South China Region Research Articles

Abnormal Change in Spring Snowmelt Over Eurasia and Its Linkage to the East Asian Summer Monsoon: The Hydrological Effect of Snow Cover

In this study, the relationship between Eurasian spring snowmelt and the East Asian summer monsoon (EASM), and its related mechanisms are investigated using observational and reanalysis data. Our analyses reveal that the interannual change of spring snowmelt over Eurasia is strongly linked to the EASM circulation variation and its corresponding summer precipitation in China. It is noteworthy that soil moisture anomaly caused by the snow hydrological effect (i.e., snowmelt) plays a bridging role in connecting the Eurasian snow cover and the EASM. The results show that increased spring snowmelt over Siberia induces anomalously higher soil moisture from spring to the following summer, thus continuously lowering the local temperature. Such a cooling effect leads to a weakened meridional temperature gradient and a decreased baroclinicity between north Eurasia and the Arctic Ocean. Consequently, the variation in atmospheric baroclinicity induced by the nonuniform heating of land surface exerts a significant impact on the synoptic eddy. The eddy forcing gives a positive feedback on intensification of the wave train over north Eurasia. Finally, the atmospheric circulation responses weaken the EASM and influence summer precipitation over China, producing excessive precipitation over most regions of South China and deficient rainfall over Northeast and North China. Our study emphasizes the hydrological effect of the sub-seasonal change of spring snow cover over Siberia, which has a significant linkage to the variation of the EASM intensity. The resultant changes in the EASM lead to an abnormal meridional dipole pattern of summer precipitation over China. These findings will contribute to the seasonal prediction of monsoon precipitation.

New Algorithm of Clay CEC for Soils in Tropical and Subtropical Regions of South China

Clay CEC is one of identification indexes of the LAC-ferric horizon which is the diagnostic horizon of ferrosols in Chinese Soil Taxonomy, and it is defined as soil CEC × 1000/clay content, rather than the measured CEC of the extracted clays; however, such a calculation method would definitely lead to an overestimation of clay CEC because it doesn’t remove the contribution to soil CEC from other soil parameters. In this study, the physiochemical data of the subhorizons from 82 soil series in the tropical and subtropical regions in south China were used, clay CEC was calculated according to the current formula and measured after clays being extracted, the measured and calculated clay CEC were compared, the influencing factors were analyzed for their difference, and the new algorithms were established for clay CEC. The results showed that the measured clay CEC was 21.86% - 99.53% with a mean of 66.88% of the calculated one (significantly lower at p 2O3 (the contribution was 52.51% and 25.36%, respectively). By comparison of established regression models of clay CEC with other soil parameters, two new algorithms were recommended for clay CEC as follows: 1) Clay CEC = 10.32 − 0.14pH − 0.05OM − 0.11Fe2O3 + 0.01Silt − 0.01Clay + 1.17CECsoil, R2 = 0.705, P −3.40 + 0.01Sand + 0.02Silt + 1.05CECsoil, R2 = 0.589, P < 0.01).

Comparison of Two Different Calculation Methods of Fractional Vegetation Cover

Fractional Vegetation Cover (FVC) is an important parameter for soil erosion equation. The Fractional Vegetation Cover of typical soil erosion county in red soil region of South China was calculated by parameter revision method (PRM) and fusion method (FM).The results of the two methods were compared from two parts of FVC level and 24 half-months FVC. The results show that the FVC level calculated by PRM was concentrated in high level, and that calculated by FM is mainly in medium-high level and high level. The time variation of FVC in 24 half-months calculated by the two methods was the same, but the majority of FVC value calculated by PRM was higher than that calculated by FM. It is better to choose FM method to calculate FVC in estimating soil erosion.

