in cities with different sizes suggested that the probability of SLH days in large cities and medium cities clearly decreased during the last 54 years. However, the probabilities of LIH days was < 10% and increased steadily. The probability of MOH days showed a clear interdecadal fluctuation and the probability of SEH days showed a weak upward trend. The probability of SLH days in small cities within 0.8° of large or medium cities decreased steadily, but the probability of LIH and MOH days clearly increased, which might be attributed to the impact of large and medium cities. The probability of SLH days in small cities >1.5° from a large or medium city showed an increasing trend and reached 100% after 1990; the probability of the other three grades was small and decreased significantly.

Spatiotemporal Variations of Precipitation in Bangladesh Revealed by Nationwide Rain Gauge Data

Bangladesh is under the strong influence of the South Asian monsoon. Extensive damages caused by frequent severe flood events in this country call for a study of nationwide precipitation climatology. Here, we examine spatiotemporal variations of precipitation in Bangladesh using rain gauge data at 35 stations for the period 2003–2016. The annual precipitation amount in Bangladesh is 2263 mm, and it shows large spatial variations. The annual precipitation amount is large in the southeastern coastal region of the country and the region close to the Meghalaya Plateau, and it is small in the west central region. 17% and 73% of the annual precipitation amount are observed in the pre-monsoon season (March to May) and monsoon season (June to September), respectively. The pattern of the diurnal variation of precipitation differs depending on regions of Bangladesh. In the northern region of the country, the precipitation maximum occurs in the late night to early morning in both the pre-monsoon and monsoon seasons. The late night to early morning maximum of precipitation is associated with the large horizontal convergence of low-level water vapor flux. The Himalaya Mountains and the Meghalaya Plateau together with more nighttime moisture transport due to the strengthened nighttime low-level wind seem to play roles in enhancing nighttime precipitation. In the southwestern region of the country, the precipitation maximum is observed in the early evening in the pre-monsoon season, which is associated with the large convective instability in the afternoon, and it is observed in the early afternoon in the monsoon season. In the southeastern region of the country, the diurnal variability of precipitation is smallest in the pre-monsoon season compared with other regions of the country in the pre-monsoon and monsoon seasons and the precipitation maximum occurs in the late night to early morning in the monsoon season.

Evaluation of the genetic diversity of six Chinese indigenous chickens.

ObjectiveThe extensive breeding of commercial chickens has led to a sharp decrease in the resources of many indigenous chickens, especially the indigenous chickens in the southeastern coastal region, which are on the verge of extinction, and the indigenous chickens in the northwestern region of China, which are also at risk. However, there are few reports on the evaluation of genetic diversity and conservation of genetic resources of indigenous chickens in remote areas in the Northwest of China.MethodsIn the present study, the genetic diversity and phylogenetic relationship of six indigenous chickens from different regions were studied based on variation in mitochondrial DNA control region (D-loop), and the degree of introgression from commercial breeds into these chickens was determined by the amount of haplotype sharing between indigenous and commercial breeds.ResultsTwenty-five polymorphic sites and 25 haplotypes were detected in 206 individuals. Principal component analysis showed that the Jingning chicken had the highest genetic diversity among the six indigenous chickens. According to the degree of introgression, the six indigenous breeds may be involved in haplotype sharing with commercial breeds, and the introgression from commercial chickens into the Haidong chicken is the most serious.ConclusionThe genetic uniqueness of indigenous chickens has been eroded, so it is necessary to consider the protection of their genetic resources. Phylogenetic analysis suggests that the six indigenous chickens have two major matrilineal origins: one from Yunnan or its surrounding areas in China and the other from the Indian subcontinent.

DNA analysis of elasmobranch products originating from Bangladesh reveals unregulated elasmobranch fishery and trade on species of global conservation concern.

