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Ancient cities are excellent spatiotemporal indicators for the study of historical human activities and environmental change. The ancient city of Sanchahe is located at the southern margin of the Mu Us Desert, China. It is an ideal location for studying the complex relationships between historical desertification and human activities. Field observations of the ancient city walls, a well, and a spring, as well as 14C dating, grain size, spatial analysis of archaeological sites, and analyses of historical seismicity, indicated that neotectonics may have contributed to crustal uplift and accelerated fluvial incision of the Wuding River. This rapid incision caused a decline in groundwater levels, which is an important reason for the irreversible environmental degradation around Sanchahe city over the past 800 yr. This study provides new evidence for such environmental degradation and may contribute to a better understanding of historical desertification in the Mu Us Desert. [ABSTRACT FROM AUTHOR]

• Three ostracod species were identified and related ecological information are reported in the Badain Jaran Desert. • The node formation of Limnocythere inopinata is affected by a combination of the salinity and Ca2+ content of lake water. • The relationship between the percentage of noded individuals and salinity of lake water is complex. Limnocythere inopinata (Baird, 1843) is a widely distributed ostracod in modern non-marine waters and Quaternary sediments. Based on its morphological variation (the number and position of its nodes), different phenotypes have been identified. However, the factors controlling its morphological variation are currently open to debate, which hinders palaeoecological reconstructions based on this species. In this study, ostracod distribution and hydrochemical analyses of the ambient environment of 21 lakes in the Badain Jaran Desert were carried out. Three ostracod species belonging to two genera are identified as Limnocyhtere inopinata , Cypris cf. granulate and Cypris sp. with the dominant species L. inopinata represented by six phenotypes. The distribution features of these ostracods in the lakes and related ecological information are reported. In addition, the factors controlling the morphological variations of L. inopinata were analysed. Our data indicate that the noded individuals of L. inopinata prefer water with appropriate Ca2+ content (30–40 mg L−1) and low salinities (below 4.60 g L−1). The percentage of noded individuals of L. inopinata increases with increasing salinity only within a certain salinity range. Hence, caution should be exercised in reconstructions of palaeosalinity based on the morphological variability of L. inopinata. [ABSTRACT FROM AUTHOR]

The northeastern part of the Tengger Desert accommodates several lakes. The effect of these lakes on local temperatures is unclear. In this study, the effects of the lakes were investigated using land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) data from 2003 to 2018 and air temperatures from meteorological stations in 2017. LST and air temperatures are compared between the lake-group region and an area without lakes to the north using statistical methods. Our results show that the lake-group region is found to exhibit a warm island effect in winter on an annual scale and at night on a daily scale. The warm island effect is caused by the differing properties of the land and other surfaces. Groundwater may also be an important heat source. The results of this study will help in understanding the causative factors of warm island effects and other properties of lakes. [ABSTRACT FROM AUTHOR]

The relationship between the variation of CO 2 flux and the pH of inorganic factors. [Display omitted] • The difference of CO 2 absorption and release is obvious during the day and night. • Yindeer Lake was a net sink of CO 2 during the study period. • The lakes can absorb large amounts of CO 2 every year to slow down global warming. • Meteorological factors controlling CO 2 fluxes differed by time scale. • pH is the main influencing factor controlling CO 2 absorption and release. Carbon sequestration levels in lakes are often underestimated despite being vital for the comprehensive analysis of CO 2 budget and significantly influencing inland lakes in arid areas. In this study, the eddy covariance (EC) technique was used to measure CO 2 flux for six consecutive years during 2012–2017 in a small salt-lake (Yindeer Lake) replenished by groundwater in southeastern Badain Jaran Desert, China. The results indicate that: (1) Yindeer Lake was a net sink of CO 2 , which led to the estimate that the lakes in the Badain Jaran Desert can absorb approximately 1.91 × 103 t of CO 2 per year and help slow down the rate of global warming. (2) The effects of meteorological factors on the CO 2 flux of the lake vary with timescales. (3) Inorganic processes, in which pH is the main influence mechanism, control CO 2 absorption and releases in Yindeer Lake. Thus, the study results provide a new guide for solving the "missing sink" problem. [ABSTRACT FROM AUTHOR]

The distinct effects of the lakes on the maximum and minimum temperatures cause a large discrepancy in diurnal temperature differences between the dry basin and lake basins. Discussion The above findings demonstrate that daily average temperature and the monthly minimum temperature inside the lake basins are warmer than those in the dry basin, particularly during the cold season. This suggests that, once the lake area reaches 1.91km SP 2 sp , the temperature difference between the lake basin and the dry basin (warm island intensity) becomes significant, but only in winter. Figure 4(a) shows that, the daily maximum temperature is lower in the lake basins than in the dry basin but differences between lake basins and the dry basin are not significant. [Extracted from the article]

The spatio-temporal characteristics and driving mechanisms of the Asian summer monsoon (ASM) during the early and middle Holocene remain unclear. Moreover, the timing of maximum monsoon precipitation in the Asian monsoon margin of northwest China during this period is also a subject of considerable debate. Herein, we analyzed phytolith assemblages within 55 calcareous root tube (CRT) samples from the hinterland of the Tengger Desert to quantitatively reconstruct Holocene millennial-scale precipitation changes and discuss the potential forcing mechanisms. Our results revealed that the mean annual precipitation (MAP) was 138 ± 53 to 149 ± 18 mm during 10.0–7.0 cal kyr BP, 179 ± 26 to 192 ± 26 mm during 7.0–5.0 cal kyr BP, and 129 ± 20 to 161 ± 13 mm during 5.0–1.0 cal kyr BP. The quantitative reconstruction results suggested that precipitation in this area was low in the early Holocene, then increased to a maximum in the middle Holocene (30% higher precipitation than present), and gradually decreased in the late Holocene. Maximum monsoon precipitation did not occur until the middle Holocene in this area because the northernmost margin of the ASM reached its northernmost latitude lagging behind its maximum monsoon intensity suppressed by high-northern latitude ice volume forcing during the early Holocene despite high summer insolation. In addition to quantifying the Holocene millennial-scale precipitation changes in the northwestern margin of the ASM, this study also provides new evidence for spatial and temporal variations of the ASM during the Holocene. [ABSTRACT FROM AUTHOR]