Investigation of Aerosol Direct Effect over China under El Niño and Its Spatial Distribution Using WRF-Chem

With rapid economic development and urbanization, the air pollution problem over China has drawn great attention. To explore the aerosol direct effect (ADE) over China, two simulations were conducted using WRF-Chem V3.5.1 in the summer of 2015. One was a control run (CTL) including aerosol effect and related physical and chemical processes, and the other one was a sensitivity simulation (SEN), the same as CTL except that aerosol-radiation interactions were turned off. The differences between two tests were analyzed, in particular over regions in South China (SC) and East China (EC). Results showed the following. (1) The large-scale circulation showed a strong El Niño signal, associated with cooling and wet anomalies over EC, while warming and dry anomalies over EC. (2) Due to ADE, there was a significant decrease in precipitation and an increase in AOD over SC and EC, albeit with different mechanisms. (3) In SC, ADE cooled the region reinforcing the El Niño impact and suppressing water vapor fluxes, which led to a more stable atmosphere and weakened water cycle. In EC, ADE caused vertical circulation anomalies opposing the El Niño impact. (4) ADE showed obvious land-sea difference in precipitation and shortwave radiation.

The impact of climate change on the distribution of Castanopsis (Fagaceae) species in south China and Indo-China region

Forests are already and will continue to experience a rapid and extreme change in climatic conditions in the future. The distributions of forests are expected to shift northward and to higher altitudes based on the results of species distribution modelling (SDM). Although SDM is criticized for lack of biotic interactions and natural migration mechanisms, it is still an important tool for understanding the influence of climate change on forest distributions at a landscape scale. We hypothesize that based on extant forest cover, distribution of protected areas and understanding on seed dispersal mechanisms, the suitable range of forest tree species will decline, and certain species might be driven to extinction in the absence of suitable space for migrations in a rapidly changing climate. To assess this scenario, we modelled the current and future potential distribution of 18 Castanopsis species in Asia using MaxENT. Mild (RCP-4.5) and severe (RCP-8.5) climate change scenarios from 17 climate change models were assessed. Three groups of current Castanopsis distribution were identified and they responded differently under climate change. One-third of the species will experience potential range reductions while two-third will have potential range expansions. However, when we overlaid the results with forest cover and protected area coverage, range expansions are unlikely to happen due to fragmented forest cover and lack of efficient seed dispersal mechanisms. Natural species migrations and local adaptation are not likely to happen for Castanopsis and therefore immediate adaptive strategies should be considered in forest management. This situation was particularly severe in the marginal tropical zones across coastal South China and the Northern Indo-China region.

Biodiversity changes of the Ordovician trilobites in the middle Yangtze region of South China

The biodiversity changes of trilobites in the middle Yangtze region of South China in the Great Ordovician Biodiversification Event and the end-Ordovician mass extinction have been analysed. The Ordovician trilobites in this region originated in the early Tremadocian and radiated from the late Floian to the early Katian. Two peaks of diversity appeared in the late Dapingian to the early Darriwilian and the early Katian. The extinction occurred in the late Katian, followed by a survival period in the Hirnantian. The Whiterock fauna began to surpass the Ibex fauna during the early Katian and were dominant by the late Katian to the Hirnantian, indicating that Cambrian Evolutionary Fauna was gradually replaced. The study once again confirms the view that the effects of factors such as sea level, climate, oxygen content, nutrient supply, and tectogenesis differ temporally and to different degrees in different regions, resulting in differences in the vertical sequence and horizontal combination of ecosystems, which is the reason for the different evolution patterns of Ordovician trilobites in different regions.

Decreasing Cropping Intensity Dominated the Negative Trend of Cropland Productivity in Southern China in 2000–2015

As the country with the highest food consumption in the world, China’s food security has been drawing global attention. The inter-annual variability of agricultural productivity and its predominant driving factors play important roles in food security and sustainable agricultural development. Here, we used gross primary productivity (GPP), which was simulated using the vegetation photosynthesis model (VPM), to quantify the spatial-temporal heterogeneity of cropland productivity from 2000 to 2015. The results showed that the cropland GPP significantly increased in northern China and markedly decreased in southern China. Socioeconomic and climatic factors jointly promoted a rise in GPP in the Northeast region, Inner Mongolia and Great Wall region, Huang-Huai-Hai region, and Loess Plateau region, with contribution rates of 93.6%, 67.9%, 73.8%, and 78.1%, respectively. The negative GPP trend in southern China was mainly attributed to the decreasing cropping intensity, with direct contributions of 54.1%, 53.9%, and 48.7% for the Yangtze River region, Southwest region, and South China region, respectively. Despite the decline in cropping intensity, the policies of Cang-liang-yu-di and Cang-liang-yu-ji can help in ensuring food security in China.