Trade involving elasmobranch products in Bangladesh is a four-decade-long practice in large scale and there is little understanding of its impact on species composition, population, and subsequent conservation. Capacity for monitoring and identification is lacking in landing and shark processing centres. A rapid survey and collection of tissue samples were performed in three landings and nine shark processing centres between 2016 and 2017 in the south-eastern coastal region of Bangladesh. Sequencing for a 707-bp fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene was used to assess the taxonomic status and species composition from 71 elasmobranch tissue samples collected from the shark processing centre only. Good quality COI sequences were obtained for 34 specimens representing 21 species—the majority of which are threatened with extinction. A total of ten species of sharks (Carcharhinus brevipinna, C. amboinensis, C. leucas, C. sorrah, C. amblyrhynchoides, Chiloscyllium burmensis, Galeocerdo cuvier, Rhincodon typus, Scoliodon laticaudus, and Sphyrna lewini), eleven species of rays (Aetomylaeus maculatus, Gymnura poecilura, Mobula mobular, M. kuhlii, Neotrygon indica, Pateobatis uarnacoides, Rhinoptera javanica, and R. jayakari), including three species of guitarfish (Glaucostegus granulatus, G. obtusus, and G. typus), were identified. Four species (14.7% of samples) were found to be listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in Appendix II. Sixteen species (59% of the specimens) were threatened with extinction according to IUCN Red List, whereas 41% were data deficient or not assessed. The results have important implications for the management of regional fisheries and the conservation of elasmobranchs as they 1) represent a preliminary understanding of elasmobranch diversity in trade; 2) depict a lack of awareness and monitoring; and 3) demonstrate a need for urgent monitoring and regulation of elasmobranch trade in Bangladesh.

How does tolerance affect urban innovative capacities in China?

AbstractThis study investigated how urban cultural and economic tolerance affects urban innovative capacities based on China's prefecture‐level cities. Several tolerance indices, including ratios of migrants, rental housing, gay people, and private economies were introduced and the cities’ tolerance scores were measured using factor analysis. The results show that cities with higher cultural and economical tolerant scores were agglomerated in three metropolitan areas in China's southeastern coastal region. The spatial regression model demonstrates that urban cultural and economic tolerance increases urban innovation output and promotes innovation capacities. We also introduced the crime rate as an instrumental variable and found that the effect of tolerance on innovation remains robust. Our study suggests it is important for the Chinese government to establish an open and tolerant environment to attract migrants, creative artists, and entrepreneurs to foster urban vitality and improve urban innovative capacities.

The coastal evacuation of Zhangpu County in early Qing: Borders, shifting zones, and social change as seen in forts and fortified villages

Qianhai, the early Qing order that forced people in southeast coast to evacuate the coast to a distance of ten to eighteen miles inland in order to eliminate anti-Qing activities, is an excellent topic through which to examine the formation of the border in Han local society. The development of regional studies during the past 20 years encourages us to both refine our local case studies and map the wider picture. The story of social transformation in Zhangpu County during the Ming-Qing transition provides a perfect case to discuss how the coastal evacuation policy was implemented in local society. It can also promote our understanding of multiple histories. First, the lineage story of the coastal evacuation can be described in greater detail. Even in a single county, there was no standard evacuation distance. Local officials relied on mountainous terrain and existing forts and fortified villages to form a line of defense that determined the scope of the evacuation. Second, the social landscape in the communities of the county demonstrates the rise and decline of local power structures. Many of the most influential and deep-rooted lineages were badly weakened by the time they returned home after the evacuation order was rescinded. On the basis of the ebb and flow of local elites, the Qing state began to regulate households more closely, and state power thus penetrated to the local level. The household registers of Zhangpu were established based on the specific historical context of the county, but the process shared with the rest of the southeastern coastal region a pattern whereby pacification and local Defense shaped state penetration. Even in a supposedly “traditional” Han region, the empire needed to handle the problems of the border and social complexity, just as it did in “non-Han” areas. This illustrates the process of late imperial state formation in practice.

