Impact of typhoon events on microplastic distribution in offshore sediments in Leizhou Peninsula of the South China Sea.

Microplastic is an emerging pollutant and a technical fossil in Anthropocene sediments. Typhoon frequency and intensity have increased due to climate change, which has a major effect on the distribution patterns of microplastics. It is still unknown, though, how the topography of the peninsula affects the reconstruction of the distribution of microplastic in typhoons. Due to frequent typhoons, the Leizhou Peninsula (LZP) in the north part of the South China Sea is an ideal place to study the impact of topographic variations on microplastic distribution during typhoon events. This study investigated microplastics ranging in size from 50 µm to 5 mm in sediment. Microscopic inspection and µ-FTIR tests were used to identify microplastic characteristics from offshore surface sediments before and after typhoons. The average microplastic abundance in offshore sediments decreased from 18 ± 17 items/kg to 15 ± 15 items/kg after typhoons. Results show that typhoons only increase the microplastic abundance in topographically protected areas along the northeast coast of LZP, with no significant difference observed in other regions. The influence of typhoon on the morphological characteristics of microplastics in sediments is more pronounced and widespread, as evidenced by a shift in the predominant shape of microplastics from fibers to fragments and a decrease in size accompanied by an increased abundance within the 100 µm-1 mm fraction. The color of microplastics remained similar before and after typhoons, and the polymer composition of microplastics became more uniform. The alteration of microplastic morphology may be attributed to the enhancement of wave intensity induced by typhoons. This study enhances the comprehension of typhoon-induced impacts on pollutant redistribution, specifically microplastics, thereby providing essential empirical evidence and theoretical foundations for pollution regulation.

Human dispersals out of Africa via the Levant.

Homo sapiens dispersed from Africa into Eurasia multiple times in the Middle and Late Pleistocene. The route, across northeastern Africa into the Levant, is a viable terrestrial corridor, as the present harsh southern Levant would probably have been savannahs and grasslands during the last interglaciation. Here, we document wetland sediments with luminescence ages falling in the last interglaciation in the southern Levant, showing protracted phases of moisture availability. Wetland sediments in Wadi Gharandal containing Levallois artifacts yielded an age of 84 ka. Our findings support the growing consensus for a well-watered Jordan Rift Valley that funneled migrants into western Asia and northern Arabia.

Impact of microplastic pollution on coastal ecosystems using comprehensive beach quality indices.

Previous studies of Microplastics (Mps) pollution focused on abundance, effect on organisms, and origins. Mps could also be indicators to evaluate pollution level. Beach Quality Indices (BQIs) are useful in understanding Mps pollution level. This study is to assess magnitude, impact and quality of beaches using BQIs, by determining abundance, shape, and size of Mps in beach sediments, which is the first effort in China. Three BQIs, i.e. Microplastic Pollution Index (MPPI), Environmental Status Index (ESI), Coefficient of Microplastic Impact (CMPI), were employed involving Sector Analysis Approach. All beaches had "very high" abundance by MPPI, were classified "bad" by ESI, and fell in "red" sector using Sector Analysis Approach by intergradation of MPPI and ESI. The impact of fiber morphology was "extreme" based on CMPI. The average abundance was 664±80 Mps/kg. Fibers occupied >97 % of Mps, with 31 % of black Mps. A model was proposed to determine Mps origins.

Spatio-temporal variations of litter on Qingdao tourist beaches in China.

Beaches are an integral part of coastal tourism, but they are deteriorated by the beachgoers and recreational activities due to lack of adequate beach environmental awareness and management. Litter is widely distributed in marine and coastal environment and has been considered a severe concern. In China investigations to determine the beach litter abundance and pollution level are limited. The aim of this study is to estimate spatio-temporal distribution and composition of litter on 10 well-known Qingdao tourist beaches, involving pollution level by beach quality indexes. Beach litter was collected within an area of 25 × 25 m2 in both summer (May, June and July) and winter (Nov, Dec and Jan) seasons, and was classified into eight categories. The abundance of beach litter was found higher in summer (0.13 ± 0.04 items/m2) than in winter (0.04 ± 0.01 items/m2). Overall, the percentage of plastics were higher in both summer (23.48%) and winter (24.04%) than that of other litter categories. Based on Clean Coast Index, 70% of beaches were very clean, 25% clean, and 5% moderately clean. Beach Grade Index showed that 15% beaches were very good, 5% good, 55% fair, and 25% poor. 85% beaches constituted some quantity of hazardous litter and 15% had no hazardous litter for Hazardous Items index. The findings suggest that the sources of beach litter along Qingdao beaches mainly come from the recreational and tourist activities. The substantial quantity of litter is also being transported by ocean (tides or current), which are finally deposited along beachfront. Despite regular cleaning operation along most of Qingdao beaches, suggested management practices involve mitigation measures, source reduction, change in littering behavior to improve further quality of beaches.