Spatial‐Temporal Distribution, Geological Characteristics and Ore‐Formation Controlling Factors of Major Types of Rare Metal Mineral Deposits in China

AbstractRare metals including Lithium (Li), Beryllium (Be), Rubidium (Rb), Cesium (Cs), Zirconium (Zr), Hafnium (Hf), Niobium (Nb), Tantalum (Ta), Tungsten (W) and Tin (Sn) are important critical mineral resources. In China, rare metal mineral deposits are spatially distributed mainly in the Altay and Southern Great Xingán Range regions in the Central Asian orogenic belt; in the Middle Qilian, South Qinling and East Qinling mountains regions in the Qilian–Qinling–Dabie orogenic belt; in the Western Sichuan and Bailongshan–Dahongliutan regions in the Kunlun–Songpan–Garze orogenic belt, and in the Northeastern Jiangxi, Northwestern Jiangxi, and Southern Hunan regions in South China. Major ore‐forming epochs include Indosinian (mostly 200–240 Ma, in particular in western China) and the Yanshanian (mostly 120–160 Ma, in particular in South China). In addition, Bayan Obo, Inner Mongolia, northeastern China, with a complex formation history, hosts the largest REE and Nb deposits in China. There are six major rare metal mineral deposit types in China: Highly fractionated granite; Pegmatite; Alkaline granite; Carbonatite and alkaline rock; Volcanic; and Hydrothermal types. Two further types, namely the Leptynite type and Breccia pipe type, have recently been discovered in China, and are represented by the Yushishan Nb–Ta– (Zr–Hf–REE) and the Weilasituo Li–Rb–Sn–W–Zn–Pb deposits. Several most important controlling factors for rare metal mineral deposits are discussed, including geochemical behaviors and sources of the rare metals, highly evolved magmatic fractionation, and structural controls such as the metamorphic core complex setting, with a revised conceptual model for the latter.

Quantitatively evaluate the effects of precipitation and vegetation variation to flood under the condition of single rainstorm: A case study of Pengchongjian small watershed, Jiangxi, China

Precipitation and vegetation are two key factors affecting floods in the watershed. Quantitative evaluating their contribution to flood is of great scientific significance to vegetation construction and water resources management. Based on the geographic information data and hydrometeorological data from 1983 to 2014, we analyzed the characteristics of rainstorm and flood in Pengchongjian small watershed in red soil region of South China by Mann-Kendall test method, cumulative anomaly method and HEC-HMS model, and quantitatively evaluated the contribution rate of precipitation and vegetation variation to flood. The results showed that the rainstorm volume and total flood volume in Pengchongjian small watershed from 1983 to 2014 showed a non-significant upward/downward trend, respectively. HEC-HMS model had good simulation effect on single rainstorm flood, with the evaluation results being within the error range. The contribution rates of precipitation and vegetation variation of different rainstorm floods were different with respect to the total flood volume or to the peak flow. The average contribution rate of precipitation and vegetation variation to the total flood volume was 66.5% and 33.5%, while to the peak flow was 58.9% and 41.1%, respectively. Our results could provide scientific basis for flood evaluation, vegetation construction and comprehensive control of soil erosion in small watershed.