Evaluation of the Supply-Side Efficiency of China’s Real Estate Market: A Data Envelopment Analysis

With the gradual slowdown of economic growth in China, the Chinese government proposed the task of supply-side reform. As a vital part of China’s economy, supply-side reform in the real estate market is particularly important. Using 29 provinces (divided into seven regions) in China as examples, this paper empirically studies the supply-side efficiency of China’s real estate market using data envelopment analysis (DEA) for the period of 2012–2016. The results showed that (1) the main problem of low supply-side efficiency in the Chinese real estate market is the low land-use efficiency, with a redundancy rate of 60.59% in China’s land space pending development; and (2) China’s southeastern coastal region, with the highest supply-side efficiency in the real estate market, reached a level of decreasing returns, and it is no longer appropriate to increase the supply-side efficiency by expanding the market scale. However, the southwestern region and the Yangtze River’s middle region, which both have lower supply-side efficiency, can improve the land utilization ratio and technology investment to change the current situations. The study results suggest (1) improving the construction land development efficiency by adjusting the input and output of the market according to the specific conditions of each city, and (2) promoting the supply-side reform of China’s real estate market and sustainable urbanization.

Phylogeographic distribution of Asperisporium caricae isolates in brazilian southeastern and northeastern coastal regions

Phylogeographic distribution of Asperisporium caricae isolates in brazilian southeastern and northeastern coastal regions

Analysis of Aquifer Pumping Test Data to Determine Deep Groundwater Security in Southeastern Bangladesh

In southeastern Bangladesh, where water quality in the upper aquifers is a serious constraint, future development will likely be confined to deep fresh groundwater. Owing to the importance and pervasive use of deep groundwater, the sustainability of water use has received extensive attention. However, excessive extraction from deep aquifers may pose a threat to the storage as well as the quality of water due to the high susceptibility to salinization and arsenic contamination from upper aquifers. Hence, determining the extension of aquifer units and the characterizing aquifer sediments are very important to ensure sustainable development and management of limited fresh groundwater resources. The study area extends over six districts of the southeastern coastal region of Bangladesh. In order to assess and monitor deep fresh groundwater potential in the study area, aquifer pumping tests were performed at six locations with up to 72 h of constant-discharge prior to recovery. Different methods were used to analyze the drawdown and recovery data considering aquifers as confined or leaky-confined. Based on transmissivity values it was found that the studied deep aquifers have moderate to high potential for potable water supply. However, this deep fresh groundwater may not be safe for a longer period where upper aquifer units contain saline groundwater and where there is no significant aquitard encountered above or below the deep aquifer. Irrigation extraction of the deep groundwater is not recommended.

Air transportation in China: Temporal and spatial evolution and development forecasts

This paper analyses the features and dynamic changes of the spatial layout of air transportation utilization among different provinces in China. It makes use of data for the airport throughput and socio-economic development of every province throughout the country in the years 2006 and 2015, and employs airport passenger and cargo throughput per capita and per unit of GDP as measures of regional air transportation utilization, which is significant for refining indicators of regional air transportation scale and comparing against them. It also analyzes the spatial differences of coupling between the regional air transportation utilization indicators and the key influencing factors on regional air transportation demand and utilization, which include per capita GDP, urbanization rate, and population density. Based on these key influencing factors, it establishes a multiple linear regression model to conduct forecasting of each province’s future airport passenger and cargo throughput as well as throughput growth rates. The findings of the study are as follows: (1) Between 2006 and 2015, every province throughout the country showed a trend of year on year growth in their airport passenger and cargo throughput per capita. Throughput per capita grew fastest in Hebei, with a rise of 780%, and slowest in Beijing, with a rise of 38%. Throughput per capita was relatively high in western and southeastern coastal regions, and relatively low in northern and central regions. Airport passenger and cargo throughput per unit of GDP showed growth in provinces with relatively slow economic development, and showed negative growth in provinces with relatively rapid economic development. Throughput per unit of GDP grew fastest in Hebei, rising 265% between 2006 and 2015, and Hunan had the fastest negative growth, with a fall of 44% in the same period. Southwestern regions had relatively high throughput per unit of GDP, while in central, northern, and northeastern regions it was relatively low. (2) Strong correlation exists between airport passenger and cargo throughput per capita and per capita GDP, urbanization rate, and population density. Throughput per capita has positive correlation with per capita GDP and urbanization rate in all regions, and positive correlation with population density in most regions. Meanwhile, there is weak correlation between airport passenger and cargo throughput per unit of GDP and per capita GDP, urbanization rate, and population density, with positive correlation in some regions and negative correlation in others. (3) Between 2015 and 2025, it is estimated that all provinces experience a trend of rapid growth in their airport passenger and cargo throughput. Inner Mongolia and Hebei will see the fastest growth, rising 221% and 155%, respectively, while Yunnan, Sichuan, and Hubei will see the slowest growth, with increases of 62%, 63%, and 65%, respectively.

