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Deserts and sandylands that are located in the semi-arid and arid regions in the middle latitudes of the Northern Hemisphere are usually regarded as environmentally sensitive change belts which respond to global climatic change. In northern China, activation or immobilization of sand dunes is mainly influenced by humid and dry variation and is related to stronger or weaker Asian monsoons. In this paper, the history of Holocene millennial-scale climatic and environmental change is reconstructed by the systematic analysis of the geochemical element contents and parameters, along with the OSL and C chronologies, from the different lithologies of the palaeosol-aeolian sand sequence in the south-eastern Mu Us Desert, northern China. Our results indicate that the region was dominated by a dry climate with intensive aeolian activity before 7.2 ka BP, and there was an optimal humid climate and fixed desert in 7.2-4.6 ka. Afterwards, the dune fields became mobile again as the effective humidity declined. Additionally, six dry events were discovered with times of ~7.2, 7.0-6.8, 6.6-5.7, 4.6-4.1, 3.7-3.5, and 3.3-2.5 ka, which were not only coincident with the intervals of millennial-scale weaker Asian summer monsoons, but also accordant with the cold events evidenced in the ice cores and deep-sea deposits of the high latitudes in the Northern Hemisphere. In general, the Holocene climatic and environmental changes had the characteristics of the 'monsoonal mode' and 'abrupt millennial-scale oscillation' in the Mu Us Desert. [ABSTRACT FROM AUTHOR]

Accurate assessment of soil C storage patterns and control factors on a regional and global scale is essential for predicting and mitigating soil C feedback to global environmental change. We used soil samples collected in the Shiyang River Basin in 2018, combined with remote sensing data, climate and meteorological data, watershed hydrological data, and soil physical and chemical properties to discuss the change characteristics and influencing factors of soil organic carbon (SOC) under different soil depths in the Shiyang River Basin in an arid area and analyze the storage model and carbon sequestration potential of soil organic carbon in different geomorphic units. The research results show that, (1) in spatial distribution, the SOC content in the Shiyang River Basin shows an obvious regional difference, and the average content of SOC in the oasis area in the middle reaches significantly higher than that in the mountain area in the upstream and desert area in the downstream. In vertical distribution, the content of SOC in the whole watershed decreases with the soil depth increase. (2) Soil carbon sequestration potential decreased with the increase in soil depth, but there were regional differences. The Oasis area in the middle reaches of the Shiyang River Basin is a high-potential area. In contrast, most of the upper mountain areas and the lower reaches of the desert area are low-potential areas. Environmental factors such as vegetation cover, meteorological factors, and physical and chemical properties of soil are important factors that promote the spatial variability of SOC content. The decisive effect of environmental factors on the SOC content is most significant in the surface layer 0–20 cm. [ABSTRACT FROM AUTHOR]

Global change caused by increasing greenhouse gas (GHG) emission has become a common concern of the international community. As the largest emitter of GHGs and the second largest irrigator in the world, a clear understanding of how much GHG is emitted from irrigation in China is of great importance. But no previous studies address this question. So based on Chinese official statistical data, this study estimates GHG emissions from agricultural irrigation in order to inform strategies for reasonable use of water resources and emission reduction. The study finds that in 2010 the total carbon dioxide (CO) equivalent (CO-e) emission from agricultural irrigation is 36.72~54.16 Mt. Emissions from energy activities in irrigation (including water pumping and conveyance) account for 50 % ~ 70 % of total emissions from energy activities in the agriculture sector. Ground water pumping is the biggest emission source, accounting for 60.97 % of total irrigation emissions. Given the extent of global ground water over exploitation, balancing conservation and exploitation of ground water resources is very important to both emission reduction and sustainable development. The GHG emission intensity of irrigation depends largely on water use efficiency, so improvement of water use efficiency (both technical and managerial) can be an effective way to reduce emissions. Enhanced overall management of water utilization, balanced exploitation of water resources to avoid excessive ground water consumption, and active promotion of water use efficiency can contribute to reducing GHG emissions and pressure on water resources and advance sustainable agricultural production. [ABSTRACT FROM AUTHOR]

The bacteria inhabiting brackish lake environments in arid or semi-arid regions have not been thoroughly identified. In this study, the 454 pyrosequencing method was used to study the sedimentary bacterial community composition (BCC) and diversity in Lake Bosten, which is located in the arid regions of northwestern China. A total of 210,233 high-quality sequence reads and 8,427 operational taxonomic units (OTUs) were successfully obtained from 20 selected sediment samples. The samples were quantitatively dominated by members of Proteobacteria (34.1% ± 11.0%), Firmicutes (21.8% ± 21.9%) and Chloroflexi (13.8% ± 5.2%), which accounted for more than 69% of the bacterial sequences. The results showed that (i) Lake Bosten had significant spatial heterogeneity, and TOC(total organic carbon), TN(total nitrogen) and TP(total phosphorus) were the most important contributors to bacterial diversity; (ii) there was lower taxonomic richness in Lake Bosten, which is located in an arid region, than in reference lakes in eutrophic floodplains and marine systems; and (iii) there was a low percentage of dominant species in the BCC and a high percentage of unidentified bacteria. Our data help to better describe the diversity and distribution of bacterial communities in contaminated brackish lakes in arid regions and how microbes respond to environmental changes in these stable inland waters in arid or semi-arid regions. [ABSTRACT FROM AUTHOR]