Evolution of Ordovician cephalopod diversity in the Middle Yangtze region of South China and its controlling factors

The evolution of Ordovician cephalopod diversity in the Middle Yangtze region of South China has been analysed. The cephalopods in this region appeared in the earliest Tremadocian, radiated in the Early–Middle Floian and Middle Ordovician, and went through an extinction period during the Late Katian and Hirnantian. The composition of the cephalopod fauna underwent major changes in the Late Floian. Specifically, all the genera occurring in previous time periods disappeared and Tarphyceratida, Actinoceratida, and Orthoceratida appeared and prospered. Differences in the evolution of cephalopod diversity between Middle Yangtze region and other regions were detected, which were caused by differences in the vertical sequence and horizontal combination of controlling factors. Changes in living environments and the distribution of food resources prompted Ordovician cephalopods to evolve adaptations for life in deep-water environments. The low-temperature ocean current near the western coastline of Gondwana created favourable conditions for the Floian peak of cephalopod diversity in South China. The tectonic movements, high rainfall, and relatively closed environment of the Middle Yangtze region led to rapid sea level rise and hindered cephalopod diversification. These processes explain the low cephalopod diversity in the Late Ordovician and the absence of the previously reported Katian radiation peak in this region.

A combined Terra and Aqua MODIS land surface temperature and meteorological station data product for China from 2003 to 2017

Abstract. Land surface temperature (LST) is a key variable for high temperature and drought monitoring and climate and ecological environment research. Due to the sparse distribution of ground observation stations, thermal infrared remote sensing technology has become an important means of quickly obtaining ground temperature over large areas. However, there are many missing and low-quality values in satellite-based LST data because clouds cover more than 60 % of the global surface every day. This article presents a unique LST dataset with a monthly temporal resolution for China from 2003 to 2017 that makes full use of the advantages of MODIS data and meteorological station data to overcome the defects of cloud influence via a reconstruction model. We specifically describe the reconstruction model, which uses a combination of MODIS daily data, monthly data and meteorological station data to reconstruct the LST in areas with cloud coverage and for grid cells with elevated LST error, and the data performance is then further improved by establishing a regression analysis model. The validation indicates that the new LST dataset is highly consistent with in situ observations. For the six natural subregions with different climatic conditions in China, verification using ground observation data shows that the root mean square error (RMSE) ranges from 1.24 to 1.58 ∘C, the mean absolute error (MAE) varies from 1.23 to 1.37 ∘C and the Pearson coefficient (R2) ranges from 0.93 to 0.99. The new dataset adequately captures the spatiotemporal variations in LST at annual, seasonal and monthly scales. From 2003 to 2017, the overall annual mean LST in China showed a weak increase. Moreover, the positive trend was remarkably unevenly distributed across China. The most significant warming occurred in the central and western areas of the Inner Mongolia Plateau in the Northwest Region, and the average annual temperature change is greater than 0.1 K (R&gt;0.71, P&lt;0.05), and a strong negative trend was observed in some parts of the Northeast Region and South China Region. Seasonally, there was significant warming in western China in winter, which was most pronounced in December. The reconstructed dataset exhibits significant improvements and can be used for the spatiotemporal evaluation of LST in high-temperature and drought-monitoring studies. The data are available through Zenodo at https://doi.org/10.5281/zenodo.3528024 (Zhao et al., 2019).

Ozone pollution mitigation in guangxi (south China) driven by meteorology and anthropogenic emissions during the COVID-19 lockdown.