Microplastic abundance and distribution in a Central Asian desert.

Microplastic pollution is widespread, affecting even the remotest places on Earth. However, observational data on microplastic deposition in deserts, which comprise 21% of the total land area, are relatively rare. The current study aims to address the knowledge gap in terms of microplastic distribution in Asian deserts. The Badain Jaran Desert in Central Asia is the second largest desert in China. We investigated microplastic distribution and deposition on dunes and lakes of this desert. Microplastics were extracted from surface sediments to determine their characteristics and polymer types by microscopic inspection and µ-FTIR. The abundance of microplastics (detection limit is approximately 40 µm) in the uninhabited area ranged from 0.7 ± 1.5 to 11.7 ± 15.5 items/kg, with an average of 6.0 ± 15.4 items/kg. Fragments and fibers accounted for 77% and 23% of the total microplastics, respectively. Epoxy resin (28%), polyethylene terephthalate (25%), phenoxy resin (25%), and polyamide (9%) were the main polymer components, whose sizes were concentrated at 50-200 µm. Back-trajectory modeling was then performed to explore the possible source direction of the microplastics. The results showed that the microplastics mainly originated from the populated areas southeast of the desert, indicating long-distance atmospheric transport and deposition in deserts. The desert-edge zone with some tourism activity contained more microplastics (8.2 ± 17.9 items/kg) than the non-tourism zone (0.9 ± 1.6 items/kg), indicating a potential contribution from tourism. The abundance in the non-tourism zone (0.9 items/kg) can be used as a reference for microplastic background values in the Central Asian deserts, as this value is critical for simulating and predicting global microplastic yields.

Different triggers for the two pulses of mass extinction across the Permian and Triassic boundary.

Widespread ocean anoxia has been proposed to cause biotic mass extinction across the Permian-Triassic (P-Tr) boundary. However, its temporal dynamics during this crisis period are unclear. The Liangfengya section in the South China Block contains continuous marine sedimentary and fossil records. Two pulses of biotic extinction and two mass extinction horizons (MEH 1 & 2) near the P-Tr boundary were identified and defined based on lithology and fossils from the section. The data showed that the two pulses of extinction have different environmental triggers. The first pulse occurred during the latest Permian, characterized by disappearance of algae, large foraminifers, and fusulinids. Approaching the MEH 1, multiple layers of volcanic clay and yellowish micritic limestone occurred, suggesting intense volcanic eruptions and terrigenous influx. The second pulse occurred in the earliest Triassic, characterized by opportunist-dominated communities of low diversity and high abundance, and resulted in a structural marine ecosystem change. The oxygen deficiency inferred by pyrite framboid data is associated with biotic declines above the MEH 2, suggesting that the anoxia plays an important role.

26Al/10Be Burial Dating of the Middle Pleistocene Yiyuan Hominin Fossil Site, Shandong Province, Northern China.

The Yiyuan hominin fossil site is one of the few localities in China where a partial skullcap and several loose teeth of Homo erectus have been discovered. Yiyuan was previously assigned broadly to the Middle Pleistocene by biostratigraphical correlation and ESR/U-series dating. Here, we report the first application of a radio-isotopic dating method to the site. 26Al/10Be burial dating results derived from two sand samples from the fossiliferous deposits show that the hominin fossils can be confidently dated to 0.64 ± 0.08 Ma (million years ago). The reliability of this age is supported by the zero age of modern fluvial sediment near the cave. Our result is consistent with the age estimation based on biostratigraphic correlation and supports the argument that the Yiyuan and Zhoukoudian Locality 1 H. erectus fossils are contemporaneous. The results presented here, along with other recent chronological studies on Chinese Middle Pleistocene hominin sites, indicate that the time span from 600-400 ka (thousand years ago) is a critical period for human evolution in East Asia. Importantly, this time bracket includes several major climatic changes that would have influenced hominins, both morphologically and behaviorally.

The Kobresia pygmaea ecosystem of the Tibetan highlands - Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet.

With 450,000 km2Kobresia (syn. Carex) pygmaea dominated pastures in the eastern Tibetan highlands are the world's largest pastoral alpine ecosystem forming a durable turf cover at 3000-6000 m a.s.l. Kobresia's resilience and competitiveness is based on dwarf habit, predominantly below-ground allocation of photo assimilates, mixture of seed production and clonal growth, and high genetic diversity. Kobresia growth is co-limited by livestock-mediated nutrient withdrawal and, in the drier parts of the plateau, low rainfall during the short and cold growing season. Overstocking has caused pasture degradation and soil deterioration over most parts of the Tibetan highlands and is the basis for this man-made ecosystem. Natural autocyclic processes of turf destruction and soil erosion are initiated through polygonal turf cover cracking, and accelerated by soil-dwelling endemic small mammals in the absence of predators. The major consequences of vegetation cover deterioration include the release of large amounts of C, earlier diurnal formation of clouds, and decreased surface temperatures. These effects decrease the recovery potential of Kobresia pastures and make them more vulnerable to anthropogenic pressure and climate change. Traditional migratory rangeland management was sustainable over millennia, and possibly still offers the best strategy to conserve and possibly increase C stocks in the Kobresia turf.