Geochemistry of the dissolved loads during high-flow season of rivers in the southeastern coastal region of China: anthropogenic impact on chemical weathering and carbon sequestration

Abstract. The southeastern coastal region is one of the most developed and populated areas in China. Meanwhile, it has been severely impacted by acid rain over many years. The chemical compositions and carbon isotope compositions of dissolved inorganic carbon (δ13CDIC) in river water in the high-flow season were investigated to estimate the chemical weathering and associated atmospheric CO2 consumption rates as well as the acid-deposition disturbance. Mass balance calculations indicated that the dissolved loads of major rivers in the Southeast Coastal River Basin (SECRB) were contributed to by atmospheric (14.3 %, 6.6 %–23.4 %), anthropogenic (15.7 %, 0 %–41.1 %), silicate weathering (39.5 %, 17.8 %–74.0 %) and carbonate weathering inputs (30.6 %, 3.9 %–62.0 %). The silicate and carbonate chemical weathering rates for these river watersheds were 14.2–35.8 and 1.8–52.1 t km−2 a−1, respectively. The associated mean CO2 consumption rate by silicate weathering for the whole SECRB was 191×103 mol km−2 a−1. The chemical and δ13CDIC evidence indicated that sulfuric and nitric acid (mainly from acid deposition) were significantly involved in the chemical weathering of rocks. There was an overestimation of CO2 consumption at 0.19×1012 g C a−1 if sulfuric and nitric acid were ignored, which accounted for about 33.6 % of the total CO2 consumption by silicate weathering in the SECRB. This study quantitatively highlights the role of acid deposition in chemical weathering, suggesting that the anthropogenic impact should be seriously considered in estimations of chemical weathering and associated CO2 consumption.

Simulated Soil Organic Carbon Response to Tillage, Yield, and Climate Change in the Southeastern Coastal Plains.

Intensive tillage, low-residue crops, and a warm, humid climate have contributed to soil organic carbon (SOC) loss in the southeastern Coastal Plains region. Conservation (CnT) tillage and winter cover cropping are current management practices to rebuild SOC; however, there is sparse long-term field data showing how these management practices perform under variable climate conditions. The objectives of this study were to use CQESTR, a process-based C model, to simulate SOC in the top 15 cm of a loamy sand soil (fine-loamy, kaolinitic, thermic Typic Kandiudult) under conventional (CvT) or CnT tillage to elucidate the impact of projected climate change and crop yields on SOC relative to management and recommend the best agriculture management to increase SOC. Conservation tillage was predicted to increase SOC by 0.10 to 0.64 Mg C ha for six of eight crop rotations compared with CvT by 2033. The addition of a winter crop [rye ( L.) or winter wheat ( L.)] to a corn ( L.)-cotton ( L.) or corn-soybean [ (L.) Merr.] rotation increased SOC by 1.47 to 2.55 Mg C ha. A continued increase in crop yields following historical trends could increase SOC by 0.28 Mg C ha, whereas climate change is unlikely to have a significant impact on SOC except in the corn-cotton or corn-soybean rotations where SOC decreased up to 0.15 Mg C ha by 2033. The adoption of CnT and cover crop management with high-residue-producing corn will likely increase SOC accretion in loamy sand soils. Simulation results indicate that soil C saturation may be reached in high-residue rotations, and increasing SOC deeper in the soil profile will be required for long-term SOC accretion beyond 2030.