With the implementation of COVID-19 restrictions and consequent improvement in air quality due to the nationwide lockdown, ozone (O3) pollution was generally amplified in China. However, the O3 levels throughout the Guangxi region of South China showed a clear downward trend during the lockdown. To better understand this unusual phenomenon, we investigated the characteristics of conventional pollutants, the influence of meteorological and anthropogenic factors quantified by a multiple linear regression (MLR) model, and the impact of local sources and long-range transport based on a continuous emission monitoring system (CEMS) and the HYSPLIT model. Results show that in Guangxi, the conventional pollutants generally declined during the COVID-19 lockdown period (January 24 to February 9, 2020) compared with their concentrations during 2016–2019, while O3 gradually increased during the resumption (10 February to April 2020) and full operation periods (May and June 2020). Focusing on Beihai, a typical Guangxi region city, the correlations between the daily O3 concentrations and six meteorological parameters (wind speed, visibility, temperature, humidity, precipitation, and atmospheric pressure) and their corresponding regression coefficients indicate that meteorological conditions were generally conducive to O3 pollution mitigation during the lockdown. A 7.84 μg/m3 drop in O3 concentration was driven by meteorology, with other decreases (4.11 μg/m3) explained by reduced anthropogenic emissions of O3 precursors. Taken together, the lower NO2/SO2 ratios (1.25–2.33) and consistencies between real-time monitored primary emissions and ambient concentrations suggest that, with the closure of small-scale industries, residual industrial emissions have become dominant contributors to local primary pollutants. Backward trajectory cluster analyses show that the slump of O3 concentrations in Southern Guangxi could be partly attributed to clean air mass transfer (24–58%) from the South China Sea. Overall, the synergistic effects of the COVID-19 lockdown and meteorological factors intensified O3 reduction in the Guangxi region of South China.

Reconstructing the Climatic-Oceanic Environment and Exploring the Enrichment Mechanism of Organic Matter in the Black Shale across the Late Ordovician-Early Silurian Transition on the Upper Yangtze Platform Using Geochemical Proxies.

Black shale deposited in the transitional period from the Late Ordovician to Early Silurian is the most important source rock and shale gas reservoir in the Yangtze region of South China. However, the source of these sediments is still controversial. In this paper, the changes in total organic carbon (TOC), total sulfur (TS), organic carbon isotopes (δ13Corg), biomarkers, trace elements, and rare earth elements in the Ordovician–Silurian boundary strata of the XK-1 well in northern Guizhou Province, South China, have been systematically studied. The paleoenvironmental and paleoclimatic conditions of the Late Ordovician to Early Silurian and their relationship with organic matter enrichment in the Upper Yangtze Platform have been reconstructed. The distribution of biomarkers reflects that the Late Ordovician–Early Silurian shale was deposited in the marine environment and was highly contributed by marine plankton/algae and microorganisms. Paleoclimatic proxies (Sr/Cu, δ13Corg) show that the global climate system experienced significant changes from a warm-humid climate to a brief period of cold-dry climate and then back to a warm-humid climate during the Ordovician–Silurian transition. This warm and humid climate condition helps to improve the biological productivity within the photic zone of the water column during deposition. In addition, the low oxygen (reduction) conditions during the deposition of the Late Ordovician–Early Silurian deposits are characterized by low Pr/Ph values (0.39–0.79) and relatively high elemental ratios of V/Ni (1.40–5.77) and V/(V + Ni) (0.58–0.85). This paleoredox condition contributes to the preservation of organic matter during deposition of the Late Ordovician–Early Silurian deposits. Therefore, it is demonstrated that the climate and ocean fluctuated greatly during the Late Ordovician–Early Silurian transition period, and this fluctuation provided necessary control factors for marine anoxia, primary productivity, and subsequent organic-rich black shale deposition in the Upper Yangtze region during the Late Ordovician and Early Silurian intervals.

Karst ecosystem and environment: Characteristics, evolution processes, and sustainable development

The studies in this Special Issue addressed environmental and ecological issues at the karst areas in the Southwest China. The contributions from these studies indicated that some active agricultural practices that were carried out in recent years reduced environmental risk and increased economic benefits at the karst areas. The results of ecosystem service value estimates in recent years showed improvements of ecosystem and environment in karst areas of China. Local farmers and government have realized the importance of protection of environment and ecosystem than before, which might promote to seek sustainable development goal in future. These studies have delivered new knowledgement that addressed the challenges of facilitating environmental sustainability with agricultural development in the karst region of South China. Meanwhile, further research should deepen science advances to improve the resilience of soil and water resources to agricultural practices in the fragile karst ecosystem.