Association analysis between spatiotemporal variation of vegetation greenness and precipitation/temperature in the Yangtze River Basin (China).

The variation in vegetation greenness provides good understanding of the sustainable management and monitoring of land surface ecosystems. The present paper discusses the spatial-temporal changes in vegetation and controlling factors in the Yangtze River Basin (YRB) using Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) for the period 2001-2013. Theil-Sen Median trend analysis, Pearson correlation coefficients, and residual analysis have been used, which shows decreasing trend of the annual mean NDVI over the whole YRB. Spatially, the regions with significant decreasing trends were mainly located in parts of central YRB, and pronounced increasing trends were observed in parts of the eastern and western YRB. The mean NDVI during spring and summer seasons increased, while it decreased during autumn and winter seasons. The seasonal mean NDVI shows spatial heterogeneity due to the vegetation types. The correlation analysis shows a positive relation between NDVI and temperature over most of the YRB, whereas NDVI and precipitation show a negative correlation. The residual analysis shows an increase in NDVI in parts of eastern and western YRB and the decrease in NDVI in the small part of Yangtze River Delta (YRD) and the mid-western YRB due to human activities. In general, climate factors were the principal drivers of NDVI variation in YRB in recent years.

Rapid and cyclic dust accumulation during MIS 2 in Central Asia inferred from loess OSL dating and grain-size analysis.

Due to lack of reliable proxies from the Westerlies-dominant region, the strength change of Northern Hemisphere Westerlies remains poorly understood. The aim of this study is to provide a reliable paleoclimatic proxy about the Northern Hemisphere Westerlies change. Here we report a 30.7 m thick loess section from the Ili basin directly controlled by the Westerlies. Based on optically stimulated luminescence (OSL) and high resolution grain-size records, we reconstruct the change history of the Westerlies strength during the last glacial period (mainly Marine Isotope Stages 2, MIS2), being similar with the Westerlies index recorded in the Qinghai Lake sediments. Within error limits, all ages are in stratigraphic order. We further compare the climatic records among the Ili loess, Qinghai Lake and the NGRIP, their similarity shows a good climatic coupling relationship among the Central Asia, East Asia and the North Atlantic, and the Westerlies plays a critical influence in transporting the North Atlantic signal to Central and East Asia.

amoA-encoding archaea and thaumarchaeol in the lakes on the northeastern Qinghai-Tibetan Plateau, China.

All known ammonia-oxidizing archaea (AOA) belong to the phylum Thaumarchaeota within the domain Archaea. AOA possess the diagnostic amoA gene (encoding the alpha subunit of ammonia monooxygenase) and produce lipid biomarker thaumarchaeol. Although the abundance and diversity of amoA gene-encoding archaea (AEA) in freshwater lakes have been well-studied, little is known about AEA ecology in saline/hypersaline lakes. In this study, the distribution of the archaeal amoA gene and thaumarchaeol were investigated in nine Qinghai-Tibetan lakes with a salinity range from freshwater to salt-saturation (salinity: 325 g L(-) (1)). The results showed that the archaeal amoA gene was present in hypersaline lakes with salinity up to 160 g L(-) (1). The archaeal amoA gene diversity in Tibetan lakes was different from those in other lakes worldwide, suggesting Tibetan lakes (high elevation, strong ultraviolet, and dry climate) may host a unique AEA population of different evolutionary origin from those in other lakes. Thaumarchaeol was present in all of the studied hypersaline lakes, even in those where no AEA amoA gene was observed. Future research is needed to determine the ecological function of AEA and possible sources of thaumarchaeol in the Qinghai-Tibetan hypersaline lakes.

High-resolution summer precipitation variations in the western Chinese Loess Plateau during the last glacial.

We present a summer precipitation reconstruction for the last glacial (LG) on the western edge of the Chinese Loess Plateau (CLP) using a well-dated organic carbon isotopic dataset together with an independent modern process study results. Our results demonstrate that summer precipitation variations in the CLP during the LG were broadly correlated to the intensity of the Asian summer monsoon (ASM) as recorded by stalagmite oxygen isotopes from southern China. During the last deglaciation, the onset of the increase in temperatures at high latitudes in the Northern Hemisphere and decline in the intensity of the East Asia winter monsoon in mid latitudes was earlier than the increase in ASM intensity and our reconstructed summer precipitation in the western CLP. Quantitative reconstruction of a single paleoclimatic factor provides new insights and opportunities for further understanding of the paleoclimatic variations in monsoonal East Asia and their relation to the global climatic system.