Holocene Environmental Changes Inferred From an Aeolian-Palaeosol-Lacustrine Profile in the Mu Us Desert, Northern China

Abstract

An excavated profile of aeolian-palaeosol-lacustrine sediments (the Wapianliang profile), located at the southeastern part of the Mu Us Desert, Northern China, was studied to reconstruct regional Holocene environmental changes. A chronology was established based on three AMS 14C and two OSL dates, and variations in the lithology and grain size, magnetic susceptibility, soil micromorphology, and chemical elements were used to explore the regional depositional environments during the Holocene. The results showed that since around 14 ka BP, this region had experienced seven alternations of wetting and drying. A shallow lake, which was identified by celadon lacustrine sediments with sporadic freshwater gastropod fossils, occurred in this area from around 13.0 ka BP to 9.9 ka BP. There existed two obvious intervals of soil formation, inferred from the environmental proxies of the palaeosol/sandy palaeosol layers, with relatively fine average grain-size, high magnetic susceptibility value, remarkable pedogenesis features, and strong chemical weathering, in particular, a well-developed palaeosol layer dating from the middle Holocene (8.6 ka BP to 4.2 ka BP). A weakly-developed palaeosol layer (from around 1.2 ka BP) at the upper part of the profile is possibly an indication of the Medieval Warm Period. This implies a forest steppe environment at both of these sedimentary stages. After 0.9 ka BP, a desert environment returned, analogous to before around 13.0 ± 1.4 ka BP, between 9.9 ± 1.1 ka BP to 8.6 ka BP, and between 4.2 ka BP to 1.6 ka BP, indicating the aggravation of aeolian activity and the expansion of mobile sand dunes. The variations in sedimentary environments were mainly triggered by changes in the East Asian Summer Monsoon (EASM).

Anthropogenic Influences on Soil Erosion since the Late Holocene and Contrasting Regional Sustainability in China

“…These observations suggest that climate alone was not adequate as the driving force of sediment dynamics and soil erosion. Previous studies demonstrated a similar monsoon-dominated variation pattern of the Holocene climate [53][54][55][56][57][58][59][60][61] and a similar magnetic enhancement model for typical loess across the CLP [48,50,54]. Based on the aforementioned fluctuations in and weakening relation between the proxies, an age frame for the Sanmenxia section is attained by interpolation with the ages of 12.9 ka, 11.7 ka, 8.2 ka, 7.8 ka, 5.9 ka, and 4.2 ka being assigned to the depth at 5.7 m, 4.25 m, 3.2 m, 2.98 m, 2.5 m, and 1.62 m, respectively (Figure 10).…”

Mineralization mechanism of organic carbon in maize rhizosphere soil of soft rock and sand mixed soil under different fertilization modes

“…In this regard, organic fertilizers play a pivotal role by enhancing soil microbial activity within the maize rhizosphere. This heightened microbial activity, as evidenced by prior research, leads to the acceleration of the decomposition and mineralization of organic matter ( Liu et al., 2021 ). The CF, DF, and MF treatments produced significant alterations in the bacterial community structure, with the CF treatment exhibiting a community structure similar to that of the CK treatment ( Figure 6 ).…”

“…Maize ( Zea mays L. ) has traditionally been cultivated in Mu Us Sandy Land. Nevertheless, in recent years, the introduction of land consolidation technology has enabled the expansion of maize cultivation from the southern desert periphery into the inland areas, leading to a transition from scattered to large-scale farming ( Liu et al., 2021 ). Unfortunately, the establishment of extensive maize cultivation areas often involves the flattening of undulating sand dunes and the mixing of sand with other soil types.…”

A prolonged dry Mid-Holocene recorded by Moon Lake in the Tengger Desert, arid and semiarid China

“…Therefore, the grain-size component is assumed to reflect fluctuations in the lake level. The aeolian sand component (38-418 μm) is transported by saltation or rolling when strong surface wind occurs (e.g., Qiang et al, 2010;Dietze et al, 2014;Mou et al, 2018;Liu et al, 2021). Moreover, this transport of aeolian sand on frozen lakes is associated with strong winds that particularly occur during winter and early spring storms (Sun et al, 2002).…”

“…Most studies suggest that the warm and wet Mid-Holocene was widely recorded in the arid and semiarid areas of China (e.g. Feng et al, 2006; Liu et al, 2018; Feng and Yang, 2019; Wang et al, 2019; Gao et al, 2020; Liu et al, 2021; Ning et al, 2021; Peng et al, 2022; Chen et al, 2023). However, some studies suggest that a dry Mid-Holocene climate has been found in desert regions of arid and semiarid China (such as the Tengger Desert, the Hobq Desert, and the Taklimakan Desert) (see An et al 2006 and references therein).…”