Fragmentation of South China from greater India during the Rodinia-Gondwana transition

AbstractLate Tonian to Cambrian sedimentary sequences in northwestern India and South China provide vital evidence for modeling their paleogeographic linkage, including their juxtaposition and subsequent separation during the transition from the Rodinia to the Gondwana supercontinents. Similarities in lithostratigraphy and detrital zircon U-Pb-Hf-O isotopic characteristics in the late Tonian sedimentary units from both regions underline a common provenance. A substantial decrease in zircon δ18O values from super- to sub-mantle compositions and simultaneous increase in the zircon εHf(t) values in South China and northwestern India for the 800–700 Ma time window suggest a common Neoproterozoic extensional magmatic event, corresponding with the Rodinia breakup. A distinct change in sedimentary provenance is noted during the Cryogenian period. Sedimentation along the northwestern margin of India for the remainder of the Neoproterozoic encompasses large volumes of clastic detritus dominated by old zircon ages, derived inboard from the Indian craton. In contrast, contemporaneous sedimentary units in the Yangtze region of South China are dominated by Neoproterozoic zircons. The detrital zircon age data underline a close paleogeographic linkage between northwestern India and South China (Yangtze and Cathaysia regions) in the Rodinia supercontinent configuration and argue for their separation through continental rifting during the Cryogenian. Northwestern India developed into a passive margin, whereas the South China block partially rifted, rotated, and migrated dextrally along the Gondwana margin toward northeastern India and Western Australia, such that the Cathaysia block continued to receive detritus from Gondwana continental regions.

Ризики розвитку іржастих грибів (Puccinia graminis Pers.) на культивованих барбарисах (рід Berberis L.)

Formulation of the problem. Representatives of the genus Berberis L. (Berberidaceae Juss.) are extremely promising as valuable medicinal, melliferous, fruitful and also decorative shrubs. But rusty mushrooms (Puccinia graminis Pers.) are progressing, which are parasitizing on cereals. The danger forgrowing cereal crops, barberries have when some of their species are growing close to the field. The aim of the study was an estimation of risk of growth rusty mushroom on cultivated species of barberries, that gave a possibility to detect the most stable to such diseases species and to recommend them for using in decorative landscaping or in plantations of raw materials. 30 species of barberries, which arecultivating in botanical garden Yurii Fedkovych Chernivtsi National University, were exploring during 2014-2018. The growth of rusty mushrooms on barberries was studied by degree of affected leaves. The analysisof weather indicator from April-May confirmed dependence from their active germination taleotospores Puccinia graminis and formation of basidiyas with basidiospores by period of outsight. The intensity of affection barberries leaves by rusty mushrooms is comparatively not high and isn’t over 12-15 %. Also 8 species of barberries are detected as absolutely resistant against rusty mushrooms, so that there were no features of affection on them. If we compare these indicators with information about origin of separate species barberries, we can mark that the most resistant to rusty mushrooms are species, which are originate from South China (East Asian) region. Most of them didn’t have any features of affection by rusty mushrooms in all period of outsight at all (5 years). The biggest affection from rusty mushrooms was noticed in species of barberries which come from the Himalayas, Central Asia and Europe. Therefore, in planning barberries cultivations it is expedient to consider the origin of separate species and accordingly determine risks of their introduction in culture. We excreted 3 groups of species among barberries by degree of fortitude to rusty mushrooms: 1. Completely resistant species, which don’t affect by rusty mushrooms in different weather conditions: (B. beaniana, B. brachypoda, B. dasystachya, B. dielsiana, B. gagnepainii, B. gilgiana, B. holstii, B. thunbergii) – 8 species; 2. Relatively resistant species, the level of affection of rusty mushrooms not more than 10 % of leaf surface (B. аetnensis, B. аggregata, B. аngulosa, B. сircumserrata, B. lycium, B. oblonga, B. orthobotrys, B.spathulata) – 8 spesies; 3. Unstable to rusty mushrooms species in which the affection is more than 10% of leaf surface (B. аemulans, B. аlksuthiensis, B. аmurensis, B. аristata, B. сoreana, B. dielsiana, B. edgeworthiana, B. giraldii, B. integerrima, B. laxiflora, B. notabilis, B. regeliana, B. reticulata, B. vulgaris) – 14 species. As we can see from the table, the intensity of growth rusty mushrooms on the barberry’s leaves are changing the separate years. The literature confirms that the activity of dissemination taleotospores, development of mushroom hyphae with formation basidiyas and basidiospores, also dissemination the last one depends on weather conditions of April-May, that is the period when they are progressing and carrying by wind and insects affecting barberries leaves. We compared the indicators of affection leaves with average indicators of total average daily temperaturesand precipitations in April-May by the period of observation, and between them had been detected certain dependence. The degree of rusty mushroom growth on barberries leaves was detected proportional to dynamics of increase middle-daily temperatures of air and inversely proportional to increasing amount of precipitation at this period. The most dangerous for cereal fields are higher named completely resistant species barberries from the first group, which we can introduce in culture for different purpose: decorative landing, plantations of medical, nutritional or melliferous purpose. Some limitationsare expedient in planning cultures with groups of relatively resistant species (the second group), which don’t have to grow close to the cereal fields. In our opinion, the sufficient barrier for them can be a protective zone with woods 10-15 meters wide. At last, unstable to rusty mushrooms species of barberries (the third group), we can grow nearby the cereal fields just in forestry environment (woods and shrubs), which must be 50-100 m wide or to cultivate them where will be no growing cereals. In conclusion. Thereby, in terms of wet and warm climate in Chernivtsi region the cultivation of most barberries (16 species of the first and second group) don’t make any significant threat for growing cereals even when the last one are close to these cultures.