In this Perspective, we discuss whether in times of quickly proceeding global environmental change, radical global interventions like "climate engineering" may gain legitimacy in China and eventually be deployed or supported. We argue that one cornerstone for whether climate engineering, and solar radiation management in particular, could gain legitimacy in China, is its current weather modification programme. In China, weather modification is institutionalized and deployed on a large scale, and current narratives around the legitimacy to intervene into the local climate may provide a rationale for interventions such as solar radiation management. In the end, in the same way as Deng Xiaoping coined the phrase "stepping on stones to cross the river" in the era of China's Industrial Civilization, narrating China's "Ecological Civilization" may want to make use of "seeding the clouds to reach the sky". [See ESM for a summary of the article in Chinese.] [ABSTRACT FROM AUTHOR]

It is the first time to document the trilobite Mucronaspis (Songxites) wuningensis and the brachiopod Paromalomena-Aegiromenella Assemblage from the Xinkailing Bed (Hirnantian, uppermost Ordovician) in Taoyuan and Cili counties, northwestern Hunan Province. Synecological analysis shows that this is a deep water shelly fauna of South China during the Hirnantian. It lived on the upper Jiangnan Slope in northwestern Hunan, adjacent to the southeast margin of the Upper Yangtze Region, and belongs to the Hirnantia fauna with cool and deep water, and low diversity affinity, similar to its contemporary shelly faunas from the southern Shaanxi Slope adjacent to the north margin of the Upper Yangtze Region, the northern Chongqing depression (new name), and the Jiangxi-Anhui-Jiangsu gentle slope of the Lower Yangtze Region. Paleoecologically, it could be attributed to the BA 4-5 benthic regime (about 60-150 m deep, and deepest to 200 m), and was significantly different from the trilobite M. (S.) mucronata and the typical Hirnantia fauna while the latters may have habited in BA 2-3 benthic regimes (about 5-60 m deep). A new paleogeographic distribution pattern of the Hirnantian shallow and deep water shelly faunas of South China is herein proposed for the first time. Assuming that the depositional rate was constant in northwestern Hunan during the end Ordovician, the duration of the Xinkailing Bed might be only 12 thousand years according to the thickness of the Wufeng Formation and the absolute age values of those relevant graptolitic biozones. Such a short time interval may indicate that the global environmental change during the crisis was much shorter than previously thought, and its influence on the deep water regime was significantly shorter than that on the shallow water regime. [ABSTRACT FROM AUTHOR]

Lake Chenpu is located in the western part of Hetao Basin approaching the Ulan Buh Desert in the upper reaches of the Yellow River in northern China. An 84 cm sediment core was collected from the center of the lake. Geochronology radiometric method using Pb was subsequently used to date the short sediment core in the hope that it would reflect environmental changes over the past 150 years. Principal component analysis and the variation of the grain-size standard deviation were used to identify latent factors and extract environmentally sensitive grain-size components in sediment. Then a combination of sensitive grain-size parameters, magnetic susceptibility, total organic matter (TOC), and total nitrogen (TN) was used to reconstruct the recent lake environmental sequence. The result showed that the lake has seen increasing salinization and swampiness over the past 150 years. Further, sensitive grain-size parameters displayed several abrupt environment changes, i.e. 1850 AD, 1920 AD, and 1980 AD, which are supported by written records. In the 1850s, the yellow clay content increased dramatically, and that of silt declined. Magnetic susceptibility and C/N values increased significantly, as indicated by flood action. In the 1920s and the 1980s, dust-sand activity was recorded twice in the lake sediments with a markedly higher value of 16-32 μm and average grain size (C2). Grain size and other environmental proxies showed the period after the mid-1990s to be mainly dominated by wind-sand activity and anthropogenic impacts, which marked by obviously increasing grain-size coarse, carbonate content, TOC, and TN values. The results show that the lake sediments provide a dependable archive for studying the environmental history of the lake. [ABSTRACT FROM AUTHOR]

Using remote sensing images, we provided the first complete picture of freshwater bodies in mainland China. We mapped 89,700 reservoirs, covering about 26,870 km2 and approximately 185,000 lakes with a surface area of about 82,232 km2. Despite relatively small surface area, the total estimated storage capacity of reservoirs (794 km3) is triple that of lakes (268 km3). Further analysis indicates that reservoir construction has made the river systems strongly regulated: only 6% of the assessed river basins are free-flowing; 20% of assessed river basins have enough cumulative reservoir capacity to store more than the entire annual river flow. Despite the existence of 2,721 lakes greater than 1 km2, we found that about 50 lakes greater than km2 have formed on the Tibetan Plateau resulting from climate change. More than 350 lakes of ⩾1 km2 vanished in four other major lake regions. Although the disappearance of lakes happened in the context of global climate change, it principally reflects the severe anthropogenic impacts on natural lakes, such as, the excessive plundering of water resources on the Inner Mongolia-Xinjiang Plateau and serious destruction (land reclamation and urbanization) on the eastern plains. [ABSTRACT FROM AUTHOR]