Tropical Cyclone Impacts on Cities: A Case of Hong Kong

The Pearl River Delta region in South China is known as a significant hotspot of tropical cyclone (TC) risk, which calls for an in-depth evaluation of TC damages and its determinants to support mitigation of associated impacts (e.g., loss of lives and infrastructure, and economic damages). Hence, in the context of TCs and cities, this study examines the historical impacts of TCs in Hong Kong and evaluates the association between economic losses and different TC hazards/parameters (i.e., wind, rainfall, and storm surge). An analysis of the reported TC-caused damages during 1988-2018 suggests a strong positive relationship between the normalized economic damages (Damage/GDP) and TC rainfall (p &lt; .001, R2 = 0.43). This relationship for TC wind (explained by the power dissipation index—PDI) is positively statistically significant (&gt;90% confidence) but insignificant for TC-induced storm surge. These results ascertain that among all three TC hazards, rainfall is the most significant factor for economic losses in Hong Kong followed by the PDI. However, it is further found that TC rainfall has significantly decreased (p &lt; .01), while PDI has increased (93% confidence) during 1988-2018. Hence, it is obvious that the increasing economic losses in Hong Kong cannot be associated with TC rainfall intensification as it has decreased while the damages are still increasing. The increasing PDI, population rise over the past few decades and growing number of buildings in Hong Kong to accommodate this population are likely the major reasons behind these increasing damages. However, further in-depth evaluations are recommended in this regard to improve our understanding regarding tropical cyclones and cities. This study further calls for such evaluations in other coastal cities to identify the city-specific significant determinants of TC-related damages in the context of supporting damage mitigation in the future.

Characteristics of extreme precipitation in South China during April–July for early rice season

Extreme precipitation has significant impacts on human society and agriculture development under global climate change as well as severe effects on rice development. However, little research has been done on the characteristics of extreme precipitation in different rice growth stages. Taking the South China region as a case study, the characteristics of extreme daily precipitation in the early rice season (April–July) from 1960 to 2009 were investigated by using percentile method. Results indicated that extreme precipitation threshold increases since the tillering stage, and there is big difference between the first and the rest growth stages. Extreme precipitation is serious in the eastern part than in the western part of South China during the seeding and tillering stage, and reverse since the booting stage. Frequency of extreme precipitation increases in recent decades after the booting stage. Finally, flood risk regions form more easily in the coastal cities and the western part of South China in the 1990s and 2000s since the tillering stage.

Early Paleozoic intracontinental granites in the Guangzhou region of South China: Partial melting of a metasediment-dominated crustal source

Whether the formation of early Paleozoic granites in the South China Block was related to intracontinental orogenic processes or oceanic subduction continues to be debated. Here, we present whole-rock major element, trace element, and SrNd isotopic data, as well as secondary ion mass spectrometry and laser ablation–inductively coupled plasma–mass spectrometry zircon UPb geochronological and HfO isotopic data, from biotite, two-mica, and muscovite granites in the Baiyunshan and Maofengshan areas of Guangzhou City, South China. Zircon UPb ages reveal that these rocks were formed during the early Paleozoic (446–438 Ma). These muscovite- and biotite-bearing granites have high SiO2 (69.0–80.4 wt%) and K2O (3.19–5.32 wt%) contents, and low MgO (0.46–1.17 wt%) contents. The granites are enriched in Rb, Th, U, and Pb, and depleted in Ba, Sr, Nb, and Ti. The Baiyunshan muscovite granites and Maofengshan biotite granites are slightly to moderately enriched in light rare-earth elements [LREEs; (La/Yb)CN = 2.27–15.1] with slight to pronounced negative Eu anomalies (Eu/Eu* = 0.27–0.72), whereas the Baiyunshan two-mica granites are significantly enriched in LREEs [(La/Yb)CN = 19.6–32.1] with moderate negative Eu anomalies (Eu/Eu* = 0.42–0.58). These muscovite- and biotite-bearing granites have enriched whole-rock Nd and zircon Hf isotopic compositions (εNd(t) = −12.1 to −7.6; εHf(t) = −11.4 to −0.8), and high zircon δ18O values (8.5‰–10.0‰). We suggest that the Baiyunshan granites were formed by partial melting of metasedimentary rocks, as they contain primary muscovite and have high zircon δ18O values. The Maofengshan granites were formed by partial melting of a hybridized crustal source containing metasedimentary rocks with subordinate amphibolites, as they have high zircon δ18O values, variable whole-rock SiO2 contents, and biotite compositions similar to those crystallized in I- and S-type magmas. These granites, along with the widespread early Paleozoic S-type granites in the Wuyi–Yunkai orogen, are distributed across a broad area rather than in a narrow belt. In addition, early Paleozoic S-type granites in the South China Block generally do not show younging trends from east to west or south to north. Moreover, the Baiyunshan–Maofengshan granites show geochemical characteristics similar to syn- or post-collisional granites and different from volcanic arc granites. We therefore propose that these muscovite- and biotite-bearing granites were formed in an intracontinental orogenic setting.

Tebeigai Soil Conditioner Can Increase Eggplant Yield, Reduce Heavy Metal Content and Improve Soil Acidification

The acidification of farmland soil in the red soil region of South China has led to the decrease of agricultural products, quality and soil degradation, which is in urgent need of improvement. In this paper, a field trial was implemented to study the effect of applying different amount of Tebeigai soil conditioner (namely 750, 1125, 1500, 1875 and 2250 kg/ha) on eggplant’s yield, heavy metal content and basic physical and chemical properties of soil in red soil area. The results showed that: compared with the control treatment, the application of different doses of Tebeigai soil conditioner could increase eggplant yield by 15.5%~55.8%; reduce As content of eggplant fruit by 12.8%~51.8%, Cr content by 33.7%~57.1%, Pb content by 1.9%~19.2%, Cd content by 14.3%~30.4%; at the same time, the soil pH increased by 5.8%~18.6%, exchangeable acid (potential acid) decreased by 37.6%~82.3%; and the contents of available Pb, Cd and Cr were decreased by 7.0% ~ 21.6%, 15.1% ~ 29.6% and 1.0% ~ 21.4%, respectively.